We have delved into the material properties – such as the physical, machining, and mechanical properties, common materials used in CNC machining, the stages of the material selection process, and the basic and advanced factors to take into account when selecting materials. These key aspects will help you determine the optimal material for any specific process or function. Let’s get started.

Understanding Material Properties 

Material properties are fundamental considerations for engineers when designing products to function effectively. Material properties can be broadly grouped into physical, mechanical, and manufacturing/fabricating properties.

Physical Properties

Within the context of CNC machining material selection, thermal, chemical, optical, electrical, and magnetic properties, as well as density and resistance to corrosion and oxidation, are of particular interest. 

1. Density

The density of a material is calculated by dividing its mass by its volume. Engineers rely on this physical property as one of the many material selection factors during the design stage. For instance, they may select certain alloys, e.g., aluminum alloys, that have the same strength as, say, steel because the alloys are less dense and are, therefore, lighter.

2. Thermal Properties

Thermal properties include the following:

1. Melting point: The melting point (MP) affects the machinability, weldability, and castability of materials. A decrease in MP improves all these factors. This is because materials with a high MP will require more energy and advanced tools to weld or machine.
2. Thermal expansion: High thermal expansion increases the internal stresses and causes cracking. In ductile material, the differential expansion causes warping. Brittle materials, on the other hand, fracture when subjected to differential thermal expansion.
3. Thermal conductivity: The best materials for CNC machining should be capable of conducting the heat generated during the cutting process. Materials with low thermal conductivity experience high temperature differences. This gradient causes inhomogeneous deformation of the part and thermal failure of the cutting tool. 
4. Specific heat: Specific heat refers to the energy needed to increase the temperature of a unit mass of material by 1 degree Celsius or Kelvin. Machining material with a low specific heat will lead to a steep increase in their temperature, with the inverse holding true. The elevated temperature impacts the surface finish and accuracy of the machining process. It also increases tool wear and leads to negative metallurgical changes in the material due to alterations to its crystalline structure.

3. Electrical and Magnetic Properties

Electrical conductivity, which is the ability of metals to conduct electric current, is vital in machining processes like electrochemical machining (ECM) and electro-discharge machining (EDM). The workpiece must conduct an electric current for effective machining during ECM and EDM. Thus, alloys that are typically less conductive than pure metals may not be ideal materials in ECM and EDM.

When it comes to magnetic properties, some materials, such as pure nickel or certain iron-nickel alloys, experience magnetostriction. Materials that experience this phenomenon change their shape, by either expanding or contracting, when the magnetic field through them changes. Coincidentally, ultrasonic machining relies on the magnetostrictive effect, among other principles, to convert oscillating electric current to mechanical vibration. Thus, if you are machining material that will be used to make a transducer in an ultrasonically vibrating machine, consider using pure nickel or some iron-nickel alloys.

4. Optical Properties

Optical properties come into play during the surface finish stage. Very smooth finishes are extremely reflective, while rough surfaces reflect light randomly. Machinists control the machining and finishing processes to generate a desired optical property. However, some mechanical properties, like hardness, may make it harder to achieve certain finishes through polishing.

5. Chemical and Corrosion Properties

The chemical and corrosion resistance properties are important in material selection. This is especially so if the material and resultant parts are to be used in environments that require stable materials, e.g., in the petroleum, food, and chemical industries. Materials used in such environments should be resistant to chemical corrosion. Some corrosion-resistant materials include nickel, pure copper, tin, lead, titanium, plastics and composites, ceramic materials, metallic glasses, and tantalum. 

Mechanical Properties

The mechanical properties of materials affect their suitability for specific machining operations. This is because the deformation of the material is correlated to the applied load. This deformation may be low even when the load is exceptionally high and vice versa. The deformation may also be low even when the load applied is commensurately low or high when the applied load is high. This behavior depends on several mechanical properties: strength, stiffness, hardness, toughness, and ductility.

1. Strength

Strength refers to the ability of a material to resist externally exerted forces. A material with elevated strength will withstand a very high level of stress (force per unit area) before failure (i.e., fractures or permanent deformation). In contrast, a low-strength material requires very little force per unit area to fail. We, therefore, deduce that strength is a measure of a material’s resistance to stress. There are various types of strength:

• Creep strength
• Fatigue strength
• Yield strength
• Tensile and compressive strength    

2. Stiffness

Stiffness refers to a material’s ability to get back to its original shape or form after bending/deforming under load. This property mostly applies to cutting tools, which must be capable of resisting deformation during the cutting process. Thus, stiffness is a primary consideration when selecting materials to use when creating custom tools.

3. Hardness

Hardness refers to a material’s ability to resist localized plastic deformation. Coupled with tensile strength, hardness indicates that a metal is resistant to plastic deformation.

4. Toughness

Toughness refers to the energy needed to crack or break a material. It is an important mechanical property for parts that will suffer impact during day-to-day use.

5. Ductility and Brittleness

Ductility refers to the ability of a material to plastically deform or stretch thin when tensile forces are applied before failure. On the other hand, Brittleness is the opposite of ductility; it is the inability of a material to plastically deform when subjected to tensile stresses. A brittle material fails when subjected to tensile forces.

Machining Properties

General manufacturing properties include malleability, workability, weldability, formability, castability, ductility, machinability, heat-treatability, and grindability. However, within the context of CNC machining material selection, only three of these properties are needed: machinability, grindability, and heat-treatability.

1. Machinability

Machinability refers to the difficulty or ease of machining or fabricating a material. This machining property is affected by various factors, including the material’s thermal, physical, mechanical, and chemical properties, as well as the cutting speeds, feed rate, and properties of the cutting tool. For this reason, machinability is related to the entire machining system operating under a specific combination of conditions. 

In practice, machinists and engineers assess the machinability using various criteria, including: 

1. Tool wear rates or tool life: machinability increases with a decrease in tool wear rates (or, relatedly, an increase in tool life) with other cutting conditions held constant.
2. Chip form and burr behavior: This criterion is typically used to test the machinability of soft, ductile alloys. This is because such materials tend to form long, unbroken chips and, as a result, form burrs as the tool wears. Generally, materials that form long chips, which are harder to manage and flush out from the machining area, are said to be less machinable than those that form short chips. 
3. Surface finish: The machinability of a material degrades when the achievable surface roughness under a given set of cutting conditions increases. This means that the machinability increases with an improvement in the surface finish achievable, all other factors held constant. 
4. Tolerance: An increase in tolerance achievable under a specific set of cutting conditions is associated with a decrease in machinability, and vice versa. This criterion, like surface finish, is useful for assessing different classes of materials.
5. Surface integrity: Materials that can be easily damaged due to the formation of residual stresses or galling of sliding surfaces are said to be less machinable.
6. Cutting forces: Machinability increases as cutting forces decrease, and vice versa. And since cutting forces are directly correlated with power consumption, machinability similarly increases as power consumption decreases.
7. Cutting temperature: Increased cutting temperatures mean the material has low machinability; high temperatures are associated with elevated friction and high cutting forces.
8. Mechanical properties: Properties like hardness, ductility, and yield strength can also be linked to machinability. For instance, hard materials are less machinable, as are ductile materials that form long chips, as detailed earlier.

2. Grindability

As the name suggests, grindability is the general ease of grinding a material. It includes additional considerations such as the wear of the grinding wheel, surface integrity, surface finish/quality of the resulting surface, and more. Grindability determines the finishing process to be used. For instance, as stated below, grinding is not often the preferred finishing method when dealing with extremely hard materials. Machining processes like hard turning or hard boring are used in such cases. 

3. Heat treatability

Some materials, such as alloys, need to be heat-treated to achieve certain properties. Heat treatment processes are usually used alongside CNC machining processes to improve qualities such as machinability, hardness, or strength. Examples of heat treatment processes include quenching, case hardening, carburizing, precipitation hardening, annealing, tempering, and stress relieving. 

Common Materials Used in CNC Machining

The most common materials in CNC machining include:

• Metals
• Alloys
• Plastics 
• Composites
• Wood

1. Metals 

Metals have high thermal conductivity and reflectivity. These materials are also malleable (meaning they can be thinned when hammered), have high tensile strength, and are tough and stiff. They are also ductile, meaning they deform plastically before fracturing or breaking. The list of metals includes iron, nickel, titanium, zinc, tin, lead, tungsten, silver, platinum, chromium, manganese, and gold.

2. Alloys

Alloys are created by mixing two or more elements, with at least one element being a metal. Examples of alloys include steels (carbon steels, alloy steels, stainless steels, and cast iron), aluminum alloys, magnesium alloys, tin alloys, zinc alloys, lead alloys, nickel alloys, copper alloys, nickel-based alloys, and cobalt-based alloys, just to mention a few.

3. Ceramics

Ceramics are inorganic compounds usually made up of one or more metallic elements and a nonmetallic element. The nonmetallic element can be oxygen (as in the case of aluminum oxide, also known as alumina, zirconia, magnesia, thoria, and beryllia), nitrogen (as in silicon nitride), or carbon (as is the case with silicon carbide, tungsten carbide, and boron carbide). Other examples of ceramic materials include magnesia, tungsten carbide, and boron carbide. Ceramics are generally hard and stiff and are excellent insulators of electricity. However, they are extremely brittle.

4. Plastics and polymers

Polymers are organic materials that are highly resistant to most chemicals, are good electrical and thermal insulators, and have low density. Plastics, on the other hand, are created by mixing polymeric materials with certain additives. Plastics are generally hard to machine, but that does not mean they cannot be machined. They are often used to make prototypes.

5. Composites

Composites are typically made by modifying the chemistry of two or more materials. For instance, thin fibers of glass and carbon can be added into a polymer matrix, creating a composite that is stronger and stiffer than the original polymer. Composites have a high strength-to-weight ratio. Thanks to the inexpensive polymer matrix, they are also less expensive than metals with the same properties.

6. Wood

CNC routers work on wood and there are different types of wood from which to choose: softwood, hardwood, and composite or engineered wood. Like other materials on this list, there are several factors to consider when determining the type of wood to use. These factors include density, hardness, strength, machinability, stability, grain size and direction, moisture content, tooling, and surface finish. 

CNC Machining Material Selection Process

There are tens of thousands of useful metallic and nonmetallic engineering materials. This sheer number makes material selection an extremely taxing task. What’s more, engineers must also consider the machining process available to them during the CNC machining material selection process. This is because some machining processes are more suited for certain materials than others. 

For instance, the hard turning process replaces grinding operations in hard materials. This is because hard turning can achieve excellent surface finish, roundness, and tolerance. Similarly, you will be more productive using hard boring to increase the internal diameter of an existing hole in a workpiece made of hard material, like hardened still, than if you opt for internal grinding.

The CNC machining material selection process, therefore, needs to be rigorous. Only then can you be assured that you have selected the suitable material that can be machined using the tools and CNC machines in your machine shop. The preferred practice involves considering the materials and machining process in the early stages of the design and defining them as the design rolls through the various stages. 

Stages of CNC Machining Material Selection

There are five main stages in the CNC machining material selection process:

1. Assessment of the Requisite Material Performance
2. Listing of Alternatives
3. Initial Screening
4. Comparison of Shortlisted Alternative Materials
5. Selection of Optimum Materials 

1. Assessment of Material Performance Requirements

As detailed earlier, engineering materials have distinct properties that combine to influence their suitability during CNC machining material selection. But, in isolation, these properties serve little to no purpose if they do not align with the performance requirements of a part. For this reason, the first stage of the material selection process is the analysis of material performance requirements vis-à-vis the material properties and other parameters. 

In this stage, you should specify the material performance requirements, including:

• Reliability requirements
• Resistance to service conditions, e.g., corrosive environments and low or high temperatures
• Functional requirements
• Machinability requirements
• Cost of material and how it impacts the overall quality of the machining process

2. Listing Alternative Materials

Once you have laid out your material requirements, the next stage of the CNC material selection process involves searching for materials that best meet those outlined requirements. To begin your search, looking at the entire range of engineering materials, including metallic and nonmetallic materials, is always advisable. This is because a number of materials can fulfill the basic functional requirement of a particular design. 

This second stage aims to create a list of possible alternatives without caring much about their feasibility. Organizations such as ASM International have comprehensive guides to the performance, structure, properties, processing, and analysis of metallic and nonmetallic engineering materials. Such guides can serve as a great starting point.

3. Initial Screening

The third stage involves eliminating unsuitable materials to create a more manageable list. This stage leans on the practicality of using materials. To help you with the screening, you can use quantitative methods like Ashby’s, Dargie’s, Esawi and Ashby’s, and cost per unit property method. You can use one or more of these quantitative screening methods. 

In addition, at this stage, you should also assess the material performance requirements based on rigid and soft requirements. Rigid requirements relate to the requirements that the material must meet, while the soft requirements are those you can compromise on.

4. Comparison and Ranking of Shortlisted Alternative Materials

While the screening process does narrow the list of possible materials, you still have to shrink this list further to a handful of promising materials. Like in the third stage of the CNC machining material selection process, you can use several quantitative ranking methods. These methods help you compare and rank the various options. The quantitative ranking methods include the weighted property method, digital logic method, performance index, limits on property method, and the analytic hierarchy process.

5. Selection of Optimum Materials

The final step in the CNC machining material selection process is selecting the optimum materials. It logically follows that materials that, based on the ranking methods, have the best performance scores are selected. And given that the selection is concurrently done during the design stage, then it goes without saying that the engineer will naturally capitalize on the material’s favorable properties when coming up with the final design. 

(For a more detailed discussion of the quantitative screening methods and quantitative ranking methods, refer to the book “Materials and Process Selection for Engineering Design.”)

Factors Influencing Material Selection

There are several factors influencing CNC machining material selection, including the following:

1. Material Properties

The properties of a material and its ability to meet performance requirements are perhaps the foundational factors influencing material selection. You cannot, for instance, select a brittle material for an application that requires ductility. Similarly, it would be illogical to select a material that is least resistant to chemical elements if the resultant part is meant to be used in a corrosive environment. The material properties also influence an additional consideration: durability.

2. Fulfillment of Material Performance Requirements

The first stage of the CNC machining material selection process involves listing the possible materials you can use and specifying the material performance requirements. The subsequent steps involve narrowing down the list of materials based on their ability to meet the specified requirements. Thus, one of the aspects to consider when selecting a material for a particular function is whether it fulfills the outlined requirements.

3. Cost

Cost is another fundamental factor in evaluating materials. Parts have a cost limit; exceeding this makes them impractical to machine as they won’t be cost-effective for buyers. If this cost limit is exceeded, engineers may be forced to change the design to enable the use of cheaper material.

When it comes to analyzing costs, engineers can conduct what is known as value analysis. This technique allows engineers to assess the value of a material by referencing it to another material that could serve the same function. To illustrate, consider material A, the reference material, that costs a given sum of money, say X. 

Suppose you are considering five possible alternatives in your CNC machining material selection process. In that case, value analysis calls for you to check the materials that exceed cost X and those below this price point, provided they can serve the same function. In such a case, you can choose the least expensive material or the more expensive material that is cheaper or simpler to machine. 

4. Product Design 

A part that serves a particular function may see the designer/engineer explore various alternatives and design concepts. In such a scenario, material A, say steel, may be perfect for design concept A, while material B, say plastic, may be ideal for design concept B. This is despite the fact that both design concepts serve the same function.

5. Machining Process

Some machining processes are better suited than others to create certain features. Similarly, some processes require fewer steps to machine a particular feature, perhaps because they support more axes. In a way, the choice of the machining process directly affects the time taken and, by extension, the cost of the part.

6. Product Scalability

Do you wish to create thousands or millions of parts for the mass market? If so, you should consider cost-effective and readily available materials. You should also select materials that have consistent properties regardless of where they are sourced. This combination of characteristics enables you to easily scale without compromising performance or quality. 

Advanced Considerations in CNC Machining Material Selection

1. Regulatory Compliance

The food, petroleum, medical device, and chemical industries have stringent standards and regulations governing material use. These regulations are usually enforced by government departments. For example, the UK Health and Safety Executive provides guidelines for accounting for corrosion when selecting materials for constructing plants and equipment.

2. Environmental Considerations

The increasing awareness of the public and companies on their impact on the environment has made environmental considerations an influential factor in the CNC machining material selection process. The choice of material and the machining process impact the power consumption. 

Manufacturing companies aiming to reduce energy consumption and environmental impact may opt for materials and processes that use less energy. After all, studies have shown that energy consumption is directly related to carbon emissions over the long term: an increase in consumption could lead to a rise in carbon emissions and vice versa.

Conclusion

To master CNC machining material selection, you must first be conversant with materials used in CNC machining and their properties of materials. Some of these properties include density, hardness, stiffness, machinability, heat-treatability, corrosion resistance, thermal properties, and grindability, just to mention a few, as they influence the ease with which you can machine a product. 

Next, you must specify the performance requirements of the material as they relate to the part you want to make. You should then use these requirements to narrow down the list of materials. This means that while you will start the CNC machining material selection process with tens – or even hundreds – of materials, you will end up with just a handful. You can also use quantitative methods to narrow down the list further. The selection process should also consider several key factors. These include the cost, environmental requirements, regulatory compliance, product design, scalability, etc. We contend that the CNC machining material selection is not always straightforward. This comprehensive guide, nonetheless, makes the process clearer and easier to navigate.

This article explores the reasons for customizing CNC tools and accessories, their benefits and drawbacks, and key considerations when designing them for optimal performance. Read on to learn how to integrate your newly produced CNC custom tools into your CNC machining operations, too.

Reasons for Customizing CNC Custom Tools and Accessories

You can design and machine or order custom CNC tools for several reasons. These include:

1. Unavailability of a standard tool or accessory for the machining job at hand: Custom tools are optimized for specific machining operations and geometries. For instance, you might need a reamer with specific diameter and tolerance requirements that are not readily available.
2. To substitute multiple different cutting tools with one CNC custom tool
3. To enhance parameters such as the tool life, material removal rate (MRR), coolant delivery, and chip removal. Analysis has shown that customizing tooling to increase the tool life by 50% lowers the total cost per part by about 1-2%. Similarly, creating a CNC custom tool with a 20% higher MRR could reduce the total cost per part by 15%. It’s important to note that tools with higher MRR are generally more expensive to produce or purchase than those with lower MRR.
4. Mass production of unique parts: CNC custom tools offer an ideal solution when standard tools and workholders cannot be used for bulk machining. Custom CNC tools and accessories are common in the automobile industry, where manufacturers regularly design and manufacture new engines with unique parts from previous models. This uniqueness usually calls for the production of new workholders, such as the tombstone-type CNC fixture for machining engine heads (shown below). Because of the associated cost, CNC custom tools and accessories make financial sense in mass production.

Illustration of a Tombstone Workholder (source)

Role of CNC Custom Tools and Accessories in Enhancing CNC Efficiency

These reasons point to CNC custom tools enhancing CNC efficiency. For instance, tool changing cycle time as well as part-to-part and new setup turnaround time are known to impact efficiency in CNC machining operations. You could create a custom workholding and toolholding accessory that simplifies the mounting and dismounting of tools and workpieces.

In this scenario, you could substantially boost the efficiency by reducing the tool changing cycle time and part-to-part or new setup turnaround time. Similarly, creating a custom tool that performs tasks requiring multiple tools eliminates the need for tool changes, further boosting CNC efficiency.

Additionally, when you look at CNC custom tools and accessories through the lens of a manufacturing company that produces parts in bulk, it is easy to see how these tools and accessories boost efficiency. The enhanced CNC efficiency again lies in the fact that the CNC custom tools and accessories reduce the time it would otherwise take to machine parts. These time savings accumulate significantly during mass production, leading to cost reductions.

Custom Tools for CNC Machines

It’s important not to confuse cutting tools with machine tools. Machine tools are responsible for moving cutting tools along a path prescribed by the CNC program. Machine tools move simultaneously along multiple axes, enabling the repeatable production of complex parts with consistent quality. Some of the components of the machine tool structure include the spindle, axis drive, automatic tool change (ATC) system, coolant system, and pallets. Cutting tools, on the other hand, are responsible for removing material from the workpiece through various machining processes.

Classification of CNC Cutting Tools

CNC custom tools, as well as standard CNC tools, are broadly classified into two:

• Single-point tools: These tools have one active cutting edge. These tools are typically used for turning and boring.
• Multipoint/multifunctional/multitasking tools: These tools have multiple active cutting edges and are used for milling, special-purpose tooling, and drilling. A single multipoint tool can machine several features or create multi-step holes.

CNC tools can also be classified based on other criteria, including clamping method, geometry, and cutting-edge material.

Types of CNC Cutting Tools

There are numerous types of CNC cutting tools:

1. Turning Tools

Turning tools are either single-point cutting tools or tools with only one active cutting surface. They are used in lathes or machining centers. Turning tools include form tools, thread-turning tools, and grooving and cutoff tools. 

Form tools are fed perpendicular to the surface of the workpiece, cutting a particular profile on a rotating part or workpiece. The profiles can be conical, concave, convex, ball, or chamfered, depending on the shape of the tools. Form tools use a single plunge cut to make this cut. Grooving and cutoff tools use inserts that create grooves inside the workpieces such that the tools are surrounded on three sides by the workpiece. 

2. Drilling Tools 

Drilling tools, which are end-cutting tools, use their leading edge to remove material. The drilling tools also feature one or more helical or straight flutes (grooves that line the outer edge of the tool) to remove the cut material (chips) from the drilled hole.

3. Milling Tools

Milling tools have multiple cutting edges and remove material through rotary action. There are different types of milling cutters, namely face milling cutters, slot milling cutters, end milling cutters, and rotary milling cutters, each suited for a specific operation. For instance, face milling cutters create flat surfaces, while slot milling cutters are used for side and face milling, as well as slotting and grooving. Additionally, end milling cutters create two working surfaces simultaneously, with rotary milling cutters used to enhance productivity.

4. Boring Tools

Boring tools act on the internal surfaces of parts in turning or machining centers. They create and enlarge holes, improving the accuracy of the internal dimensions. Two types of boring tools exist: single-point boring tools and multipoint boring tools. Single-point boring tools are essentially long boring bars with small diameters and an insert mounted at a single point. For this reason, they have the least rigidity of all cutting tools. On the other hand, multipoint boring tools feature multiple inserts mounted on opposite sides or at different points along the longitudinal edge of the boring bar.

5. Deburring Tools

Deburring tools are designed to remove burrs. Burrs are unwanted material projections that occur after machining. The burrs are caused by plastic deformation during machining. There are various deburring methods, including abrasive-jet/water-jet deburring, barrel tumbling, centrifugal barrel tumbling, ultrasonic deburring, chemical deburring, electropolishing, sanding, brushing, ice-blasting, mechanical deburring, electrochemical deburring, and more. Tools for deburring holes can include chamfering tools that chamfer the exit or entrance of holes.

6. Reamers

Reamers are used to enlarge holes and improve their precision and finish. This means reamers are deployed after a drilling, boring, or milling operation. There are several types of reamers: adjustable/expansion reamers, single- and multi-diameter reamers, straight and tapered reamers, and single- and multi-flute reamers.

7. Threading Tools

As the name suggests, threading tools cut screw threads. There are various types of threading tools: cut taps, thread chasers, thread mills, roll form taps, thread turning inserts, and dies.

8. Grinding Wheels

Grinding wheels are made of abrasives bonded together using a bond material. In this case, the bond material acts as a toolholder (more on this below). Grinding wheels rotate against the surface of a part to remove material.

9. Microsizing Tools

Microsizing tools have a fixed diameter and operate using a single stroke. These microsizing tools are used to adjust the internal diameter, roundness, surface roughness, and positional tolerances of bores.

10. Honing Tools

Honing tools are made up of abrasive stones held in the tool body and expand repeatedly to exert pressure on the bore wall. These honing tools are passed through the bore in a multi-stroke movement. Like microsizing tools, honing tools are used to correct the internal diameter, roundness/shape, surface roughness, and positional tolerances of bores.

11. Burnishing Tools

There are two types of burnishing tools – ball and roller. These tools are rotated against a workpiece’s internal or external surfaces to improve their surface strength and surface finish.

Producing CNC Custom Tools

With CNC custom tools, you can design and machine them in-house if your workshop has the expertise and machines. Alternatively, you can hire specialists to create custom tools for you. A simple online search of companies that design and produce CNC custom tools presents numerous results for you to choose from. 

Custom Accessories for CNC Machines

Today, there are several service providers and precision instrument companies that let you order custom accessories. Such companies walk with you throughout the journey, consulting you as they develop designs that best suit your workholding and toolholding needs. If you possess the necessary skills, you can design and machine custom accessories yourself based on your prevailing requirements. 

Like standard CNC accessories, custom CNC accessories come in various designs, shapes, and sizes, but can be broadly categorized into four types: 

• Workholders/Fixtures
• Toolholders/adapters
• Toolholder accessories
• Measuring tools

Toolholders

Toolholders hold cutting tools in the machine spindle. Types of toolholders include: 

• Tool Chucks: These toolholders clamp tools with cylindrical cross sections. Examples of tool chucks include collet chucks (precision and standard), hydraulic chucks, shrink-fit chucks, drill chucks, milling chucks, Weldon-type chucks, and Clarkson-type chucks
• Arbors: arbors act as the interface between the cutting tool and the drive spindle of the CNC machine. They facilitate rapid tool changes and accurate machining.
• Adapters: adapters are designed to adapt the shank of a cutting tool with the machine taper (discussed below), enabling you to use a toolholder of a particular size in a machine with a larger spindle holder. Adapters can also be considered toolholder accessories if used to adapt the toolholder with the machine taper.
• Reduction sleeves: Reduced sleeves connect a larger toolholder to a smaller spindle holder. Essentially, they are the opposite of adapters.

Fixtures

Also known as fixtures, workholding devices or workholders are generally used to clamp, secure, locate, and support parts and workpieces. Fixtures that have a built-in feature for guiding/controlling the lateral movement of the tool are known as jogs. Workholders consist of several elements, including the supporting structure, clamps, and locators. These elements hold the workpiece in position, ensuring that the cutting and clamping forces do not affect the specified tolerances. Workholders can be broadly categorized into:

• General-purpose fixtures, which are designed to hold any workpiece regardless of geometry 
• Dedicated/custom fixtures, which are meant for specific machining operations or particular workpiece geometry

Under the two categories mentioned, we have the following types of workholders, including:

• Workpiece chucks, e.g., lathe chucks
• Standard clamps
• Vises
• Universal indexing heads
• Sine and angle plates
• Live and dead centers, which hold or support workpieces in lathe machines

This article will focus on custom fixtures, which are primarily used in unique production settings. For instance, if machining loads primarily come from one direction, a custom fixture can be designed to provide enhanced support in that direction. This also applies to situations where the part to be machined has a unique geometry that general-purpose fixtures cannot accommodate.

Dedicated fixtures are usually made from casting or tooling plates. However, they are usually more expensive, more complex, and often have longer construction lead times. For these reasons, dedicated fixtures are preferred in high-volume production as they more than pay for themselves. 

Tool and Toolholder Accessories

Tool and toolholder accessories are detachable components that, when attached to tools or toolholders, enhance

Examples of toolholder accessories include:

• Spacers
• Sleeves, sockets, and bushings
• Pull studs

Measuring Tools

There are various types of measuring tools, including dial gauges, testers (e.g., hardness testers), calipers, micrometers, and probing tools. While it may be illogical to customize standardized measuring tools like digital micrometers, dial gauges, and calipers, you can work with experts in precision measurement to order some custom measurement systems for CNC machine tools. 

For instance, you can work with Renishaw, which offers expert advice and design services for anyone looking for custom probes or tool-setting solutions. The company has a custom products team that designs and makes high-quality measuring tools at competitive prices and with fast delivery times. Additionally, Renishaw supports the installation process regardless of whether you are working with a new or old CNC machine. 

Benefits and Drawbacks of Custom Tools and Accessories

Benefits of Custom Tools and Accessories

The advantages of custom tools and accessories include:

1. Improved productivity because the custom tools are optimized for operations that other standard tools are not and, thus, improve the MRR, leading to faster machining operations
2. Reduces the setup and processing times, as the custom tools are designed to be easy to mount and dismount
3. Better machining performance because with custom tooling, you can select materials with the best mechanical, thermal, and chemical properties that have a high MRR and can support high cutting speeds without being susceptible to shocks or stresses

Disadvantages of Custom Tools and Accessories

The drawbacks of custom tools and accessories are:

1. Custom tools and accessories require a long lead time, as they need to be designed, prototyped, tested, and manufactured
2. They can be more costly per item than mass-produced tools and accessories, especially in cases where they are not manufactured
3. It can be difficult to find a supplier/company with the necessary expertise to design and produce a custom tool and accessory

Designing Custom Tools and Accessories

Design of Custom Tools

As with all other cutting tools, the design of custom cutting tools significantly impacts machining performance. Well-designed tools produce parts and features of consistent quality and have long, predictable useful lives. On the contrary, poorly designed tools may wear or chip easily, rapidly, and unpredictably. These tools often need frequent replacement, which increases costs. They also affect productivity and reduce the quality of parts. This means that tooling significantly impacts the productivity and economics of a machining operation.

Material for CNC Custom Tools

Another consideration you should make during the design phase is the choice of cutting-tool materials and their properties. Ideally, you should choose materials with the following characteristics:

1. Enhanced penetration hardness at high temperatures to resist abrasive wear
2. Elevated deformation resistance to avoid deformation or collapse of the edge under stresses caused by chip formation
3. High thermal conductivity to reduce the temperatures near the edge of the cutting tool
4. Low friction vis-à-vis the work material to prevent built-up edge (BUE)
5. High thermal shock resistance to prevent tool breakage when cutting is periodically stopped
6. Low chemical affinity to resist chemical wear
7. High fatigue resistance to enable continuous machining
8. Elevated stiffness to ensure continued accuracy and precision
9. High fracture toughness to prevent the edge from breaking or chipping

CNC custom tools can be made from materials such as carbides (e.g., tungsten carbide), polycrystalline materials (e.g., polycrystalline diamond and cubic boron nitride), ceramics, cermets (composites of metal and ceramic), steels, high-speed steels (HSS), and superabrasives. 

You can also consider coating the tools made using HSS, tungsten carbide, and ceramics to increase the allowable cutting speeds and enhance the tool life. Some of the conventional coating materials include aluminum oxide, titanium nitride, titanium carbide, boron carbide, hafnium nitride, chromium nitride, titanium diboride, titanium aluminum nitride, and titanium carbo-nitride.

Design of Custom Accessories

The design of custom accessories takes multiple factors and parameters into consideration. After all, these components are subjected to considerable amounts of forces, stresses, temperatures, and more that may affect performance. As shown in the image below, several factors can influence the design of a custom fixture.

Factors Affecting Design of Custom Fixtures

Similarly, custom toolholders and toolholder-spindle interfaces should be properly engineered to ensure high performance and throughput. After all, a particular toolholder and/or toolholder interface is only effective if used for the application it was initially designed. Put simply, all toolholders and/or toolholder interfaces are not to be universally deployed in all types of machining. They must first meet the performance requirements to be fit for purpose and for the best results.

Poorly engineered toolholder interfaces result in reduced accuracy, shorter tool life, diminished rigidity, and lower repeatability. This is because the toolholder may wear out at its interface with the spindle if it improperly fits the opening or is out of tolerance.

Thus, when designing a toolholder and the toolholder-spindle interface, you should consider structural and dynamic characteristics such as cost, chemical and thermal behavior and stability, maintenance requirements, ease of mounting and dismounting, manufacturing tolerances, radial and axial positioning accuracy and repeatability, force transmission capabilities (based on cutting forces and torque), and clamping forces. 

The other factors/characteristics you should consider are fatigue life and durability, momentum and torque characteristics, connection rigidity, sensitivity to corrosion and contamination, ability to transmit coolant, safety, retention force requirements, storage and handling cycles, time on the machine, tool weight and capacity, and much more. Additionally, you must decide whether the body of the toolholder should be one solid piece or a modular design that uses a mechanical connection.

Integration of Custom Tools into CNC Operations

Designing custom CNC tools is only the first step. You must undertake additional software-based steps to integrate them into a particular CNC operation. Normally, whenever you want to produce a part of an existing 3D model, you first have to import it into computer-aided machining (CAM) software. Besides importing, you have to provide information such as the machine, cutting tools, and machining parameters to be used. The CAM software then liaises with a software called a post-processor to produce machine-specific instructions.

The cutting tools are usually stored in a tool library. The tool library is a database of tools that can be updated by adding new tools or editing tool settings. So, if you want to use a new tool that is not among the options in the tool library, you must update the database. This process applies to custom tools as well. And many CAM software products do, in fact, let you add custom tools to the library. To add a CNC custom tool to the CAM software’s tool library, follow the following general steps:

1. Open the tool library
2. Click the “Add” button or “Plus”) icon
3. Enter the name of the custom tool
4. Select the type of custom tool
5. Input the custom tool’s dimensions, cutting speeds, and feeds
6. Save the tool information

Now that the custom tool is part of the tool library, you can generate the CNC program. It is worth noting that while creating this program, the post-processor considers the information you will have specified while adding your custom tool. As such, the program will be customized for your tool, preventing unforeseen issues like collisions or unsupported feed rates and cutting speeds that may lead to tool breakage.

Conclusion

CNC custom tools and accessories are quite common in the machining practice. They are preferred when standard tools for a particular job are inefficient or unavailable. Alternatively, they are chosen when you want to increase productivity or use tools that are optimized to enhance certain parameters. However, custom CNC tools are more expensive than standard tools. Their use, therefore, makes the most sense in mass manufacturing operations. When it comes to designing and producing custom tools and accessories, you can opt to do everything in-house or outsource that service to specialist companies. And once you have created the CNC custom tools and want to integrate them into your machining operations, you should remember to add them to your CAM software’s tool library.

If you are inclined to use the embedded simulation and verification feature that comes with a CAM system, it is always advisable to bear in mind that some CAM systems are less reliable and slower than others. Given the consequences of errors—such as tool breakage, material waste, machine downtime, labor costs, and even injury—choosing a better solution is essential. The better solution takes the form of CNC simulation software.

This article explores how CNC simulation software enhances the precision and accuracy of CNC machining. As we detail later, this software identifies errors in G-code (CNC programs) that may lead to collisions. They also create digital twins of CNC machines, displaying an interactive machining environment that improves visualization. You can use such an environment for virtual prove-outs, safeguarding your CNC machine, as well as for training employees. We also cover the top 5 CNC simulation software options, including their features, advantages, and disadvantages.

Understanding CNC Simulation Software

CNC simulation software is standalone software that creates digital twins of CNC machines and machine tools. The software uses provided data – such as the CNC program, material type and size, and custom tool specifications – to simulate the cutting process. The software uses the digital twin and the CNC positioning data in the NC program to realistically and accurately depict/simulate the actual machine behavior. 

This simulation captures machine kinematics, fixture and holder collisions, multiple setups and tool changes, precise multi-axis (3, 4, 5, or more axes) and rapid motion, complex tool shapes, and, depending on the software, complex controller functions. By visually depicting the machine behavior and machining process in a virtual environment, the CNC simulation software acts as a visual check.

In addition to simulating the real machining environment and process, the CNC simulation software verifies and optimizes the toolpath. The verification and optimization processes improve the machining process, save time, and reduce manufacturing costs. 

CNC Simulation Software vs. Internal CAM Software Simulation

CAM software does support CNC simulation. However, a study by MLC CAD Systems, a Cimco and Mastercam reseller, found that it is slower than dedicated CNC simulation software. The study established that Mastercam’s simulator tool took 15.22 minutes to complete a complex model simulation. In contrast, Cimco Edit took 4.9 minutes. The study confirms that dedicated CNC simulation software is faster than the built-in simulation feature in CAM software. 

CNC simulation software offers additional advantages:

1. Dedicated CNC simulation software frees up CAM software to carry out its primary functions, like generating toolpaths and creating CNC programs
2. CNC simulation software can verify toolpaths and CNC programs generated by any CAM software, providing flexibility and consistency, while CAM systems primarily verify toolpaths they have generated
3. Compared to CAM software, whose developers license simulation algorithms from third-party developers like ModuleWorks and integrate them into their products, CNC simulation software developers use their own simulation kernels and engines. These engines are built from the ground up with the user in mind or based on feedback from users and hence consider the needs of the market

For context, ModuleWorks is not your typical software; it is a software – or, more accurately, a set of algorithms – designed to be integrated into other software. You, therefore, cannot download and use it as you would conventional CNC simulation software. To use it and enjoy its advanced simulation capabilities, you must install software that has integrated the ModuleWorks simulation algorithms.

Software like Mastercam, PTC Creo, and Fusion 360 uses some or all ModuleWorks components, including simulation, multi-axis toolpath generation, and toolpath calculation technologies. Under the Strategic Partner Program, ModuleWorks has worked with PTC Inc. and Autodesk, CNC machine builder DMG Mori, CNC machine tool builder DN Solutions, and CNC control system suppliers Mitsubishi Electric and FANUC.

Benefits of Using CNC Simulation Software

There are plenty of benefits of using CNC simulation software. They include:

1. Improved safety: CNC simulation software creates a virtual machining environment that enables programmers, machine operators, and students to verify programs and simulate machining processes without manually interacting with the CNC machines. This reduces the risk of accidents, especially among trainees who are still not yet well-versed with operating machinery. 
2. Collision detection: These software products simulate the interactions between machining tools and the workpieces, which helps identify collisions. It enables the programmers to change the G-code before exporting it to the CNC machine. This way, CNC simulation software prevents tool breakage.
3. Detection of programming errors: CNC simulation software can identify errors in CNC programs. These include syntax and cuspidal/pinch point errors on cutter-compensated machine tools.
4. Cost savings: Simulation is one of the technologies you can use to reduce CNC machining costs. Simulation software creates a virtual environment that helps you identify potential collisions early on before you get into production. This prevents real-life collisions between tools and workpieces, which may break expensive machine tools. You, therefore, don’t risk expensive machinery. Additionally, with CNC simulation software, you do not need to take machines out of production to perform prove-outs; you can simply verify the CNC program within this virtual environment. Hexagon, the developer of NCSIMUL, states that its simulation software helps manufacturers and machine shops save up to $25,000 per machine per year. For its part, CGTech, the developer of VERICUT, notes that prove-outs of new NC programs on the machine can cost $24,000 per machine per year.
5. Safe and Interactive Training: You can use CNC simulation software to train students, operators, and programmers without risking expensive CNC machines, tools, or accidents. Some software allows users to manipulate the 3D simulation, providing an interactive way of training employees and students. (More on this below.)
6. Increased precision: Some CNC simulation software products verify and optimize toolpaths, ensuring precision during actual machining. 
7. Improved productivity: The simulation software products enable machine operators to test programs and visualize the machining process before embarking on actual machining. This has twofold benefits – it ensures that the programs run seamlessly on the CNC machines and decreases the setup time as the operator has a concrete idea of what to do and expect. Additionally, CNC simulation software improves productivity by freeing up CAM software to generate toolpaths, their intended function. 

CNC Simulation Software in Training Programs

It may not always be economically feasible to purchase multiple expensive CNC machines solely for the purpose of training students or new employees. And if the machines are already present, it may also not make financial sense to take them out of production just to train newbies. At the same time, the potential for tool breakage adds to the reasons why CNC machines may not be used for training.

In practice, CNC simulation software is used in training programs. These products simulate the CNC machines and machine controllers, giving trainees a glimpse into real-life machining operations, albeit in a virtual environment. CNC simulation software promotes safety, inclusiveness (as every student can interact with a virtual machine via the software), and cost savings. And by interacting with the software, students and trainees gain hands-on knowledge and experience that they can later use to operate actual machines.

Today, there are numerous CNC simulation software specifically designed for CNC training and employee training: 

1. Siemens SinuTrain for SINUMERIK
2. FANUC CNC Simulation Software
3. SwanSoft CNC Simulation software (discussed in greater detail later)

SinuTrain for SINUMERIK

SinuTrain creates the digital twin of the CNC SINUMERIC One machine. It also features the same programming and user interface as the SINUMERIC’s control system. SinuTrain, therefore, is an identical programming station for CNC program creation, production planning, and training. It also enables you to prepare and finish work at home or to verify a CNC program without worrying about breaking something.

FANUC CNC Simulation Software

FANUC’s CNC simulation software products are twofold:

• FANUC CNC Machining Simulation for Workforce Development
• FANUC CNC Simulator’s CNC simulation software 

FANUC CNC Machining Simulation for Workforce Development 

Powered by ModuleWorks, the FANUC CNC Machining Simulation for Workforce Development is a realistic CNC simulation software that facilitates virtual CNC training. It creates a digital twin of the CNC machine and the tools and uses it to simulate the cutting/machining process. This way, the software enables budding professionals to train on FANUC controls operation and part programming. All this is done without risking expensive machinery or accidents. You also do not have to stop production just to facilitate training. Unfortunately, this product is only available in North America.

FANUC CNC Simulator’s CNC Simulation Software

The second CNC simulation software from FANUC can be found in the FANUC CNC Simulator. Powered by the FANUC Manual Guide I software and based on the actual Fanuc Series 0i-MODEL F Plus CNC controller, the simulator aims to familiarize students with the layout, function, feel, and look of the actual CNC control without the need to connect it to the CNC machine. It ships with all the functions of a typical control system, including the e-stop switch, feed override, manual pulse generator, and much more.

The simulator’s software uses a graphical user interface that allows you to interact with the user-friendly icons. It displays all the relevant information you may need on one CNC screen. The software is designed to enable you to create part programs without needing to know G-code. This is because it uses conversational programming instead. Besides enabling you to create and edit programs, the software lets you import programs and use simulation to check programs.

The built-in CNC simulation software in the FANUC CNC Simulator lets you specify the size of the blank material and the tool you intend to use. It also lets you change the orientation of the workpiece relative to the cutting axis of the CNC machine. This capability enables you to better visualize the machining operation. You can also rewind, stop, pause, or control the speed of the simulation. You can also visualize the toolpath, which the software displays as a wireframe animation.

FANUC CNC Simulator’s Software Interface (source)

Top 5 CNC Simulation Software Products 

1. VERICUT

VERICUT User Interface (source)

Developed by CGTech, VERICUT is software that simulates CNC machining. It detects errors, potential collisions, and inefficiencies in the NC programs. This CNC simulation software simulates all types of CNC machine tools from leading vendors like DMG Mori, Okuma, Makino, Mazak, etc. It can also be integrated with leading CAM systems

Features of VERICUT

1. Tool path verification and optimization
2. Realistic 3D simulation that recreates the exact machining environment and simulates precise multi-axis and rapid motion, collisions, machine kinematics, and more
3. VERICUT’s new Heat Map display shows the wear pattern on machine tools and uses a combination of colors and messages to demonstrate how each tool was used
4. CNC Machine Connectivity facilitates real-time data transfer by enabling VERICUT to connect directly with a CNC machine
5. VERICUT sends email or Teams notifications with a summary of results whenever it completes a simulation (you can configure the software to send these notifications after certain events like collisions, tool changes, errors, etc.)
6. Enhanced simulation timeline, which contains error markers that let you click directly on an error marker to review an error in the simulation and investigate the reason it occurred
7. Enhanced support for CNC machines and programs that use tools mounted in multi-tool stations (MTS)

Pros of VERICUT

The advantages of VERICUT include:

1. VERICUT can be used with all CNC machines and is compatible with all CAD/CAM/PLM systems, including CATIA, Creo, CAMWorks, SurfCAM, GibbsCAM, Esprit, Mastercam, NX, Edgecam, Fusion 360, Cimatron, SolidCAM, and more
2. It verifies and optimizes toolpaths, enhancing process efficiency
3. CGTech, VERICUT’s developer, provides training across various topics and classes, from simulation and verification, machine and control building to force optimization
4. VERICUT offers superior collision-checking
5. The software provides realistic 3D simulations of CNC machines, including milling, grinding, EDM, turning, and drilling machines, offering multi-axis support, automatic workpiece transfer, and more
6. It enhances operational safety
7. The software improves productivity by lessening the time you would take to understand and operationalize new CNC machines
8. VERICUT improves presentations and documentation
9. Many CNC machinists and operators recommend VERICUT

Cons of VERICUT

The disadvantages of VERICUT include:

1. VERICUT is expensive, with users stating that this CNC simulation software can cost anywhere between $20,000and $50,000
2. VERICUT training courses can be expensive, with online courses going for $400/day and on-site training costing $1950 per day

2. Cimco Edit

Cimco Edit User Interface (source)

Cimco Edit offers several essential tools for editing NC programs. It is also capable of simulating machining processes. Here, simulation is made possible by a backplot and solid simulation feature on Cimco Edit and the Cimco Machine Simulation add-on (purchased separately). 

The built-in simulation feature simulates NC programs in 3D using a multi-axis backplotter, which shows the toolpaths for turning and milling. It can simulate, using solid or wireframe view, material removal, collision detection, and more. The add-on, on the other hand, lets you prove-out your G-code on a digital twin of a CNC machine. This way, you can visualize and see the exact movements of the machine tools. In addition, Cimco Machine Simulation detects collisions and out-of-limit moves.

Features of Cimco Edit

Cimco Edit and the Cimco Machine Simulation add-on have the following features:

1. GPU-accelerated high-quality simulation
2. Interactive 3D simulation that supports zooming, panning, and rotating, as well as speed adjustments
3. The simulation in Cimco lets you jump to the previous or next tool, cutting pass, or move
4. Cimco generates a simulation report containing all the errors and collisions and the corresponding line in the G-code responsible for the error. Thus, by selecting an error and jumping to the line of code, you can easily modify the code and, using the subsequent report, verify that the issue has been resolved.
5. An extensive library of CNC machines’ digital twins, which can be downloaded to the Machine Simulation add-on
6. Cimco automatically pauses/stops the simulation under certain circumstances, including after collisions, when travel limits are exceeded, and during tool changes
7. Geometry manager: Cimco features a Machine tree (shown in the table below) that enables you to view machine properties as well as the properties of components like the workpiece, head, base, and table. In addition, the manager enables you to configure the origin, work offsets, and the machine’s geometry.
   
   
   

   Geometry Manager in Cimco Edit (source)

8. The axis control feature lets you control the machine’s travel limits, ensuring all axes fall within these limits.
9. Cimco easily integrates with CAM software like Mastercam, SolidCAM, and more
10. Solid mode, which simulates stock material removal
11. Machine configuration editor lets you define machine setups

Pros of Cimco Edit

The advantages of Cimco Edit include:

1. Cimco supports more than 20 languages
2. It enables you to identify inaccuracy by comparing the simulated stock to the design model
3. The simulation report enables quick program editing and verification
4. Cimco’s online library of digital twins includes pre-configured CNC machines from a number of vendors, including Haas, DMG Mori, DN Solutions (formerly Doosan Machine Tools), Quaser, and more. The local library can be updated by downloading and installing the machines from the online library. 
5. Cimco offers free online courses

Cons of Cimco Edit

The cons of Cimco Edit include:

1. Cimco is only available on Windows OS
2. The Cimco Edit software and the Cimco Machine Simulation add-on are priced separately

3. NCSIMUL Machine

NCSIMUL Machine Interface (source)

A product of Hexagon Manufacturing Intelligence, NCSIMUL Machine is an advanced CNC machining verification software. It enables manufacturers to virtually build a real-life machining environment before embarking on production. This CNC simulation software uses the real characteristics of your CNC machine to create a direct digital twin of your machines, tools, workpieces, and material. It then utilizes this information to simulate, verify, and optimize G-code programs. The software is available for complex CNC machining, multi-axis (3 to 5-axis) milling, drilling, and turning.

Features of NCSIMUL Machine

1. Error and collision detection: NCSIMUL Machine uses 3D graphics to display CNC collisions in real time
2. Realistic CNC machine simulation: NCSIMUL Machine creates digital twins of machines, with the resulting simulations including machine accessories and a macro for probing. In addition, the simulation demonstrates a number of crucial processes, such as tool changes and material cutting.
3. Part inspection: NCSIMUL Machine can use user-defined tolerances to quickly and easily compare part gouging or material residual against the design model
4. G-code decoding and verification: This involves automatic programming error detection (e.g., syntax errors and inconsistencies in the program) and interactive toolpath tracing. 
5. Certification of program modifications: NCSIMUL Machine automatically checks program modifications and automatically optimizes them as other production or programming tasks continue.
6. Integration with NCSIMUL Player: NCSIMUL Machine integrates with NCSIMUL Player, which provides an immersive channel to view and share simulations. NCSIMUL Player enables colleagues to manipulate the simulation in 3D space and access various functionalities such as dimensioning and measurement.

Pros of NCSIMUL Machine

The advantages of NCSIMUL Machine include:

1. It optimizes cutting tool feeds and speeds to reduce cycle times
2. NCSIMUL Machine aids collaboration by generating CNC technical documents and 3D simulations that can be shared and reviewed
3. Its G-code verification capability delivers accurate machining cycle time
4. NCSIMUL Machine integrates with CAD/CAM software, enabling you to seamlessly import CAM data; this way, you do not have to rebuild tool libraries, ultimately saving time
5. By detecting collision pre-production, the NCSIMUL Machine software facilitates safe and collision-free machining and avoids downtime that may have otherwise resulted from tool breakage
6. This CNC simulation software reduces cycle times by optimizing toolpaths
7. NCSIMUL Machine enables manufacturers to reduce the cost of proving out CNC programs by as much as $25,000 per machine per year, according to Hexagon
8. The software performs dimensional analysis, enabling you to identify features that are out of tolerance or forgotten tool offsets
9. Hexagon claims that NCSIMUL Machine can process more data more quickly than the competition, translating to fast simulation
10. NCSIMUL Machine has a short learning curve and is easy to use

Cons of NCSIMUL Machine

The disadvantages of NCSIMUL Machine include:

1. NCSIMUL Machine does not simulate the interface of the CNC machine’s control system
2. Pricing information is not readily available, making it impossible to compare at first glance its price with that of CNC simulation software solutions

4. SwanSoft CNC Simulation (SSCNC)

SwanSoft CNC Simulation User Interface (source)

Developed by Nanjing SwanSoft Technology Company, SwanSoft CNC Simulation software, or SSCNC, is designed for teachers and students. It helps students simulate the machining operations in real-life CNC machines, allowing them to acquire the requisite knowledge quickly without using real machinery. Using SSCNC, learning institutions do not have to spend a fortune purchasing machines.

Features of SSCNC

SwanSoft CNC simulation software ships with the following features:

1. SSCNC’s library includes at least 203 operational panels, 81 CNC controllers, and 22 CNC brands
2. It simulates the programming and processing functions of various controllers, including FANUC, SINUMERIC, Mitsubishi Electric, HAAS, GTC, Mazak, Heidenhain, MORI SEIKI, and many more
3. 3D simulation based on OpenGL
4. Windows MACRO recording and replay
5. 2/3 axis milling simulation
6. G-code debugging tool
7. Automatic tool changes, including various types of turrets
8. Simulations for coolant, sound, and iron fragment effect
9. Measurement tools, including calipers, micrometers, feeler gauges, and edge finders, among others
10. Support for custom tools
11. Roughness or surface finish measure based on cutting tool parameters
12. Simulations for workpiece setting and mounting
13. Support for dynamic interaction with the simulation, including zoom, full screen, switch views, and move

Pros of SSCNC

SwanSoft CNC Simulation software offers the following advantages:

1. SSCNC reduces the cost of training, as it helps colleges and training institutions train students without having to invest in expensive machines and controllers
2. It trains students on different machine controllers, as it simulates their respective interfaces and all their built-in functionalities
3. SSCNC promotes safety by ensuring that students learn about machining operations without directly interacting with CNC machines
4. It is ideal for both handwritten NC programs as well as programs generated by CAM software
5. SSCNC supports various languages, including Chinese, English, Korean, Turkish, Portuguese, Polish, Hungarian, Russian, and Spanish

Cons of SSCNC

The disadvantages of SwanSoft CNC Simulation software include:

1. SSCNC is only available on Windows OS
2. Nanjing Swansoft Technology Company does not regularly update the trial version of the SSCNC software
3. Multi-axis machining in SSCNC is limited to two and 3 axes

5. CNC Simulator Pro

CNC Simulator Pro Interface (source)

CNC Simulator Pro is a full 3D CNC machine simulation software. It simulates over 40 machines across five categories. It also supports more than 30 different materials. Besides being a CNC machine simulator, CNC Simulator Pro is a modern CAD/CAM system, a 3D model milling software, an advanced CNC programming editor, and a gear creator. It is also ideal for training students and new operators.

Features of CNC Simulator Pro

CNC Simulator Pro has the following features:

1. CNC Simulator Pro simulates milling, turning, 3D printing, and cutting (laser, plasma, and water jet cutters) machines, plotters, and more
2. Its library contains the digital twins of more than 43 machines in five categories
3. It supports over 30 different materials, including aluminum, nylon, steel, wood, titanium, ABS (acrylonitrile butadiene styrene), brass, copper, magnesium, and more.
4. CNC Simulator Pro includes the SimCAM integrated CAM system, which adds CAD/CAM capabilities
5. It includes a virtual CNC controller inspired by FANUC and others
6. Free cloud-based storage
7. Macro programming, which enables you to customize or automate processes
8. Fast backplotting 

Pros of CNC Simulator Pro

The advantages of CNC Simulator Pro include:

1. CNC Simulator Pro features digital twins of both industrial machinery as well as hobbyists’ tools and machines
2. It is ideal for hobbyists, industrial machine operators, teachers and students
3. This CNC simulation software ensures safety by limiting their interaction with CNC machines and preventing accidents that may result from errors in G-code
4. CNC Simulator Pro improves the speed of writing and editing CNC programs since its intelligent code editor highlights various types of codes and suggests changes or better code
5. The software has plenty of built-in tools, including Gear Maker, Image Maker, and 3D Maker, which help you write your CNC programs faster and more accurately 

Cons of CNC Simulator Pro

CNC Simulator Pro has the following drawbacks:

1. CNC Simulator Pro is only available on Windows and only runs on 64-bit versions of the software
2. Its longer update cycles mean users wait for long periods to receive updates. For instance, CNC Simulator 4 has been in beta since September 2021.
3. The long update cycles quickly make the 3D simulation graphics appear outdated, especially as better monitors/displays and GPUs become available.

Implementing CNC Simulation Software

CNC simulation software products are different – with the nuanced differences emanating from the number of CNC machines in their libraries, ease of use, integration with CAM systems, and simulation capabilities, just to mention a few. Cost should also be another aspect that guides the implementation of this CNC simulation software. Additionally, you should check whether the developer regularly updates their software. 

Thus, when choosing your preferred CNC simulation software, it is essential to check the following: 

1. CAD/CAM integration: It is advisable to check whether the software seamlessly integrates with your go-to CAM system. This consideration ensures continuity. It also helps you avoid creating new libraries for tools and machines because you can simply migrate that data from one software to another.
2. Cost: Some software products, like VERICUT, are more expensive than others. Additionally, some developers offer free online courses, while others charge their learners. Thus, depending on the number of seats you want to purchase, it may be financially prudent to purchase a cheaper yet formidable solution instead of an expensive one. 
3. Training for use: All software applications have a learning curve – the difference lies in the steepness of the curve. So, you should understand that you must train your employees on how to use the CNC simulation software should you want to boost productivity and ensure you enjoy the aforementioned benefits of the product. At this stage, you should also factor in the cost of training.
4. Regularity of updates: Software updates typically resolve bugs and introduce new features that enhance the software’s functionality. CNC simulation software that is rarely updated will, therefore, have outdated features and vice versa.

Conclusion

CNC simulation software plays a crucial role in enhancing CNC precision, productivity, and safety, facilitating training, and helping companies and learning institutions reduce the cost of machining. To benefit from these advantages, select the CNC simulation software that best meets your needs. This selection hinges on a number of elements, chief among them the ability to simulate CNC machining operations. Besides function, other elements to consider when selecting simulation software include cost, regularity of updates, the learning curve, and compatibility with available CAD/CAM systems. You should also assess their features, pros, and cons, which we have discussed in detail in this article.

If you are looking for a simulator for your commercial operations, there are plenty of operations from which to choose. Our list of top 5 CNC simulation software includes VERICUT, Cimco Edit, NCSIMUL Machine, CNC Simulator Pro, and SSCNC. And if you are searching for a solution solely for training purposes, you can choose from a pool that includes Swan Soft CNC Simulation software, Siemens SinuTrain, and FANUC CNC Simulation Software. 

Understanding Surface Finish in CNC Machining

The term surface finish refers to the overall characteristic and description of a surface, including any coating applied, dimension accuracy, texture, roughness, flaws, materials, flatness, waviness, and form. Simply put, surface finish defines the external topology (three-dimensional profile) of surfaces. CNC surface finish is so important in manufacturing and machining that it directly measures the quality of produced parts and products. 

Naturally, engineering surfaces machined using different processes have varying topographies. For instance, a surface produced from a milling operation is spatially inhomogeneous. On the other hand, a surface on which a grinding operation has been completed may feature troughs and pits, while a honed surface has cross-hatched grooves. 

Against this backdrop, an engineer should decide on the type of surface that will best fulfill the intended function of the part. To make this decision, they must consider factors like friction, adhesion, desired luster, and more. Once they make this decision, the next challenge is to pick the appropriate machining operation to achieve the desired surface finish.

Components of Machined Surface Finish

There are two components to machined surface finish:

1. Geometric or Ideal Finish

This is the surface finish that results from the kinematic motions and geometry of the CNC machining tool. This is the most dominant component of the finish in operations whereby the cutting forces and tool wear are low. One example of such an instance is when diamond tools are used to machine aluminum alloys.

2. Natural Finish

Also known as inherent finish, natural finish results from such factors and parameters as vibration and dynamics of the cutting process, tool wear, rapture at low cutting speeds, built-up edge formation (BUE), inhomogeneity, and work material effects like residual stresses. A natural finish is difficult to predict, unlike an ideal finish. It is the predominant component of surface finish in cases where carbide tooling is used to machine steels and other hard materials or when machining inhomogeneous materials like powder metals or cast iron.

Surface Finish in Various CNC Machining Processes 

Surface Finish in Turning

Turning is a CNC machining process usually done using a lathe machine. In turning, a cutting tool is fed into a rotating workpiece. The tool works on the outer surface of the workpiece, creating a conical or cylindrical surface depending on the number of axes along which the tool is allowed to move. 

The surface finish in turning depends on factors such as the tool nose radius, depth of cut, feed and feed rate, tool wear, inconsistencies in the work material, vibrations, machine motion errors, and discontinuous chip formation. To put this into perspective, a larger tool nose radius, a low feed rate, and a small depth of cut improve the surface finish. Additionally, surface finish increases with an increase in cutting speed (because it reduces the cutting forces), provided it does not cause vibration and excessive tool wear.

Surface Finish in Milling

The CNC surface finish in milling is generally less uniform compared to single-point boring and turning. Put simply, milling results in a surface that has spatial variations. This is typically because of a few factors, including:

• A varying effective feed rate, which changes based on the angle of the cutting edge from the feed direction
• Grinding or setup errors, which cause the cutting edges to be cut at slightly different depths of cuts and feed rates
• Vibration caused by the interrupted nature of the milling process
• Changes in cutter position due to spindle and cutter runout

Surface Finish in Drilling

Drilling generally combines cutting and rubbing actions, each of which independently impacts the CNC surface finish. For instance, the surface finish attributed to the cutting action depends mainly on the feed rate per revolution. Conversely, the finish associated with the rubbing action is dependent on the hardness and ductility of the workpiece, as well as the margin design and land width of the drill.

That said, drilling is regarded as a roughing process. As such, not much can be said about its influence on the CNC surface finish. In practice, machinists rarely monitor the surface roughness of drilled holes. Nonetheless, drilled holes that must have fine finishes are normally machined using surface finishing processes such as honing, burnishing, reaming, or boring – more about these processes in the section below.

Surface Finishing Processes

Most CNC machining operations are not designed to produce smooth surfaces. Therefore, machinists must finish the parts using surface finishing processes to solve this shortcoming. These processes typically remove a very small amount/layer of the material from the surface, measuring a few micrometers or nanometers. This section covers the various processes of achieving the desired CNC surface finish.

1. Grinding

Grinding produces parts with tight tolerances and fine surface finishes. It uses a rotating abrasive wheel to remove material from the surface of an object. This grinding wheel has small particles of aluminum oxide or silicon carbide, which act as abrasives and are bonded together by a suitable material. The particles can vary in size, with this variation creating a wide range of grinding wheels.  Silicon carbide wheels are ideal for grinding materials with low tensile strength, while aluminum oxide wheels are better suited for materials with higher tensile strength. 

It is worth pointing out that grinding removes very little material from the surface. This process achieves a good surface finish and gives high dimensional accuracy to parts already machined by other CNC machining methods. It is worth pointing out that grinding as a surface finishing method is typically used to machine materials that are too hard to machine using other processes.

Typically, the ground surface finish depends on several factors, namely:

• Wheel type and properties, including the wheel grit size and spacing, hardness, and effective diameter; for context, a wheel with high effective diameter and hardness as well as fine grains achieves smoother surface finishes
• Wheel dressing method, e.g., rotary diamond dressing and single point dressing, which determine the topography of the wheel surface
• Grinding conditions, e.g., cylindrical plunge grinding, straight surface grinding, creep feed grinding
• Vibration/chatter: vibration adversely affects the ground surface finish 

2. Reaming

Reaming combines cutting and rubbing actions to produce a surface. Like drilling, its kinematics involve both linear and rotational movements, with the former occurring along the axis of rotation. The reaming process is done using a reamer. 

There are three types of reamers:

• Single-blade reamer: these reaming tools have one cutting edge.
• Adjustable multi-flute reamer: These tools have multiple cutting edges. The ‘adjustable’ tag stems from the fact that they can expand, increasing the reaming diameter.
• Nonadjustable multi-flute reamer: These are reaming tools with multiple cutting edges. However, they cannot expand, meaning the reaming diameter remains fixed throughout the finishing operation.

3. Burnishing

In burnishing, a hard, smooth roller or ball is pressed against the part’s surface. It generates the desired surface finish through plastic deformation. In addition to improving the CNC surface finish, burnishing increases the surface hardness, enhances the fatigue life, and controls tolerance.

4. Finish Boring

To understand what finish boring is, let’s first discuss what boring is. In boring operations, a cutting tool is fed into a rotating workpiece to generate conical or cylindrical internal surfaces along the axis of rotation. Generally, boring is a roughing operation. Finish boring, therefore, is a type of boring operation that primarily achieves dimensional and surface finish tolerances. It is used to finish drilled holes or the internal surfaces of castings. 

5. Lapping

Lapping is a process in which the surface of a workpiece is rubbed with a rotating tool called a lap. The lap is made of soft, porous material (e.g., copper or cast iron); it is embedded with an abrasive paste/slurry made by mixing oil or water with fine particles of abrasive materials such as aluminum oxide, silicon carbide, emery, or diamond. 

This surface finishing method is preferred in cases where the machinist intends to produce a finish for two contact surfaces that are meant to fit snugly. This is because the process achieves high dimensional accuracy and fine surface finish. In addition, it results in geometrically true and very flat surfaces.

6. Honing

Honing uses abrasive stones or sticks to finish the external or internal surfaces of cylindrical workpieces. Usually, the abrasives are fixed around a metal cylinder called a mandrel, creating a honing tool.

7. Hydrohoning

The hydrohoning surface finishing process uses a stream of abrasives-carrying liquid to smoothen surfaces. This process is usually deployed to remove burrs and marks in metal molds.

8. Superfinishing

The superfinishing process uses large, bonded abrasive stones that move in a reciprocating motion and lightly press on the workpiece. On its part, the workpiece is reciprocated or rotated depending on its shape. Superfinishing produces an extremely high-quality surface finish. Superfinishing is also known as microhoning.

This process is commonly used in the automotive and bearing industries. It is preferred to other surface finishing technologies because it improves the surface finish of the parts.

9. Polishing

Polishing is a surface finishing process that removes small defects and scratches from the surface. It uses a rotating wheel onto which fine abrasive particles (that form a slurry) are applied. During polishing, these particles are responsible for removing the defects through cutting action. Usually, the rotating wheel, which is made of felt, leather, or cloth, is rotated against a workpiece that is held in place.

10. Buffing

Buffing is a refined type of polishing. It produces a mirror finish otherwise unobtainable using the polishing method. In buffing, very fine abrasives are applied to a wheel that is rotating at high speeds. The wheel is itself made of soft material such as a sewn layer of cloth or felt.

11. Shot or Grit Blasting

This process is used to remove burrs, rust, scales, etc. It relies on particles of abrasives, which, moving at high speeds, strike the surface of a material. Shot or grit blasting achieves a matte finish.

12. Shot Peening

Shot peening is a surface finishing process that strengthens and hardens the surface. It uses steel balls moving at high velocity. The balls strike the surface, making it fatigue resistant and work hardened.

13. Barrel Finishing

In barrel finishing, parts are placed inside a barrel containing abrasive materials and a suitable liquid. The barrel is rotated for a given period, promoting contact between the parts and abrasives. It is this impact that removes surface imperfections. 

Influence of Material and Machining Parameters on CNC Surface Finish

There are several factors that impact the CNC surface finish. They can arise from cutting conditions, CNC machine operations, or material properties. 

Machining Parameters

A number of machining parameters that can be set well in advance of any cutting or machining operation affect the surface roughness. Given that surface roughness is an indicator of the quality of the surface, tweaking these parameters beforehand can lead to a better surface finish. To help you understand what to do, here are the machining parameters you should consider:

1. Cutting/machining forces: A larger magnitude of cutting forces during conventional machining can unintentionally deflect the cutting tool, leading to unstable cutting. This can contribute to poor surface finish. 
2. Cutting speed: Generally, an increase in cutting speed (measured in m/min) improves the surface finish by decreasing the surface roughness. This is because a high cutting speed reduces the cutting forces and chatter. However, increasing the speed during some machining processes generates a different result. For instance, an increase in cutting speed during helical milling increases the surface roughness. The high surface roughness is attributable to the fact that a high speed often leads to chatter and unstable cutting. This means that a high cutting speed reduces the quality of the surface, leading to a poor CNC surface finish. 
3. Feed rate: An increase in the feed rate results in a poor CNC surface finish because of increased surface roughness. Conversely, a lower feed rate produces a better surface finish.
4. Depth of cut: There are two types of depths of cut: the radial and axial depth of cut. A lower value of the radial depth of cut leads to a better CNC surface finish. The inverse is also true. On the other hand, the higher the axial depth of cut, the better the surface quality.
5. Nose radius: A high nose radius leads to lower surface roughness, translating to a better CNC surface finish.
6. Tool geometry: Tool geometry is defined by the rake, lead, helix, and relief angles, tool overhang, and radial and axial runout. Briefly, a positive rake angle reduces the surface roughness. A larger lead angle (smaller entering angle) is associated with a better surface finish, while the relief angle indirectly impacts surface roughness through its direct influence on the rate of tool wear. Additionally, the tool overhang increases surface roughness. For a more comprehensive discussion on how these cutting tool factors impact surface roughness, check out this 2024 study.
7. Tool wear: Tool wear negatively affects the quality of the surface. Specifically, a worn-out tool increases the surface roughness. In addition, it causes the surface to develop many partially developed cracks.
8. Cutting fluids (coolants and lubricants): As discussed extensively later in this article, lubricants and coolants improve the surface finish.

Material Considerations

The type of material affects the surface finish. Typically, different materials have varying degrees of chip formation and hardness. Hard materials increase the rate of tool wear, which, as we have described above, causes a poor CNC surface finish. At the same time, a low harness value may cause BUE formation, which reduces the surface finish. 

Illustration Showing Built-up Edge (BUE) Formation and Its Impact on Surface Roughness (source)

In certain cases, the workpiece may be heated to make it softer and easier to cut. It has been shown that elevated workpiece temperature reduces the cutting forces. This results in better surface roughness, translating to a good CNC surface finish. Given the various properties of materials and their respective impacts on machining conditions, surface roughness and finish vary from material to material.

Other Considerations for Superior CNC Surface Finish

1. Vibration/Chatter: Vibration negatively affects the surface finish.
2. Cutting Strategies: Computer-aided manufacturing (CAM) software recommends many complex cutting strategies that can be easily incorporated into modern machining operations. These strategies include plunge, zigzag, zig, follow-part, trochoidal, etc. Studies have shown that some of these strategies, particularly the trochoidal and follow-part strategies, result in superior CNC surface finish.

Role of Coolants and Lubricants in CNC Machining

CNC machining processes like grinding, milling, turning, and drilling result in significant thermal stresses that are experienced by both the workpieces and cutting tools. In addition, they produce swarf, which affects the performance of the machining operation as well as the quality of the surface. Thus, coolants and lubricants prevent the negative implications of friction and heat. 

Generally, within the context of CNC machining, which involves cutting operations, coolants and lubricants are collectively known as cutting fluids. These fluids serve the following functions:

• Dissipate heat generated in the contact zones between the workpiece and cutting tools
• Remove chips from the surface of the workpiece
• Reduce friction
• Prevent overheating of the CNC machine
• Protect against corrosion 
• Resist the formation of sticky, gummy residue on parts and machine tools

How Coolants and Lubricants Promote CNC Surface Finish

But perhaps the most crucial function, at least within the context of this article, is the fact that using lubricants and coolants improves the surface finish. The heat produced during CNC machining, primarily due to friction, can affect dimensional accuracy, damage the surface and subsurface, and induce residual (internal) stresses. Residual stresses disturb the initial mechanical equilibrium, causing changes in the form/deformations. Thus, by dissipating heat, cutting fluids facilitate better surface quality.

Coolants and lubricants also impact CNC surface finish by removing chips. Naturally, processes like drilling, which involve continuous cutting, produce strain-hardened continuous chips. These chips rub against the newly generated hole surface, leading to unplanned deep grooves and scratches. Thus, the cutting fluids improve the surface finish by flushing out these chips.

Using Coolants and Lubricants Efficiently for Good CNC Surface Finish

When it comes to CNC machining, machinists have to decide on the cooling action. Typically, they are presented with four cooling choices:

1. Dry machining

This option involves coating the cutting tool tip to reduce friction. It relies on the coating deposition technology. It is ideal for machining aluminum and carbon steels, wherein the chips dissipate the heat. 

2. Flooding

Flooding is the most common option. In this system of cooling workpieces, a nozzle directs the coolant to the cutting zone, dissipating the heat produced and flushing away the swarf. Flooding is ideal for operations like grinding, drilling, and milling. However, it is a costly method, given the running and maintenance costs of the coolant system.

3. Cryogenic machining

Cryogenic machining uses cryogenic gasses like hydrogen, nitrogen, helium, oxygen, and neon as coolants. These gasses typically have a low temperature of below -150°C. Unfortunately, cryogenic machining is comparatively new and requires specially designed cutting tools, which presents certain difficulties. In addition, this method is ideal for use with certain materials, as it can result in thermal cracking.

4. Minimum quantity lubrication (MQL)

MQL aims to reduce the quantity of coolant required while also lessening tool wear and thermal stress at the point of contact between the tool and the workpiece. In MQL, machinists aim to use no more than 50 ml of the lubricant per machining hour (mL/h). However, the recommended range is between 50 and 500 mL/h. This range is roughly three or four orders of magnitude lower than the volume released during flooding.

Of the four cooling options, MQL enables the efficient use of cutting fluids as well as promotes a good CNC surface finish. According to a 2023 study, MQL achieves good surface roughness. It also facilitates lower cutting temperatures, feed rate, and cutting speed. Moreover, the MQL increases the efficiency of CNC machining processes, leading to better performance than the other cooling choices. Other additional benefits of MQL include a reduction in maintenance costs and the cost of running coolant pumps and other management resources. Put simply, MQL helps you reduce CNC machining costs.

Troubleshooting Common Surface Finish Issues

The CNC surface finish is an excellent indicator of underlying issues that affect the machining process. A poor surface quality signals an issue with the machine, tool, or machining process. For instance, reduced surface quality can indicate progressive tool wear, nonhomogeneous workpiece material, cutting tool vibration, and other underlying issues. 

Given that the surface finish is a marker of the quality of the products your CNC machining shop produces, any deviations from the norm warrant an assessment to identify the cause. Here are some of the aspects you should check as part of the troubleshooting excessive:

• Check the machining tools: this helps you identify the level of tool wear or incorrect toolholding, which may, in turn, affect the tool geometry and cause chatter.
• Review the machining parameters: It is clear from the discussion above that machining parameters directly affect CNC surface finish. In this regard, it is crucial to regularly review them to identify deviations from correct settings.
• Monitor levels of cutting fluids: Cutting fluids improve the surface quality. And given that the flow rate of coolants and lubricants also affects the machining performance and efficiency, it is easy to recognize the importance of monitoring their levels. 
• Ascertain workpiece and machine stability: Vibration can sometimes be caused by workpieces that are not tightly held in place or machines that are not securely fastened to the ground. 

Conclusion

Machinists always aim for quality, which often means striving to achieve a superior surface finish. This is because CNC surface finish is one of the properties that define the desirability and appearance of parts. To achieve a good surface finish, you must use dedicated surface finishing processes like polishing, grinding, burnishing, reaming, barrel finishing, honing, superfinishing, and so on. The necessity of these processes stems from the fact that conventional machining operations, such as drilling, milling, and turning, do not produce features that have good surface quality. And while the surface finishing processes promise good surface finishes, it is vital to consider machining parameters, CNC machine conditions, material considerations, and operating conditions.

This article delves into the various cost items to consider if you run a CNC machining operation. We discuss the factors affecting CNC machining costs, how to optimize various aspects of your CNC machining business to reduce costs, and how to leverage software and technology to achieve this target.

Breakdown of CNC Machining Costs

CNC machining costs naturally vary from one machining shop or manufacturing company to another. That is simply because of the choices these shops or companies make. For instance, small machining shops can purchase cheaper CNC machines that align with their needs. On the other hand, large machining shops and companies often opt for more expensive parts, which can run continuously, generating thousands of parts within each shift. Generally, machining shops and manufacturing companies consider the CNC machining detailed below.

1. Equipment Costs

There are numerous categories and types of CNC machines that cater to the needs of hobbyists, entry-level machinists, manufacturing shops, and woodworking shops. Obviously, the price tags attached to these machines are not uniform. Machines designed for desktop use are a lot cheaper than machines meant for large-scale metal fabrication or parts production.

Thus, the cost of a CNC machine does impact the CNC machining costs. In addition to the initial capital outlay on equipment, machine shops should also factor in repair and maintenance expenditures as well as depreciation. These additional overheads contribute to the total cost of the equipment.

2. Tooling Costs

Within the context of CNC machining, the term ‘tooling’ simply refers to the cutter you intend to use. However, in addition to cutting tools, you also need a variety of additional tools, including inserts, honing wheels, drill bits, work-holding components, and additional consumables for machining. The range of tools is necessary to achieve a particular desired surface finish, reach hard-to-machine areas, perform optimal cuts at speeds the machine can support, and so on. Also, these tools have a limited life and must be replaced periodically. In this regard, the amount spent purchasing and replacing these instruments increases the overall CNC machining costs. 

3. Material Costs

Material costs as a share of total production costs vary greatly based on location, type, quantity, and availability of material, prevailing market conditions, and much more. Logically, for example, metals are more expensive than plastics. But these two types of materials are susceptible to market conditions, which cause price fluctuations. 

The bottom line, therefore, is that material costs are always bound to fluctuate in response to the above-mentioned factors and more. In this regard, CNC machining shops and companies should always strive to maximize material utilization, as this can dramatically reduce both waste and cost. And as we detail later, machine shops can also reduce material costs – and, by extension – overall CNC machining costs, by having engineers or designers recommend cheaper materials.

4. Inventory Costs

Once you purchase material, the next step is ensuring the material reaches your storage facility or workshop. And in taking this step, you must also consider additional factors, such as how you will store, carry, and manage the material. Against this backdrop, inventory cost refers to any direct or indirect cost that arises from transporting, carrying, storing, managing, and processing inventory. 

5. Labor Costs

Machine shops require and pay machinists and operators to perform a number of duties, which include changing tools, programming parts, performing quality control against applicable standards, ensuring regulatory compliance, monitoring to promote CNC machine safety, assembling parts, and operating machinery, just to mention a few. For these machine shops, the cost of labor will depend on the prevailing wage rates, the machinists’ experience level, the availability of talent, and their productivity. And with high costs impacting the machine shop’s competitiveness and the cost of the parts, labor is a crucial consideration in CNC machining economics.

6. Energy Costs

There are many types of CNC machines, from waterjet machines, laser cutters, plasma cutters, and routers to lathes, milling machines, and grinders. And while you would ordinarily expect the machines’ cutting or machining operations to consume a large percentage of the electricity, this is not usually the case. 

CNC machines comprise many additional components, including motors, fans, computers (machine control systems), coolant pumps, feed drives, and spindles. These auxiliary systems account for much of the energy consumption, up to 85% of the total energy consumption. It is worth pointing out that some machines lack certain auxiliary systems. This means that the specific energy consumption profiles vary from one CNC machine to another. 

In addition, parasitic losses and energy losses from inefficient designs (e.g., the design of machining tools as well as the designs fed into the machines for fabrication) can increase energy consumption. It goes without saying that high energy consumption increases energy costs.

7. Overhead Costs

Overhead costs include utilities, rent, insurance, administrative expenses, and taxes. And while they are indirect costs, they are still linked to machining operations. Therefore, overhead costs influence CNC machining costs.

Factors Affecting CNC Machining Costs

There are a number of factors that directly affect CNC machining costs, including:

• Cycle time and machining time
• High part rejection rates
• Complexity of designs

Cycle Time and Machining Time

Also known as part-to-part turnaround time, cycle time refers to the time required to unclamp and unload a finished part and then load and clamp the second one. In addition to covering the time taken to unload and reload, cycle time also encompasses the time a machinist takes to clean the setup of chips and dirt. A long cycle time reduces the efficiency of the CNC machine, as less time is spent on actual machining. This subsequently increases the machine’s idle time, negatively affecting the economics of the machine.

On the other hand, the duration of machining operations has a direct bearing on the CNC machining costs as well as the machine’s productivity. How so? Firstly, it results in the production of fewer machined parts within a given time, ultimately reducing the efficiency of the CNC machine. Secondly, longer machining time increases the energy and labor costs per part. In addition, longer machining time may result from wrong selections of parameters such as the cutting speed, feed rate, and rate of discharge of the coolant or lube, which, in turn, negatively affects the tool life by increasing tool wear; in this regard, longer machining time may increase the tooling costs.

To better understand how both the cycle time and machining time directly impact CNC machining costs, let’s remind ourselves of one crucial fact: CNC machines have a high capital cost. So, for a CNC machine to pay for itself, generate profits, offset overhead costs, and pay wages, it must be productively working 90 to 95% of the time. Thus, long cycle and machining times reduce the machine’s productivity, affecting its ability to offset CNC machining costs.

Fortunately, machinists can get around this problem by implementing simple strategies that increase productivity and reduce the costs per part. They can streamline machining processes, use better tools, and implement automation. 

Quality and Rejection Rates

A high part quality rate is an excellent indicator of efficiency in CNC machining. Conversely, a high rejection rate, i.e., a high production of scrap parts, signals inefficiency. A high part quality rate optimizes material usage, reducing wastage. It also leads to fewer revision requests and reduces supplementary processing costs. Overall, a high part quality rate reduces CNC machining costs. The inverse is true with high rejection rates. 

Conveniently, a machine shop contending with high part rejection rates can remedy the situation by providing training, implementing better processes that effectively reduce defects, and adopting quality control measures. These measures can help the shop optimize the CNC machining costs.

Complexity of Designs and Parts

It is advisable not to overly complicate your designs because it makes fabrication difficult. You can look at a few characteristics of your design to assess whether it bears the hallmarks of a complex design. The first obvious characteristic is the number of features. To some extent, more features require that you make various numerical callouts describing measurements. Unfortunately, such numerous callouts and features increase the likelihood of errors during machining, which can increase waste and scrap.

If you discover that you have designed an overly complex part, you could choose one of two options. You could redesign the part or split it to create an assembly or multiple separate parts that can be welded or bolted together.

Surface Finish

The consensus is that the surface finish directly affects CNC machining costs. This is because achieving a fine surface finish will require multiple passes as well as a selection of precise tools and machining operations. This translates to longer machining times and, by extension, higher costs due to more energy consumption and labor costs.

Strategies for Cost Optimization

Here are the various strategies you can employ to optimize the cost of CNC machining operations:

1. Quantify Machining Costs

Making decisions from a point of knowledge has always proven wise. And within the context of CNC machining costs, you cannot optimize that which you do not know. Thus, to optimize cost, you have to determine how much it costs to run a machining operation. This is a foundational strategy for cost optimization. 

For the best results, you could conduct a feasibility analysis before purchasing a CNC machine. In fact, it is normal for businesses to embark on such a study whenever they want to spend large sums of money on assets and machinery. Such a study helps the company determine the type of machine to purchase, energy consumption, number of CNC axes required, spindle configuration, and much more. 

Through the feasibility study, the machine shop also investigates how the machine’s productivity could impact the harmonious flow of parts and whether this could trigger bottlenecks. But perhaps the most important study item, at least within the context of this article, is cost.

A company pegs the decision to purchase high-cost machines on its ability to minimize the payback period. As such, the company considers the overall cost over the lifetime of the machine and comes up with a minimum payback period. It then comes up with measures to maximize the financial rewards by, for instance, using the machine on more shifts. This strategy helps lower the hourly machine rate. The intensive utilization compensates for the high initial investment.

2. Re-engineer Parts

As introduced earlier, the machining time directly impacts the cost of machining as well as the pricing of machined parts. In fact, the machining time is considered the most significant cost driver during machining. So great is it, in fact, that it outweighs the setup costs, material costs, and costs of achieving custom finishes through plating or anodizing. In this regard, it is crucial to reduce the machining time. And that is where re-engineering of parts comes in; it involves going back to the drawing board, as it were.

As an engineer or designer, you can re-engineer parts by ensuring your 3D model has rounded internal corners. This accommodates tools like mills, which, due to their geometry, leave rounded inside corners. In addition, you should avoid designing parts with deep internal cavities, which are often time-consuming to machine. Other considerations include:

• Limit the number of features, if possible
• Thicken thin walls to avoid vibrations (chatter) and distortion, which prompt a reduction in cutting speeds
• Recommend and use less expensive materials
• Avoid mixing finishes
• Do not overly complicate parts

3. Reduce Part Rejection Rate

Manufacturers worldwide are increasingly targeting zero defects in their manufacturing processes. One strategy they are using to achieve this target is lean manufacturing. Lean manufacturing aims to identify and eliminate waste by continuously improving the product. Another strategy is the Six Sigma managerial approach, which looks to enhance performance by eliminating defects and resource waste. The implementation of this approach results in 3.34 defects per million produced. Incidentally, the lean manufacturing philosophy can be combined with the Six Sigma tools to create Lean Six Sigma.

4. Implement Just-in-Time (JIT) Manufacturing

Also known as the Toyota Production System (TPS), just-in-time (JIT) manufacturing is a strategy that helps manufacturers improve efficiency and decrease waste by receiving materials only when they need them for CNC machining. This strategy reduces CNC machining costs by lowering the inventory cost. 

5. Select Optimal Tools and Parameters

One of the ultimate goals of CNC machining, which incidentally impacts costs, is efficiency. Efficiency in CNC machining refers to the number of parts produced within a given timeframe. High efficiency depends on the selection of optimal parameters like the appropriate feed and feed rate, cutting speeds, revolutions per minute, and much more. Similarly, you should use the right tool for each operation to avoid tool breakage and unnecessary tool wear.

Leveraging Software and Technology

You can use a number of technologies to reduce CNC machining costs. They include:

• CNC automation
• Predictive maintenance
• Simulation
• Prototyping
• Multi-tasking CNC machines

CNC Automation

CNC automation takes many forms. The first involves the use of computer-aided manufacturing (CAM) software, which generates NC code (G-code) that controls the CNC machine’s machining operations. Once the machinist uploads the NC code into the machine control system, they can rely on several built-in robotic tools. 

CNC machine manufacturers often include these robotic tools to increase productivity. The tools automatically load and unload parts, suppress vibration upon detection, clean the work area, and remove chips. In addition, some machines can be configured to include automatic tool changers (ATCs), designed to change tools more rapidly than manual approaches.

Predictive Maintenance

A CNC machine is only profitable if it is up and running. This only means that besides being potentially expensive to repair, unexpected breakdowns cause manufacturing downtimes. Even more concerning, the breakdowns can stop production for prolonged periods. However, given the evolution of modern monitoring technology, the ripple effect can be nipped at the source through predictive maintenance.

Predictive maintenance involves monitoring a CNC machine’s performance, health, and status during machining. It relies on sensors and modern technologies like the Internet of Things (IoT), the digital thread, and the digital twin to track and represent various machining parameters and conditions. 

Typically, the sensors collect information such as sound, temperature, vibration, lubrication, etc. If, upon analysis, it is noted that the new data varies from what is considered normal, the monitoring tools send out real-time alerts. This way, the operator knows beforehand of any emerging issue. They then schedule the repair well in advance, before the issue boils over, enabling better planning and avoiding unplanned downtime. Put simply, predictive maintenance prevents breakdown, helping curtail losses and, in effect, reduce CNC machining costs.

Simulation 

CAM software ships with numerous features, including cutting simulation. Alternatively, you can use dedicated CNC simulation software, which use better simulation engines to improve simulation performance and speed. This software simulate the movements of the cutting or grinding tools per the selected toolpath and NC program, allowing you to visualise the process. This visualization facilitates collision detection, enabling you to correct the toolpath/code. By avoiding collision, which can cause tool breakage, simulation enables you to lower CNC machining costs. In addition, the simulation lets you to compare different toolpaths and, using that information, choose the best, most cost-effective alternative.

Prototyping

We have discussed the importance of re-engineering parts as a cost-reduction measure in CNC machining. In some cases, however, it may not be possible for design teams to assess the actual cost of manufacturing parts without relying on a physical model. During such instances, prototyping and rapid prototyping become a reliable mechanism to fabricate models that teams can use to assess the potential cost of manufacturing parts. 

If the assessment shows that the manufacturing cost will exceed the budget, companies can consider either of two approaches. First, designers can opt to modify the design to create parts that are less complex or parts that require less expensive fabrication processes. Alternatively, the machining team can choose a different machining process.

Multi-Function/Multi-Tasking CNC Machines

Certain parts need to go through different CNC machines. For instance, a motor vehicle engine housing has to go through a vertical lathe for internal and external turning. Next, it needs to be machined using a machining center to reduce weight. While necessary, this procedure loses plenty of valuable time when setting up, loading, and unloading. And as we have already detailed, such time penalties increase CNC machining costs.

Fortunately, some modern CNC machines can perform two or more machining operations. For instance, the duoBLOCK series from DMG Mori combines 5-axis milling with 5-axis turning. Others, like the G5 CNC Grinder 5-axis horizontal machining center from Makino, can mill, drill, tap, and grind, all on the same machine. 

Makino’s G5 CNC Grinder 5-axis Horizontal Machining Center (source)

When it comes to machine economics, such machines, while expensive, can lower CNC machining costs because they can be cheaper than the combined price of separate machines that individually perform a different machining operation. They also occupy less space, eliminating the need to lease, rent out, or build larger warehouses. In this regard, they reduce CNC machining costs even further.

Conclusion

Understanding the CNC machining costs helps you arrive at the cost per part and the machine cost per part. This information then enables you to optimize the CNC machine as well as your operations by adjusting various parameters and implementing cost optimization strategies, thereby ensuring profitability and sustainability. Typically, you should consider the equipment costs, labor costs, overhead costs, energy costs, tooling costs, material costs, and inventory costs. You should also take factors like the required surface finish, complexity of parts, cycle and machining times, and part rejection rates, which, in the end, affect CNC machining costs.  

Understanding Efficiency in CNC Machining

Efficiency in CNC machining simply refers to the number of parts a CNC machine can produce within a given timeframe, often in an hour. Efficiency offers several benefits, including less time spent at the machine. Other benefits include better quality parts and cost savings due to the ability to work on a large number of parts in a short time. 

The quest for improved efficiency began in the mid-1980s. This was just a few years after the development of CNC and computer-aided manufacturing (CAM) in the 1970s. But already, the positive impact of efficient machining had become apparent. The 1980s saw the development of multitasking CNC machines. This resulted from better and more powerful chips that increased processing and calculation speeds. It also became easier for operators to create programs thanks to fully functional graphic programming and machine controllers with graphical programming interfaces. 

Advancements in the CNC and CAM spaces became commonplace in the 1990s and 2000s. For instance, during the last decade of the 20th century, PC-based CAM software had become so evolved that operators no longer had to write programs using the machines’ controls. Instead, they wrote the programs on their computers at the office desks. By the 2000s, automated CAM software was doing much of the programming.

Similar advancements were also witnessed in the world of CNC machining. Today, machine control systems collect data, monitor and alter machining parameters, and automate various manufacturing processes. They also precisely control machinery movements, tool changes and adjustments, and production sequences. As a result, they ensure consistency in product quality, reduced human intervention, and greater efficiency. As CNC machining technology evolves, CNC machines can accomplish more operations in one setup, taking up less time. 

Core Efficiency Metrics in CNC Operations

A common practice in many shop floors is the reliance on CNC machine control systems to collect performance-related information during machining operations. Sensors fitted into the machines facilitate continuous data collection on various aspects of operations, from production-related characteristics and performance metrics to machine health and efficiency metrics. For instance, these sensors measure parameters like vibration, temperature, and motor current. They also monitor machine components like tool heads, bearings, spindles, motors, and actuators, just to mention a few.

Analyzed data helps with predictive maintenance of CNC machines, enabling control systems to detect irregularities or signs of wear. In addition, the embedded machine control systems use this data to automatically manage and modify process parameters, thereby maintaining accurate operating conditions throughout the metal fabrication process. They rely on this data to optimize machining efficiency. This brings us to the core efficiency metrics in CNC operations collected by machine control systems:

1. Cutting Speed

Also known as the surface speed, the cutting speed takes on many definitions depending on the type of cutter. The surface speed of a drill, for example, refers to the speed in meters per minute or feet per minute of the drill rim. The cutting speed of a sawing machine refers to the blade’s velocity, expressed in meters per minute or feet per minute. It is worth noting that the cutting speed depends on the hardness, machinability, and structure of the material being machined.

A low cutting speed translates to low efficiency. Conversely, when the cutting speed is too high, the blade or drill dulls or wears too quickly, prompting regular replacements and regrinding of cutters damaging the workpiece. If the cutter is not changed, it can burn up due to excessive fiction, ruining the workpiece. Extremely high cutting speeds also affect machine efficiency.

2. Feed Rate

Feed rate refers to the speed at which the cutter travels along a distance known as feed before reaching the workpiece. It is measured in millimeters per minute (mpm) or inches per minute (ipm). Feed rate directly affects the productivity and efficiency of a CNC machine. For instance, a high feed rate could damage work tools and the workpiece, requiring corrective measures that could take unnecessarily long to complete. This way, a high feed rate would negatively impact quality. Thus, the feed rate must fall within the optimum ballpark for the best results. 

The feed rate is independent of the spindle speed (the RPM of the spindle). Feed rate depends on a number of factors, including:

• Availability of lubrication
• Depth and width of the cut/hole (which affects the ability to remove chips out of the hole)
• Workpiece material type and its strength and material uniformity
• Cutter parameters like the size of the cutter, cutter material, cutter sharpness, and type of cutter
• Expected finish
• Required accuracy or tolerance of the hole
• Power, rigidity, and strength of the machine/setup

3. Material Removal Rate (MRR)

One of the efficiency metrics in CNC operations, material removal rate (MRR) is the volume or weight of material removed from the surface of a material within a given period, usually per minute. A high MRR indicates high efficiency, while a low MRR signals low efficiency. The MRR depends on the combined effect of the feed rate, cutting speed, and depth of cut. For instance, slow cutting speeds result in inefficient MRR because of tool breakage, poor finish, and slow production, while optimum cutting speeds cause efficient MRR.

4. Tool Wear and Tool Life

Tool wear is one of the efficiency metrics in CNC. It is a crucial predictor of the useful life of tools. In addition, it affects the quality of machined parts. For instance, tool wear causes a loss in the dimensional accuracy of finished products, decreases the surface integrity, amplifies unwanted vibrations in the tool and workpiece (chatter), and damages the workpiece. These outcomes often affect efficiency. 

You can measure tool wear either indirectly or directly. The former approach involves the estimation of the signals emanating from various signals, such as current consumption, vibration, feed forces, acoustics, and surface texture. The latter involves using a calibrated tool to take measurements over the tool wear zones. 

The CNC machine control system can be configured to detect a decrease in the tool life, at which point it can adjust parameters that prolong tool life. For instance, it can adjust the cutting speed, feed rate, and volume of lubricant discharged. 

5. Revolutions Per Minute (RPM)

Revolutions per minute or RPM is the spindle speed. It is defined as the number of times per minute the spindle goes around the longitudinal (spindle) axis. RPM affects the surface speed. Larger drills require slower RPMs than smaller drills to achieve the same surface speed at their rim. For instance, drills smaller than 3 mm or 1/8 inches in diameter require a high RPM of 12,000 or more for efficient cutting and to avoid breakage. A larger drill will require less RPM.

In addition to the cutter size, factors like the type of alloy being machined, its hardness, and the operation being performed also affect the RPM. This means there is an optimum surface speed for each material being drilled or cut. Within the context of drilling, five different approaches have been advanced to determine the right RPM for a drill, including:

• Built-in RPM calculations in CAM software
• Dedicated calculator app
• Operator experience
• Standard formula (RPM equals four multiplied by the surface speed divided by the diameter of the drill)
• RPM chart

Advanced Metrics for Deeper Insights

1. Rejection Rate and Part Quality Rate

The rejection rate is the number of parts fabricated within a given period that do not conform to the design specifications and must, therefore, be discarded. In this regard, rejections simply signify that time was lost when creating the defective part. A high rejection rate indicates failures at different stages of the metal fabrication or machining process. Put simply, it negatively affects the efficiency of the CNC operation. 

On the opposite end of the spectrum is the part quality rate. The part quality rate relates to the number of quality parts produced within a given timeframe. A high part quality rate indicates the high efficiency of the CNC machining process.

2. Overall Equipment Efficiency

Overall equipment efficiency (OEE) is a measure of machine performance. It is affected by problematic events such as damage to machine components. OEE is expressed as a percentage. It is calculated by multiplying various variables, including the availability of the machine, part quality rate, and performance efficiency. To assess the availability of the machine, you have to consider the setup time, tool change cycle time, breakdown time, maintenance downtime, and work time. 

3. Power or Energy Consumption

Power or energy consumption is one of the advanced efficiency metrics in CNC machining. It is an excellent indicator of a CNC machine’s uptime. The longer a machine runs, the higher the energy consumption. In the same vein, a higher machine’s uptime leads to the production of more units, hence higher efficiency. If the energy consumption is low, that typically implies that the machine ran for a short time and, as a result, produced fewer units. Put simply, low energy consumption signals less efficiency.

4. Cost per Part

Cost per part is calculated by dividing the total production costs by the number of parts machined. A lower cost per part indicates that more parts have been produced, signaling higher efficiency. Conversely, a higher cost per part signifies that few parts have been produced, translating to lower efficiency.

Other Parameters Affecting Efficiency in CNC Machining

Besides the core efficiency metrics in CNC machining, other factors or parameters can impact the efficiency of your CNC machining operations. They include:

1. Part-to-Part and New Setup Turnaround Time

Whether you want to make a one-off part or several parts, you have to set up each individually. For added accuracy and, by extension, to boost efficiency, you have to undertake probing in CNC machines, either manually or automatically. Therefore, within this context, the turnaround time refers to the time it takes to secure a part using chucks or change parts. The turnaround time usually depends on the type of CNC machine. Machines that support automatic part changes generally have a shorter turnaround time than manual machines.

Another factor affecting the turnaround time is the work-holding method (e.g., jawed or collet chucks). For instance, collet chucks have a faster turnaround time than jawed chucks. On the other hand, mandrels have a moderately slow to very slow turnaround time, while face plate setups are very slow. 

2. Inefficient CNC Programs

Naturally, an inefficient CNC program translates to inefficient machining. Such a program can contain instructions defining inefficient and unnecessary toolpaths that lose valuable machining time. For this reason, it is crucial to write programs that define better and dynamic toolpaths. 

These toolpaths are bound to provide new and efficient ways of machining materials. Coupled with the fact that modern machines can perform high-speed machining, these toolpaths greatly enhance efficiency. It is worth pointing out that the skill to write such CNC programs comes with experience. So, if you are a beginner, you can use CAM software to generate the programs.

3. Ongoing Maintenance Downtime

CNC machines require regular maintenance. Typically, operators refill lube and coolant levels, replace drill cutters, and service motors, just to mention a few maintenance activities. While these tasks do not ordinarily involve machining, they must occur to ensure the longevity of the expensive machines. 

In some cases, some of these tasks can be undertaken as the machine is running. But in other cases, operators have to switch off the machine to carry out maintenance. This is known as maintenance downtime. It affects efficiency or efficiency metrics in CNC machining because it reduces the number of parts a machine can make within a given fixed timeframe.

4. Tool Changing Cycle Time

Modern CNC machines can store, sort, and automatically change the machining tools. Some can store at least 16 to 18 cutting tools and are configured with conveyor systems or tool carriage extensions to hold the tools and facilitate tool changes. 

However, despite the existence of such features, tool changes are not instantaneous. The machine has to stop machining, retract the tool, change it, and then move the tool to the workpiece to continue machining. The time difference between the sequential cuts with two different tools is known as the chip-to-chip or tool-to-tool cycle time. It goes without saying that a long cycle time affects efficiency.

5. Hybrid Manufacturing

Hybrid manufacturing combines two or more manufacturing processes, each using a distinct technology or active energy source. These processes, technologies, and energy sources interact and influence each other, either sequentially or simultaneously, in a controlled manner within the same machine. This interaction promotes faster material removal (i.e., shortens the machining time), enhancing efficiency. Similarly, hybrid micro-machining achieves efficiency in more or less the same manner. 

6. Retract Height and Rapid Travel

The retract height, R, is the safest distance from a workpiece at which the tool is positioned. On the other hand, rapid travel (or simply rapid) is the fastest speed a CNC machine can produce to move the tool from the retract height to the workpiece for machining or from the workpiece to the retract height for a tool change. 

The rapid and retract height impact efficiency since shortening the retract height reduces travel distance. While this helps save only a few seconds or milliseconds, the time savings often compound. It is, however, worth pointing out that a short retract height can cause safety issues. So, only shorten this distance if you are an experienced operator and if your shop’s policy allows.

Illustration Showing Retract Height (R) (source)

In addition to the above, other factors affecting the efficiency of CNC machines include: 

• Machine control systems’ user experience (user-friendliness)
• Faster acceleration in CNC waterjet machines.

Improving Efficiency through Technology

Technology is increasingly finding its way into manufacturing plants and machine shops as companies and professionals look for ways to improve efficiency and productivity and reduce costs. This is part of a concerted effort to embrace and implement Industry 4.0, a paradigm characterized by integrating smart digital technologies into industrial and manufacturing processes.

The list is endless, from model-based enterprises (MBEs), which rely on 3D CAD models to manage and organize business processes, to the digital thread, digital twins, and more. Companies also use cloud computing, edge computing, the Internet of Things (IoT), artificial intelligence, robotics, automation, and much more to improve efficiency. The following technologies can be used to improve the efficiency of CNC machining:

1. Sensors

Sensors collect and monitor crucial manufacturing and machining data. Sensors measure crucial operational parameters like temperature, vibration, humidity, and pressure. These parameters are reliable indicators for issues that can impact efficiency. For instance, vibration or chatter can indicate excessive RPM speed, poor holding method, high depth of cut, and more. Elevated temperatures coupled with low humidity can indicate a lack of lubrication.

2. CAM Software

CAM software can improve CNC machining efficiency by ensuring precise, accurate, and fast machining. For instance, this software can quickly identify and create drill points around the cross-section of the digital model of a part. The software can also create cut sequences that remove excess material before actual machining commences. Moreover, CAM software can calculate the requisite drill RPM, which promotes efficiency.

In addition to these capabilities, advanced CAM software can regenerate or reprocess a CNC program once generated to create more efficient arcs that fit irregular shapes. This way, CAM software enables operators to machine creative new shapes that would be impossible to make otherwise. CAM software also makes it easier and less costly to use CNC machines.

3. Robotics and Automation

The availability of skilled labor is one of the challenges plaguing manufacturers in today’s fast-paced world. And with machinists and operators constantly needing to learn new skills to keep up with emerging trends, human resources can be a thorn in the flesh for manufacturers. This is despite the fact that such companies must continuously increase overall efficiency. Fortunately, companies can solve the human resources challenges by embracing automation. Automation maximizes machining by eliminating human-induced delays. 

Today, some modern CNC machines, like Okuma’s ARMROID and STANDROID, have built-in robots packaged within the machine. This robot performs in-machine cleaning, part loading and unloading, chip removal, and chatter suppression. To further boost automation, you can configure your CNC machines with automatic pallet changers and gantry loaders. 

4. Artificial Intelligence

There are plenty of different ways artificial intelligence (AI) can be applied to enhance the efficiency of CNC operations. For instance, data collected by the various sensors can be analyzed to establish trends that can accurately predict events. It is this exact approach that makes predictive maintenance possible. Machine learning algorithms use the data collected to build models that can predict future breakdowns. Predictive maintenance helps avoid unexpected breakdowns, which could result in prolonged downtime, adversely affecting efficiency.

The second application of AI is in CAM software. For instance, CAM Assist, a plug-in for Autodesk’s Fusion 360 software, uses AI inference techniques and computational optimization to establish the toolset and manufacturing strategy needed to create a part. It also uses this technology to determine the optimum feed rate and cutting speed. Reports show that the plug-in can reduce by 80% the time it takes to create a CNC machine program. In a typical machine shop or manufacturing company, such a reduction enhances efficiency and saves time. Other software like GibbCAM, Cimatron, and SigmaNEST are also using AI to boost the efficiency and productivity of the programming process.

Strategies for Continuous Improvement

1. Real-time Monitoring

Real-time monitoring refers to the practice of continuously receiving up-to-date data on CNC machines, machining processes, and systems with no delay between data collection and analysis. Access to real-time data enables machine operators, manufacturers, and shop owners to identify and respond swiftly to any emerging issue that may affect efficiency. This way, real-time monitoring reduces downtime. And given that CNC machines must have an uptime of 90-95% to pay for themselves, the wages of operators, overhead costs, and profits, real-time monitoring has a financial benefit, too.

2. Lean Manufacturing

Lean manufacturing focuses on quality control to eliminate waste and enhance process and product quality. It is intended to satisfy customer demand, meaning products are only produced if and when needed. As a result, companies that adopt lean manufacturing principles use less material and inventory, require less investment, and take up less space. Still, additional benefits abound. For instance, companies implementing lean principles have reported a 90% reduction in cycle time, a 50% increase in productivity, and an 80% improvement in quality.

3. Training

Training is a proven strategy to equip your employees, colleagues, and machine operators with the knowledge and skills to easily identify and eliminate wastefulness and boost efficiency. For instance, the training programs could discuss important efficiency metrics in CNC, including materials’ best cutting speed and feed rate. They could also detail how MRR, tool wear, cost per part, part quality rate, and other efficiency metrics in CNC boost quality. It is worth pointing out that the knowledge gained from training programs will likely also enhance employees’ productivity.

4. Updating and Using High-Quality CAM Software

Always use high-quality, up-to-date CAM software. This is because such software will expectedly have advanced features that enhance the efficiency of CNC operations. Moreover, up-to-date software includes newly introduced features, some geared towards greater efficiency.

5. Regular Maintenance

Regular maintenance of CNC machines boosts uptime. It enhances the machines’ work time, ensuring they produce parts longer, thus improving efficiency. Regular maintenance achieves this by maintaining the machine in top-notch condition and preventing breakdowns that could lead to prolonged downtimes.

Conclusion

Efficiency is a much sought-after outcome for manufacturing companies. It helps them reduce costs, optimize energy consumption, and enhance productivity. Efficiency in CNC machining refers to the number of parts or units produced within a given period. It depends on several factors, including tool changing cycle times, part-to-part turnaround time, usage of hybrid manufacturing methods, the rapid and retract height, efficiency of the CNC programs, and ongoing maintenance downtime. 

While you can measure efficiency directly by counting the number of parts produced in a given time unit, you can also use a number of efficiency metrics in CNC. These include the cutting speed, tool wear and tool life, feed and feed rate, material removal rate, and revolutions per minute. You can also use advanced efficiency metrics in CNC machining, including the overall equipment effectiveness, rejection rate and part quality rate, cost per part, and energy consumption. If, by using these metrics, you establish that your CNC machines’ efficiency is wanting, you could integrate technologies like sensors, AI, automation, and advanced CAM software to improve efficiency. You could also implement strategies like real-time monitoring, regular maintenance, training, and lean manufacturing to further boost the efficiency of your CNC machining operations.

Against this backdrop, national, regional, and international standards organizations were set up and tasked with developing agreed standards. As a result, today, many such bodies have set and are constantly updating standards and regulations. The standards cover virtually all industries, from design to manufacturing and construction. Given the panoply of regulatory standards, getting lost in the sea of specifications and regulations is easy. So, how about we narrow it down for those in the CAD and/or CNC industries? Today, let’s talk about CAD/CNC compliance with regulatory standards.

Key Regulatory Standards in CAD/CNC Industries

What is a Regulatory Standard?

A regulatory standard is any set of rules, regulations, or guidelines set forth by a regulatory body or industry standards organization and widely accepted by general consent as the most appropriate way of doing things. A standard is often viewed as a recommendation; it provides the minimum requirements. It tells professionals and users how to perform a certain task but does not have an anchoring in law. 

Thus, while following the recommendations of a standard can be beneficial, not doing so may not result in a penalty. In fact, you can exceed the requirements stipulated in a standard if doing so has certain demonstrable benefits. The bottom line is that a regulatory standard is not always enforceable.

What is enforceable is a code, which, by definition, is a set of standards that are set and enforced by a body such as a local government for the protection of health and public safety. Therefore, in practice, many standards combine to create a code. And it is only when these standards are part of a code that they become enforceable. Today, there are many codes that cover multiple industries, from design (CAD) to manufacturing (CNC). These include: 

• Health code: It contains a set of standards that document the health requirements for ventilation, air conditioning, and plumbing) 
• Building code: It is a set of regulatory standards that ensure the structural safety of buildings)
• Fire code: It provides specifications for emergency exits and fire escapes
• Highway code: It documents information, advice, guides, and rules for all road users

Importance of Regulatory Standards

1. Welfare Protection

Regulatory standards and codes help regulatory agencies and governments protect the welfare of the population they serve. For instance, within the context of urban planning and architecture, regulatory standards set limits on what can be designed and developed. This prevents congestion, boosts residents’ quality of life, and avoids straining public facilities. 

The same applies to regulatory standards that govern the design and manufacture of vehicles and aircraft. With the safety of road users and passengers being paramount, regulatory agencies require manufacturers to adhere to strict guidelines that reduce the severity of accidents or eliminate them.

Broadly speaking, regulatory standards and codes aim to prevent injuries or loss of life and prevent property damage. They provide pointers that help organizations and professionals to eliminate, reduce, or avoid definable hazards. 

2. Conformity

Standards help companies to evaluate the conformance of all parts they design and produce. They provide a template against which to analyze and assess deviations from the recommendation. Moreover, considering the industry-wide adoption of the standards, consumers and companies can make head-to-head comparisons between competing products. Let’s look at the vehicle manufacturing industry to illustrate this point better. 

Here, different manufacturers design and manufacture various models for each class of vehicles. Classes in this context refer to coupes, sedans, trucks/pickups, and lorries, just to mention a few. But for a car to be placed in any of these categories, it must meet certain standards and requirements, such as the interior space and number of doors, for example. Such standards ensure conformity. They allow consumers and companies to compare the available models of cars within a particular class, even when they are made by different manufacturers. 

3. Performance

As a recommendation, a regulatory standard provides the minimum requirements needed to achieve the minimum level of performance. This means that exceeding the standards can be advantageous if this intervention has demonstratable benefits. 

For instance, the IEC 60601-1-11 standard stipulates the general requirements for basic safety and essential performance of medical electrical equipment used in the home healthcare environment. It recommends an operating temperature range of 5°C to 40°C. Yet, some environments have harsh weather and climatic conditions. 

To accommodate such areas, manufacturers can design, manufacture, and test equipment that withstands harsh environments. This could benefit customers in such areas, as it would reduce the chances of device failure or regular service. Simply put, meeting performance targets sometimes requires teams to go beyond minimum CAD/CAD compliance. 

4. Ensure Quality and Reliability

CAD/CNC compliance with the various regulatory standards maintains the quality and reliability of manufactured parts. For instance, as we detail below, specific standards require process validation, which helps identify flaws. Process validation helps machinists and companies to confirm whether the CNC machine can fabricate parts that meet specifications and do so repeatedly. In this way, compliance produces consistent production results. Similarly, machinists can consistently produce quality products by complying with standards that require safe machine operation. 

Regulatory Standards in CAD and CNC Industries

There are various government regulatory standards and bodies that require CAD/CNC compliance, including: 

• ISO standards like 9001 and 14000
• The US Food and Drug Administration (FDA) regulations 
• The US Federal Aviation Administration (FAA) regulations
• EU’s Restriction of Hazardous Substances (RoHS) directive
• The International Traffic in Arms Regulations (ITAR)
• The American National Standards Institute (ANSI) standards
• Eurocode standards
• The International Electrotechnical Commission (IEC) standards
• The Institute of Electrical and Electronic Engineers (IEEE) standards
• American Society of Mechanical Engineers (ASME) standards

This section covers a few regulatory standards from these bodies that specifically apply to the CAD and CNC industries. These include:

1. ISO 9001 Quality Management Systems

The ISO 9001 standard helps companies address all elements of managing the quality of their product. It emphasizes customer satisfaction and the continuous enhancement of the formalized system of processes, procedures, and responsibilities for implementing quality policies and achieving quality objectives. 

2. ISO 14001 Environmental Management Systems

The ISO 14001 standard guides the implementation of ISO 14000. For its part, ISO 14000 is a family of environmental management standards covering greenhouse gas accounting, carbon footprint measurement, and verification and emissions trading. ISO 14001 provides a guide that helps organizations, including those in the CAD and CNC industries, minimize the environmental impact of their operations. CAD/CNC compliance with this standard helps organizations to improve their environmental performance on an ongoing basis.

3. ISO 23125 Machine Tools Safety

The ISO 23125 standard specifies the compliance requirements as well as measures to reduce the risks or eliminate the hazards in a specific group of CNC machines called turning centers and turning machines. It ensures the safe operation and use of turning centers and machines. 

4. ISO 12100 Safety of Machinery

The ISO 12100 standard is designed for companies that design machinery, including but not limited to CNC machines. It specifies the principles of identifying, assessing, estimating, evaluating, and reducing risk with the aim of achieving safety. It helps designers of CNC machines to design safe machines.

5. ISO 45001 Occupational Health and Safety

The ISO 45001 standard provides a framework CNC machinists and companies can use to identify, assess, manage, and reduce the risks associated with health and safety within the workplace. It also helps organizations to improve operational health and safety (OH&S) performance. It establishes criteria for OH&S objectives, policies, auditing, review, operation, implementation, and planning. 

6. IEC 60204-1 Safety of Machinery

The IEC 60204-1 standard applies to the electrical, electronic, and programmable electrical parts or equipment found in CNC machines and other machines. It helps minimize or eliminate occupational hazards while operating machines that use either direct current or alternating current. It helps operators and machinery manufacturers to adopt the best industry safety requirements.

7. ISO 13485 Medical Devices

The ISO 13485 standard aims to ensure the safety, quality, and effectiveness of medical devices. It is designed for companies and businesses that design, produce/manufacture, install, and service medical devices. It outlines requirements that ensure CAD/CNC compliance within the medical devices industry.

In a bid to promote consistency in the regulation of medical devices, the FDA in February 2024 issued the Quality Management System Regulation (QMSR) Final Rule. The rule becomes effective two years after publication and incorporates the ISO 13485 standard. This regulation includes requirements that specify recommended methods for designing, manufacturing, and servicing medical devices.

8. AS9100 Aerospace Management Systems

The AS9100 standard is based on and works in conjunction with ISO 9001. It is a standardized quality management system for the aerospace (aviation, space, and defense) industry. The standard sets the basic quality management system requirements, adding more than 100 compliance requirements to the ISO 9001, with these additional requirements applying only to the aerospace industry. AS9100 is designed for companies that design and manufacture aerospace products or components as well as those that supply materials to the industry. Thus, AS9100 required CAD/CNC compliance within the aviation, space, and defense industries.

9. ITAR Compliance

For US companies that design, manufacture, sell, and distribute defense and space-related products and services defined in the United States Munition List, compliance with the International Traffic in Arms Regulations (ITAR) requirements is paramount. It restricts access to data related to defense and military technologies to US citizens only.

10. CAD Standards

Revisiting our discussion that provided a comprehensive guide to help you navigate the world of CAD standards, we can deduce that those standards can apply to various sectors that need CAD/CNC compliance. After all, for a CNC machine to fabricate a part, there is a high likelihood that a CAD drawing of the part exists. To deliver that CAD drawing, the designer or engineer must follow a set of rules that have been accepted within their organization or industry as CAD standards.

Compliance Requirements for CAD/CNC Operations

These standards and regulatory bodies place requirements such as audit trails, risk management, document control, safety, and more. For simplicity, we have grouped the requirements into three categories: data management, design, and manufacturing safety. 

Compliance Requirements for Data Management

CAD and CNC operations involve the generation and use of data, usually stored in files. The data can contain privileged and proprietary information, necessitating the need to regulate access. Additionally, for traceability, it is essential to track changes and record the names of the people who made them. Against this backdrop, common regulatory requirements for data management include:

• Provision of information about changes like the user information and timestamps that are made to files
• The need for specific permissions for accessing, editing/modifying, and approving files
• Documentation of electronic approval or review mechanisms such as digital signatures
• Ability to track outdated files
• Separation of the different levels of access and control for documents and detailing exactly which documents have controlled access
• Retention of old versions of files
• Provision of the ability to search and find documents within a database
• Training requirements for system administrators

Compliance Requirements for Design

In the vehicle manufacturing sector, regulators require manufacturers to implement measures that facilitate easy access to the car, make the car easier to operate, and improve the safety of occupants and pedestrians. For this reason, the European Commission’s Directorate for Mobility and Transport, for example, lists the recommended dimensions for the height of door frames above ground, seat height above ground, width of door openings, door opening angle, doorsill height, and more. These dimensions are incorporated early in the product lifecycle during the design phase.

Similarly, regulatory bodies like the US Federal Aviation Administration (FAA) and the European Union Aviation Safety Agency (EASA) have stringent requirements for emergency exits, aisle widths, video monitor position, fittings, and more. In addition, the FDA has compliance requirements related to the methods used for designing medical devices. The body mandates device manufacturers to formulate and follow quality systems known as current good manufacturing practices (CGMP).

Compliance Requirements for Manufacturing Safety

A lot can go wrong during manufacturing, leading to injuries, damage, or loss of life. However, proper safeguards can prevent or eliminate these adverse events. To achieve this, machine manufacturers have to design their machines for safety. They must include safety features like spindle or foot brakes for CNC lathe machines and reachable emergency stop buttons. Moreover, manufacturers need to provide clear instructions and make it easy for users to perform regular maintenance.  

What’s more, regulatory bodies require manufacturers to establish and abide by quality systems that help them ensure their products consistently meet relevant specifications and applicable regulatory requirements.

Implementing CAD/CNC Compliance Strategies 

Compliance with regulatory standards and regulations should start during the early design process. This approach eliminates surprises that can lead to missed milestones, delays, penalties, and expensive reworks. And given that funding for small companies and start-ups in industries like medical device manufacturing is tied to regulatory milestones, missing such milestones can lead to closure or bankruptcy. It is, therefore, essential to implement the following CAD/CNC compliance strategies that ensure adherence to regulatory standards:  

1. Identify and understand applicable/relevant regulatory standards
2. Consult regulatory affairs experts and incorporate their expertise
3. Develop a compliance management system
4. Implement training programs
5. Conduct regular reviews and compliance audits
6. Use compliance software tools
7. Validate CNC machining capabilities and other fabrication processes
8. Implement traceability

Identify and Understand Applicable Regulatory Standards

The foundational step involves identifying regulatory standards that require CAD/CNC compliance. These standards will, of course, vary from one industry to another. This means that you do not expect that certain regulations that medical device manufacturers follow should apply to a woodworking workshop. 

To further illustrate the fact that standards are not always universally applicable, let’s take the example of ISO 9001. This standard is broadly designed to provide a template against which companies across all industries can implement quality management systems. However, as we have highlighted, some industries have used this standard as the basis for creating customized compliance requirements for the organizations therein. 

Consult Regulatory Affairs Professionals

Companies can – and should – incorporate regulatory affairs professionals or professionals with extensive regulatory experience directly into the CAD design teams. This incorporation ensures that the professionals address regulatory concerns and requirements early during the planning and design phases. This strategy ensures that team members create designs that subsequently allow the manufacture or construction of products, parts, or buildings that align with compliance requirements and regulatory standards.

Develop a Compliance Management System

A compliance management system captures the compliance policies and procedures that detail approaches to follow in order to comply with regulatory requirements. Thus, to build the system, you implement the following:

• Identify compliance requirements
• List compliance policies and procedures and assign responsibilities
• Inform employees of the regulatory requirements and their role in ensuring compliance in the CAD and CNC industries
• Schedule CAD/CNC compliance audits and mechanisms to monitor regulatory changes
• Implement measures to update policies and procedures based on identified changes

Implement Training Programs

Frequent compliance training workshops, seminars, or programs enable employees to learn about the regulatory requirements. The programs also allow them to learn their roles in promoting CAD/CNC compliance. These training programs often cover a variety of topics, including regulations and guidance, quality, safety, and more. 

Companies can conduct the training in-house or enroll their employees in training programs offered by third parties. The programs keep employees abreast with the latest regulations, providing resources that promote CAD/CNC compliance with the standards. It also equips machine operators and CNC machinists with the knowledge and proficiency to safely operate machinery, deal with emergencies, and identify and manage hazards.

Perhaps to supplement the training initiatives by companies, regulatory bodies can – and often do – offer training programs. For instance, the FAA’s Regulatory Standards Division provides technical training to inspectors, engineers, and pilots. This training program aims to help the professionals work together to set and maintain the highest standards of safety. It is also designed to enable them to provide the public with the safest national airspace. This training covers the fields of manufacturing, avionics, aircraft certification, and more.

Conduct Reviews and Compliance Audits

Regulatory standards are updated from time to time. At the same time, regulatory agencies regularly introduce new rules that come into effect after a predefined period. Companies, therefore, need to always be on the lookout for changes. They must also ensure their internal policies and procedures, training programs, and tracing methods align with the changes. This is where auditing comes in. 

Compliance audits evaluate policies and procedures, training programs, data management, and traceability methods to identify non-compliance. They aim to identify gaps in your CAD/CNC compliance system. They also provide the information needed to take corrective action. Moreover, the audits illuminate compliance risks and point out ways to avoid them. 

In addition to the in-house audits that companies conduct, regulatory bodies like the FDA usually perform their own regulatory audits. Such bodies hire out this task to recognized auditing organizations. These inspections/audits aim to assure compliance with regulatory requirements.

Reviews, on the other hand, are essentially internal discussions that involve various team members from different departments. They assess designs, manufacturing and metal fabrication processes, and technologies (like the digital twin and digital thread) to identify and resolve regulatory issues. The discussions can create opportunities to change designs, averting costly modifications later during other stages of the product’s lifecycle. They can also birth decisions to change manufacturing approaches or the technologies used. The main objective of the reviews is to ensure that at no point is any underhand approach used to circumvent regulatory compliance or obscure them.

Use Compliance Software and Tools

Technology, if used as intended, can help to streamline processes. Today, there are a multitude of tools that can simplify compliance with complex compliance requirements. A few examples of software tools that aid in CAD/CNC compliance include: 

1. Tekla Tedds Integrator: this CAD tool can check whether steel connections in a Tekla Structures model comply with Eurocode design. The tool includes built-in automatic data transfer for simple steel connections, structural concrete, and precast concrete elements. 
2. STAAD.Pro: this CAD design tool can perform design based on specific provisions of various design codes. These include the British, American, Australian, Canadian, European, German, French, Japanese, Russian, South African, and Indian codes, just to mention a few.
3. CAVA (CATIA Automotive Extensions Vehicle Architecture): CAVA is an industry-proven add-on software by Technia. It helps vehicle manufacturers to validate design and architecture compliance. The tool provides, as CATIA features, rules, norms, and standards that vehicle manufacturers must fulfill. It then checks the vehicle geometry against the rules, ascertaining that it meets legal requirements. CAVA fully integrates with CATIA V5, CATIA V6, and CATIA 3DExperience.
4. SolidWorks PDM can facilitate compliance with government regulatory requirements and industry standards. It can help organizations secure, track, and protect their product data. 
5. PTC’s WindChill ships with productivity tools that comply with the FDA’s Unique Device Identification (UDI) requirements. The UDI requirements call for the capturing of product numbering, version information, and configuration data. In addition, the UDI capabilities support review and approval workflows that automate the processes of submitting product data to the FDA.
6. PTC’s Creo automatically checks tolerances for compliance with the American Society of Mechanical Engineers (ASME) Y14.5 standards.

Validate CNC Machining Capabilities 

Quality management standards like ISO 9001 or AS9100 have process validation requirements. Process validation helps companies ascertain that their subtractive manufacturing (CNC machining) or additive manufacturing processes result in parts that conform to specifications. One of the ways to validate manufacturing processes is through first-article inspections (FAI).

In FAI, an external inspector takes a random sample from the initial production run. They then use the custom specifications to evaluate conformity. Usually, the inspector uses scrape testers, calipers, micrometers, millimeters, 3D scanners, and coordinate measuring machines to measure dimensions and features to confirm whether they conform with the engineering drawing. 

Another validation method is the process capability analysis (PCA). Like FAI, PCA also involves sampling. Under PCA, however, data is corrected from multiple parts manufactured during the initial run. These data are then used to predict whether the manufacturing process can repeatedly fabricate or create parts that conform to specifications.

FAI and PCA validate a CNC machine’s ability to fabricate a designed product. It ensures CNC compliance with quality management standards. 

Implement Traceability

Traceability is the next logical step that follows the discovery that a production process or machine is flawed. This requires tracing parts or errors to an operator, machine, method, measurement system, material, and environmental conditions. Traceability helps companies improve processes, ensuring CAD/CNC compliance with quality management standards. 

The Impact of Non-Compliance

There are several consequences of non-compliance, including:

1. Delayed Approval 

Regulatory bodies only issue approvals when they are satisfied with the demonstrated level of compliance with regulatory standards, codes, rules, and regulations. For instance, a lack of CAD/CNC compliance during the design and manufacturing stages can lead to multiple rounds of regulatory reviews. 

In some cases, the non-compliance may be because of a lack of information on the applicable regulatory requirements. And while this is no excuse, it is an understandable oversight. However, in other cases, the non-compliance results from a deliberate effort to game the system to speed up processes. But as it quickly becomes clear, delayed approvals greatly slow down the processes. They lead to missed milestones and deadlines. 

2. Added Expenses 

In addition to wasting time, non-compliance can be costly. The delays, which affect the delivery of products, lead to missed revenues. Additionally, the numerous rounds of regulatory review mean the company spends more on outsourced review experts, which adds a substantial cost to the development budget. Additionally, non-compliance can – and often does – lead to penalties. One company that best illustrates this is Boeing. In 2021, the FAA ruled that Boeing should pay at least $17 million due to non-compliance. This was on top of other penalties announced that year.

3. Injuries and Loss of Lives

Non-compliance can have disastrous consequences. Injuries and loss of lives become likely outcomes in cases where safety is disregarded. And if it is proven that the injuries or deaths resulted from a deliberate disregard for safety, a company could incur additional monetary liabilities. Another intangible loss that would likely follow is reputation damage.

4. Poor Quality of Products

Certain regulatory standards emphasize quality. Design or manufacturing processes that disregard the quality recommendations will likely produce poor-quality products. 

Conclusion

Navigating the complex web of regulatory requirements can be daunting, from the complexity of the regulations to the fact that they are constantly updated. This makes compliance a not-so-straightforward process. Fortunately, there are compliance strategies and tools you can use. To comply with these requirements, you must identify applicable regulations, create policies and procedures that guide compliance, conduct regular audits, train employees, validate processes, implement traceability measures, and more. Within the context of CAD/CNC compliance, software can be handy compliance tools that help simplify certain aspects of otherwise complex processes. Given that adhering to the regulatory requirements offers benefits such as welfare protection, savings, prompt approvals, performance, and quality, the decision to comply with the standards and regulations is indeed wise. 

This ultimate guide is a comprehensive discussion of CNC machining for metal fabrication, beginning with the fundamentals of CNC machining and metal fabrication, transitioning into the role of CNC machining, the materials employed, as well as associated challenges and solutions.

Understanding CNC Machining

What is CNC Machining?

Computer Numerical Control (CNC) machining is a manufacturing process where programs, written in languages like G-code and M-code, direct and operate machine tools. Often, the programs direct the tools to cut or shape material, creating parts with distinct forms and features. CNC programs achieve this by: 

• Directing the movement of the tools along the various axes
• Regulating spindle speed, cutting speed (the distance the tool moves inward relative to the machined part), or feed rate (the distance the tool travels in relation to one complete revolution of the part) 
• Initiating automatic tool changes
• Executing on-and-off functions like controlling how and when the machine sprays the coolant
• Regulating the rotational speed of a part around the z-axis, typical in a turning center.

Importance of CNC Machining

CNC machining offers numerous advantages, which have influenced the ballooning use of CNC machines in manufacturing. In fact, the global CNC machine market size is projected to grow immensely from $86.83 billion in 2022 to $140.78 billion in 2029. Driving this expected growth are the following benefits:

1. Greater Efficiency

Typically, an operator or technician checks the path in computer-aided manufacturing (CAM) software before post-processing. During such checks, the software simulates the cutting action, allowing the technicians to identify and correct actions that the machine or its tools cannot perform practically.

2. Enhanced Flexibility

CNC machining supports a variety of operations within the same machining cycle, provided the program contains code that directs all these operations.

3. Better Safety

CNC machining promotes safety by automating processes and operations that were previously conducted manually. This means operators no longer need to handle certain tasks like changing cutting tools or adjusting feed rates manually. They instead sit or stand in a safe position, away from the orderly mayhem of the machine.

4. Improved Accuracy

By doing away with manual operations, CNC machining eliminates human errors, thus boosting part accuracy. It, therefore, makes it possible to achieve tighter tolerances.

5. Less Lead Times

CNC machining reduces lead times by expediting machining jobs. Moreover, the machines can optimize the feed rate and cutting speeds based on the material. What’s more, the CNC machines ensure less part handling. Combined, these factors significantly reduce machining time.

6. Better Mass Customization Capabilities

With workshops and manufacturing plants increasingly adopting technology to improve efficiencies, digital manufacturing has become a reality. With it, mass customization has equally gained traction. Currently, with the use of online tools, it is possible for customers to order personalized designs or to personalize existing designs. Their orders are then incorporated into the production process using product lifecycle management (PLM) software. But that’s not all. The design files are converted to instructions that are fed into CNC machines for production. CNC machining, thus, enables machine shops to produce bespoke products at scale with little to no variations in the cost per unit. 

7. Increased Production

By reducing the machining time, CNC machining facilitates increased production. More parts can be produced within a short time.

8. Ability to Machine Complex Parts

The machines can produce complex parts by simply following a predefined path. Moreover, CAM software and the integrated post-processors can generate instructions for even the most complex parts. Thus, you need not have a background in creating G-code or M-code to machine intricate features that form complex parts.

9. Reduced Storage Space and Inventory Requirements

CNC machining reduces setup time and increases the speed of production. At the same time, these advantages minimize the wait times, which means materials spend less time in storage awaiting fabrication. Combined, these advantages diminish storage space and inventory requirements.

10. Less Scrap

CNC machines automate manual processes, eliminating errors that would have arisen from human input. Moreover, depending on the machining process, these systems can achieve tighter tolerances. Combined, these factors increase the accuracy of cuts or welds, leading to less scrap.

11. Improved Production Scheduling

CNC machines can optimize cutting speeds and feed rates. This, coupled with the fact they take away the need to have humans handling, loading, and unloading times, leads to known production times. And working from such a point of knowledge enables operators to accurately schedule when to fabricate parts as part of an ongoing production process.

12. Longer Tool Life and Lower Tool-Related Costs

Machining technology has advanced significantly; CAM software can now generate tool paths that align with the tool’s shape. This eliminates the need to create precision-ground form tools, as was the case before the advent and increased popularity of CNC machining in metal fabrication. Moreover, CNC machining optimizes the cutting speed and feed rate. This results in longer tool life because the fabrication process does not result in unnecessary tool wear associated with the imposition of an unnecessary amount of force.

13. Overall Cost Savings

In summary, the combined advantages, including longer tool life, reduced production times, enhanced safety, and more, lead to overall cost savings in manufacturing.

Metal Fabrication and Its Importance

What is Metal Fabrication?

Metal fabrication is the process of shaping, assembling, or building a part, product, or equipment from raw metal stock. IIt encompasses various manufacturing steps and processes: cutting, burring, material removal, bending, assembling, welding, and finishing. The primary goal of metal fabrication is to produce products with a specific form or shape.

In an industrial context, metal fabrication also encompasses essential non-machining procedures, including planning, bill of materials preparation, raw material identification, purchasing, and storage. However, as mentioned above, CNC machining reduces storage space and inventory requirements. For the purposes of this article, we will concentrate on the machining procedures rather than the non-machining procedures.

Metal Fabrication Steps Explained

Cutting essentially involves removing material along a particular path to obtain a workpiece with a desired length. On the other hand, material removal entails indiscriminately removing material from a particular section of a workpiece or the entire surface of a workpiece. 

Processes for cutting and metal removal encompass milling, drilling, plasma and laser cutting, flame cutting, turning, EDM, waterjet cutting, and punching. In cases where thermal processes are used to cut workpieces, deburring procedures are normally undertaken immediately thereafter. Deburring removes burrs (small imperfections) caused whenever the material in the heat-affected zone melts.

Assembling entails positioning all the parts accurately. In this step, the parts also need proper orientation relative to each other. And to prevent movement, you can tack weld or use clamps to hold them in place. Next, depending on what you are manufacturing, you can weld the parts permanently together. Alternatively, you can bolt the parts in place or use rivets to permanently join them. The subsequent step is finishing. 

Finishing processes can include grinding to achieve a certain surface finish or remove imperfections. Alternatively, to enhance the product’s strength or achieve specific properties, various heat treatment methods can be employed. 

Benefits of Metal Fabrication

The benefits of metal fabrication include:

• The ability to create complex parts
• Versatility and flexibility
• The ability to create products with certain properties

Complex Parts Creation

Metal fabrication can mold metals into distinct shapes and forms. And the advantage of combining CNC machining with metal fabrication lies in the use of CAM software, which simplifies the generation of tool paths that the machines follow when machining features into parts. The instructions are optimized based on the available tools, machines, and processes. Impressively, the software can auto-generate instructions, producing ready-to-use programs. You only need to load the programs to the CNC machine to begin metal fabrication.

Versatility and Flexibility

Various processes can be employed in metal fabrication, including cutting, welding, milling, drilling, turning, and folding, among others. Moreover, you can perform these processes manually or automatically, with the latter approach being more accurate and faster. To automate such processes, you can use CNC machines, which accentuate the role of CNC machines in metal fabrication. 

Achieving Desired Properties

Metal fabrication leverages the inherent properties of metals, allowing the creation of parts and products that retain these desirable characteristics. Still, by using finishing processes such as heat treatment, you can improve the strength attributes of the parts or products.

The Role of CNC Machining in Metal Fabrication

CNC machining and CNC machines play a number of roles in metal fabrication. More specifically, they are used to complete multiple crucial operations, including:

Prototyping

Before a workshop or manufacturing plant decides to build a particular product, a lot has already taken place. For instance, the engineering team will have already used computer-aided design (CAD) software to come up with the designs. They will also have analyzed the models/designs and performed simulations using computer-aided engineering (CAE) software. However, software has its limitations. So, beyond a certain point, it is necessary to perform actual tests using physical models. Enter prototyping and rapid prototyping. 

Rapid prototyping is a collection of techniques used to fabricate within a short time a scale model. This process aids in design evaluation, verification of the functions of models, obtaining customer feedback, and more. 3D printers, a type of CNC machine, are often used to perform rapid prototyping. You can also use CNC mills. Prototyping creates a physical sample for testing and improvements. However, it’s slower than rapid prototyping. 

Milling

In milling, the mill cutter moves along two different axes. For simplicity’s sake, the cutter uses vertical movement while also moving horizontally. This enables the milling machine to create features with distinct shapes. The features can also have varying sizes, with their diameters being much larger than the diameter of the cutter. This contrasts with the capabilities of drilling, as discussed below. 

CNC mill machines are used to automatically perform milling. They can work on hard materials such as titanium, steel, and aluminum. And given that a program dictates how they operate, these machines can make delicate and accurate cuts.

Drilling 

In basic drilling, the drill typically moves along a single axis. This, therefore, means that CNC drilling machines only make cuts or holes of a given diameter or size based on the diameter of the drill. And like the CNC mill machines, the CNC drilling machines complete their operations automatically with minimal operator input.

Turning

Turning is a machining process in which a non-rotary cutting tool moving linearly along two axes (normally the x- and z-axes) removes material from a workpiece rotating along the z-axis. The tool’s movement along the x-axis represents inward and outward movement intended to alter the thickness of the material. On the other hand, the tool’s movement along the z-axis helps the tool reach the entire outer cross-section of the workpiece. This promotes uniformity of material removal. Typically, CNC machines known as lathe machines perform turning operations. 

Electrical Discharge Machining (EDM)

Electrical Discharge Machining, or EDM, is a popular, non-conventional machining process that uses thermal energy to remove material from a workpiece’s surface. It uses electrical current discharges between the cathode (the tool) and the anode (the workpiece) to promote the erosion of material. For the process to work as desired, there must always be a small spark gap between the cathode and anode. The tool feed rate controls the width of the gap.

EDM can machine any material regardless of its hardness. However, its efficiency is limited by a lower material removal rate and significant tool wear. It is also known to result in poor surface quality and residual stresses. That said, hybrid manufacturing methods have been developed to overcome these challenges. These methods include abrasive-assisted EDM, Electrochemical Discharge Machining, and vibration-assisted EDM. 

EDM typically requires electrodes of various shapes. The electrodes can be tube-shaped with one or more bores to drill holes into the workpiece. On the other hand, sinker electrodes remove material by erosion, creating cavities or imprints. They have a 3D configuration and are immersed in the dielectric. However, wire EDM was developed to replace the variety of tools initially required when performing conventional EDM.

Metal Cutting

There are multiple distinct ways to cut metals using CNC. These include waterjet cutting, laser cutting, plasma cutting, metal punching, and flame cutting.

Waterjet Cutting

CNC waterjet cutting machines fire highly pressurized water through a diamond or ruby nozzle at a workpiece. The high-pressure stream of water erodes material from the workpiece along a path dictated by the program. However, in some cases, the water stream alone is ineffective at eroding material. In such cases, granular abrasives are added to the waterjet to enhance its cutting power. Modern CNC waterjet cutting machines are advanced enough to allow users to switch between cutting purely using water or adding abrasives to the water based on the properties of the workpiece. 

Plasma Cutting

Plasma cutting is a thermal cutting process because it uses heat to melt a material. CNC plasma cutters pass electric current, in the form of an electric arc, through a compressed stream of gas. As a result, the arc raises the temperature of the gas to a very high value and ionizes it. The gas is in a highly electrified state known as plasma. (Plasma is considered the fourth state of matter.) 

The machine then forces the plasma gas through a very tiny opening. The plasma strikes the surface of the material at a very high temperature and speed, increasing the temperature above the boiling point. The material is melted and vaporized. 

Laser Cutting

Also known as laser beam machining, laser cutting is a thermal process that removes material by melting and vaporization. In this process, a laser beam of high energy density focuses the heat energy on a particular point of the workpiece at a time, removing material at the micron level. Lasers work best for steel (carbon steel and stainless steel). Metals such as aluminum and copper are difficult – or perhaps more accurately slower – to cut using lasers because they reflect the light and conduct/absorb the heat.

Flame Cutting

Flame cutting, like plasma cutting and laser cutting, is a thermal cutting process. CNC machines that use this process to cut materials combine oxygen and a fuel source to create a cutting torch that melts material from a workpiece along a predefined path. But the cutting process is often much more complicated than this. 

More technically, the oxygen oxidizes the material, generating heat from the exothermal reaction of oxidation. This heat supports ignition, meaning it must be sufficient to maintain the ignition temperature. On the other hand, the oxidation forms an oxide. And for successful material removal, the oxide must have a lower melting point than the surrounding material. If all these requirements are satisfied, a fast-flowing stream of oxygen mechanically blows away the melted oxide, effectively removing material from a section of the material in which the chemical reactions have taken place.

Usually, the fuel source is a gas such as propane or acetylene. The flame-cutting process is mainly used to cut steel. It can cut workpieces with a thickness of up to 100 inches (about 2.5 meters). Flame cutting differs from laser cutting because the touch flame is not focused on a very tiny spot. The flame affects a broader area compared to the focused spot in laser beam machining.

Metal Punching

Metal punching exerts a tremendous amount of cutting force using a steel punch tool, removing material from a sheet. The shape of the punch tool dictates the shape of the hole or material removed. The consistent shape of the punch tool is why metal punching is ideal for creating precision metal parts. 

The metal punching process can be used on iron, aluminum, copper, and steel. However, the pressure and force exerted by the punch tool varies from material to material, given they each have their own strength and hardness. Another property to consider whenever you intend to punch metals is the thickness of the material. Typically, the process can be used to cut sheet metals and materials with a thickness of up to 30 mm.

While you can manually carry out metal punching by controlling the punch tool, CNC punching machines are a great alternative that not only boosts accuracy and productivity but also reduces the amount of scrap (unusable material) left after punching. CNC punching machines automatically move the punch tools. They also optimize the cutting process to ensure they cut back on wasted material. 

Folding

CNC machines perform folding procedures by applying compressive forces to a particular section of material/sheet to create a bend. Often, the machines use a punching tool or hydraulic press to apply the forces against the worksheet. The tool presses the worksheet against a die, aligned to predefined axes, that matches the shape of the punching tool, like shown below. 

An Illustration of the Folding Metal Fabrication Process (source)

The number of axes along which the forces are applied dictates the number of bends. The more the bends, the more complex the part’s shape. Folding creates parts or products with distinct, permanent shapes. These products can then be assembled and subsequently finished. For instance, they can be welded, riveted, or bolted together.

You can program CNC machines to fold sheets of metal. These machines can perform folding procedures of up to eight axes, meaning they fold material along eight different axes in a single operation. However, the thickness of materials affects the folding capabilities of the machine. Thicker materials lead to larger tolerances because of the large curvature formed along the edges of the folds. Inversely, folding thinner materials leads to tighter tolerances.

Welding

Welding is an assemblage technique that permanently joins parts together. While you can manually weld the parts together, the speed at which you assemble the parts improves with the use of CNC. CNC welding machines follow a welding path. As a result, they can assemble both simple and complex parts with a high degree of accuracy and precision.

Grinding

Grinding is a metal polishing process carried out towards the end of the metal fabrication cycle. Fabricators use it to achieve the desired finish, enhancing the surface quality of the machined part. For instance, grinding helps remove defects and spatters due to defective welds. It, therefore, smooths the surface. 

CNC grinding machines control the movement of the rotating wheel using programmed instructions written in G-code and M-code. The program dictates the rotation speed, the path along which the wheel will move, and the number of passes. The program also automatically decides when to spray coolant based on programmed logic statements. In this regard, a CNC grinder only requires minimal intervention from the operator; it executes every function automatically.

Casting

CNC machining also indirectly facilitates casting. Casting is a form of metal fabrication in which molten metal is poured into a pre-made mold to create a desired shape or pattern. CNC machines can be used to create molds of various forms and shapes. The fabricator will then pour molten metal into the mold. This creates a part whose shape conforms to that of the mold.

Materials Used in CNC Machining for Metal Fabrication

There are various materials you can use in CNC machining for metal fabrication. However, the choice depends on the exact machining process you are employing. For instance, laser beam machining works best with steel. On the other hand, EDM machines work with electrically conductive materials, which include most metals. 

Challenges and Solutions in CNC Machining for Metal Fabrication

The main challenges affecting CNC machining for metal fabrication are:

• High capital requirements
• Need for secondary operations and processes
• Quality control
• Programming knowledge

Fortunately, as discussed below, there are solutions to these challenges.

High Capital Requirements

Indeed, CNC machines are quite expensive. The cost might seem more justified if a single machine could handle multiple fabrication processes. However, most machines specialize in only one or two operations. Thus, if you wish to carry out all the metal fabrication procedures, you have to purchase multiple CNC machines. This translates to high capital requirements.

That said, you do not have to purchase all these machines in one go. You could start with the necessary equipment and expand your offerings as your workshop or machine shop grows.

Need for Secondary Operations and Processes

Even with a full suite of metal fabrication machines, post-fabrication care is often necessary. For instance, your customers may need you to paint the parts. 

Quality Control

While CNC machines drive automation, they need to be constantly monitored to ensure they continuously meet the desired level of quality, accuracy, and tolerance. Fortunately, you can also infuse automation into quality control and quality assurance. 

You can, for example, integrate predictive maintenance with preventive and reactive approaches. Predictive maintenance predicts failure before it occurs, allowing your technicians to service the equipment long before it breaks down or its components get out of sync.  

Moreover, you can rely on probing in CNC machines. Probing inspects the lengths of tools, automatically loading offsets. The tool offset compensates for the identified tool wear, which maintains the consistency of the cuts. Probing also checks for tool breakage and damage, alerting the machine. This stops further machining that would have otherwise impacted quality.

Programming Knowledge

CNC machines in metal fabrication are controlled using programs. This means you may need to know how to write the programs. However, the existence of CAM software means that you do not have to possess programming knowledge to write the programs.

Conclusion

CNC machining and metal fabrication are interconnected in a number of ways. And as manufacturing practices increasingly demand more accuracy, speed, and efficiency to accommodate growing market needs, the popularity and adoption of CNC machining in metal fabrication are rapidly growing. CNC machines not only automate various metal fabrication processes but also execute them with high precision and accuracy. As manufacturing needs continue to grow and evolve, CNC machining will continue to play a crucial role in how metals are fabricated.

Previously, manufacturing plants would rely on preventive and relative maintenance, which, though beneficial, disadvantageously caused – and still cause – productivity losses due to costly, unexpected breakdowns and downtime. However, as technology evolved and enabled the integration of advanced methods, a shift from the traditional model began to address these issues. As more and more workshops and plants embrace predictive maintenance, the resulting benefits are becoming clear for all. To put it simply, predictive maintenance has proven to be a significant game changer for the longevity of CNC machines and manufacturing equipment. This article details exactly how this has been achieved.

Understanding Predictive Maintenance

What is Predictive Maintenance?

Predictive maintenance is a type of maintenance that involves tracking a CNC machine’s performance, status, and health as the machining or fabrication process is ongoing. With predictive maintenance, manufacturing plants use sensors and other advanced technologies to monitor and test different parameters and conditions such as temperature, vibration characteristics, bearing speed, lubrication, and sound. 

These tools detect deviations from normal operations, sending real-time alerts if the parameters do not fall within the specified range. This way, the tools and technology alert the operator to a potential future breakdown. In actuality, predictive maintenance adopts a predictive model, which uses probability to estimate the time potential failures may occur.

To better discuss predictive maintenance, we will examine how it compares to other maintenance approaches and strategies.

Maintenance Approaches and Strategies

Preventive Maintenance

Preventive maintenance entails proactively performing fixed-in-time or scheduled routine maintenance operations or inspections to fix the issues before they occur. This maintenance approach helps prevent breakdowns or failures. It follows a schedule that is based on prior failure experience or data collected by the machine’s manufacturer. 

This means that the only factor that technicians consider before undertaking any maintenance task is the time that has elapsed since the previous maintenance operation. Nonetheless, preventive maintenance helps technicians identify in advance the frequent causes of failures and breakdowns, either from experiments or experience.

Reactive or Corrective Maintenance

Also known as corrective maintenance, reactive maintenance involves servicing a CNC machine only when it breaks down, fails, or stops working. This maintenance approach is intended to maximize the productive manufacturing time. However, this advantage can be short-lived as this manufacturing approach also introduces issues such as unexpected irreversible damage due to the complete failure of the machine’s components. 

As a result, it can cause unknown amounts of downtime, especially if the failure of one component damages more components. However, the repair work and the loss of productive manufacturing time can prove expensive in the long run. It can even harm customer relationships due to missed deliveries.

Predictive Maintenance

Unlike other maintenance approaches, predictive maintenance has a real-time attribute to it. It relies on data generated by the sensors in real time. It then uses predictive models to identify patterns in the data that indicate a potential anomaly. If the patterns point to an impending breakdown, the system posts a notification or alert. Technicians then take over by scheduling the much-needed service. Typically, predictive maintenance is used alongside other maintenance approaches to minimize maintenance costs and eliminate unplanned downtime.

Techniques and Technologies in Predictive Maintenance

Predictive Maintenance Techniques

A comprehensive predictive maintenance program includes multiple monitoring and diagnostic techniques. These techniques are deployed based on the type of machinery being monitored or operated. The predictive maintenance techniques include:

• Vibration monitoring
• Thermography
• Tribology
• Visual inspection
• Ultrasonics
• Nondestructive testing techniques

Vibration Monitoring and Analysis

As the name suggests, vibration analysis monitors the levels of vibrations that a machine produces to detect anomalies. It is a common technique that detects loose, misaligned, and imbalanced parts in rotary CNC machines. In this type of analysis, instruments monitor vibrations whose frequencies range between 1Hz and 30,000Hz. 

Thermography

Thermography is a predictive maintenance technique that entails monitoring the surface temperature of CNC machines, such as 3D printers and other machinery, to determine operating conditions. This technique uses instrumentation that monitors how much infrared energy a machine emits. By design, machines operate optimally within a given range of temperatures. Anything higher or lower than the set range is considered a thermal anomaly. Thus, by detecting such anomalies, predictive maintenance instrumentation alerts technicians. The technicians then work to locate and define the cause of the problem, nipping it in the bud before it can cause failure.

Tribology

Tribology is the study of friction, wear, and lubrication. Against this backdrop, tribology as a predictive maintenance technique entails tracking surfaces within the CNC machine that, due to their relative motion, cause friction and, therefore, require lubrication. Two approaches are often used in tribology: lubricating oil analysis and wear particle analysis. 

Lubricating oil analysis is used to determine the condition of the oils used in the equipment by taking oil samples. However, unlike other predictive maintenance techniques, which can be used to identify failure modes or the actual cause of problems in machines, lubricating oil analysis cannot. Instead, it is mainly used to conserve and extend the useful life of lubricating oils. It also helps determine the best and most cost-effective interval to undertake oil changes and as a quality control exercise.

On the other hand, wear particle analysis focuses on the particles found in the sample of lubricating oil. It specifically analyzes their quantity, size, composition, and shape with the aim of pointing out the wearing condition of the machine’s parts.

Visual Inspection

In visual inspection, technicians perform daily checks of CNC manufacturing systems. This predictive maintenance technique aims to identify potential failures or problems associated with maintenance that could adversely affect production costs, the quality of the parts, and the machine’s uptime or reliability. Even with the advent of Industry 4.0, visual inspections are still applicable and should be included even in modern predictive maintenance programs.

Ultrasonics

Also known as sonic acoustical analysis, ultrasonics is a category of noise analysis that monitors noise frequencies beyond 30,000Hz. These frequencies are often converted into visual signals, making the trend easy to visualize. In fact, because of the signals, technicians can document the ambient noise levels in the workshop or manufacturing plant. Using this as the baseline, they can easily detect anomalies such as noise level spikes. 

These anomalies can result from under-lubricated or worn-out bearings. Additionally, the ability to monitor frequencies above 30,000Hz makes ultrasonics ideal for such applications as detecting leaks. Usually, leaking fluids cause high-frequency noise due to compression or expansion as they flow through the crack or orifice. Unfortunately, you cannot use ultrasonics to diagnose or establish the cause of the identified problem.

Nondestructive Testing Techniques

Nondestructive testing techniques, such as electrical testing, can be used to identify problems in CNC machines. They are used to determine the integrity of insulation, electrical impedance, and electrical resistance. However, these techniques are often too costly to justify their complementary use in predictive maintenance programs. Plus, they cannot be applied in a broad range of applications. 

Technologies Used in Predictive Maintenance

The advent of Industry 4.0, which is centered around digitizing the manufacturing sector, including how plants and workshops carry out maintenance and servicing, expanded what predictive maintenance programs encompass. The technologies used in predictive maintenance now include:  

Sensors

Sensors collect data on physical parameters such as rotation speed, temperature, vibrations, flow, fluid characteristics such as compression, expansion, and more. There are two types of sensors applied in predictive maintenance;

• Process sensors: Machine manufacturers integrate them into their machines to monitor various properties during operations.
• Test sensors: They are added by manufacturing plants or workshop owners specifically to detect anomalies. For instance, you can add accelerometers to identify irregular vibrations.

Scanners

In some cases, scanners can be used to monitor certain parameters. For instance, infrared instruments known as line scanners measure temperature. They provide a one-dimensional scan of the comparative heat radiated by the machine. However, scanners are not widely used in predictive maintenance of CNC machines.

Machine Learning and Artificial Intelligence

The role of artificial intelligence (AI) in design, manufacturing, and other industries is expanding. AI broadly encompasses creating computer systems that simulate human intelligence. It is quite a broad field comprising, among others, components such as machine learning (ML). ML focuses on creating programs known as models that learn patterns in data and use the learnings to identify patterns within new data. Backed by the ability to identify patterns, the models make intelligent decisions without additional and obvious programming.

In the context of predictive maintenance, where sensors collect data about various parameters of the CNC machines, AL and ML play a crucial role. Specifically, the models, known as predictive models, created with the help of AI and ML, can identify patterns in new sensor data, facilitating the prediction of potential failures.

Industrial Internet of Things (IIoT)

The Internet of Things (IoT) broadly extends computing capabilities and network connectivity to components or objects that may otherwise not be regarded as computers. By connecting the various objects and components, IoT allows for data mining and access to the data collected. It also facilitates the remote management of data. IoT can be applied in a myriad of industries. 

IoT is called the Industrial Internet of Things (IIoT) when it is incorporated in manufacturing plants and workshops. It brings together a number of elements and domains, including traditional automation and machine-to-machine communication, big data and machine learning, software, and systems that integrate computational and physical components to control and monitor physical processes. By incorporating these domains, IIoT facilitates data collection from CNC machines, as well as its subsequent analysis and use, often in real time, to detect incipient problems and improve operations. 

Cloud and Edge Computing

Cloud computing provides centralized, off-site storage and advanced processing capacity. It is advantageous in many ways. For instance, it lowers the cost associated with operating and maintaining powerful computers/servers that handle storage and processing. 

Moreover, cloud computing supports virtualization and parallel processing. It also offers unmatched data security, especially if you choose reputable service providers. Combined, these advantages facilitate efficient processing of large volumes of data. By using cloud solutions, you can rest assured that there is enough bandwidth and computing power to train complex predictive models on a variety of conditions.

Cloud computing is nevertheless not always perfect. In fact, it is limited by speed and latency issues. It takes time to send large volumes of data hundreds or thousands of kilometers away to data centers and more or less equal time to receive responses once the data has been processed. Latency may not be an issue for a majority of cloud computing applications. However, in predictive maintenance where real-time responses are essential, latency can be a source of unreliability. 

To deal with this limitation, edge computing is used. It reduces the amount of data transmitted to the cloud by processing it closer to where it is generated. This means the data does not have to travel long distances to data centers to be processed.

IIoT Solutions Architecture (source)

Implementing Predictive Maintenance in CNC Machines

If you are looking to integrate predictive maintenance in your CNC machine workshop, it pays to take a strategic approach. To enjoy the accompanying benefits, you must consider various factors and elements. To help you in the journey and to ensure you have checked all the requisite boxes, here are the five steps you should follow whenever you want to implement predictive maintenance:

1. Create a predictive maintenance plan or program
2. Get input from management and technicians
3. Choose a partner or partners
4. Build a predictive model
5. Install the predictive maintenance technologies and deploy the model

We have discussed each of these steps in greater detail below.

Create a Predictive Maintenance Plan or Program

CNC machines vary from one to another. Based on the technology employed, some feature more moving parts than others. Some generate more heat than others, while for some, vibrations are the rule rather than the exception. Given these differences, predictive maintenance techniques and approaches will vary. This, in turn, will translate to differing predictive maintenance programs.

Based on the foregoing, creating tailor-made plans for each manufacturing plant and CNC machine is important. Such plans will, of course, capture the exact conditions of the machine rather than taking a one-size-fits-all approach. Because you understand your workshop’s situation, you also recognize which machine conditions, if disrupted, would be extremely costly for your business. Working together with teams drawn from multiple departments, you can draw up a plan to access the data that will show, in real time, the very operation-critical machine conditions. 

Get Input from Management and Technicians

However, a plan is useless without widespread acceptance – including from management – or without feedback from its intended user. For this reason, the first step would entail getting the green light from management, if the idea did not originate from the top of the organizational hierarchy. One of the approaches you could use is listing the goals and benefits of the predictive maintenance program.

Secondly, it is equally important to ask your technicians for comments on whether or not they think the plan will work and how to improve aspects they deem unviable. After all, a successful predictive maintenance program depends on the people who will be using the technologies. Using their feedback, you can modify aspects of the program, optimizing them to align with the end-users’ preferences. Getting the technicians to buy into the predictive maintenance plan will ramp up their confidence levels in the data generated by the technologies.

Choose a Partner

Predictive maintenance in CNC machining relies on data. And in a typical plant where CNC machines run around the clock and are equipped with a large number of sensors for data collection, the storage and component management requirements are equally high. It would be illogical for such a company to manage all these tasks in-house, especially when they lack the specialized expertise. For this reason, it is crucial to choose a partner or multiple partners, each specializing in a specific aspect of the predictive maintenance ecosystem. 

For instance, you might engage a cloud storage company for data architecture, design, governance, storage, and management; enlist model-building experts to craft predictive models; hire simulation experts, and so forth. You could also look for providers of quality sensors and actuators, not to mention management software. And given that you are starting out, you may not have the accurate data on which to train the predictive model, yet a third-party provider or the original equipment manufacturer may have it. Therefore, you could engage companies that will provide access to accurate training data.

Build a Predictive Model

After identifying the right partners, collaborate with them to develop a predictive model. The model will use the data collected from sensors and institutional knowledge of your CNC machines’ or machine’s conditions to predict future breakdowns. Such models will typically look at trends in the data, flagging any abnormal change or outliers as an indicator of incipient failure. Of course, not all changes are indicative of impending breakdowns. Some may point to factors that, if dealt with, can improve product quality.

Predictive Model Delivery Methodology (source)

Install Predictive Maintenance Technologies and Deploy Models

The final step in implementing predictive maintenance is installing and deploying the technologies and predictive models. By deploying these critical components, you initiate the program and start reaping the benefits of integrated predictive maintenance systems in CNC machines. 

Benefits of Predictive Maintenance in CNC Machines

Implementing predictive maintenance in CNC machining carries the following advantages:

1. Reduced Cases of Breakdowns

Predictive maintenance anticipates failures. It, therefore, enables technicians to diagnose and repair the cause before the problem escalates to a full-blown and unexpected breakdown.

2. Decreased Downtime

Unexpected breakdowns lead to unplanned downtime, which can negatively impact customer relationships. Such downtimes reduce productivity and, sometimes, even the product quality. Moreover, if the nature of the failure is extensive, the downtime can extend for an unknown period. Fortunately, predictive maintenance prevents these issues by anticipating potential failures. It allows technicians to schedule maintenance works, dealing with the problem early on. According to PTC, this maintenance approach decreases unplanned downtime by up to 30%.

3. Better Planning

A reliable predictive model offers accurate predictions. This accuracy manifests in the short interval between the estimated failure and the actual functional breakdown. In this regard, such a model improves planning. It informs technicians and service teams precisely when to plan maintenance. 

4. Improved Productivity 

Predictive maintenance of CNC machines maximizes uptime and guarantees peace of mind. Teams can operate without the fear of unforeseen breakdowns, allowing them to accept as many orders as the machinery can handle. 

5. Increased Service Resolution

The predictive model lets them know the exact cause of the problem. As a result, it reduces the time taken to resolve the issue. As a result, according to PTC, a reliable model reduces the time on site by up to 75%. Moreover, with predictive maintenance programs backing the work of technicians, they resolve service requests faster by up to 83%.

6. Enhanced Safety

Unexpected failures can create hazardous workspaces. But by accurately forecasting when a failure is expected to occur, the models allow you to evacuate the area surrounding the machine when it breaks down. However, it does not always have to come to this point. Technicians can service the equipment before the expected failure or the machine becomes a workplace hazard.

Challenges and Solutions in Predictive Maintenance

1. Cost

Predictive maintenance technologies such as sensors can be costly. Fortunately, the cost of electronics has been dropping while their inherent capabilities have been increasing. This trade-off is increasingly making predictive maintenance of CNC machines more cost-effective.

2. Inadequate Training Data

A predictive model should be capable of accurately detecting potential failures. However, the model is only as accurate as the training data used. This means that the data should be all-encompassing. It should detail all aspects of the machine’s behavior and conditions, from how it functions normally, which is known as its signature, to how it behaves when there is an impending problem or outright breakdown. If the training data does not capture all aspects, then the model cannot forecast future failures correctly. 

Unfortunately, this comprehensive data is rarely available because many companies do not maintain detailed records of past failures. Moreover, these manufacturers do not always supply or use process sensors to monitor certain events. These shortcomings make the training of the models quite challenging.

To solve this challenge, companies must maintain records of failures. Furthermore, they should use all the sensors incorporated into their machines to monitor all phenomena envisioned by the manufacturers. 

3. Unreliable Predictive Models

Before the predictive model is refined to boost its reliability and accuracy, the time interval between the estimated failure and actual functional breakdown may be quite huge. This is untenable from a cost perspective; it can force teams to more frequently schedule unnecessary maintenance operations. It goes without saying that unnecessary maintenance operations can considerably impact productivity. 

To solve this issue, it is necessary to minimize this interval. This can be achieved by collecting as much training data as possible. This data should include accurate depictions and descriptions of the machine’s conditions at different levels of performance and health.

4. Data Fragmentation

Tracking the right parameters can sometimes involve using multiple sensors. And while the ideal setup would have the sensors working in concert, this is not always the case. The sensors often tend to work in isolation, generating fragmented data. This often means that the data is then sent to different systems, known as data islands, and is stored using a variety of formats. While the data is theoretically usable, it cannot be easily and practically integrated as real-time training data, for example. As a result, the fragmented data cannot enrich the existing sensor data towards enhancing the accuracy of predictions. 

Leveraging cloud and edge computing solutions mitigates these issues. You can set up all the sensors to send data to centralized repositories, eliminating unconnected data islands. This way, the sensors are architected to work together even when they are not directly interconnected.

Conclusion

Predictive maintenance of CNC machines and other manufacturing equipment has been a game-changer. It has been instrumental in extending the lifespan of machinery. Compared to conventional maintenance approaches like preventive and reactive maintenance, predictive maintenance has been shown to decrease unplanned downtime by 30% and the time on site by up to 75%. Its use also leads to faster resolution of breakdowns by as much as 83%, thus boosting worker productivity. The benefits of predictive maintenance of CNC machines are undeniable. But its implementation is often affected by data fragmentation, unreliable predictive models, cost, and inadequate training data. Fortunately, you can deal with these problems.

Consequently, alongside the automated manufacturing of CNC machining, there has always been a need for an automated approach to measurement and inspection. This requirement gave birth to probing. This article discusses probing in CNC machines, detailing what it is, probing techniques, types of probes, how probes work, and perhaps most importantly, the advantages and applications of probing in CNC machines.

Understanding Probing in CNC Machining

What is Probing in CNC Machining?

Probing is the use of devices to inspect and measure machined features and/or machining tools. This process can be executed on a CNC machine or a coordinate measuring machine (CMM). In CNC machining, this operation is executed before, during (as in-process inspection), and after (post-process monitoring) the machining process. In-process inspection refers to the practice of measuring or analyzing a produced feature and its dimensional characteristics immediately after it has been machined without altering the process flow. This aids manufacturers in identifying errors early in the production process, thus saving time and money. 

However, not all CNC machines can carry out in-process inspection. In such cases, CMMs, which are stand-alone inspection units, are used. They are complex devices that measure the geometry or dimensions of parts and physical objects by locating discrete points on them. However, CNC machines can be retrofitted with additional tools to transform them into CMMs. 

It is worth highlighting that probing is not a plug-and-play operation. Rather, one must outfit the CNC machine with a probe and then input lines of code to instruct the machine on how to use it. Neglecting to integrate these lines into the CNC program can result in breakage, as the machine may drive the probe into a workpiece, treating it like any other tool. 

Probing Techniques in CNC Machining

There are three main probing techniques in CNC machining:

• Contact or tactile probing
• Noncontact or nontactile probing
• Simulated probing

Contact or Tactile Probing

In contact or tactile probing, the probes touch the workpiece and maintain contact during data collection. This probing technique is favored for working with larger parts, as well as those with complex geometries and features. Hard probes, touch trigger probes, and analog scanning probes are examples of probes that collect data by touching workpieces or parts.

Noncontact or Nontactile Probing

Probes that undertake nontactile probing do not make contact with the workpiece. Instead, they make the measurements by relying on light. They are used when working with smaller, complex, and higher-precision parts. Laser and vision probes are examples of probes that collect data through noncontact probing.

Simulated Probing

As the name suggests, simulated probing is not a physical probing technique. Instead, it is completed in software using products such as VERICUT and Renishaw’s Productivity+, which simulate the movement of a probe device along a path. This technique is nonetheless beneficial in many ways, considering that certain undesirable movements could easily break the expensive probes. Additionally, it prevents time wastage and lowers the cost of manufacturing by enabling you to check the design/model for errors before sending the CNC program to the shop or importing it into a CNC machine.

In CNC machining, simulated probing is utilized to:

• Emulate the CNC machine
• Check the part before actual machining starts, thus saving time by ensuring only complete designs/models end up getting worked on
• Detect errors, such as the absence of features on a part, even before the program is exported from the computer-aided manufacturing (CAM) software
• Prevent mistakes in the CNC program that could lead to probe breakage 

Understanding Probes in CNC Machining

What is a Probe in CNC Machining?

A probe is an extremely sensitive switching device designed to originate and send signals, providing accurate, repeatable geometric data. Probes are used to inspect and measure geometric characteristics of machined features or machining tools. Modern probes are operated using programs created with dedicated software such as Renishaw’s Productivity+. Nonetheless, if you have G-code programming experience, you can create probing programs using a CNC machine’s controller. This approach, in fact, eliminates the need for post-processing, as everything is done natively on the machine.

How Probes in CNC Machines Work 

On machining centers, probes are mounted on the spindle, while on turning centers, they are mounted on the turret. However, spindle-mounted probes do not rotate in the spindle when in use. In either case, though, they are used for inspection and measurement operations. However, while this description is accurate, it is quite simplistic and doesn’t capture the full scope of how probes operate.

As we have introduced above, probes are not plug and play. And that is because they work based on programmed instructions. Additionally, probes must also send signals during the execution of the programmed instructions. So, in this section, we will detail how probes work by compartmentalizing their operations into two categories.

Creating Inspection and Measurement Programs

You can write the probing instructions directly as G-code or indirectly using dedicated probing software. The latter approach, however, is easier to use because it does not require you to have a G-code programming background – it creates programs directly from imported solid models. 

The software also provides a graphical user interface (GUI) that allows you to refer to the model when deciding which feature to measure. The GUI lets you modify parameters such as the tolerance and toolpath type. Moreover, the software can simulate the probing operation, enabling you to detect beforehand any mistakes that would otherwise lead to collisions and breakage. In this section, we will focus on the use of dedicated probing software to create inspection and measurement programs. 

Probing software serves as a programming interface, allowing you to integrate inspection and measurement probe routines into machining cycles. It also lets you establish specific parameters that it then uses to emplace logic statements in the code. These statements instruct the CNC machine to make in-process decisions. 

Running Inspection and Measurement Programs

After creating an inspection routine/cycle using the probing software, you then have to post-process the program, as you would using conventional CAM software. Then, send the output files, usually a collection of multiple programs, to a CNC machine. These programs will include a main program that defines all the sub-programs needed to operate the probe, the positions of the features and the correct callouts, and directions on how to write the results. For the sake of simplicity, we will refer to the collection of the main program and the sub-programs as the probing program. 

You can choose to run the probing program as the main program to set the coordinate system. Alternatively, you can embed the probing program into your cutting code. But the most preferred course of action is running the probing program separately. Under this option, you set your CAM program to call the probing program, ensuring that both programs work independently but seamlessly together. Ultimately, the probe’s movements adhere to the instructions specified in the code. 

Signal Transmission

By following the probing program, the probe takes the measurement. However, it does not store data; it, therefore, must transmit it immediately upon collection to the control unit through signals. There are four ways the probe sends signals to the controller:

• Optical signal transmission: In this method, the battery-powered probing device is fitted with an LED that emits light signals – in the form of an infrared light beam – towards a tuned receiver. The receiver is designed to pick signals from a distance of up to 3 meters or 10 feet. This method requires a clear path between the LED and the receiver. If this is not possible, another transmission method is used.
• Radio signal transmission: In this method, the probe, powered by a small battery installed in the device’s body, generates a radio frequency signal. The radio signal transmission method is used in large CNC machines and in cases where optical signal transmission is not feasible.
• Inductive signal transmission: In this method, the signals travel using electromagnetic induction between two modules separated by a small air gap. One of the modules is located on the spindle, while the other is on the probing device. 
• Wired signal transmission: In this method, the signals travel through a signal cable. The cable connects the probe to a machine unit interface. This cable carries both the probing signals and power. For its part, the interface converts inspection probe signals to voltage-free solid-state relay outputs that are then transmitted to the machine tool controller. 

Illustration of Wires Signal Transmission (source)

Probe Calibration in CNC Machines

To guarantee the expected high-accuracy measurements, the probing device is calibrated. The probe calibration process adjusts for inherent characteristics within the measurement system that could cause inaccuracies. The calibration considers characteristics such as the stylus ball’s offset from the spindle center line, its radius, the length of the probe, and the pre-travel. 

There are multiple probe calibration methods, which are applied based on the type of probe. One of the most common methods for calibrating measurement touch trigger probes (work probes) uses a test rod and a master ring gauge to establish the offsets in the X, Y, and Z axes. On the other hand, tool probe calibration involves the use of a calibration bar, which is mounted into the spindle. That said, you do not have to master the various calibration methods, as CNC machine and probe device manufacturers usually provide step-by-step guides.

When are Probes Used in CNC Machining?

Probes can be used before, during, and after CNC machining. Some of the activities that require the use of a probe before machining can start include:

• Tool setting, which establishes the length of the tool and its diameter
• Part setting to establish the position of the datum, orientation of the part relative to the CNC machine axes, and component or billet size to determine the stock characteristics

Moreover, you can also use probes to undertake the following operations during machining:

• Breakage detection
• Tool wear detection
• Test cutting tools for wear and deflection to autoload offsets
• Test parts for distortion due to thermal effects
• Inspect parts’ dimensions to ascertain adherence to defined tolerances

Lastly, once the machining has been completed, you can use probes to check the finished parts against their specifications. This allows you to generate reports documenting component conformance.

Types of Probes in CNC Machining

There are six types of probes used in CNC machines:

• Job contact probes
• Touch trigger probes
• Hard probes
• Analog scanning probes
• Laser probes
• Camera/Vision Probes

Hard Probes

Hard Probe (source)

A hard probe is made up of a solid sphere of known diameter connected to a solid steel shank. To use the probe, an operator manually brings the sphere into tangency with the workpiece and allows the machine to settle. Next, they manually signal the machine to record the probe’s position. The machine’s software then takes over, automatically adjusting the readings to account for the actual diameter of the probe. 

For example, if you are using a hard probe to read the diameter of a hole, the software will compensate for the diameter of the probe to display the actual diameter of the hole. However, these probes are primarily used to swiftly locate holes. 

Hard probes are not connected to the control unit, meaning they do not relay any information to the machine. This drawback severely limits the latitude of their use. Hard probes can only be used on manually controlled machines; they cannot be used in CNC machines that run automatically.

At the same time, this type of probe is susceptible to human errors. This is because they are wholly controlled by human operators who dictate their approach speed and bounce back. If the operator is not experienced or skilled enough, then they can introduce inaccuracies. And even if they are experienced and skilled, they can still make mistakes. These factors limit hard probes’ usefulness and accuracy. 

Job Contact Probes

Job Contact Probe (source)

A job contact probe can only be used with electrically conductive materials. The probe is fitted with light-emitting diodes (LEDs) and is powered by batteries. When the tip of the probe’s stylus makes contact with the surface of the material, an electrical circuit is completed. The LEDs light up, indicating that the stylus has touched the surface of the workpiece. Job contact probes are mainly used as visual indicators of contact during workpiece setup and inspection. 

Touch Trigger Probes

Touch Trigger Probe (source)

Touch trigger probes are the most common type of probes in CNC machines. They are more technically advanced than job contact probes. And unlike the latter type, whose use is confined to electrically conductive materials, the former (touch trigger probes) can be used on any material, provided it is hard enough to cause the stylus to deflect upon contact. 

A touch trigger probe has a spherical tip, made from ruby or another suitable material, attached to an omnidirectional joystick/stylus. Thanks to this omnidirectional property, the stylus can deflect in every direction, including inwards. 

The touch trigger probe, which is directly connected to the CNC machine’s control unit, works as follows: when the stylus deflects, it changes the electrical characteristics of the circuit, triggering a signal that is sent to the control unit. However, it is worth pointing out that for the stylus to trigger the signal, it must deflect beyond a minimum dimension. This minimum dimension depends on the length of the stylus.

Whenever the control unit receives the signal, it switches off the power to the drive motor, in effect stopping the movement that initially caused the deflection. It is, however, essential to note that touch trigger probes do not measure. Instead, they provide the CNC machines with touch capabilities, enabling the accurate and consistent detection of surfaces or edges. Moreover, the probe does not provide positional information. This role is reserved for transducers. 

Touch trigger probes are either table-mounted or spindle-mounted. Table-mounted probes are stationary and are used to check the tools. On the other hand, spindle-mounted probes move to make contact with the workpieces and are used to check and inspect the workpiece.

Analog Scanning Probes

Analog Scanning Probe (source)

A scanning probe typically comprises a scanning module, which houses sensors, and an affixed stylus. The module can carry styluses with lengths from 20 to 400 mm. Depending on your chosen stylus, you can even scan the internal surfaces of features deep inside bores. Scanning probes can collect data from several hundred surface points per second, enabling them to measure the size, position, and form of the part. At the same time, they can acquire data from discrete points, similar to how touch trigger probes work.

Analog scanning probes are preferred when the workpiece comprises irregular or complex surfaces. This is because the stylus tip is brought into contact with the part or feature and then moved along the surface, collecting data during motion. Moreover, the stylus length

Laser Probes

Laser Probe (source)

Laser probes are permanently fixed at a specific distance from the machining area. They are primarily used for tool monitoring and tool measurement. Laser probes are U-shaped, with one arm equipped with a laser emitter and the other a lens that serves as a laser receiver. 

To measure the length and dimensions of the tool as well as to monitor its characteristics during machining, the tool is moved to the opening in between the receiver and emitter. The tool activates the probe whenever it blocks the emitted laser from reaching the receiver.

Laser probes measure the geometric characteristics of tools by comparing their measured positions with the measurements of the reference gauge. This gauge, whose length and dimensions are known, calibrates the laser probe during the setup.

Camera/Vision Probes

Vision Probe (source)

Vision probes do not directly measure features or parts. Instead, they take a picture of a section of the part, effectively digitizing it and generating multiple measurement points. The probe then uses a database of pictures of electronic models of known dimensions to measure the features of the just-taken image. It achieves this by counting the number of pixels between the measurement points. 

This type of probe is mainly used in inspection jobs, particularly in projects where the workpiece is changed frequently. However, the vision probe’s field of view limits the minimum size of features or holes they can inspect. The larger the maximum field of view, the larger the size of the features or holes should be, and vice versa. Vision probes are used to inspect laser-drilled holes or thin sheet metal parts.

Applications of Probing in CNC Machining

Probing systems in CNC machines are used to:

• Measure tool length offset, which lets the CNC machine know how far each tool extends from the spindle to the tip
• Set the Z-axis coordinate
• Identify and set up parts that have been automatically loaded onto a CNC machine 
• Measure the dimensional characteristics of features
• Monitor workpiece surface condition
• Inspect and verify the dimensions of finished components
• Identify and measure geometric errors in machine tools, thus verifying tool performance and machine health prior to machining operations
• Detect inaccuracies induced by the control unit or servo drive motors
• In-process gauging, which is the process of measuring a part as it is being machined, allows for adjustments caused by out-of-tolerance tools
• Scanning the form of prototypes to create a raster image file that can be converted to vector formats using software like Scan2CAD
• Tool setting: Tool setting probes are normally table-mounted. They measure the length and size/radius of the tools before cutting commences and check for tool breakage, damage, or wear during the machining operation (by referencing the tools’ dimensional characteristics recorded before cutting started). If the probe detects tool wear, damage, or breakage, it will send a signal to the control unit, whose software alerts the machine.
• Monitor or test cutting tools to autoload offsets

Advantages of Probing in CNC Machining

Probes and probing in CNC machines are advantageous in a myriad of ways, including:

• On-machine part inspection enables part re-working without having to reposition the workpiece
• Probes facilitate efficient production through proper part positioning 
• The method of measuring the tool length offset using tool presetting probes is faster, safer, and more accurate than other measurement methods such as part datum or a 1-2-3 block
• Probes eliminate manual part and tool setting errors
• Probing devices reduce with the reliance on fixtures
• They boost productivity by automating tasks that were previously manual, thereby reducing non-productive manufacturing time
• Probing in CNC machines ensures that all parts are correctly machined by enabling the controller to compensate for misaligned parts
• It reduces off-machine inspection requirements
• Probing reduces scrap associated with differences in the sizes of the stock billets

Challenges and Solutions in Probing

The challenges of probing in CNC machining are:

• Probes are expensive
• They can break easily when driven into the workpiece
• Probes can be a source of errors if not calibrated or if mounted incorrectly

Fortunately, you can easily avoid or solve these problems. For one, you can and should follow the manufacturer’s guidelines on how to set up and calibrate the probes. Secondly, you can generate probing programs using dedicated software. Such software is ideal for both experienced and inexperienced G-code programming professionals. It provides a GUI and menus that ease the process of customizing the probing job based on your needs. The visual aid that probing software provides eliminates the guesswork, especially among inexperienced personnel. Moreover, by simulating the probing work, the software lets you visually identify errors that may lead to breakage. It’s equally important to choose the right probe for the task.

Conclusion

Probing in CNC machines enhances automation by streamlining the measurement and inspection processes of manufacturing. This eliminates bottlenecks that otherwise exist if the parts, features, and tools are measured and inspected manually using conventional tools. Probing, however, is more than just inspection and measurement. It encompasses the creation of probing programs, choosing the right type of probe based on the probing technique, probe calibration, and signal transmission. 

However, by following manufacturers’ guidelines, you can enjoy the numerous benefits of probes and probing in CNC machines. The advantages include a reduction in non-productive manufacturing time, elimination of manual part and tool setting errors, reduction in scrap and off-machine inspection requirements, and much more. You will also get to use probes in a myriad of ways, from tool setting and tool monitoring to in-process gauging, monitoring workpiece conditions and characteristics, and more.

This ultimate guide will discuss what hybrid manufacturing is, the various types and categories of hybrid manufacturing, the advantages and limitations of each type, and what to consider if and when you want to implement hybrid machining/manufacturing processes. Let’s get started.

Understanding Hybrid Manufacturing

There are several definitions of hybrid manufacturing. The first, put forth by the International Academy for Production Engineering, defines it as processes based on “the simultaneous and controlled interaction of process mechanisms and/or energy sources or tools having a significant effect on the process performance.” The second definition describes hybrid manufacturing as a combination of additive and subtractive methods.

More broadly, when considering the definition of a hybrid process, hybrid manufacturing is a manufacturing approach that combines either two or more manufacturing processes belonging to distinct categories of technologies or an active external energy source and a machining process that interact and influence each other, either simultaneously or sequentially, within the same machine. 

The interaction of processes within the same platform or machine indicated that these processes are controlled. That feeds into the first definition above. Similarly, the requirement that two or more processes must belong to different categories of technologies supports the second definition. Thus, we can consider the broader third definition as the all-encompassing definition of hybrid manufacturing.

Hybrid manufacturing can combine (either simultaneously or successively) the following processes:

• Additive and subtractive manufacturing processes
• Two or more subtractive manufacturing processes
• Two or more additive manufacturing processes

Categories of Hybrid Manufacturing Processes

There are two main types or categories of hybrid manufacturing:

• Combined hybrid manufacturing
• Assisted hybrid manufacturing

In both categories, interactions involving heating, melting, mechanical abrasion, evaporation, dissolution, and plastic flow occur. These interactions change not only the physical and chemical conditions of the processes but also the properties of the workpiece material. These interactions can largely be grouped into mechanical, thermal, and chemical and electrochemical. Therefore, the development of hybrid manufacturing processes involves using these different interactions, either simultaneously or in succession.

Combined Hybrid Manufacturing

In combined hybrid manufacturing, all constituent processes are applied directly and simultaneously to remove or add material from a workpiece. Examples of hybrid manufacturing processes that fall into this category are:

• Electrochemical Discharge Machining (ECDM)
• Electrochemical Arc Machining (ECAM)
• Electrochemical Grinding (ECG)
• Abrasive Electrochemical Honing (AECH)
• Turn-milling

Assisted Hybrid Manufacturing

IIn assisted hybrid manufacturing, one process is responsible for adding or removing material, while the other plays only an assistive role. The main process is, therefore, referred to as the primary process. By extension, this means the process that plays an assistive role is known as the secondary process. 

One example of assisted hybrid manufacturing in action is the use of a machining process, such as grinding, to remove excess materials following 3D printing, an additive manufacturing process. This is known as abrasive-assisted hybrid manufacturing. Examples of assisted hybrid manufacturing processes include:

• Abrasive-assisted hybrid manufacturing, e.g., abrasive-assisted Electrical Discharge Grinding (AEDG), Abrasive-assisted Electrical Discharge Machining (AEDM), and abrasive-assisted electrochemical machining
• Vibration-assisted hybrid manufacturing, e.g., vibration assisted Electrochemical Machining, vibration-assisted Electrical Discharge Machining, and vibration-assisted laser beam machining
• Laser-assisted hybrid manufacturing, e.g., laser-assisted electrochemical machining, laser-assisted turning, laser-assisted electro-discharge machining, laser-assisted etching, laser-assisted water jet machining, and laser-assisted oxide film lithography
• Plasma-assisted hybrid machining, e.g., plasma-assisted turning (PAT)
• Magnetic field-assisted hybrid manufacturing, e.g., magnetic field-assisted electrical discharge machining and magnetic field-assisted electrochemical machining
• Fluid-assisted polishing hybrid manufacturing, e.g., abrasive waterjet machining and electrolytic in-process dressing (ELID) grinding
• External electric field-assisted hybrid manufacturing, e.g., electric-field assisted direct writing (EADW), which is a type of metal 3D printing 

Types of Hybrid Manufacturing Processes

1. Electrochemical Discharge Machining

Electrochemical discharge machining, also referred to as electrochemical spark machining, is an advanced hybrid manufacturing process. It comprises two machining techniques: electrochemical machining and electro-discharge machining. For this process to work, there must be an electrochemical cell that comprises two electrodes: the tool and auxiliary electrodes, both dipped in electrolyte. In this process, the tool is connected to the negative terminal of a pulsed DC power supply, while the positive terminal is connected to the auxiliary electrode. The workpiece is not connected to any terminal.

Electric current flows through the cell when an external potential is applied between the electrodes. This generates gas bubbles because of electrochemical reactions, with a layer of gas bubbles forming around the cathode (tool). When the applied voltage exceeds a certain value, electric sparks appear across the gas bubble layer at the electrode-electrolyte surface on the smaller electrode. This phenomenon is known as the electrochemical discharge.

The electrochemical discharge mechanism removes material from a workpiece by melting and vaporization if and when the workpiece is placed near the sparks/discharges.

Holmarc makes electrochemical discharge machining systems like the HO-ECDM-01, although its machines have a small footprint, as they are designed for laboratory use. If you are looking for industrial-grade ECDM systems, check out KRC Machine Tool Solutions, which manufactures custom ECDM machines.

Advantages of Electrochemical Discharge Machining

• It can be machine electrically non-conducting materials like glass, alumina, composites, and ceramics
• Electrochemical discharge machining can machine parts whose dimensions range from meso (0.1mm to 5mm) to micron scale (it can be used in micro-machining)
• It can machine chemically inert materials
• The process can generate non-circular or complex-shaped cavities

Limitations of Electrochemical Discharge Machining

• The process produces a poor surface finish
• It results in tool wear due to electrochemical dissolution
• Electrochemical discharge machining can only remove material at shallow depths

2. Electrochemical Arc Machining

Electrochemical arc machining, or ECAM, combines electrochemical machining (ECM) and electro-discharge machining (EDM). It specifically applies pulsed DC voltages between a tool (the cathode or negative electrode) and a workpiece (the anode or positive electrode) separated by a thin film of electrolyte to produce electrochemical dissolution and electro-discharge erosion.

Advantages of Electrochemical Arc Machining

• It has a very high metal removal rate: between 5 to 40 times greater than ECM and EDM
• Electrochemical arc machining achieves a better surface finish
• It leads to less tool wear
• The heat-affected zone is less than in ECM and EDM

Limitations of Electrochemical Arc Machining

• Its use is restricted to electrically conductive material
• The accuracy is reduced compared to ECM and EDM

3. Electrochemical Grinding (ECG)

Electrochemical grinding combines conventional grinding with electrochemical machining. However, it differs significantly from conventional grinding, which uses a grinding wheel to which abrasives have been bonded. This abrasive-bonded grinding wheel induces a cutting force on the workpiece, generating heat and removing material. However, this is not the case when it comes to ECG.

In ECG, a metallic wheel is used in place of the abrasive-bonded wheel. The metallic wheel does not contact the workpiece, meaning it does not induce any cutting force. Instead, it acts as a cathode and rotates above the anodic workpiece, with both the wheel and workpiece immersed in an electrolyte.

This process is particularly effective for producing fragile parts, thin-walled tubes, tungsten carbide cutting tools, and machining parts made from materials that are difficult to cut, among others.

Advantages of Electrochemical Grinding

• It produces a flat surface with excellent quality
• The process does not lead to distortion or stress development on the workpiece because of the lack of contact
• It eliminates grinding burrs
• Electrochemical grinding has a high material removal rate
• The rotating wheel has a longer service life
• It produces workpieces with narrow tolerances

Limitations of Electrochemical Grinding

• It is slower and, therefore, less efficient than conventional grinding
• The use of electrochemical grinding is restricted to electrically conductive materials
• It requires a higher capital investment than conventional grinding machines
• Electrochemical grinding machines have a higher maintenance cost
• The electrolyte can corrode the workpiece and tools
• It requires regular filtering as well as disposal of the electrolyte

4. Abrasive Electrochemical Honing

Abrasive electrochemical honing combines an abrasive and anodic dissolution in an electrolyte to produce smooth internal surface finishes. Although it uses abrasives, most of the material is removed by dissolution, unlike conventional honing.

Advantages of Abrasive Electrochemical Honing

• Abrasive electrochemical honing is faster than conventional honing as it combines mechanical erosion with dissolution for material removal
• It achieves extremely good surface finishes, which do not have micro-scratches
• The process achieves better dimensional tolerances than conventional honing
• The mechanical action improves the fatigue strength of the finished workpiece because it produces compressive residual stress

Limitations of Abrasive Electrochemical Honing

• Its use is restricted to electrically conductive material

5. Abrasive-Assisted Electrical Discharge Machining

Abrasive-assisted electrical discharge machining was developed to solve some limitations of the conventional EDM. Ordinarily, the EDM process removes material using a series of spark discharges. However, its use often results in poor surface quality, a relatively low material removal rate, and tool wear from material vaporization. In abrasive-assisted EDM, the properties of the dielectrics are modified by introducing additives like metal powders and abrasives. These additives have been shown to improve machining performance and increase efficiency. 

But what function do the additives play? Adding the metal powder or the abrasive decreases the electrical resistivity of the dielectric and expands the spark gap. The abrasives also help remove molten material from the craters, translating to better material removal (flushing). The abrasive-assisted EDM can also achieve a mirror finish, but this result depends on the optimal settings of electrode polarity and pulse parameters.

Advantages of Abrasive-Assisted Electrical Discharge Machining

• It takes a shorter time to machine the materials compared to conventional EDM
• Abrasive-assisted EDM achieves a better surface finish
• By increasing the spark gap, the metallic (conductive) abrasives reduce tool wear
• Semiconductive abrasives increase material removal depth as they reduce the spark gap

Limitations of Abrasive-Assisted Electrical Discharge Machining

• Semiconductive abrasives increase tool wear
• The process requires you to make various modifications (e.g., the type of abrasive, electrode polarity, and pulse parameters) to achieve certain finishes, which can be overwhelming

6. Turn-Milling Process

Turn-milling combines two conventional machining processes: turning and milling. In this process, both the tool and the workpiece rotate. As a result, it is used to create complex and unconventional shapes, which cannot be generated in separated processes.

Illustration of Turn-Milling Process (source)

Advantages of Turn-Milling Process

• It increases productivity
• The turn-milling process produces better surface finish
• It reduces tool wear, thus improving tool life
• The process has a high material removal rate
• It is used to create complex eccentric shapes

Limitations of Turn-Milling Process

• There are many parameters that affect the process, impeding optimisation

7. Abrasive-Assisted Electrochemical Machining

In abrasive-assisted electrochemical machining, abrasive grains are added to a high-velocity-flowing electrolyte to prevent the formation of a thin oxide layer on the workpiece’s surface. In conventional ECM, the film, which is electrically non-conductive and sticky, prevents smooth machining. Thus, the abrasive grains prevent the formation of the film, accelerating the anodic dissolution of ECM. The abrasives also remove minor burrs from the surface of the workpiece.

Advantages of Abrasive-Assisted Electrochemical Machining

• The grains increase the efficiency of the ECM process

Limitations of Abrasive-Assisted Electrochemical Machining

• The abrasive grains may cause tool wear and can wear out the machine parts
• The abrasives modify the properties of the electrolyte

8. Vibration-Assisted Mechanical Machining

Mechanical machining methods include drilling, grinding, turning, and milling. They use a cutting tool to remove material from a workpiece. The tool must make contact with the workpiece, with a cutting force subsequently applied to induce material removal. Introducing vibration creates movement similar to hammering, which can be disadvantageous as it can generate cracks. However, it reduces the machining forces by ensuring the cutting tool intermittently loses contact with the workpiece at a specified amplitude and frequency.

Examples of vibration-assisted mechanical machines are the OptiSonic CNC Ultrasonic Machining Centers, which combine mechanical machining methods with ultrasonic vibration to reduce the force applied to both the tool and workpiece. These machines can perform ultrasonic milling, ultrasonic grinding, and ultrasonic core drilling.

Advantages of Vibration-Assisted Mechanical Machining

• The vibrations reduce the cutting or drilling forces

Limitations of Vibration-Assisted Mechanical Machining

• Vibration-assisted milling and grinding are less common because they would require complicated machine architecture and structure

9. Vibration-Assisted Electrochemical Machining

The vibrations help remove the thin oxide layer resulting from electrochemical passivation. It also induces waves within the gap between the workpiece and the tool, aiding in flushing out gas bubbles. By creating better flushing, the vibrations help control the machining process.

Advantages of Vibration-Assisted Electrochemical Machining

• The vibrations improve the reactions that remove material
• They decrease the rate of formation of the oxide film
• The vibrations increase machining efficiency

Limitations of Vibration-Assisted Electrochemical Machining

• There are multiple parameters to consider, which can complicate the process

10. Vibration-Assisted Electrical Discharge Machining

Vibration-assisted electrical discharge machining introduces small-amplitude and specific-frequency vibrations to the electrodes or dielectric fluid. The vibrations help improve machining efficiency by improving flushing.

Advantages of Vibration-Assisted Electrical Discharge Machining

• Ultrasonic vibration-assisted EDM improves the surface finish and fatigue behavior
• Vibration increases machining efficiency, as it improves flushing

Limitations of Vibration-Assisted Electrical Discharge Machining

• Vibrations of specific amplitude and frequency are required to achieve optimal results

11. Vibration-Assisted Laser Beam Machining

Laser beam machining removes material from workpieces through thermal action. It can machine any material regardless of its mechanical properties or electrical conductivity. However, the process has a few drawbacks arising from the use of heat energy. Laser beam machining produces thermal damage and cracks. It also melts materials or causes the re-deposition of molten metal. To overcome these limitations, vibration is used in an assistive role. Vibration plays several significant roles. It prevents surface oxidation and the formation of a re-deposition layer.

Advantages of Vibration-Assisted Laser Beam Machining

• It improves the surface finish
• Vibration increases heat transfer, producing a cooling effect that reduces the chances of particles being deposited and sticking to surfaces

Limitations of Vibration-Assisted Laser Beam Machining

• There are various types of vibration that you can deploy, e.g., ultrasonic vibration and mechanical vibration, each producing different results

12. Laser-Assisted Mechanical machining

The laser-assisted mechanical machining (LAMM) process uses a defocused laser beam to pre-heat and soften the workpiece during conventional milling, drilling, or turning. LAMM is used on materials whose high strength and low thermal conductivity or high strength and heat resistance make them difficult to machine. Such materials require high cutting forces and temperature when machined using conventional manufacturing methods. However, this often leads to short tool life.

Thus, using the laser, a heat source, softens the workpiece, changing the deformation behavior. It causes the material to be ductile instead of brittle. LAMM methods are used to machine materials such as titanium alloys, nickel superalloys, and ceramics, which, ordinarily, are difficult to machine.

There are several types of laser-assisted mechanical machining methods:

• Laser-assisted turning: In this process, a laser beam and a cutter remain stationary as the workpiece rotates around an axis perpendicular to the tool and source of the laser beam.
• Laser-assisted milling: In this process, the cutter and laser beam move along a pre-defined toolpath while the workpiece remains stationary

Illustration of Laser-Assisted Turning (source)

Illustration of Laser-Assisted Milling (source)

Advantages of Laser-Assisted Mechanical Machining

• Laser-assisted mechanical machining reduces tool wear
• The processes decrease the cutting forces required
• Laser-assisted turning has a high material removal rate
• Laser-assisted turning results in a good surface finish

Limitations of Laser-Assisted Mechanical Machining

• It is important to accurately and appropriately position and orient the beam on the workpiece, which requires great attention to detail

13. Laser-Assisted Advanced Machining

There are several laser-assisted advanced machining methods, including:

• Laser-assisted waterjet machining: In this process, the laser softens the workpiece material, thus decreasing the cutting forces required. 
• Laser-assisted etching: This process is used to etch ceramics, high polymers, metals, and semiconducting materials. The heat energy from the laser does not melt the materials. Rather, it supports the motion of the dissolution of materials.
• Laser-assisted electric discharge machining: In laser-assisted EDM, the laser is used to pre-machine the basic part features, e.g., creating a hole or groove. EDM is then used to remove defects that result from the heat from the laser beam. EDM also produces a better surface finish.
• Laser-assisted electrochemical machining: This process couples a laser with electrochemical machining to enhance the dissolution process wherever the laser beam hits the workpiece.

Advantages of Laser-Assisted Advanced Machining

• Laser-assisted EDM achieves a superior surface finish
• The laser beam reduces the cutting forces
• The processes make it easy to machine difficult-to-machine materials
• It solves some of the main drawbacks of individual processes like laser beam machining, EDM, waterjet machining, and more

Limitations of Laser-Assisted Advanced Machining

• Laser-assisted machining involves multiple parameters, including the machining parameters, properties of the workpiece, and laser parameters, which make it challenging to optimize the process

14. Directed Energy Deposition and Mechanical Machining

This hybrid manufacturing method combines directed energy deposition (DED), an additive manufacturing process, with subtractive mechanical machining operations such as milling or turning. DED is a broad 3D printing technology that covers various sub-technologies, including laser metal deposition (LMD), direct metal deposition, laser-engineered net shaping, and more. 

In DED, energy is focused on a specific area, heating the metal powders. Upon melting, the material is deposited onto the surface, where it solidifies. (If a laser generates the energy, then that process is called LMD.) Subsequent mechanical machining methods are employed to remove excess material from the part, resulting in a smooth surface finish. 

Hybrid manufacturing systems that combine additive and subtractive manufacturing processes can be used to repair damaged or worn parts, such as turbine blades with surface cracks or cavitation pits. Additionally, they can be used as part of the rapid prototyping process.

Hybrid Manufacturing Technologies

1. Hybrid 3D Printing

3D printing technology, particularly DED, is perhaps the most commonly discussed hybrid manufacturing technology. This is because most industrial systems that can perform DED can also complete other operations. A hybrid 3D printer can, for instance, perform such operations as laser metal deposition, hardening, subtractive machining, and grinding all in one machine.

OKUMA’s MU-8000V LASER EX and DMG MORI’s LASERTEC 3000 DED Hybrid are examples of 3D printing hybrid machines. The former performs laser metal deposition, hardening, subtractive machining, and grinding in one machine. The latter, on the other hand, performs additive manufacturing (DED) as well as turning or milling.

2. CNC Machines

When you think of machines that perform hybrid manufacturing, you might picture sophisticated systems capable of undertaking more than one machining process. While this is true for CNC multitasking machines, that description does not apply to the entire hybrid manufacturing domain. Some systems are just CNC machines that can only perform a single machining process but which have been modified. Take the example of an abrasive-assisted electrical discharge machining system.

In a study investigating the optimal machining conditions in abrasive-assisted EDM of a titanium alloy, researchers added silicon carbide particulates to commercial-grade EDM oil, which is ordinarily used as a dielectric. They used the CMAX S645, a dedicated advanced CNC die sinker electrical discharge machine. Similarly, to convert a dedicated waterjet machine into a hybrid machining system, simply mix suitable abrasives with the water. 

3. CNC Multitasking Machines

Other machines have built-in multitasking capabilities. They can perform two or more machining operations, either simultaneously or in succession, in the same system without requiring manual intervention. 

These machines automatically handle and load/unload parts from the initial to the final operation. Their multitasking capabilities save time in job setting, scheduling, and material handling. Moreover, the CNC multitasking machines improve part accuracy, lower the cost required to manufacture parts, and reduce unnecessary (non-value added) manufacturing time.

But that’s not all. By eliminating the need for multiple dedicated CNC machines, multitasking systems reduce the required floor space, lower the power consumption, and increase throughput. However, compared to dedicated machines, multitasking systems are more expensive and harder to maintain.

Advantages of Hybrid Manufacturing

Hybrid manufacturing, in general, has the following advantages:

• It produces a better surface finish 
• Hybrid manufacturing, in most cases, reduces the machining time
• The processes reduce tool wear, thus improving the tool life
• Hybrid manufacturing operations have a higher material removal rate
• The hybrid processes solve the shortcomings of dedicated processes

Limitations and Solutions of Hybrid Manufacturing

We have elaborated some of the individual limitations of hybrid manufacturing processes earlier, but more broadly, hybrid manufacturing is beset by the following challenges:

• Some hybrid manufacturing systems can be expensive and harder to maintain than dedicated systems
• Vibration-assisted processes can decrease the machining accuracy because of the influence of the vibratory movements
• Thermal-assisted processes can increase the number of cracks and burrs

While these limitations and challenges can delay the progress of manufacturing activities, they are not insurmountable. Experts recommend selecting proper parameters based on suitable process-material interactions to prevent such issues as poor accuracy and undesirable surface finishes as well as heat-affected zones (HAZ) with microcracks. 

This recommendation hinges on the fact that hybridizing multiple processes using various thermal, chemical, or mechanical interactions is an extremely complex practical and scientific issue. This hybridization applies to various aspects, including the machine tool (and such properties as the accuracy of both the control systems and feed drives and thermal stability), the process itself, and process monitoring.

Implementing Hybrid Manufacturing

Currently, manufacturing best practices lean towards processes that increase productivity, efficiency, and flexibility while maintaining exemplary quality. Given the advantages of hybrid manufacturing, it can be tempting to want to procure a hybrid manufacturing system. But such a machine may not be suited for your shop’s or company’s needs. 

Hybrid manufacturing systems are preferred in manufacturing cycles with multiple stages, each involving a different manufacturing machine. This is quite the norm when machining objects with complex features and shapes. In such cases, the part must be unloaded, handled, loaded, and positioned in a different vice whenever you want to use a different machining process. 

From a productivity perspective, these steps significantly increase the production time. Yet, they are not value-adding. Over time, the cost associated with this non-value-added manufacturing time compounds significantly. Additionally, the steps can be a source of inaccuracies and inefficiencies. And, of course, multiple dedicated machines will require a larger space. Given such a scenario, it is advisable to implement hybrid manufacturing.

Conclusion

Hybrid manufacturing has evolved as a product of continuous advancements in machining processes. Driven by the pursuit of enhanced efficiency, productivity, and flexibility, manufacturers and researchers have melded individual processes and integrated diverse energy sources, giving rise to an array of hybrid manufacturing techniques. Today’s industrial landscape boasts a plethora of such methods, including but not limited to electrochemical discharge machining, electrochemical grinding, abrasive-assisted electrical discharge machining, vibration-assisted laser beam machining, and laser-assisted mechanical machining. While each process has its unique advantages, they also come with inherent limitations. As such, it’s crucial for manufacturers to undertake a comprehensive analysis of their operational needs to determine if hybrid manufacturing can offer tangible benefits to their production cycles.

While most, if not all, CNC systems promise to deliver these benefits, the results achieved can differ from one woodworking CNC machine to another. Naturally, this means that some machines are better than others, which is why this article discusses the best CNC machines for woodworking. We will also discuss the factors to consider when choosing a woodworking CNC machine.

The Best 6 CNC Machines for Woodworking

1. SainSmart Genmitsu 3018-PROVer CNC Router Machine

Size and build: 260mm x 155mm, with 35mm Z-axis travel

Software: Candle, which is based on the open-source GRBL software and runs on the main controller

Ease of Assembly: Easy (Assembly instructions and videos are available; most of the tools you need to assemble the machine are provided)

Starting Price: $269.00

Features of SainSmart Genmitsu CNC Router Machine

On the lower end of the pricing spectrum is the entry-level SainSmart Genmitsu 3018-PROVer woodworking CNC machine. A capable system, the 3018-PROVer is designed for engraving and light cutting tasks. Its gantry can support a laser engraver and a router. And according to some reviews, the machine can even drive a high-speed spindle. Compared to less powerful routers, spindles are better suited for engraving hard-to-cut materials and increasing the speed and accuracy of the machine.

Users report that the SainSmart Genmitsu 30-18-PROVer is easy to assemble. Moreover, they point out that the machine is easy to understand and use, given its excellent design, but fault the Candle software that is shipped with the system. The candle runs on Windows and Linux PCs.

The Candle software loads, edits, saves, and sends G-code to the machine. It can also visualize the cutting action. Once the G-code is sent to the GRBL-based Genmitsu, you can disconnect your computer, and the router will continue cutting with no issue – at this time, all operations are controlled by the controller and its GRBL firmware. 

However, some users report that using the software causes the machine to freeze. Instead, they recommend creating the G-code on your computer and subsequently sending the files via a microSD card to the machine’s controller.

Pros of SainSmart Genmitsu CNC Router Machine

• It is affordable
• The woodworking CNC machine has a small footprint
• The router can continue cutting without being connected to a computer, which means your computer doesn’t need to be exposed to dust
• You can easily replace the stock spindle with a bigger and more powerful one
• It uses lead screws, which are more durable and reliable than belts for driving movement along the x and y axes

Cons of SainSmart Genmitsu CNC Router Machine

• The stock clamps are quite small, so they cannot lock down thick materials
• Its recommended Candle software causes lags

2. Maslow Woodworking CNC Machine

Size and build: Variable

Software: Ground Control

Ease of Assembly: Difficult (Building the frame takes at least five hours if you have basic woodworking knowledge. Adding the electronics and installing the software require an additional hour or so.)

Starting Price: $439.00

Features of Maslow Woodworking CNC Machine

The Maslow CNC Cutting Machine is the most unique woodworking CNC machine on this list. While the other systems are oriented vertically, making vertical cuts, the Maslow machine is oriented horizontally. Created for enthusiasts and hobbyists, this machine is the result of an open-source project that began in 2015. Over the years, and thanks to the contribution of its vibrant community, the Maslow machine has become a reliable cutting solution for large sheets.

The starting price of the Maslow CNC machine is about $439.00. However, this price doesn’t include the materials needed to build the machine’s body and cutting bits. But you may be smitten to find out that you can use it to work on large sheets of wood – as large as 4’ by 8’. And contrary to what you would expect, it does not occupy a large floor space because of its cutting orientation. 

As the machine is oriented horizontally, diagonal cables hold the router in place. It is also weighted to maintain contact with the surface of the material. Unlike other woodworking CNC machines that are shipped with all necessary parts for assembly, the Maslow woodworking CNC machine is not. Instead, you have to improvise to build the frame that will anchor the cables and the sheet. The frame can be large enough to accommodate 4’ by 8’ sheets or, according to its makers, it can be smaller; it all depends on your workflow and preferences. The Maslow machine is primarily a 2-axis machine (refer to our comprehensive guide on CNC machine axes for a detailed explanation).

Pros of Maslow Woodworking CNC Machine

• The machine can work on large sheets of wood – as large as 4’ by 8’
• It can also work on smaller sheets
• The Maslow woodworking CNC machine is quite affordable
• It takes up less floor space

Cons of Maslow Woodworking CNC Machine

• Machine setup is quite difficult and time-consuming as you have to make the frames from scratch – it is a DIY machine
• It is slow

3. BobsCNC Quantum CNC Router

Size and build: 24” by 24” with 3.8” Z-axis travel

Software: GRBL firmware on the microcontroller paired with the BobsCNC’s Basic Sender software (installed on a laptop), which sends G-code files to the microcontroller

Ease of Assembly: Difficult – this woodworking CNC machine contains many wooden parts, and assembly can take at least eight hours

Starting Price: $1,280.00

Features of BobsCNC Quantum CNC Router

The BobsCNC Quantum CNC Router is a 3-axis desktop machine designed for 3D carving and 2.5D projects. It is suited for making home décor items, signs, and more. Unlike the other woodworking CNC machines on this list, the BobsCNC Quantum machine is made of wood, specifically plywood. The machine consists of numerous parts and flanges that are screwed together to promote rigidity. While the number of parts is beneficial in this regard, it increases the complexity and time taken to assemble the machine. 

That said, the cutting action remains unaffected, as it utilizes a Makita router. Belts drive the gantry’s movement along the X and Y axes, while a nut mounted on a lead screw controls movement along the Z axis.

All in all, this wooden woodworking CNC machine has the following features:

• Rigid laser-cut frame
• Self-squaring gantry
• Clamping table with aluminum T-slots

Pros of BobsCNC Quantum CNC Router

• The manufacturer provides excellent assembly instructions
• BobsCNC calibrates the Makita router to the woodworking CNC machine, promoting convenience

Cons of BobsCNC Quantum CNC Router

• The Makita router is loud, with peak noise levels of about 103 dB
• The accuracy of the BobsCNC Quantum woodworking CNC machine is easily impacted by factors such as micro-stepping, bit deflection, lead screw error, belt stretch, and more

4. Axiom Precision Iconic 8 CNC Machine

Size and Build: 24” by 48” with 4” Z-Axis travel

Software: Vetric VCarve Software (recommended)

Ease of Assembly: Varies, depending on whether you purchase the stand along with the machine. If you just purchase the machine, the assembly is easy. Nonetheless, setup and assembly instructions are available online on video and in a written manual.

Starting Price: $5,999.00

Features of Axiom Precision Iconic 8 CNC Machine

Compared to the more expensive ShopBot Desktop Max, the 3-axis Axiom Precision Iconic 8 CNC Router offers value for money. Not only does it have a larger bed/table size, but it also ships with an optional stand with built-in casters, leveling feet, and a toolbox. It offers accuracy and has been rigorously tested by its manufacturer.

The Precision Iconic 8 is designed for hobbyists. However, this doesn’t diminish its accuracy and ability to maintain precision over repeated use. It uses a high-rigidity extruded aluminum frame. If you are looking for a professional-grade machine from Axiom Precision, you can go with the Axiom Pro V5 Series. It measures 24” by 48” and costs $8,499.00 without the stand.

Some of the Precision Iconic 8’s features include:

• 1.1 HP spindle
• RichAuto B11 Industrial 3-axis controller
• Available stand with built-in casters, leveling feet, and optional toolbox
• Optional customization with accessories such as tooling, dust collection, software, clamping, and much more
• Prismatic guides in all axes

Pros of Axiom Precision Iconic 8 CNC Machine

• The assembly is relatively straightforward, given the availability of instructions
• The machine uses a spindle, which is more powerful and accurate than a router
• It is very stable even when running at a high RPM

Cons of Axiom Precision Iconic 8 CNC Machine

• It cannot be run directly from a laptop or PC
• The Axiom Precision machines with HUST controllers confine you to using the Vetric software, as there is a lack of post-processors for various CAM software in the market
• The Axiom Precision Iconic 8 is quite expensive, considering it is designed for hobbyists. Yet there are cheaper CNC machines for woodworking for this category of people, including the Carbide Shapeoko 4. That said, the Shapeoko 4 uses a router rather than a spindle

5. Phantom SCV 44

Size and build: 4’ by 4’ work area with 9” of Z-axis travel

Software: Phantom CNC’s custom software running on the HD-100 Pendant Controller

Ease of Assembly: Easy – the machine is shipped pre-assembled

Starting Price: $10,950

Features of Phantom SCV 44 Woodworking CNC Machine

The 3-axis Phantom SCV 44 CNC machine is a compact version of Phantom CNC Systems’ larger S and T series. Therefore, it retains most features found in the larger models, features that make it a perfect production-grade woodworking CNC machine. These features include:

• Multi-zone 4’ by 4’ vacuum table
• 6.1 HP air-cooled spindle
• Oil-mist cooling system
• Automatic rollers with 600 pounds of pressure

The Phantom SCV 44 can be compared to the PRO4848 4’ by 4’ CNC router from Avid CNC. However, the latter woodworking CNC machine suffers from rigidity issues, given that the parts that make up its frame are not rigidly fixed. Additionally, it is prone to stepping issues, which misalign the y-axis, substantially affecting the accuracy of the cuts. But even with the flaws, the PRO4848’s price can be as high as $17,305, depending on the configurations. These shortfalls influenced the inclusion of the Phantom SCV 44 in this list of the best CNC machines for woodworking.

Pros of the Phantom SCV 44 Woodworking CNC Machine

• It comes standard with automatic rollers, which work in conjunction with the vacuum table to securely clamp the sheet
• The machine offers easy controls via the handheld pendant control system

Cons of the Phantom SCV 44 Woodworking CNC Machine

• The Phantom SCV 44 machine is heavy, weighing 1,350 lbs. (612 kg)

6. Phantom S Series  CNC Machine

Size and Build: 4’ by 8’ or 5’ by 10’ stock sizes (although you can request custom sizes) with 8” or 11.8” of Z-axis travel

Software: Phantom CNC’s custom software running on the HD-100 Pendant Controller

Ease of Assembly: Easy – it comes pre-assembled

Starting Price: $20,500

Features of Phantom S Series Woodworking CNC Machine

The 3-axis S Series is an industrial-grade woodworking CNC machine from Phantom CNC Systems. It enables you to perform complex and high-precision operations. It is also capable of running for prolonged periods. Moreover, its automatic oiler feature increases convenience by undertaking some of the machine’s maintenance on your behalf.

The main features of the Phantom S Series include:

• 6.1 HP spindle (6000-18000 RPM)
• Multi-zone vacuum table
• Air and oil-mist cooling
• Automatic oiler
• Automatic pneumatic roller with 600 pounds of pressure
• HD-100 pendant control system
• Accessories such as vacuum pumps and dust collectors (sold separately)

Pros of Phantom S Series Woodworking CNC Machine

• It comes standard with a multi-zone vacuum table that firmly secures the sheet in place
• The Phantom CNC S Series offers high rigidity because it has fully welded steel frames
• This woodworking CNC machine is cheaper than some of its solid frame competitors, e.g., the ShopSabre Pro Series, CAMaster Panther Series, and Laguna Tools’ SmartShop M
• It ships with automatic pneumatic rollers that provide 600 pounds of pressure pressing the sheet to the table – this feature enables you to work on otherwise warped sheets
• Its gantry is gear-driven, which promotes precision
• The machine’s handheld control system makes it easy to control

Cons of Phantom S Series Woodworking CNC Machine

• It’s shipped pre-assembled, which may increase shipping costs due to its weight
• The Phantom S Series woodworking CNC machine is heavy, weight between 2,300 lbs. (1,043 kg) and 2,600 lbs. (1,179 kg)

Factors to Consider When Choosing a CNC Machine for Woodworking

Many of the factors considered when choosing the right CNC machine for your business also apply to woodworking. However, some factors are specific to machines used for woodworking. In this section, we will discuss all of them. 

Size

Most enthusiast/hobbyist-grade CNC machines have a small footprint. The footprint increases with the increase in utility. Generally, systems that are used in production must occupy a larger area because they are designed to cut large sheets of wood. They also feature additional components such as vacuum pumps, dust collection units, and pneumatically controlled rollers, just to mention a few. These extra components also occupy additional space. So, it is essential to consider the available space in your workshop whenever you want to purchase a woodworking CNC machine.

Setup or Assembly Time

Some CNC machines come pre-assembled from the factory, while others are shipped in tens of boxes for you, the buyer, to assemble. Putting the various parts together is a time-consuming exercise. It can even take several days, depending on the size of the machine and the number of people taking part in the assembly. This time could otherwise be spent on productive tasks. In a business setup, this adds to the labor cost. Thus, if you are not looking to allocate valuable time to assemble the CNC machine, purchase a machine that is shipped in a pre-assembled/complete state.

Frame and Table Rigidity

Some CNC machine manufacturers produce frames from extruded aluminum. Besides being easy to manufacture, this material makes the CNC machine easy to ship, especially because the manufacturer ships the parts in boxes for the user to assemble. It also has the added advantage of facilitating upgrades. If you later need a larger table, you can simply replace the shorter frame components with longer ones.

However, the lightweight nature of the material, plus the fact that assembly is done using bolts rather than welds, presents a problem: chatter or unwanted vibrations. The entire table vibrates when the spindle is rotating at high RPMs or moving at the maximum supported rapid. These vibrations can be a source of inaccuracy.

To avoid this, select a CNC machine whose parts, including the table, are welded firmly together. This manufacturing approach ensures the machine is rigid enough to resist any vibration. The rigidity improves performance and precision.

Upgradeability

If you are starting out, you may want a machine whose table size you could upscale later. CNC machines, such as the Pro4896 CNC router from Avid CNC, are constructed with upgradability in mind. This machine is built using lightweight material – extruded aluminum, with the various parts pieced together using bolts and screws. Thus, in the event that you want to upgrade the machine to a bigger size, you could simply order longer components that will replace the shorter parts. In contrast, machines whose parts are welded together cannot be upscaled. 

Purpose

Do you intend to use the CNC machine for business or as an additional tool in your woodworking hobby? The answer to this question will guide your decision making. Factors typically considered when choosing an ideal system for your business include accuracy, precision, and speed. 

In a business setup, you would want a machine that makes products using the shortest lead time. This would come in handy during rapid prototyping. This would necessitate selecting a machine that supports rapid cutting speeds without compromising accuracy or precision. Therefore, this would mean that you would go with an expensive machine that has a large footprint and is gear-driven rather than belt-driven. For instance, the SmartShop series CNC machines from Laguna Tools, whose tables can be up to 5’ by 12’ in size, have a starting price of $39,500. 

In contrast, your approach would be vastly different if you were a hobbyist. Naturally, you would be less concerned with the speed of the cuts, the accuracy, or the precision. You would also want a CNC machine that takes up less space. The Maslow CNC machine, for instance, has a starting price of about $439.00.

Budget

There is a woodworking CNC machine for each budget. This is reflected in our list of the best CNC systems for woodworking. Generally, however, the cost depends on the size and features. But the most expensive machine is not necessarily the best. You can find a cheaper option with more features.

Similarly, the least expensive system is not always the worst. This is particularly true if you require a machine for straightforward tasks. Thus, you should also consider other factors besides the cost. 

What Items You Will Make

One of the primary considerations to keep in mind when shopping for a woodworking CNC machine is what you plan to use the system for. Some machines excel at engraving, while others are better suited for carving. Similarly, the sort of machine you would use for milling furniture will be different from the ones you would use to carve signs or engrave parts.

Router or Spindle 

The spindle vs. router debate is quite common, with many discussing the differences and sometimes attempting to answer the question, which is better? Woodworking will definitely rope you into this debate. This is because the choice between a spindle and a router will significantly impact the quality and quantity of your work – and your wallet. Granted, both are rotary components responsible for rotating the attached cutting tool in order to remove material for a wooden workpiece. However, they differ in how they operate, i.e., their performance and output, as well as their cost.

Spindles are rated for continuous use, while some routers are not. Compared to routers of the same size, they are powerful and quieter, and their speeds are more easily controlled via CNC. These benefits generally make them more expensive. But they outlast CNC routers and thus do not require replacement during the machine’s service life. These characteristics make spindles ideal for use in high-powered industrial machines or professional-grade CNC machines, which are generally costlier. For instance, the SmartShop series CNC machines use a spindle setup rather than a router.

Nature of Control

Some woodworking CNC machines come with a pendant control system. This pendant features a USB port that enables you to send G-code files from computer-aided manufacturing (CAM) software via a USB flash drive. Other machines do not have built-in controllers. Such machines require a constant connection to a computer where the supported software is installed. However, due to the dust generated by woodworking, such machines could expose your computer to dust accumulation. Over time, this dust can clog the computer’s cooling system and lead to overheating. 

Broadly, the control method impacts your flexibility at the workstation. A pendant controller offers more flexibility than a PC-controlled system. What we mean by this is that you can easily move the machine without taking into account factors such as the location of a desk where you will place your laptop or desktop computer.

CAD/CAM Software

Manufacturers take different approaches to providing CAD/CAM software. Some, like Carbide, develop and sell software alongside their CNC machines. Others use open-source software to control their machines, while others use handheld pendants. That said, the specific CAD/CAM software that comes with your machine should not be a major concern. After all, the majority of CAD/CAM systems are compatible with most CNC machines.

Conclusion

There are tens – if not hundreds – of CNC machines for woodworking. Each offers several features designed to improve its capabilities. But like in every sector, some machines are better than others. In this article, we have compiled a list of the best woodworking CNC machines across various price ranges. However, it is worth pointing out that this is not a review. Instead, its purpose is to inform, which is why we have also discussed factors to consider when choosing a woodworking CNC machine. These considerations include size, budget, frame rigidity, control method, whether it uses a router or spindle, setup or assembly time, intended use of the machine, among others. In summary, here are some top CNC machines for woodworking, categorized by specific needs:

• Best affordable woodworking CNC machine: SainSmart Genmitsu 3018-PROVer
• Best woodworking CNC machine with an alternative format: Maslow Machine
• Best value-for-money production woodworking CNC machine: Phantom S Series

In this article, we discuss linear and rotary axes, concepts that introduce us to the different CNC machine axis configurations in various systems. We will explore the various types of CNC machines based on the number of axes they have, ultimately covering whether systems with more CNC machine axis counts are better. 

Basics of CNC Machine Axes

Linear Axes

The Cartesian Coordinate System is a reference system widely used in mathematics and other areas such as computer-aided design (CAD) and manufacturing. It is within the domain of manufacturing that CNC machines fall. This system is based on the concept of three mutually perpendicular axes that intersect at the origin. We refer to these axes as the linear axes, and they include:

• X axis, which is the movement from left to right and vice versa (parallel to the cutting tool)
• Y axis, which is the movement from front to back and vice versa (perpendicular to the cutting tool)
• Z axis, which is the movement from top to bottom and vice versa (perpendicular to the cutting tool)

Rotary Axes

Indeed, we have grown used to the above-mentioned linear axes (X, Y, and Z) from our Math classes. However, when it comes to machining, a new class of axis – the rotary axes – enters the picture. Namely, the A axis, B axis, and C axis, these rotary axes help improve the accuracy and cycle times of fabrication processes. They do so by enabling the cutting tool to reach and work on a few more sides than would have been possible with linear axes. And as will be discussed in greater detail below, this is due to the part’s rotational shift in position.

Rotary axes get their name from their association with rotation. And given that these rotations always happen around one of the three linear axes, the relationship between rotary and linear axes becomes clearer. Typically, this relationship is as follows:

• A axis is the rotation or tilt around the X axis; the A axis is also known as the tilt axis
• B axis is the rotation around the Y axis
• C axis is the rotation around the Z axis

So, what is a rotary axis or rotary axes? The rotary axes relate to rotations around the linear axes by the rotary table that enable the cutting tool to access parts at different angles in order to machine features on the fourth or fifth side of the part. 

Understanding Linear and Rotary Axes

You can think of a CNC machine axis as representative of the side from and dimension along which a feature on a workpiece can be machined. However, the term side does not necessarily mean the external face. Instead, and for simplicity, it can also refer to any internal surface that is parallel to the external face of a cube or cuboid. 

Starting from the basics, if you encounter a term such as a 2-axis CNC machine, that means the system can only machine features on two sides of a workpiece at a time. As will be detailed below, these machines comprise a combination of two linear axes. 

Similarly, if you come across the term 3-axis CNC machine, remember that such a machine performs the cutting action on three sides of the workpiece at a time. These sides will typically be the length (X axis), width (Y axis), and depth (Z axis), with the cutting or drilling tool traveling left to right (and vice versa), front to back (and vice versa), and top to bottom (and vice versa), respectively.

The introduction of the rotary axes gives rise to 4-axis and 5-axis CNC machines, also known as multi-axis machines. But following the same principle introduced above, a 4-axis machine can work on four sides of the part at a time. On the other hand, a 5-axis machine can manipulate and fabricate features on five sides of the part secured in the vise at a time. The multi-axis CNC machines’ additional capabilities, compared to the 2-axis and 3-axis machines, emanate from the ability of the cutting tool and rotary table (bed) to shift positions linearly and rotationally, respectively, which changes the part’s orientation relative to the cutting tool, exposing more sides.

2-Axis CNC Machines

As the name suggests, the 2-axis CNC machine has moving components that travel along two axes. Depending on the type of machine and the work envelope’s orientation (i.e., horizontal or vertical), these two axes can be a combination of the x-axis and y-axis, the x-axis and z-axis, or the y-axis and the z-axis. 

X and Z Axes in CNC Lathe Machine

CNC lathe machines and turning centers fall into this category. They mostly support movement along the x-axis and z-axis. These machines have a number of components, but in this article, we will focus on the chuck, which attaches to the main spindle and holds the workpiece in place, and the cutting tool. The chuck, for its part, rotates around the z-axis. On the other hand, the cutting tool moves along both the x-axis and z-axis. 

As far as the cutting tool is concerned, the X axis relates to inward or outward movement. On the other hand, the Z-axis is associated with longitudinal movement (i.e., along the axis around which the chuck rotates). The movement of the cutting tool influences the classification of CNC lathe machines and turning centers as 2-axis CNC machines.

Multiple manufacturers, such as Haas with its ST-series turning centers and Knuth with its Forceturn series, produce and sell high-performance CNC lathe machines and turning centers. Some compact vertical milling machines and high-precision CNC grinding machines also fall into this category of 2-axis CNC machines.

3-Axis CNC Machines

The 3-axis CNC machine configuration is primarily found in CNC milling machines. In these machines, the workpiece is held in place by a vise. The vise, in turn, is fixed to a moving table. Designed to move, the table travels along the X and Y axes, while the drilling or milling tool travels along the Z axis. The combination of these movements means the CNC machine can simultaneously remove materials from the sides that correspond to the length, width, and depth.

This CNC machine axis configuration is ideal for machining simple parts with only a few features. These machines are also ideal for situations where the part does not require a lot of detailing. 3-axis CNC machines can also machine complex parts with numerous features. However, this will likely take longer than it would with systems that have more CNC machine axis configurations. More on this in the below section discussing whether more CNC machine axis configurations are better. 

Examples of commercially available 3-axis CNC machines are EC-1600ZT, VF-1, VF-2SS from Haas Automation, the BO 90 CNC and BO T CNC 110 series from Knuth, the VX8 from Huron, and the GENOS M series machines from Okuma.

4-Axis CNC Machines

In 4-axis CNC machines, the axis count is 4. Such machines have the capabilities of a 3-axis machine, i.e., their cutting tool and/or table can move along the X, Y, and Z axes. However, they also support rotation around one of these linear axes. This rotation is thanks to their use of either 4th-axis (single-axis) rotary indexing tables or a 4th-axis swivel head. 

Rotary indexing tables have built-in motion systems comprising, among others, fixed motors that link to a fixture plate that rotates around a single axis. They expose a new surface for machining. This process is technically known in manufacturing as indexing. Accordingly, the part clamped onto the fixture plate rotates based on the CNC program generated by the Computer-Aided Manufacturing (CAM) software. 

Generally, 4th-axis rotary tables are available in right-hand, left-hand, or bottom configurations, with a bottom-, top-, side-, or back-mounted motor. They also come in different sizes to accommodate different sizes of parts or fixtures. These rotary tables are compatible with CNC machines that have a 4th-axis drive and firmware that supports full 4th-axis operations.

4th-Axis Rotary Table (source)

However, not all machines utilize rotary tables. Some have a swivel head paired with a non-rotating table that is nonetheless capable of traveling along the linear axes. The swivel action of the head introduces 4th-axis rotation. However, this is more accurately described as a tilt because the movement does not constitute a complete 360º rotation. Examples of 4-axis swivel-head machines are the VMX42SWi, VMX60SWi, and VMX84SWi from Hurco.

4-Axis Swivel Head Machine from Hurco (source)

5-Axis CNC Machines

A 5-axis CNC machine has a CNC machine axis count of 5. This number includes the three main linear axes (X, Y, and Z) and any two rotary axes. This means that a 5-axis CNC machine includes the X, Y, and Z linear axes, along with two of the following rotational axes: A, B, or C. The additional two axes in the 5-axis CNC machines originate from two different mechanisms, resulting in two types of 5-axis CNC machines:

• Swivel-rotate-style 5-axis CNC machine
• Trunnion-style 5-axis CNC machine

Swivel-Rotate-Style 5-Axis CNC Machine

Also known as the swivel-head rotary table CNC machines, the swivel-rotate-style 5-axis CNC machines essentially have a swivel head that tilts around the B-axis, with a rotary table that rotates around either the A or C axis. This table supports the full 360º rotation, while the swivel head’s tilt is often less than 130º on either side of the vertical axis. It is worth mentioning that the tilt angle depends on the manufacturer. Hurco SRTi Series swivel-head rotary table machining centers support a maximum tilt of 92º on either side of the vertical axis, for example.

This type of 5-axis CNC machine is ideal for machining heavier parts. It is also less prone to tool interference issues. This is because the rotating table rarely interacts with the cutting tool, regardless of length. Moreover, the swivel-rotate-style machine offers flexibility and versatility. This is because it can machine both heavy and light parts.

Examples of swivel-rotate-style 5-axis CNC machines include the Hurco VMX60SRTi and VMX42SRTi.

Trunnion-Style 5-Axis CNC Machine

The trunnion-style 5-axis CNC machine introduces the rotary axes via dual-axis rotary tables and indexers. These dual-axis rotary tables orient the part to the cutting tool to take advantage of the cutter’s geometry. As a result, they expose as much as the part’s five sides to the cutter. 

These tables tilt around the A or B axis by a specific angle on either side of the vertical axis. This angle typically depends on the manufacturer. CNC machines from Haas Automation support a maximum tilt of 120º each way. In contrast, those from Huron support a maximum of 110º. However, when it comes to the movement around the C axis, all rotary tables and machines support a full 360º rotation.

Haas TR200Y Trunnion-Style Rotary Table (source)

However, these machines have a downside. Due to the rotary table’s continuous rotation and twisting of the part, the risk of tool interference significantly increases. Additionally, the rotation limits the weight of the part that the table can support. In this regard, trunnion-style machines are mostly ideal for machining light to medium-weight parts. 

Some examples of Trunnion-Style 5-Axis CNC machines are the VC500i and VCX600iXP from Hurco, the VC-X350from OKK, and the VR series and UMC series machines from Haas.

Multi-Axis CNC Machines

Multi-axis machines are those that have a CNC machine axis count that is greater than three. This means such machines have one or two rotary axes on top of the three linear axes. Compared to conventional CNC machines with two or three linear axes, multi-axis CNC machines offer several advantages:

• Multi-axis CNC machines require fewer setups as their cutting tools can access more sides than conventional machine’s cutters and mills
• The fewer setups translate to less cycle time, i.e., the amount of time spent machining a part with all designed feature
• These machines are more accurate because they eliminate the likelihood of human errors during setup – they have fewer setups and part-loading instances

As with all other machines, multi-axis CNC machines also have a few disadvantages, including:

• They are more expensive to purchase than conventional CNC machines
• Multi-axis CNC machines, particularly the trunnion-style 5-axis machines, are prone to collisions between the nose of the spindle of the machine and the side of the rotary table

Image Showing Close Proximity of Spindle Nose to Side of Rotary Table (source)

While the first disadvantage is unavoidable, measures can be taken to prevent the second. Running the machine slowly after loading the part can ensure safety and allow you to monitor the spindle nose’s proximity to the rotary table. If you establish that a collision is more than likely, there are two approaches you can take. First, you can use longer tools. Alternatively, you could attach your tools to an ER collet chuck to elongate them. That said, a few questions linger.

3-Axis CNC Machine vs. 5-Axis CNC Machine

Are higher CNC machine axis counts better? Are multi-axis CNC machines better than conventional CNC machines? To help answer the questions, Haas Automation conducted an analysis. In this analysis, a machinist separately created two identical parts using a 3-axis CNC machine and a 5-axis CNC machine. Though the analysis was not scientific, it offers insights that point to the fact that multi-axis CNC machines are better for machining parts with a high level of complexity. 

This is because the use of the 5-axis CNC machine resulted in a 26.6% reduction in the cycle time. This implies that the machinist took less time to machine the part with the 5-axis machine compared to the 3-axis machine. Moreover, the former required just two setups or part loadings, compared to the latter’s five setups. The machinist also had to set the work offset during each setup. This means there were five different sets of work offsets in the 3-axis machine. In contrast, the 5-axis machine just required two. Furthermore, the fewer setups and work offsets because of using the latter dramatically reduced the chances of human error.

Another drawback of the 3-axis CNC machine that the analysis uncovered relates to tooling. The machinist had to constantly change the tool. And he did so even when that tool was required later to machine a feature on the part’s other sides. This added a few minutes to the cycle time. In contrast, the 5-axis machine would complete all machining operations required of the cutter by simply changing the part’s orientation. Only after the cutting tool had finished its job would it be changed. This helped reduce the cycle time. 

Are Higher CNC Machine Axis Counts Better?

So, are more CNC machine axis counts better? Yes, they are. In fact, they are preferentially used in high-performance machine shops for pretty much this reason. However, multi-axis CNC machines may not be suitable for all types of machining jobs. This leads us conveniently to the next section, which discusses what goes into choosing the right number of axes.

Choosing the Right Number of Axes

There are numerous factors to consider when choosing a particular CNC machine axis count. These include:

• Cost
• Function
• Part complexity
• Future Plans

Cost

Different CNC machine systems come with varying costs. Naturally, 5-axis CNC machines are more expensive than 3-axis CNC machines. This is because you need to purchase additional accessories, e.g., the trunnion-style rotary table, longer tools, and collet chucks. However, industrial-grade, high-performance 2-axis CNC turning centers can also carry a high price tag. So, the cost may not always be the most crucial factor to consider when choosing the most appropriate CNC machine axis count for your machine shop.

Function

Indeed, Haas Automation established that 5-axis CNC machines are inherently better than 3-axis machines at working on complex parts. However, multi-axis machines are not always ideal for all operations. In machining jobs that require 2-axis CNC machines, such as the CNC lathe or grinder, systems with more CNC machine axis counts will not cut it. Therefore, considering the intended function is crucial when selecting the appropriate number of axes. 

Part Complexity

The complexity of a part increases the number of machining operations and tools to be used. And if the machined features are found on multiple sides of the part, then its orientation should be constantly changed. This is done to ensure the cutting tool accesses the different sides. Here, you can use a 3-axis system or a multi-axis system with a CNC machine axis count of 5. However, the former would require additional setups and sets of work offsets, which could compromise accuracy. In contrast, the latter would be a better option thanks to fewer setups and sets of offsets.

Future Plans

It is also important to consider your vision for your machine shop. This should be the case even when your current budget does not allow you to actualize this vision. Do you wish to scale up your operations? Are you looking to eventually reduce operational expenditure by lowering the cycle time? If the answer to both of these questions is an emphatic yes, you could initially purchase a machine whose capabilities can be upgraded later via the purchase of accessories. For instance, you can purchase a 3-axis CNC vertical milling machine that supports the fourth- and fifth-axis drives. You can then enhance your machine shop’s capabilities later by adding a trunnion-style rotary table.

Conclusion

Each CNC machine has a specific CNC machine axis count, depending on whether it employs only linear axes (X, Y, Z), or a combination of linear and rotary axes (A, B, C). While the CNC machine axis configuration is factory-imposed, you can increase the count for some types of machines by purchasing accessories such as a rotary table. All in all, the number of axes found in CNC machines influences their capabilities and functions. For example, while multi-axis machines are optimal for complex parts, 3-axis CNC milling machines are more suitable for simpler operations. Besides the function and part complexity, there are other factors you should consider when choosing the right number of axes. When choosing the right number of axes, consider factors such as function, part complexity, cost, and your machine shop’s future plans.

Potential Hazards of CNC Machines

CNC machines and CNC machining can be as dangerous as they are life-altering. The likelihood of exposure to conditions that can cause serious injury or death is exceptionally high. This is why it is often advisable to be extremely vigilant when working in a machine shop. The importance of vigilance emanates from the potential hazards of using CNC machines as well as the heavy materials fed into these machines. The hazards that threaten CNC machine safety include:

1. Noise

Machine shops are generally noisy. But this is expected since the cutting action, which often involves a tool made up of a hard material gliding over or grinding against another material, will naturally produce sound. However, machining is an ongoing process, given shops can run 24/7. This means that, in most cases, working in these environments translates to prolonged exposure to excessive noise levels. 

Governments the world over enforce laws requiring employers to prevent or reduce risks to safety and health arising from exposure to noise at workplaces. In the United Kingdom, the Noise Regulations 2005 set the legal noise limit as 85 dBA, the same value as the United States, according to OSHA guidelines. Despite the stipulated limits, CNC machines often exceed the values. For instance, CNC lathes, milling, and drilling machines produce noise up to 104 dB, while CNC grinders can produce noise up to 134 dB.

This level of noise can be disastrous, per the Centers for Disease Control and Prevention (CDC), which notes that prolonged exposure to noise above dB may start to damage your hearing. Moreover, loud noise that exceeds 120 dB can immediately harm your hearing ability. Noise in industrial settings such as CNC machining could have been a contributing factor for some of the 14,500 people who experienced work-related hearing loss illness in 2019. Of this number, 75.9% occurred in the manufacturing industry, pointing to the danger of noise.

2. Chips

Another byproduct of the machining process is the waste material removed from the workpiece. This waste exists as metal particles, which are known as chips. Chips are an ever-present concern for machinists, who must find ways to keep these waste materials under control. They are extruded as either short or long particles, each a hazard in its own way. Generally, chips are hot immediately after they are made, reaching over 500ºC (1,000ºF). When such hot materials get into contact with synthetic clothes such as nylon and polyester, they stick, then melt through the material. As such, they can cause burns. Chips are sharp and can, therefore, cause deep or shallow cuts, especially given they fly from the surface of the workpiece at extremely fast speeds. Moreover, because they are generally made from the same strong material as the workpiece, long chips can catch and drag an unalert machinist into the machine.

3. Moving Components or Machinery

Most CNC machines (mills, drills, lathes, routers, and grinders) cut via rotating motion. Others, like CNC waterjet machines, CNC plasma cutters, CNC laser cutters, and 3D printers, also involve some motion. It is, therefore, accurate to state that CNC machines are, by their very nature, made up of moving components or machinery. These moving components can easily latch onto machinists’ sleeves, apron strings, or loose clothing, dragging them into the machine, a CNC machine safety issue.

4. Falling Heavy Objects

Large-scale or industrial-grade CNC machines are designed to work with heavy workpieces. While the role of loading the workpieces is sometimes left to a specialized crew due to the dangers involved, machinists cannot absolve themselves from certain personal responsibilities. As a machinist, you must always be watchful of your surroundings and the positioning of heavy objects, taking great care to ensure you look before moving. You should also not walk or work below suspended material or objects. 

5. Heat from the Cutting Process

CNC machines, such as laser and plasma cutters, remove material by way of melting and vaporization. The heat generated during this process is in itself a hazard. Similarly, some rapid prototyping machines such as extrude hot material. In both cases, the parts will still have elevated temperatures that can cause burns, even after the machining or prototyping process is complete. Combined, these factors call for extra care when working with such material. Even so, it is equally important to tread carefully as far as the other types of CNC machines are concerned, because friction during machining can generate heat.

Safety Features of CNC Machines

Understanding the hazards associated with their equipment, manufacturers of CNC machines implement safeguards to reduce the chances of accidents and health issues. The CNC machine safety features include:

1. Safety or Containment Shield

In simple terms, a safety shield is a vapor or spray containment barrier. It prevents chips, vapor (from the cutting process), or spray (from the interaction between the cooling fluid and the rotating cutting tool) from escaping the work area. The shield is also designed to provide a safe barrier behind which the machinist can observe the cutting process. 

2. Video Cameras

While the containment shield is also designed to enable the machinist to safely monitor the cutting process, it is not always effective in this regard. Sometimes, the work area gets messy, with the shield getting clouded by the cooling fluid’s spray and flying chips. However, the machinist still needs to monitor the progress of the cutting process. 

To solve the visual obstruction brought by the fluid and chips, CNC machine makers include as an add-on accessory video cameras. These cameras record the activities inside the machine in real time, enabling you to track the process. They are also convenient because they ensure you are not in harm’s way. By sitting behind a monitor rather than directly in front of the cutting area, you avoid being situated along the path of flying chips or fluid.

3. Cooling fluid 

Cooling fluids come in four different forms, namely petroleum oils, synthetic fluids, semi-synthetic fluids, and soluble oils. Regardless of the type, these cooling fluids are intended to serve several known functions, including:

• Reduce the external and internal heat generated by the cutting process
• Lubricating the interface between the cutter and the work material, thus reducing friction, heat, and pressure
• Reduce horsepower needed to drive the motor and cutting tool (due to reduced friction)
• Enhance tool life and service life of the machine
• Prevent oxidation on some materials
• Improve surface finish

While the cooling fluid achieves these functions, it contributes significantly to CNC machine safety. For instance, it safely and efficiently flushes away chips, which has a ripple effect. By flushing away the chips, the cooling fluid not only increases the material removal rate but also contributes to machine safety. Additionally, it prevents the chips from bunching up in the cutter flute, which can reduce the efficiency of the cutter.

4. Controller Alarm

Experienced machinists possess the necessary skills to detect many potential problems, some related to CNC machine safety. However, in some cases, the machine’s controller can announce these problems in code or words, known as alarm conditions. If the machine uses codes, the machinist must decipher what went wrong. In contrast, with words, the exact problem is displayed on the screen. Whether the controller displays a word or code depends on the model or version of the machine. Still, these alarm conditions offer insights that could prevent a disaster. 

The alarm conditions can be grouped into:

• Physical and hardware errors: These are associated with the CNC machine and include, but are not limited to, low coolant, hydraulic, or lube oil; servo errors; hard limit overtravel; and more. It is these hardware-related issues that can threaten CNC machine safety.
• Syntax errors: These are errors that lie within the CNC code

5. Emergency Stop (E-Stop) Button

The emergency stop, or e-stop, button stops motion along all axes. It also stops the spindle, cooling fluid, and all other ancillary functions. Once depressed, the e-stop button stays engaged until it is manually unlocked. Also, suppose you engage this button during machine use. In that case, you must reinitialize the CNC machine, power all axis drives anew, manually move the cutter away from the workpiece, and then start over the program. For this reason, only use this button in cases where all other halt interventions are too slow to be safe.

Emergency Stop Button

6. Slide Hold Button 

If you do not want to use the emergency stop button, you can press the slide hold button, which is another halt intervention. It stops motion along all axes but does not impact other functions or the program, as is the case with the e-stop button.

7. Locking Key Switch

The locking key switch, a key-protected switch on the control panel, allows the machinist to set specific levels of responsibility for the protection of people, machines, setups, and programs. For instance, the switch can be set to operate, the lowest level of responsibility. Operate allows all program run and half functions but disallows edits and setup information changes. Alternatively, the switch can be set to setup, the medium level. As the name suggests, setup allows the machinist to make setup/process changes, e.g., tool diameter and length. However, it disallows program edits. The highest level of responsibility, known as ‘edit,’ grants complete control, allowing access to all functions and setup information, as well as the ability to change existing programs and write new ones. It allows access to all functions and setup information, as well as changes to existing programs and the writing of new programs.

Key-Operated Locking Switch

8. Feed Rate and Rapid Override Buttons

The feed rate is the speed at which the cutter moves against a workpiece. On the other hand, rapid travel refers to the fastest speed at which a CNC machine can move the cutting tool from one position to another. Given that these speeds can be extremely fast, manual override buttons are necessary to safeguard CNC machine safety. 

Machinists use the feed rate and rapid override buttons to protect against poorly written programs. How so? Usually, these buttons allow machinists to manually adjust the feed rate or rapid travel speed downward based on pre-set figures. For instance, the button can be set to reduce the speed to zero or a certain percentage of the maximum speed. These buttons come in handy when machinists observe unusual speeds.

9. Automated Chip Removal Conveyors

In large-scale machining operations, the equipment is constantly processing numerous workpieces. This means the machines generate a large quantity of chips within a short time. Coupled with the fast-moving machinery, the constant flow of cooling fluid, and the containment shield, this makes manual chip removal quite hazardous. To improve CNC machine safety, manufacturers often include automated chip removal conveyors. As the name suggests, these crucial components automatically remove chips from the work area, carting them to a collection bin for recycling or disposal.

Essential Safety Guidelines for Operating CNC Machines

While CNC machine manufacturers strive to safeguard CNC machine safety, the onus is still on the machinists to take extra care. To avoid work-related incidences, we have compiled essential safety guidelines for operating CNC machines, as below:

1. Always Use Personal Protective Equipment (PPE) 

Despite its effectiveness, the containment shield cannot guarantee 100% CNC machine safety. This is because you are likely to walk through sections of the machine shop that house machines that might not have the shield. Additionally, some grinding equipment, such as grinders that use grinding discs, do not come with containment shields. At the same time, the shop is a noisy place. And as we have discussed earlier, the probability of losing your hearing increases with every minute you spend in the noisy shop. In this regard, it is advisable to use personal protective equipment such as safety glasses, full-face shields, gloves, and hearing protection. 

2. Properly Secure Workpieces

Loose workpieces can easily detach from their harnesses and fly away, hitting and damaging crucial components inside the CNC machine or the containment shield. They can also damage the cutting tools and result in poor-quality machining. Thus, properly securing all workpieces can minimize the risk of accidents, upholding CNC machine safety.

3. Put on Well-Fitting Clothes

As previously mentioned, working around moving machinery poses a risk. Therefore, it is always advisable to protect yourself by putting on well-fitting clothes that will not get tangled in the moving parts. Your clothes should have no sleeves, pockets, or tie strings/cords. Plus, you should always tuck in your shirts.

4. Wear Clothes with Natural fibers 

Natural fibers like wool or cotton in clothing provide a protective barrier against hot flying chips. They do not burn through upon getting into contact with the chips. By contrast, synthetic fibers melt.

5. Always Wear Steel-Toe Boots or Shoes

Regardless of how careful you are, you may not always foresee certain risks. One such inevitability is falling heavy objects. For this reason, wearing steel-toe boots is better than putting on regular shoes. The former protects your toes, preventing injuries.

6. Avoid Accessories

Do not wear accessories such as necklaces and bracelets, which might get caught in the moving machinery.

7. Tie Your Hair Up

Much like how toddlers grab onto long hair, moving machinery can do the same, but with much more force. The ease with which loose hair can get tangled in such machinery does not help. You might lose a few strands of hair at best, and at worst, you might get sucked into the machine head first. To prevent such a disaster, always tie your hair up or cover it.

8. Have an Emergency Action Plan

Given that machines in workshops move at high speeds, emergencies are not uncommon. Similarly, crashes can occur, given that most materials and machines are extremely heavy. That said, the ability of an operator to maneuver through these issues by following an action plan depends on pre-planning and practice. 

The issues can be categorized into three levels. The first includes non-emergency incidents that might get worse over time. The second level encompasses low-level emergencies, such as chip build-up, that might degrade with time. The third level covers a situation that is extremely dangerous to the machine and operator. Each of these incidents should have an action plan, with the third level requiring the operator to immediately hit the e-stop button.

Haas Controller with E-Stop Button for CNC Machine Safety (source)

9. Monitor Cutting Progress

The transparent CNC machine safety shield is intended to ensure the operator can monitor the progress of the machining process. In cases where the view is obstructed by a mixture of the flying chips and cooling fluid, a video camera is provided. But these are not the only avenues through which you can monitor the progress. You should also pay attention to the sound made. 

The logic behind constantly monitoring the progress is to notice abnormal movements or sounds that might threaten your health and safety. Then, depending on the severity of the issue (which you will have documented in your emergency action plan), you can use the slide hold button, feed rate and rapid override buttons, or e-stop buttons.

10. Perform Routine Inspection and Maintenance

Routine maintenance can help you prevent certain issues from escalating. It solves issues at their formative stages, nipping them in the bud. For instance, by maintaining the hydraulic or cooling fluid pump, you can avoid a potential explosion or failure that can otherwise cause a level-three emergency. Similarly, regularly servicing the chip conveyor can help you avoid a breakdown that might lead to chip build-up, a level-two issue. Put simply, routine maintenance promotes CNC machine safety.

Training and Education for CNC Machine Safety

In many countries, including the UK and USA, the standards require employers to conduct employee training at least once every 12 months. Such training achieves the following:

• Educate supervisors, workers, and managers about recognizing and mitigating potential hazards
• Equip employees with the knowledge to accurately report and control hazards
• Aid professionals in working both productively and safely
• Enhance understanding of CNC machine safety and machine shop health and safety programs. With this understanding, workers and managers can contribute to their improvement, development, and implementation

Implementing a Safe CNC Machine Environment

Hazards directly affecting CNC machine safety, i.e., machine hazards, are only one piece of the puzzle. Others include:

• Electrical hazards, including shocks and fires, resulting from faulty wiring, damaged insulation, improper grounding, or power surges
• Chemical hazards from exposure to coolants, metal dust, lubes, and solvents, leading to skin irritation, allergies, respiratory issues, etc.
• Waste management: it is important to consider how you dispose of waste such as used oils, coolant, chips, and unwanted material from the machined workpiece

Taking each of these factors into consideration and implementing the best industry practices contributes to a safe CNC machine environment. For this to succeed, management must establish a safety culture. After all, the managers are supposed to develop specific training for each CNC machine equipment in a shop and adopt additional safety rules as necessary.

Conclusion

Accidents in machine shops are not unheard of, given that the CNC machines are heavy and rotate at high speed, not to mention they sometimes work on heavy materials. It is, therefore, crucial to implement CNC machine safety guidelines and best practices to prevent such accidents. For a start, modern machines come with safety features. Nonetheless, they do not guarantee 100% safety. However, the responsibility for safety still lies with the operator or machinist. They must wear PPE, perform regular inspections and maintenance, wear suitable clothing, avoid accessories, have an emergency action plan, and more. Furthermore, participation in safety training and education is crucial to maintaining a safe CNC machine shop environment.

History of CNC Machining and Machining Approaches

Before going further, a little background is necessary. CNC was born circa 1970 when machines that RAM became commercially available; G-code, however, is much older. Later, around 1975, CAD and CAM began, driven by the affordability of PCs and the fact that programming had become a little bit simpler. However, it wasn’t until 1980 that fully-functioning graphic software and multitasking CNC machines were introduced and widely used. And by 2000, automated CAM software could now convert solid drawings into programs that CNC machines could execute to create physical representations of the drawings. 

This brief chronological history introduces the fact that CNC machines use programs to machine parts. At the formative stages, before computer-aided manufacturing (CAM) applications could convert 2D drawings or 3D models to programs, programming was handled manually by operators. These individuals manually wrote machine code and fed it into the machine. As part of their code-writing responsibilities, they planned and documented the sequential processing steps the machine should follow. These sequences included:

• Tool movement, e.g., position, direction, and speed
• Spindle rotation speed and direction
• Tool selection, tool offsets, tool compensation, and tool change
• Application of cooling fluid
• Cutting speed

As computers’ processing capabilities improved, computer-assisted programming emerged. This approach was more simplistic and saved a lot of time. Operators no longer had to write machine code – G-Code and M-code. Rather, they simply wrote statements that followed an English-like syntax. Then, the computer compiled these statements, converting them to machine code. This approach was advantageous because it reduced the burden of knowing how to code extensively. However, it was disadvantageous because it used English-like commands to define geometry rather than graphical elements, which were more convenient. As technology advanced, in came CAD and CAM software, substantially improving the experience.

How CAD and CAM are Applied in CNC Machining

The CAD/CAM approach is currently the most popular method of creating code for CNC machines compared to other approaches. The process begins with creating a 2D drawing or 3D model of a part using CAD software like AutoCAD, SketchUp, and more. The procedure then follows these steps:

1. Next, the model is imported into CAM software, a program that automates the manufacturing process.
   However, software applications such as SolidWorks and Fusion 360 combine CAD and CAM capabilities; they are known as CAD/CAM software. With these programs, all you have to do to use the built-in CAM capabilities is enter the manufacturing mode. Fusion 360, for instance, requires you to change the workspace from ‘Design’ to ‘Manufacturing.’ On the other hand, in SolidWorks, you have to open the SolidWorks CAM add-in. 
2. Next, select the CNC machine, cutter, and coordinate system. 
3. Create a manufacturing sequence, also known in SolidWorks as an operation plan.
4. Next, prompt the software to generate a toolpath.
5. Run a simulation to verify that the operation plan and toolpath selected by the software align with your machine shop practices.
6. Generate the G-code file, also known as post-processing, and save it. Importantly, post processing builds all the information above into the program. And given that the post processor must be able to translate the code to the specific machine’s convention, selecting one that corresponds with your CNC machine is crucial. Such machine-specific processors utilize a library that contains machine-specific controls. This is partly why most CNC machines come with their own CAM systems. However, these manufacturers also accommodate conventional, popular CAM software.
7. Lastly, import the file into the CNC machine for machining

It is worth pointing out that modern CAM software can automatically detect design changes and update the NC program. These are just some of the advantages of CAD/CAD programs. Overall, by combining this software with CNC machines and computer-driven feed drives, there is practically no 3D shape you cannot create.

CAD Design Considerations for CNC Machining

Every time you wish to create a design for CNC machining, you must first use CAD software. This makes design the first foundational stage. Machining operations are generally more expensive than other manufacturing processes, requiring skilled labor, substantial capital investments, significant amounts of energy, and relatively slow production. Therefore, it’s important to consider several factors when designing for CNC machining to save time and costs. These considerations help create a design that is suited for a particular machining process. In addition, they contribute to cost and time saving – more on this below, where we discuss the importance of the collaboration between designers and machinists. 

The CAD design considerations are generally regarded as design for machining rules; they include:

1. Optimize Tolerances

Geometric dimensioning and tolerancing (GD&T) provides machinists with greater control and flexibility downstream. Machining a feature, such as a drilling hole, requires the hole to be the right size and position. (A feature is any aspect of a part that is dimensioned and toleranced.) Depending on the utility, it must also have the right shape. Usually, these properties are defined by the nominal dimension and annotations, which provide additional information. 

Realistically speaking, though, it is impossible to achieve exactness or perfection. Even if it were possible to achieve exactness, it would require additional grinding or honing operations for specific surface finishes and reaming processes for specific diameter sizes, which would slow down the machining process and increase manufacturing costs. These additional operations slow down the machining process and increase the cost of manufacturing. 

For this reason, tolerances, which define the amount of allowable variation from the nominal dimensions, are used. Tolerances should be optimized based on the following factors:

• Tool change schedule
• Compensation capabilities of the tools
• Part geometry
• Supports built into the fixture
• Tool guiding jigs

To understand the significance of these factors, designers should collaborate with machinists.

2. Type of Material

The type of material greatly impacts the quality of the machining operation as well as the cost. This is because it determines the tool materials, motor power, cutting speeds, tolerances, and surface finishes. To select the material, you must consider the chemical and physical properties as well as functional requirements outside of machining.

3. Minimize the Number of Machined Features

The general rule of thumb is that features should be machined only when they require tolerances (dimensional or surface finish tolerances) that other manufacturing processes cannot achieve. Machining is usually used for features that require:

• Dynamic balance
• Press fitting
• Locating
• Locking
• Bearing
• When subsequent assembly considerations call for a close dimensional tolerance

If possible, minimize the number of machined features through alternative methods such as undercutting, chamfering, and casting in holes, especially if the specified tolerances allow for it.

4. Minimize Machined Stock Allowance

Always minimize the material that needs to be machined away to produce the final part. This amount is known as stock allowance) Failure to do this increases costs such as the cost of replacing worn-out tools (tool wear per part increases with the increase in stock allowance), material costs, and equipment costs. It also increases the time taken to produce a part. 

Minimizing the stock allowance is achieved by optimizing the dimension based on the size of the material loaded into the CNC machine. The whole unmachined material is technically known as the stock, billet, or blank. 

5. Standardize Features

Make sure you standardize features as much as possible. You can achieve this by selecting hole diameters from a limited range of sizes. You should also limit the number of different diameters in a single part.

6. Surface Finish

The desired surface finish determines the machining operation used. However, certain operations such as diamond turning, precision grinding, lapping, and honing can achieve small surface finish tolerances (<0.4 micrometers) but increase machining costs.

7. Provide Adequate Strength and Stiffness

CNC machines are driven by powerful motors that, in turn, generate massive cutting forces. These forces can break, bend, or deflect the part. They can also cause unstable vibrations. This is particularly the case if the strength and stiffness are inadequate. Therefore, designers should ensure that the part has adequate stiffness and strength, particularly in the loading directions.

8. Provide Adequate Accessibility

Feature locations should be accessible with standard machining tools. Avoid locating features on remote faces or inside cavities. If the features are located in hard-to-reach areas, specialized tooling is necessary. However, such tools may create unstable vibrations or deflections. Furthermore, using these tools and attachments increases the machining costs and limits the allowable tolerances.

Preparing CAD Files for CNC Machining

Once the designer or engineer finalizes the product design process, which generally includes conceptualization, synthesis, analysis, evaluation, and documentation, the CAD file is sent to the machinist for CNC machining. As a machinist, you do not have to understand how the product or part works – that is reserved for the engineer or designer. However, there are a few things you need to know and do, including.

1. Remove Unwanted Layers

Dimensions and notes are ideally designed to help machinists visualize and understand the part. To put it simply, they provide additional information. Thus, they do not in any way contribute directly to the creation of the part. This means you should remove these informational elements as you prepare the CAD file for CNC machining.

2. Choose the CNC Machine

Most CAD/CAM programs will let you add a CNC machine to the database. And to further promote the accuracy of the program, this software also has dialog boxes where you can customize the settings to match your machine’s capabilities and features. For example, you can select a matching post processor and tool crib within this dialog box. Additionally, you can input values such as horsepower, maximum feed rate, and more.

SolidWorks CAM Machine Database Dialog Box (source)

When preparing your CAD files for CNC, you must specify the exact machine you will use. This choice is crucial, as the designer envisioned a specific machining process when creating the design.

3. Assign Machining Data

Machining data includes the type of cutters, cutter size(s) – diameter and length – and the number of roughing and finishing passes. Assigning the data hardcodes it into the G-code, which guides the machine as it executes its machining operations. It is, however, worth mentioning that some machines come with a built-in database of tools. This means that you do not need to assign tool data contained. Even so, keep in mind that you must load these cutters before the machining process can commence. 

4. Undertake Element Sequencing 

You should undertake element sequencing when working with 2D wireframe line drawings and 3D wireframe geometries. Naturally, the CAM software does not know that the lines or arcs define the geometry or surface of a material. Instead, it views these geometric components as mare lines or arcs. In this regard, you must sequence these elements, i.e., point out using a mouse the individual elements of the drawing in the order in which they are to be machined. In addition, you must indicate the side of the line the machine should place the cutter.

However, if you are dealing with solid models, the software will automatically sequence the elements. SolidWorks CAM add-in, for example, achieves this by generating an operation plan. Here, an operation plan refers to the physical steps needed to create a suitable toolpath using which the CNC machine will turn the digital part and its features into a physical part.

5. Run Simulation

A simulation allows you to assess whether the operation plan generated matches your shop’s capabilities. If not, the CAM software has provisions that let you tweak the operation to match shop practices. The simulation enables you to check for errors. Furthermore, it helps you avoid wastage and the associated costs.

6. Post Processing

Post processing refers to the conversion of toolpath data (TPD), which describes the operations a CNC machine should follow, to numerical control (NC) code. It is worth pointing out that TPD is machine independent, while the code must conform to a particular machine’s conventions. For this reason, choosing a post processor designed for your specific machine and its unique needs is particularly vital.

Best Practices for CNC Machining Preparation

1. Study the Technical Drawing Carefully

By studying the engineering/technical drawing, you can identify issues and inconsistencies in dimensioning and tolerancing. Then, using this revelation, you can send the files back to the designer for clarification or revisions. 

Additionally, studying the drawing enables you to visualize the model. This way, you can better understand what the designer had in mind when coming up with the design. Sometimes, you can simplify the visualization process by relying on images of the CAD-drawn model of the part. CAD/CAM software makes visualization quite a breeze. 

In addition, studying the technical drawing enables you to locate the datum. A datum is a theoretically perfect axis or surface that is used as a reference. Datum ensures the exactness of measurements and machine operations. And given that there can be multiple datums in a drawing or CAD file, it is important to identify the primary datum, which is often used to start a machining job.

What’s more, studying the drawing allows you to check the number of parts, which can determine elements such as tooling. It also enables you to establish the material type, raw stock size, and how to avoid excessive stock allowances.

2. Understand Design Priorities and Functional Priorities

Design priorities tell you where to begin machining. On the other hand, functional priorities detail the order of importance of a part’s features. Together, they provide insights into how to position or hold the part for machining, the cuts to take first, and how to measure the results. 

3. Ensure the NC Code Comprehensively Captures all Operations

Typically, NC code is made up of commands that tell the machine what to do. These commands comprised words using six prefixes – G, M, F, T, S, and N – each representing a particular operation. G, for instance, represents motion words, F represents the feed rate, and M represents words that cause utility functions such as tool change and spindle on or off. Using some or all of these prefixes, you can ensure that your NC code captures all the operations. 

Fortunately, CAM software simplifies the code-writing process by generating the NC code. But these applications are not always perfect. For this reason, you should also be able to read the generated code to understand beforehand what the machine will do and make changes if need be. This brings us to the next crucial practice: optimizing the code. 

4. Optimize the Program

Inefficient programs are a leading contributor to manufacturing downtimes. Such programs may include unnecessary movements, e.g., traveling of the cutter without making contact with the workpiece, excessive tool changes, or moving parts between setups too many times. Of course, this increases the cost. This makes it extremely crucial to optimize the program for efficiency and safety. Some CAM software, such as MasterCAM, come with built-in editors that enable you to edit the G-code and even compare the new version with the old one. 

5. Create Clear, Detailed Instructions for CNC Operators 

Just as the programs should clearly and comprehensively outline what the machine should do, you should also prepare similarly detailed instructions for the CNC operator. Such instructions can take the form of remarks, which are notes embedded in the program. Additionally, notes found on the shop/technical drawings can guide the inspection and testing process. 

Collaboration between CAD Designers and CNC Machinists

A common thread that ties the above sections together is the needed collaboration between CAD designers and CNC machinists. Each can benefit from the other’s skill sets. For instance, machinists are conversant with the design for manufacturability (DFM) concept, which calls for the development and design of parts for efficient and cost-effective manufacture. However, they may lack the engineering knowledge to design robust products. Similarly, engineers may lack extensive machining knowledge.

Thus, engineers/CAD designers should consider machinists’ input during the product design phase. This is because the input will provide insights into how the design will impact the machining process and vice versa. Additionally, through collaboration, machinists will clearly communicate their shops’ capabilities. This collaborative approach ensures the designers do not come up with a design that is challenging to produce. Also, it clearly shows ways the design can be streamlined and modified to ensure it conforms to the DFM concept. 

Furthermore, the designers should make the machinists’ work easier by communicating more effectively. For example, they should deliver thoroughly annotated drawings, complete with detailed notes. Plus, they should ensure consistency in units of measurement. 

Conclusion

From the outset, machining is extremely expensive. Therefore, methods that bring down some of the costs are much appreciated. This is where preparing CAD files for CNC machining comes in. However, the making of the CAD files, i.e., the design phase, is foundationally crucial as it has a trickle-down effect. Thus, designers should embrace design for machining, which includes considerations such as strength and stiffness of the material, optimized tolerancing, standardizing features, and more. Afterward, the machinist should prepare the CAD files for machining by removing unwanted layers, choosing a machine and tool crib, undertaking element sequencing, running a simulation, and generating a program. Crucially, there are certain CNC best practices that machinists should follow. They should also collaborate with the designers for the best results possible. 

Note: Refer to this book for a comprehensive discussion of some of the sections herein, e.g., the history of CAD/CAM in CNC machining, the NC code prefixes, datums, and GD&T, discussed in this article; we have extensively used it as a reference.

Types of CNC Machines

There are nine main types of CNC machines, namely:

1. CNC Router Machines

CNC Router (source)

CNC routers are primarily designed to cut soft materials like wood, foam, and plastic. That said, some specialized routers can also cut soft metals such as aluminum. CNC router machines only work with soft materials because they have less torque – they use rotational speed to cut through materials. As such, they do not have enough power to cut hard materials.

In CNC router machines, the material lies stationary on the bed/table while the router head moves across the three axes, as in 3-axis CNC routers. (The router head houses a rotating router bit.) Some router machines are capable of additional movements. These are known as 5-axis routers. Typically, a 5-axis machine allows movement or rotation around 5 CNC machine axes: three linear axes (X, Y, and Z) and any two of the three rotary axes (A, B, and C). A rotates around the X-axis, B rotates around the Y-axis, and C rotates around the Z-axis.

The advantages of CNC router machines include:

• They are fast and offer great productivity

The disadvantages of CNC router machines are:

• They are less accurate than some other CNC machines
•  CNC routers are limited to working with soft materials

2. CNC Mill Machines

CNC Mill Machine (source)

A CNC mill machine is a high-precision machining tool that can work with hard materials such as aluminum, steel, and even titanium. It is capable of making more delicate cuts than a router machine. In addition, CNC milling machines can be used to shape, bore, and drill metal. To achieve various milling operations, the machines utilize different types of cutters (mills), including end mills (e.g., ball nose end mills and bull nose end mills), fly cutters, and face milling cutters.

This type of CNC machine also differs from the CNC router in another way. As indicated above, the workpiece in a CNC router remains stationary while the router head moves across the various axes. However, in CNC mill machines, the spindle head moves along the X- and Y-axes while the workpiece moves along the Z-axis. It is worth noting, however, that the cutting action is produced because of the cutter’s rotating motion. The moving workpiece contributes to the CNC mill machines’ increased precision.

The advantages of CNC mill machines include the following:

• They can work on hard materials
• CNC mill machines offer great precision, with some accounts noting that they can make cuts to within thousandth of an inch
• They support numerous operations, including shaping, boring, drilling, and cutting
• CNC Mill machines are suitable for mass production as they guarantee consistency and quality

The disadvantages of CNC mill machines are:

• They can be costly

3. CNC Lathe Machine

CNC Lathe Machine (source)

CNC lathe machines are primarily used to create cylindrical or round shapes. They are used for machining parts through a cutting process. Usually, the part or material is radially affixed to a rotating platform, which rotates it at a predetermined RPM. The cutting tool, on the other hand, moves laterally at a feed rate measured in inches per revolution. The cutting tool can also move inward or outward, thus altering the thickness of the material. 

The CNC lathe machine is ideal for creating parts that should have the same symmetry around a given axis. In addition, it can be used to perform several operations, including threading, boring, drilling, reaming and facing (cutting across the end – face – of a part). 

4. CNC Plasma Cutting Machine

CNC Plasma Cutter (source)

A CNC plasma cutting machine injects an electric current into a compressed stream of air or gas (such as argon, nitrogen, oxygen, or hydrogen), creating a high-energy, electrified gas that is passed through a nozzle. This causes the air/gas to squeeze through at high speed, forming plasma. (Plasma is the fourth state of matter in which charged particles comprising a combination of electrons and ions exist.) It is this plasma that melts the metal, essentially cutting it. However, the heat generated can be disadvantageous, as it modifies the region adjacent to the cut boundary.

There are three types of CNC plasma cutting machines based on the cutting process, which include:

• High-frequency contact: This low-budget process poses a risk to modern equipment and is, therefore, not used in CNC plasma cutters. It uses a high-frequency spark (which forms when the plasma torch contacts the cut metal, closing the circuit) along with a high voltage. The closed circuit creates the plasma that is used for cutting.
• Pilot arc: This second process combines a high voltage and a low current circuit to create a spark within the plasma torch (rather than outside). When the plasma cutter contacts the metal or workpiece, it creates a cutting arc, after which cutting can begin.
• Spring-loaded plasma torch head: This process relies on the creation of a short circuit when the torch is pressed against the metal and the release of this pressure, which establishes a pilot arc.

The CNC plasma cutting machine can be used to cut aluminum, stainless and mild steel, copper, brass, or cast iron. Essentially, it can cut any metal that conducts electricity. However, this can be a limitation, as it only cuts conductive materials. Beyond this, it offers a number of advantages, including:

• It produces high-quality cuts
• The CNC plasma machine is fast, being faster than laser cutters when cutting thick metal sheets
• It offers high precision
• The machine can be used in situations that require repeatability. This is particularly true when cutting thick metal sheets due to the associated speed.

This type of CNC machine has a few disadvantages, including:

• It is noisy
• The CNC plasma cutting machine produces fumes
• Some of its components, such as the nozzle and electrode, require periodic replacement
• It is unable to cut extremely thick materials.

5. CNC Waterjet Machine

CNC Waterjet Machine (source)

The CNC waterjet machine uses a CNC-directed vertical waterjet to cut materials such as titanium, paper, foam, marble, glass, and ceramics. However, when cutting hard materials, abrasives are added to the water stream (after it exits the nozzle) to enhance the cutting power. Generally, this machine produces clean cuts without burn marks or burrs (irregular rounded masses). While it is primarily used for cutting operations, the CNC waterjet machine can be deployed in a few other areas. For example, using multiple rotating waterjets, the machine can be used in paint stripping and surface preparation operations. 

CNC waterjet machines offer several advantages:

• They do not leave water behind, even when used to cut absorbent material. This is due to the velocity of the water.
• They produce clean cuts without burn marks or burrs
• The waterjet does not produce heat, which means they do not introduce mechanical stresses, surface hardening, or propagate cracks
• The water can be reused repeatedly, as the method does not pollute the fluid
• It can slice a moving slab of material 

There are several manufacturers of CNC waterjet machines, including Flow International Corporation, which sells the Mach line-up of products. Others include Techni Waterjet with its Intec G2 Waterjet CNC machines and Knuth’s Waterjet B-series machines, just to name a few.

6. CNC Laser Machine

CNC Laser Machine (source)

CNC laser machines are used to either cut material or mark parts. These machines work in one of three ways. The first involves the CNC program directing the laser over the surface of the material. The second involves the program moving the platform’s axis that carries the material, with the stationary laser beam. This movement defines the shape of the cut material. The third utilizes computer-positioned mirrors that direct the laser to the material – neither the laser nor the material moves. These mirrors move in three axes, expanding the working envelope without necessarily increasing the machine’s footprint. 

The energy produced by the laser beam can be varied. In this way, CNC laser machines can be used to remove material from only a fraction of the surface. Or, they can extend the cutting to great depths. Other advantages of the CNC laser machine include:

• They produce little heat-impacted zones due to the narrowness and intensity of the laser beam
• These machines are highly accurate
• They are quiet
• When used to mark parts, they produce fast and permanent marking
• CNC laser machines offer excellent sheet utilization. 

7. CNC-Driven Electrical Discharge Machine

CNC-Driven Electrical Discharge Machine (source)

Electrical Discharge Machining (EDM) is a metal-cutting technology. It is used in cases where the target shape is impossible to achieve using other processes or where the metalwork is too hard to machine conventionally. It is also selected when a mirror finish is required. These machines cut metal by generating millions of tiny electric arcs between the workpiece and the electrode. These arcs act as the ‘cutting teeth,’ vaporizing and melting the metal, creating microcraters. The melted particles cool and are immediately flushed away, as the metal is submerged in a fluid. Besides washing away waste, the fluid, which is a dielectric, also provides a cooling effect and controls the cutting process, thus promoting accuracy.

The advantages of a CNC-driven electrical discharge machine include:

• It produces a mirror finish
• The machine can cut any metal regardless of the hardness

However, there are a few concerns that are worth taking into account when it comes to this type of CNC machine. This can be summarized as the disadvantages of CNC-driven EDMs: 

• The heat produced can modify the material
• The depth of the cut decreases the flushing ability of the fluid. In fact, the particles of the metal, the destroyed electrode, and the burned fluid build up within the gap
• As the cutting action progresses, the energy spread increases over the expanding area, reducing the arcs’ temperature to a less-than-useful level.

8. CNC Grinding Machines

CNC Grinding Machine (source)

CNC grinding machines utilize a rotating wheel that removes material from a metallic workpiece. They produce very high-quality surface finishes and are, therefore, mostly used during the finishing stages of the machining/manufacturing process. This surface finish quality depends on the grinding wheel’s speed, which should remain constant throughout the process. Therefore, the motor should be capable of delivering the required torque consistently and reliably. Additionally, since the process generates a lot of heat, a lubricant is used to cool the workpiece’s surface.

9. 3D Printer

3D Printer (source)

3D printing is an example of CNC machining. However, it differs from all the other types of CNC machines above, which use subtractive manufacturing. 3D printing is an additive manufacturing process that relies on the G-code programming language to guide its movement. It involves melting and extruding material, such as resin or metal, layer by layer to create physical shapes from a digital 3D model or CAD file.

Factors to Consider When Choosing a CNC Machine

Choosing a CNC machine can be daunting. However, we have compiled a list of ten factors to consider whenever you wish to make this crucial decision.

1. Motor Power

The motor drives the cutter in CNC mills and lathe machines and the grinder in grinding machines. Therefore, when choosing a CNC machine, consider whether its motor can deliver the power for the intended task. For instance, if you intend to use your CNC router to smooth the edges of wood products, then a lower horsepower machine will suffice. In contrast, a higher horsepower machine is better suited for more extensive jobs.

Additionally, consider whether the motor power is supplied by hydraulic pumps or electric current. Hydraulic motors generally offer more power, durability, and efficiency than electric motors. As a result, they are primarily used in precision CNC grinding machines.

2. Type of Drive Motor Used

CNC machines use motors to drive movement along or around the various axes. The motors should be capable of moving the same way every time upon receiving a given amount of energy. The acceleration and deceleration curves should also be similar. However, not all motors have these properties. In this regard, the type of drive motor should also be a prime consideration when choosing a CNC machine.

There are three types of drive motors: the servo motor, stepper motor, and hydraulic motor. The hydraulic motor is driven by pumps but is less common. The servo motor is highly controllable; it delivers predictable speed, power, and acceleration curves based on the input energy. As the input energy increases, this type of motor exerts more force or spins faster. DC-driven servo motors are the most common and are preferred in heavy machining. Servo motors require tuning for proper system operation. 

Moreover, they are generally more expensive than stepper motors. However, these factors should only concern you if you are building a CNC machine; if you purchase a ready-made CNC machine, the manufacturer will have already tuned the motors.

Lastly, as the name suggests, the stepper motor moves in small increments based on the energy received. This type of motor requires computation as the CPU must coordinate the timed input of energy, measured in pulses, with the programmed feed rate. The faster the pulses are sent to the motor, the faster the motor rotates. Stepper motors are best suited for woodwork or detailing work. That said, they are cheaper and simpler to understand and work with; moreover, they do not require tuning.

3. Material

Two related but fundamental questions you should ask yourself are: What material will you be using? What will you make? This is because CNC machines are suited for different functions. For instance, say you are into woodwork; the kind of machine you would use to mill furniture parts is very different from the one you would use to carve signs. It is evident that wood has significantly different properties from metal. Thus, if you are looking for a CNC machine best suited for milling or cutting metal, avoid selecting a CNC router. Instead, choose other options such as the CNC mill machine, CNC plasma cutter, or CNC laser cutter.

4. Budget

Different manufacturers cater to different market segments, developing and selling CNC machines for various price points. It is important to note that sub-$1000 CNC machines are not suitable for commercial use. Instead, these machines are designed for hobbyists. Thus, if you need a CNC machine for your business, consider choosing a slightly more expensive machine designed for commercial use. 

Additionally, the prices of CNC machines vary based on the technology used and the capabilities. For instance, the Fab Light laser cutter for sheet metal and tubes starts at $65,000. On the other hand, the Trulaser 3030 2D laser cutting machine, which boasts high performance, high-speed cuts, and is much larger than the Fab Light machine, costs north of $1 million, according to one YouTuber. Moreover, the Tormach 1100MX CNC mill starts at $26,975, despite being slightly larger than the Fablight machine. 

TruLaser 3030 CNC Laser Cutting Machine (source)

Conversely, entry-level CNC plasma machines, suitable for small welding shops, are priced around $18,000 (£15,000). Industrial plasma cutters cost between $113,000 (£90,000) and $315,000 (£250,000).

5. Size, Work Capacity, and Production Volume

Some CNC machines, especially those designed for mass production of parts, have a large footprint comparable to a small car or SUV. In addition, in some cases, machines such as laser cutters require additional equipment such as an air compressor, auxiliary air tanks, a compressed air dehumidifier, and a dedicated dust collection and air filtration system. Thus, before you choose a CNC machine, ask yourself whether your workshop is large enough to house all this equipment. 

And if the workshop is large enough, is your production volume commensurate? Large CNC machines are intended for mass production. Thus, if you want to choose a CNC machine that will help you iterate prototypes and produce products faster, then a large machine with all the necessary tools is desirable. This is due to their continuous duty rating. However, the size also impacts the price. For instance, the Trulaser 3030 2D laser cutting machine, which is larger than the Fab Light machine, costs north of $1 million, according to one YouTuber. It, however, boasts high performance and high-speed cuts.

On the other hand, if you choose a machine with a small footprint, it is equally important to consider the usable area. The machine should not be so small that it prevents you from accomplishing the tasks or working on certain sizes. Therefore, when selecting a CNC machine, look for terms like ‘working envelope,’ ‘work zone,’ and ‘usable area.’ These terms define the exact area within which the cutting tool can operate.

6. CAD/CAM Software

Most consumer-grade CNC machines come with a CAD/CAM program included or available as an option. Still, you do not need to worry about the program that comes with the machine. Most CAM software, such as Fusion, SolidWorks, CATIA, BobCAD, and more, are compatible with most CNC machines.

However, some manufacturers, such as CarveWright and ShaperTools, maintain a closed ecosystem, developing proprietary systems that are intended to control the toolpaths. This, therefore, means you have to learn how to use such software, adding unnecessary steps to the manufacturing process. Occasionally, these programs are only accessible by paying a subscription fee. Thus, when looking to choose a CNC machine, consider whether it can be operated by third-party software or if the software is free.

7. Cutting or Machining Technology

Indeed, there are different types of CNC machines, each using its own cutting or machining technology. As highlighted above, these technologies are suited for different materials and produce different results. In addition, some cutters, such as CNC waterjet machines, can be used not only to cut material but also to strip paint and prepare the surface. Others, like CNC mills, can be used to drill, bore, and shape metals, while CNC lathe machines can be used for threading, boring, drilling and reaming, and facing. Thus, you should consider the machining technology as it opens you up to multiple other operations beyond cutting.

8. Nature of Control (PC or Handheld Control)

Some CNC machines, like the Shaper Origin from ShaperTools, are handheld. This means they assign you, the user, the responsibility to manually steer the machine as it makes the cuts. Nevertheless, these machines have intelligent features that compensate for human errors. For instance, the Shaper Origin makes real-time adjustments to ensure clean cuts. Also, if you steer outside the programmed path, the machine’s spindle automatically and safely retracts.

Shaper Origin Handheld CNC Router (source)

On the other hand, other CNC machines, their cutting tools, and their movements are 100% controlled either via a control system on your personal computer or through the software installed on the machine itself. The latter category operates without requiring a PC connection. But this convenience comes at a cost, as this type of CNC machine is often more expensive than PC-based machines. This is due to the fact that they have a built-in computer and storage that handles the computing tasks. A PC-controlled CNC machine example is the CNC Shark by Rockler. On the other hand, the Axiom Precision line-up of machines and some Fanuc-, HAAS-, and Bridgeport-branded CNC machines do not require a PC connection; they come with controllers or control panels.

9. Online Forums

Like all other mechanical components and software, CNC machines and systems can sometimes be problematic and complicated. Fortunately, reputable manufacturers have online forums that allow users to share experiences, ask questions, and receive answers to queries. These online communities are valuable resources for gathering real users’ opinions, which can help you compare machines. Additionally, they can help you familiarize yourself with the machines’ workings.  

10. Operator Skill Level

The CNC machines function quite differently, meaning the operator has to learn how each machine works. The knowledge gained while working with a particular type of CNC machine may not apply to another, especially if it is manufactured by a different manufacturer. Nonetheless, to get around this problem, machinists can use the same universal CNC controller for each machine.

Manufacturers such as Fanuc sell a wide range of CNC control systems. This line-up includes systems for standard machining applications to those capable of handling the most complex machining processes. These systems are compatible with CNC machines produced by other manufacturers. So, you can consider purchasing a universal CNC control system.

Fanuc’s Line-up of CNC Control Systems (source)

Choosing a CNC Machine Supplier

Even with the tips above, choosing a CNC machine and a supplier can be intimidating. This is because there are multiple options in the market. And given that the machines are expensive, going with the wrong one poses a significant monetary risk. Therefore, it pays to take time before deciding to choose a CNC machine and supplier. This calls for a strategic approach that follows the following six tasks or activities:

1. Research and Compare Different Suppliers and Offerings

Of course, there are multiple suppliers of each of the nine types of CNC machines. To stay ahead of the competition, these manufacturers promise various offerings, including after-sale services, features, and tools. Thus, if you hurriedly choose one supplier, you might eventually find out that you got a raw deal. We, therefore, advise that you carry out extensive research, utilizing both online and offline resources. Next, compile a comprehensive list of the different suppliers and their offerings. Using this list, you will then be able to compare these manufacturers and what they have to offer.

2. Evaluate Supplier Support and Training Resources

A simple look at the various suppliers’ sites shows a glaring difference: they have different approaches to offering support and training. For example, most offer learning materials in the form of in-depth training classes and courses on metalwork or woodwork, how-to resources, project ideas, step-by-step explanations of the features of the CNC machines (product training), and more.

At the same time, the suppliers offer support quite differently. For example, most usually staff their support team with field technicians (factory-trained employees) who have first-hand experience and can help clients with all service needs. This approach enables them to fix incidents via phone calls without having to dispatch technicians. As a result, downtime is minimized, especially given these individuals are available round the clock, 24/7. 

However, you may be surprised to realize that some suppliers do not provide supplier services – at least, that is what we gathered by extensively going through their websites. (We cannot mention names, though.) For this reason, it is crucial to choose a CNC machine supplier that promises 24/7 support. After all, the mechanical equipment is bound to break down at one point during its service life.

3. Check Customer Reviews and References

As a business operator or owner, you may know a few other businesses that operate in your specific sector. And even if you do not, you can always create rapport by reaching out and asking about their preferred CNC machines. Armed with such information, you can easily choose a CNC machine over another. Alternatively, you can go through customer reviews on social media or dedicated review sites like Trustpilot. However, reviews are hard to come by because industrial-grade machines are rarely sold online but rather by directly contacting the manufacturer or supplier.

4. Go Through Online Forums

Online forums are convenient platforms where customers share their experiences with the manufacturers’ CNC machines. They also ask questions about problems encountered during use, expecting answers from other users or the company’s representative. Therefore, these online forums, which are maintained by the manufacturer, are an ideal way to gather data on problematic machines. This way, you can identify those to avoid, thus helping you narrow down your search.

5. Evaluate After-Sale Services

Some suppliers – such as FANUC and Flow Shape Technologies Group – work on the premise that every customer’s needs differ. They, therefore, adapt their after-sale services to suit these specific needs. As a result, they offer predictive, preventive, and reactive maintenance, as well as a comprehensive catalog of OEM parts. 

Preventive maintenance involves undertaking scheduled maintenance after a given number of hours or months. Predictive maintenance entails remotely monitoring the condition of your equipment to determine when the supplier should schedule the maintenance. This approach predicts breakdowns before they can result in downtime. Lastly, reactive maintenance involves scheduling repairs immediately after the equipment breaks down, with the work carried out by local OEM-trained service engineers.

Some suppliers only offer some of these services, while others offer all. However, the latter is predicated on selecting and paying for the maintenance package containing all these services. So, if you want to enjoy all these perks, choose a CNC supplier who promises these offerings and subscribe to the service.

6. Negotiate Fair Price and Warranty Terms

Once you have arrived at a few viable options of equal quality and caliber, it is time to purchase. It is nonetheless important not to rush into it. Instead, contact the suppliers and negotiate a fair price and warranty terms. But the likelihood of a successful negotiation is dependent on multiple factors. It goes without saying that these suppliers have dealt with big-name clients. So, exercising patience, deploying soft negotiations, and showing what you bring to the table is crucial.

Assessing Machine Performance and Maintenance

Unplanned downtimes can be expensive. Automotive companies, for instance, lose an average of $22,000 per minute when the production line stops. For smaller manufacturers, this figure is likely smaller. Still, data shows that the average manufacturer suffers 800 hours of equipment downtime every year or over 15 hours per week. This downtime is often attributed to reactive maintenance processes, where companies wait for the equipment to break down before they can repair it. However, predictive and preventative maintenance has been shown to keep production running and improve uptime. So, how can you achieve maximum uptime and productivity?

1. Monitor Productivity

It is important to establish the baseline performance. Once a machine’s productivity falls below this figure, it can be said to be performing under par. This can point to a developing problem, helping you predict and prevent future breakdowns. In fact, some suppliers who provide predictive maintenance services use this approach. They connect their servers to the machine, collecting and monitoring data on its performance over time and the performance history throughout its lifecycle. This data enables them to identify issues and speedily resolve them.  

2. Identify Common Maintenance Issues and Costs

By assessing the machine’s performance history, you can gather information about common maintenance issues and the associated costs. You can then use this data to purchase the required spare parts. By having a catalog of parts, you can replace those that break down as soon as they stop working, allowing you to reduce downtime. This data also helps you allocate a budget for repairs or maintenance, ensuring you are always prepared for any eventuality. 

3. Evaluate the Need for Additional Software or Hardware Upgrades

It is advisable to consider an upgrade, especially if adding certain software or hardware can help improve performance or the maintenance procedure. For instance, a combination of software and hardware upgrades could enable you to collect data remotely, assisting in predictive maintenance. However, first, conduct an in-depth assessment to establish whether it is a worthy investment. After all, such upgrades can be extensive. 

Conclusion

There are multiple types of CNC machines, some of which can be an excellent fit for your business. These include CNC router machines, CNC mills, CNC plasma cutters, CNC waterjet machines, CNC lathe machines, CNC laser machines, 3D printers, CNC-driven electrical discharge machines, and CNC grinding machines. Coupled with the presence of numerous supplies, this wide variety of viable options makes the act of choosing the right CNC machine daunting and intimidating. In this guide, we have highlighted factors to consider when choosing a CNC machine, approaches to use when selecting a supplier, and how to assess machine performance and performance to boost uptime.

1.0 Introduction

In this ultimate guide for converting files to g-code, we will delve in-depth to the raster and vector file types that you can convert to G-code.

We will discover how CNC machinists can further expand the files suitable for cnc cutting by converting their JPG, PNG, STL, DXF, DWG files (and more) to a G-code file format, including CNC, .NC and TAP.

Those who have constant requirements to convert files to G-code may wish to make-use of a batch conversion tool, this is software which will automatically convert a large number of files in a single operation. We will discuss how this is possible with suitable CAD/CAM batch conversion software.

This article also considers the requirements of users who wish to convert their files to g-code offline, by downloading and installing Windows or macOS software to convert their files. This ultimate guide is the prime destination for all machinists wishing to convert their files, therefore, without further ado, let’s jump right in!

2.0 What is G-Code?

Mostly all products these days are manufactured using a CNC machine. CNC stands for Computer Numerical Control and is a machine that uses computer software to produce a product or object to a drawing specification. This process is commonly called Computer Aided Manufacturing (CAM).

CNC machines require inputs that the machine then translates into machining actions like drilling or cutting. The ability of a CNC system to execute these instructions is reliant on outputs from CAM software in the form of G-code.

There are multiple G-code file extensions produced by a range of different CAM software programs. However, regardless of extension, the file should contain the instructions to aid the manufacturing process.

To create G-code, CNC machinists can write the G-code program, alter existing one or generate a new program by converting CAD files to G-code.

3.0 Which file formats can be converted to G-Code?

There are many files that you can convert to G-Code from. We cover a number of them below.

3.1 How to convert STL to G-Code

STL is an acronym for STereoLithography, which is an industrial process of printing 3D models. Since STL was created in 1987, it has become the defacto format for 3D printing – something that was required due to the range of native file formats that can be created by CAD programs when 3D modelling. Most CAD packages can export to the STL format making the manufacturing or 3D printing process easier.

Dolphin triangle mesh (source)

STL is a 3D digital mesh that consists of triangles and this triangle tessellation (the interconnection of triangles) describes the surface of the model or object. The vertices in the mesh contain coordinate-based information of the model with the complexity and resolution of the model defined by the number of triangles. More triangles, more complexity.

Despite STL being a very useful and sophisticated format, it has drawbacks over G-Code, which you can read about in our guide to converting STL to G-Code. However, these drawbacks can be resolved by completing the STL to G-code conversion using a software known as a 3D slicer. Examples of common 3D slicing software include Ultimaker Cura, Simplify3D, FormWare, and ChiTuBox, just to mention a few.

As the name suggests, a 3D slicer essentially slices the 3D model into layers of a defined thickness. The software allows you to set the layer thickness as well as other settings such as the wall thickness, temperature of the extrusion, cooling, and more. The slicer then codifies the settings by creating a G-code file containing instructions that conform to your chosen settings. In that regard, you can use the G-code file generated to create a physical 3D representation of the model.

3.2 How to convert OBJ to G-Code

Short for the word ‘Object,’ OBJ is a file format used in 3D printing, 3D graphics design and modelling, and game development. It defines 3D geometry as well as color and texture. The color and texture properties make this format ideal for printing colored 3D objects. In this way, OBJ differs from the STL format, which does not contain color or texture information. However, OBJ is less common or universal than STL. As a result, it is supported by fewer 3D software than STL.

As an ASCII-based file format, OBJ represents the 3D objects and models in a file using alphanumeric characters and special symbols. These characters and symbols form part of mathematical equations that define tessellated polygons that, combined, form the outer surface of the 3D model. The equations represent elements such as the polygons’ vertices, points, faces, curves, free-form surfaces, lines, and more. The formulae and characters define the virtual limits of a 3D model, which can be transformed into a physical 3D object through 3D printing.

However, to 3D print an OBJ file, you have to undertake a few steps. Key among the steps is what is known as slicing, which simply refers to the process of converting OBJ to G-code. Completed using software known as 3D slicers, slicing entails dividing the vertical layout of a 3D model into layers of a defined thickness. The 3D printer will then print each layer individually. And it is the combination of these individually printed layers that create a physical 3D object.

You can use different tools to convert OBJ to G-code in bulk, offline, and on mobile or tablet. We have discussed each of these conversion approaches below.

3.3 How to convert DWG to G-Code

DWG, or Drawing, is a binary vector file format that stores 3D and 2D drawing data in addition to metadata such as headers, settings, dictionaries, classes, and more. It is the default file format for AutoCAD. A proprietary format owned and maintained by the CAD behemoth Autodesk, DWG is not based on an open specification like DXF, which Autodesk also developed.

Instead, its source code and definitions are closely guarded and can only be used upon purchasing a license to the RealDWG library. But software developers have made efforts to reverse engineer the source code with much success. Even so, AutoCAD displays an error message whenever it detects that a DWG file was not created using the code found in the RealDWG library.

DWG is used to create and render 2D drawings and 3D models. Designers, architects, and engineers using CAD software that support DWG can also collaborate without having to convert their files to other file formats.

2D Image Printed Using a 3D Printer (source)

But the utility of DWG is restricted as the file format is primarily used for design. For example, it cannot be deployed directly in CNC machining or 3D printing. CNC machines and 3D printers cannot read or interpret DWG files, but they can follow the instructions contained in G-code. This points to the need to convert DWG to G-code. And there are several ways you can complete such conversions: in bulk or offline using Scan2CAD. In fact, Scan2CAD goes a step further by enabling you to convert DWG to G-code with accurate scaling.

3.4 How to convert DXF to G-Code

DXF, an abbreviation for Drawing eXchange Format, is a vector file format that stores vector graphics using ASCII text or binary. (This means there are ASCII DXF files – which are more widely used – and binary DXF files.) As we have highlighted above, DXF was created by Autodesk as a way of enabling collaboration. Little wonder then that the DXF format specification and documentation have been openly published to ensure more CAD software support it.

Since its creation in the early 1980s, the DXF format has primarily been used to transfer drawings and design details among designers, builders, engineers, architects, and suppliers. However, teams working in the 3D printing and CNC machining spaces cannot use it to transfer instructions for their machines or 3D printers. For the design details to be used in these scenarios, the DXF files must first be converted to G-code.

You can use various approaches and tools to convert DXF to G-code. For instance, if you are working with hundreds or even thousands of files, you might consider solutions that support batch conversions. Similarly, if you do not have an internet connection, you might want to choose desktop software that can complete the conversion offline. In the below section, we detail how to convert DXF to G-code in bulk and offline software.

Of the different conversion solutions in the market today, Scan2CAD stands distinct. It enables you to export DXF files as G-code. In addition, Scan2CAD includes tools that, when used, allow you to convert DXF to G-code with accurate scaling.

3.5 How to convert JPG to G-Code

An abbreviation for the Joint Photographic Experts Group, JPG or JPEG is a raster file format used to digitally store 2D images using the lossy compression method. As a lossy format, JPG offers a higher level of compression than PNG, a factor that comparatively reduces its quality.

This image format was introduced in 1992 and has grown to be the world’s most widely used image standard. In fact, by default, your mobile phone camera saves all its images using JPG. Additionally, Common Crawl ranks JPG as the third most popular image format on the web.

This popularity has been influenced by the benefits of the JPG file format. Firstly, JPG files are highly compressible, meaning they can take up less disc space. This small file size makes JPG one of the best formats for web-based images. This is because it will require additional resources that may slow down the loading speed. At the same time, JPGs support variable compression. This means you select different degrees of compression based on your needs. Thirdly, JPG images are compatible with virtually all devices and can be imported into a majority of the software.

But when compared to vector file formats, JPG does not offer the same level of quality – the quality and resolution drop significantly the more you zoom into a given section. Furthermore, while a variety of devices and software, including 3D printers, support the JPG format, the format can only be used to transfer or represent an image. As such, you cannot import a JPG file directly into a 3D printer with the intention of using it directly to create a physical model. Instead, you must first convert JPG to G-code. And as with the other file formats, there are various ways to complete the conversion.

3.6 How to convert PNG to G-Code

PNG, or Portable Network Graphics, is a raster file format that stores lossless, portable, compressed, bit-mapped images. In this regard, the PNG specification, which defines the PNG format, supports lossless compression. Compared to JPG’s lossy compression, PNG’s lossless method reconstructs the image data without losing any information. This means PNG images are higher quality than JPG images.

PNG was first introduced in 1996. Its development aimed to improve and replace the Graphics Interchange Format (GIF). Though possibly unintentional, the improvements gave rise to numerous advantages that have cemented PNG’s superiority over other raster file types, particularly the JPG and GIF. For instance, PNGs maintain better detail and color contrast than JPGs. They also boast better text readability than JPGs. PNGs also offer a wide color depth, support transparency, and are ideal for editing images.

But when compared to vector image formats like SVG or CAD design formats like DXF and DWG, PNG lags a tad behind, particularly when it comes to resolution. Scaling up a PNG image distorts the quality, as it makes the image appear more pixelated.

At the same time, PNG images cannot be used directly to print 3D objects or create objects using CNC machines. This is because 3D printers and CNC machines can only read and interpret G-code, which contains instructions that govern their movements. Fortunately, you can go around this problem by converting PNG to G-code.

3.7 How to convert SVG to G-Code

Short for Scalable Vector Graphics, SVG is a digital vector format that stores graphics and text in Extensible Markup Language (XML) files. The graphics are defined by mathematical formulas based on geometrical shapes such as lines, circles, and curves that are laid over a cartesian plane. This means the quality of the images does not change however much you resize them. As a result, SVG files are preferred by web designers and graphic designers who wish to exploit the format’s resizing capabilities.

Generally, the SVG format is primarily used to display 2D illustrations, logos, charts, infographics and graphics on websites. And being XML-based, it can be created or edited using either text editors or vector graphics software. In addition, it can be rendered by software that can interpret XML files, including web browsers.

But as with the other image formats, SVG cannot be directly imported into CNC machines or 3D printers with the aim of creating the objects represented therein. Therefore, it is crucial first to convert SVG to G-code.[/su_spoiler]

4.0 FAQ

4.1 Why convert to G-Code?

G-code is one of the industry-standard file formats for CNC machines. The power in the format lies in its simplicity, unlike many other formats, the code of the G-code file format can be read by the human eye. This somewhat simple format contains the instructions for CNC machines including the direction, depth and rotation of the cutting machine. There are many more such ‘codes’ within the G-code file structure which defines all aspects of a CNC machine’s cutting movement. Given the benefits of g-code files for CNC machine users, if they have a design which they wish to cut, that is not in G-code format, they can convert this file to g-code using conversion software such as Scan2CAD.

4.2 How can I save a file as G-Code?

To save a file as g-code you must first convert the file to confirm to the G-code file structure. Most typically, CNC machinists wish to convert raster images (such as JPG, TIFF, PNG etc.) to G-code so that they may cut the design contained in their raster image with their CNC machine. The conversion of a raster image to g-code requires a raster-to-vector conversion software, such as Scan2CAD. After the image is converted to the g-code file structure, the user may save (or export) the file to a g-code file extension, such as .nc, .cnc and .tap.

4.3 What software can be used to open G-Code files?

G-code files are designed for CNC machines, controlling every aspect of the CNC machine’s movements. Therefore almost all CNC viewers, controllers or design software applications will support G-code files.

Applications which support G-code files will most-likely have the ability to open files with the .nc, .cnc and .tap extensions. This is because the file specification for files with these extensions is identical.

Some software applications which open g-code files include:

• Blaze3D (Free. Available for Windows & Linux)
• GCode Viewer (Free. Available for web)
• NCViewer (Free. Available for web)
• G-Wizard (Premium. Available for Windows)
• NCPlot (Premium. Available for Windows)
• CIMCO Edit (Premium. Available for Windows)
• Which software can be used to edit G-Code files?

The list of g-code file editors is smaller than the list of g-code file viewers. Viewing the contents of a G-code file is a much more simplistic requirement than offering the complexity of editing the contents of a G-code file, especially if the software is editing in such a way that is optimal for the CNC machine’s cutting. Many G-code editing applications will run simulations of the cutting path proposed by the design held within the g-code file. After the simulation is complete, the application may provide recommendations to optimize the design for the best and least-wasteful cut.

Some software applications which open g-code files include:

• Blaze3D (Free. Available for Windows & Linux)
• G-Wizard (Premium. Available for Windows)
• NCPlot (Premium. Available for Windows)
• CIMCO Edit (Premium. Available for Windows)

4.4 Why should you avoid online G-Code converters?

There are very few online websites which offer to convert raster images (such as JPG, TIFF, PNG etc.) to G-code. There are few such solutions because there are many pitfalls in attempting to convert an image to G-code online.

In order to convert an image to g-code, the software must first perform an accurate raster-to-vector conversion and subsequently convert the vector paths within the vector image to cut-friendly paths written in a G-code file.

This is a very complex procedure which cannot realistically be achieved with a free online converter website. Instead a user should utilize an offline software application which they will download and install on their Windows or macOS computer. This software will make-us of the power of the computer’s processing to perform complex and accurate conversions of the images to g-code. One such solution us Scan2CAD.

5.0 Conclusion

In this ultimate guide, we have discovered how CNC machinists have almost limitless options for converting their raster and vector files to g-code.

From vector file formats such as DXF and DWG to raster image file formats such as PNG and JPG, they may all be converted to G-code by utilizing suitable software. As discussed in this article, the unique capabilities of g-code files make them one of the default files types for controlling CNC machines. The vast majority of CNC controller and editing software applications support the three primary g-code file formats (i.e. .CNC, .NC and .TAP.)

Given the vast advantages of converting ones’ files to G-code, it may come as no surprise that many CNC machinists have attempted to perform their conversions using free online g-code conversion websites. However, as we have discussed in this article, users have found that the online conversion solutions are not accurate and not secure. Instead users opt to download software to convert their files to G-code with a Windows or macOS computer. With the introduction of CAD/CAM conversion software, users have many new options for creating suitable ‘cut-friendly’ CNC designs.

The versatility in terms of what you can use them for, as well as the varying magnitude of their use cases, is because CNC machines and routers are available in different sizes. They come in small, medium, and large (industrial) body sizes, each with its own attributes, including cost, speed, power, degrees of freedom (axes), and more. It is noteworthy that your CNC machine’s footprint – whether small, medium, or large – does not limit you from undertaking woodworking. 

Therefore, in this article, we have come up with a list of the top 10 CNC products for wood routers. The projects highlighted herein are perfect for both beginners as well as experienced CNC users, both of whom can benefit from Scan2CAD’s ability to convert an image to CNC. So, before listing the top 10 wood router CNC ideas, let’s discuss what CNC is as well as how Scan2CAD can help you simplify your workload.

What is CNC?

Computer numerical control (CNC) refers to the use of a computer to automatically control machining tools such as routers, 3D printers, laser cutters, plasma cutters, mills, drills, and lathes. Thus, CNC goes hand in hand with CNC machining, which is the use of a CNC machine to drill, engrave, carve, or cut various materials, including composite, plastic, wood, metal, or ceramic. 

The CNC machine performs various movements thanks to its motorized, rotary nature – the higher the motor’s power is, the faster the machine will be. The machine is also supported by a movable arm that changes the position of the cutting bit based on specific instructions known as G-code.

G-code is a programming language that instructs CNC machines on what maneuver or movement to undertake. It also specifies how fast the machine should move, the direction of motion, and the depth of the cut. As a CNC machinist, you can create a G-code program from scratch, modify an existing G-code using an editing program, or generate G-code through vectorization using a G-code converter such as Scan2CAD.

Generating G-code Using Scan2CAD

With Scan2CAD, a leading vectorization software, you can convert various file formats to G-code. These include JPG to G-code; images saved using formats such as PNG, BMP, and TIF, to G-code; raster PDFs to G-code; and vector file formats such as DXF to G-code.

Though there are tens of known G-code file formats, Scan2CAD lets you convert any non-G-code format .CNC, .TAP, or .NC, three of the most popular G-code file types.

Having detailed how to generate G-code, let’s now hop onto the wood router CNC ideas.

Top 10 Wood Router CNC Ideas

Living Hinge Furniture

A living hinge is a flexible wooden hinge connecting two rigid wooden portions. The flexible hinge is made using a CNC router, which cuts a beautiful, precise pattern into a thin wooden panel, removing all structural rigidity, thereby making the cut piece foldable. A combination of the rigid and flexible portions within the same wooden board enables you to create unique, artsy furniture such as chairs, wardrobe or closet doors and carved sides, and more. 

Living Hinge Chair (source)

Signs

CNC machines are standard in sign shops. This is because they can be used to carve specific patterns into wooden panels. At the same time, there are several bits that allow you to engrave letters and words as well as logos. 

You can use CNC machines to make signs for your business (shop, restaurant, pub, or office), exhibitions, and more. And given the accuracy of the wood routers, you can rest assured that the signs will feature precise and professional finishes and, depending on the design you go for, and accurate portrayal of vintage accents. 

CNC Sign (source)

Wall Art

The preciseness of CNC machines, coupled with the fact that you can use Scan2CAD to convert images to G-code, means that you can fabricate artistic pieces. For instance, you can use wood routers to fashion flowers, exotic leaves, scenic vegetation, animal figures, clouds, inlay artwork, or even portraits from wooden panels. Simply, CNC machining offers endless possibilities. There are many wood router ideas you can think of and subsequently convert them into physical objects.

Coasters

Coasters do an excellent job at protecting your table from damage. Even so, they can also help beautify the tablespace. You can create artistic coasters that feature unique patterns as well as inlay artwork, thus ensuring that the coasters are not bland. 

CNC Coasters (source)

Miniature Models of Planes, Cars, and Trucks

You can use CNC machines to carve out a car, truck, ship, or airplane from a block of wood. You can also rest assured that the CNC product will be accurate. This is because the process mainly focuses on creating a model that 100% replicates the real vehicle. CNC machining helps you maintain minimal tolerances with other connected components such as wheels (in cars and trucks) or wings (in planes). 

Crates/Cases/Boxes

A CNC machine enables you to create various types of boxes for disparate applications. For instance, you could carve out a unique case for your beer or soda bottles, complete with engraved circular beds, to facilitate the stability of the bottles during transit. 

You can also use the accuracy attribute of CNC machining to create interlocking wood joinery such as finger/comb joints. This way, you will ensure the various sides fit precisely. The perfect fit promotes strength, stability, and straightness.

Finger-jointed Crates (source)

Frames and Frame Stand

Frames and their respective stands are one of the many wood router CNC ideas you can machine. You could use the frame to enclose the outer edges of a mirror, painting, or picture. At the same time, using a CNC machine to create a stand ensures that the frame and base fit perfectly. It eliminates unnecessary wobbles that would be witnessed if unskilled carpenters made the stand. 

It is noteworthy that you can also use the CNC machines to add unique, decorative accents to the frame, further embellishing the painting, picture, or mirror.

Tray

The versatility of CNC machines lets you create a variety of trays, including serving and egg trays. As with all other use cases, you can opt to beautify the trays and add a touch of uniquity. You can accomplish this by engraving unique patterns. This way, the trays can also serve as decorative accents in whichever space. In addition, they can be categorized as one of the special wood router CNC ideas. 

Engraved Serving Tray (source)

Holder

You can carve out various types of holders using CNC machines. These include pen holders, paintbrush holders, candle holders, keyholders, and cardholders/wallets. The holders could be fashioned into different shapes. In fact, and thanks to the living hinge concept, you can create cylindrical holders using CNC machines. 

Living Hinge Pen Holders (source)

Bespoke Shelves

Suppose you are looking to beautify your living room, bedroom, or office using unique and novel decorative pieces. In that case, you can rely on the versatility of CNC machines to help you accomplish this feat. You can create bespoke shelves that feature unique patterns and shapes that work in concert to beautify your space.

Additionally, you are guaranteed unmatched strength and stability. This is because you can carve the shelves from a single block of wood, 

It is worth reiterating that you can use Scan2CAD to convert your wood router CNC ideas, which may initially be saved as images or PDFs, to G-code. This will enable you to create CNC products for wood routers. As a matter of fact, you can try Scan2CAD for free throughout a 14-day free trial.

Parting Shot

CNC machining has emerged as a useful process that lets users create accurate, beautiful, and unique CNC products using different materials, including wood. In this article, we have explored wood router CNC ideas that you can use to guide your CNC work. These top 10 CNC products for wood routers are perfect for both beginners and seasoned CNC machinists. Hobbyists or astute businesspeople can also use them. 

All you need to get started is a CNC machine and G-code, the programming language that dictates the movements of the routers. With Scan2CAD, you can take care of the latter as this conversion software lets you convert raster images and PDFs to G-code. Try Scan2CAD today.

Regardless of the route, one thing is always paramount and certain: the need for accurate scaling. Machined components, created from drawings, usually serve a specific function and are more often than not part of a larger machine/device. As such, they should fit snugly with other components of the system. And if they contain holes, then the hole patterns should align with the respective connectors in the adjoining parts. 

In this article, we will discuss how you ensure that such drawings have accurate scales, dimensions, and units. Specifically, we will look at converting DXF to G-code with accurate scaling.

What are DXF and G-code?

Created by Autodesk in the early 1980s, DXF or Design eXchange Format is a file type that stores vector graphics. The idea behind its creation was in order to facilitate the exchange of data between Autodesk’s AutoCAD and other CAD or between CAD programs and downstream CAM/CAE programs.

On the other hand, G-code is any programming language/code that issues instructions to the CNC milling or machining tools. G-code, therefore, tells CNC machining tools the type of actions to undertake. 

Designing for CNC

When it comes to creating designs that are to be turned into actual objects through CNC machining, the process normally follows a few common steps. First, a designer sketches a freehand design on a piece of paper. Using it as a guide, they then create the design using CAD or CAM software. If the drawing is created using CAD software, then it would be stored as a DWG file. Conversely, if the designer uses CAM software, then they would save the design using the DXF file format. 

The second step would typically entail converting the DWG or DXF file to G-code. This would involve importing the DWG or DXF file into a CAM/CNC software to generate the G-code. Notably, though, you can bypass this second step by again using Scan2CAD.

Alternatively, the designer can manually trace an image to generate a vector layout, which they can then save as a DXF file for importation into a CAM or CNC program. Notably, CAM and CNC programs convert the file into G-code, a programming language that enables CNC systems to execute machining instructions. 

However, these manual methods are time-consuming.

To save time, the designer may opt to convert an image to DXF or DWG using Scan2CAD. In fact, as the world’s leading conversion software for engineers and designers, Scan2CAD goes beyond simply facilitating the conversion of images to DXF or DWG file formats. With this software, you can convert an image directly to G-code. 

Scan2CAD automatically converts drawings stored as images or raster PDF formats into DXF or DWG or even G-code format such as .CNC.

Tips to Consider When Designing for CNC

In an earlier guide, our experts shared 8 tips you need to take note of when designing for CNC. These tips include:

• Defining the scale
• Cleaning up the CAD drawing before importing it into CAM by reducing vector lines to the lowest number of nodes that will not affect quality, placing your geometry on one layer, and exporting only the relevant parts
• Converting arcs and splines to polylines
• Deleting spaces and cavities
• Combining adjoining polylines into one entity
• Removing overlapping lines
• Setting the default Z-axis value
• Understand the cut width of the machining tool

Regarding the first tip – defining the scale – our experts recommend that it is crucial to set the system units to millimeters and the precision/tolerance to 0.5 micrometers for precision CNC work. 

As a follow-up to the earlier guide, this article is designed to offer you additional information regarding the first tip. Specifically, we will focus our attention on converting DXF to G-code with accurate scaling.

Converting DXF to G-code with Accurate Scaling

Video Tutorial: Converting DXF to G-code with Accurate Scaling

Step by Step Guide

1. Import the DXF file into Scan2CAD.
2. Delete unnecessary objects in the imported file, including some dimensions.
3. Click the File tab, and on the resultant dropdown menu, select Scale Options.
4. On the resultant pop-up window, click Measure, which creates a Measure and Scale toolbar on the screen’s right-hand side (RHS).
5. Click Calibrate on the RHS toolbar. Also, ensure you have checked the Snap to End Points to simplify the measuring process.
6. Place the cursor at the beginning of a reference line/dimension line, whose length and units you already know. Next, click and drag the cursor to the line’s other endpoint. This step allows Scan2CAD to measure the length of the line using pixels. The software will automatically populate the Pixels field on the RHS toolbar.
7. Select the units under the Is equal to the field, and input the reference line’s dimensions.
8. Click Apply on the RHS toolbar to guarantee that Scan2CAD will convert DXF to G-code with accurate scaling.
9. Delete the reference file.
10. To save the file, click Export, which will create a Save As pop-up window. On this window, type the file name and select the file type. Notably, Scan2CAD supports three G-code file formats, namely .CNC, .TAP, and .NC. Therefore, Scan2CAD effectively allows you to convert DXF to G-code with accurate scaling by choosing any of these formats. Finally, click Save to complete the conversion.
11. Clicking Save results in a CNC Export Options pop-up window that allows you to tweak a few settings. Leave the existing default settings unchanged. Next, click OK to complete the process of converting DXF to G-code with accurate scaling.

Importance of Converting DXF to G-code with Accurate Scaling Using Scan2CAD

The steps above highlight the procedure of correcting any errors that could result in wrong scales and dimensions. As stated earlier, milled components are usually part of a larger machine/device with other components requiring snug fitting. In this regard, when a converted DXF file results in wrong milling instructions, the resultant part would be rendered useless and, therefore, a waste. In addition, it would result in lost time that would need to be recovered, thereby affecting workflow. Simply put, a scaling mistake is expensive.

These factors make converting DXF to G-code with accurate scaling using Scan2CAD a critical process as it aids with the following:

• It saves time that would have otherwise been lost in preparing new G-code instructions – by converting DXF to G-code with accurate scaling – had the initial conversion not included the correct scaling and dimensions
• Furthermore, given that Scan2CAD’s tracing and conversion processes are automated, the software simplifies processes, thereby saving even more time
• It helps avoid wastage of materials by ensuring all components, once machined, fit snugly with other machined or non-machined parts
• It simplifies the process by eliminating the need for additional programs/software, some of which are extremely expensive to procure – with Scan2CAD, you no longer have to import a DXF file to a CAM/CNC software that would then convert DXF to G-code
• Scan2CAD offers additional conversion capabilities, in that you can also directly convert images to G-code or PDF files to G-code

Practical Demonstration

Orthographic Drawing (source)

To put each of these vital points into perspective, let’s consider the orthographic drawing above. It features dimensions that show the distances between hole positions, the diameters and depths of holes, as well as the heights, length, and width of the different parts of the component. 

If, for instance, a designer forgets to set the dimensions’ units as millimeters while converting the image to G-code and instead uses centimeters, the machined component would be larger than desired. This would render the machined piece unusable because even the screws that were initially supposed to be threaded through the thru-holes would be smaller. These shortcomings would mean that the designers would have to recreate the G-code, losing valuable time. 

On the other hand, the machined component would either be melted to create a new, unaltered surface/material that the CNC machine will work on or discarded for being unusable. For instance, an error in the G-code, possibly in the dimensions of the cut pieces in the image below, would cause the machinist to discard the entire sheet of metal and the cut components. Naturally, melting the material takes up unnecessary resources in the form of time and energy, while discarding the piece altogether causes losses in the form of wastage. 

CNC Milling Machine

Parting Shot

The importance of converting DXF to G-code with accurate scaling cannot be gainsaid. It helps avoid wastage of resources such as time, money, and materials, and as we have demonstrated, using Scan2CAD offers additional benefits. With this guide, we hope that the process of converting DXF to G-code with accurate scaling is now clear and that we have equipped you with the necessary knowledge to avoid mishaps during CNC milling.

The most expensive CNC machines are the 6-axis and 5-axis robotic CNCs that are used in manufacturing high-end military equipment and cost in the excess of millions of dollars. On the other hand, there are very affordable CNC machines that can be used by entry-level hobbyists that cost as low as $150.

Before delving into the costs of various CNC machines, we shall first look at the various factors that affect the CNC machine cost.

Factors Affecting CNC Machine Cost

Figure 1. 5-axis LaborMac CNC Milling Machine (source)

• Size of the CNC Machine

In CNC machines, the size of the machine is determined by the length that the cutting end can travel along the XYZ axes. The longer the range, the larger the machine and the more expensive the machine is.

• Machining Speed

In CNC machining, the cutting speed directly affects the efficiency of production and the quality of the finished products. Faster speeds translate to smoother finishes and generally mean that the work will also be performed faster and more efficiently.

Another factor when it comes to speed is the Rapid Motion speed, which is the rate at which the machine repositions itself after cutting. The faster the Rapid Motion Speed, the faster the machine can take on multiple tasks. There are CNC machines that have a Rapid Motion speed of more than 1000 inches per minute.

In general, the faster the high the maximum machining speed that a CNC machine can reach and the Rapid Motion speed, the more expensive the CNC machine is. 

• Machining Tolerances and Accuracy

CNC machines that can attain higher machining tolerances and accuracy are generally more costly. Needless to say, accuracy and perfection are expensive!

• Number of Axes

The more degrees of freedom that a CNC machine has, the more expensive it is. For example, a 5-axis CNC machine is more expensive than a 3-axis CNC machine.

Most hobbyists’ CNC machines have 3-axes.

• Power

CNC machine’s brute power is measured in terms of things like the RPM of the spindle and the torque it can handle. 

However, larger professional CNC machines are rated depending on the size of their servo motors.

For example, the stepper motor of a hobbyist Sainsmart Genmitsu runs at 0.18 ft-lb while that of a professional 6-axis CNC like the Zimmerman FZ100 can run at 68 ft-lb. if you do the math, the 6-axis CNC servo motor is about 400 times more powerful than the hobbyists CNC. 

As a result, the 6-axis CNC costs way higher than the hobbyists CNC.

Categories of CNC Machines and their Price Ranges

Besides the factors outlined in the section above, other factors like where someone is purchasing the CNC machine also affect the price. Generally, Chinese CNC machines are generally cheaper compared to the US and European-made CNC machines.

If you are shipping the machine, one will need to also take note of the shipping charges and taxes since they will determine the overall cost of the machine.

To assist those looking for affordable small hobbyist CNC machines choose the correct CNC machine depending on the above table of costs, we shall briefly look into what the Entry Level Desktop CNC Routers, Hobby CNC Router Machine, Small CNC Lathe machines, and Entry-Level 2-axis Lathe machines are used for.

Entry Level Desktop CNC Routers

Figure 2. SainSmart Genmitsu Desktop CNC Router Machine 3018 PROver (source)

These are considered to be the best CNC machines for testing the waters if you are just venturing into CNC machining and you do not intend to undertake very complex tasks.

The most common type under this category is the Generic desktop 3018 CNC.

Just as the name suggests, these machines are the size of a desktop with an approximate size of 30 inches by 18 inches. 

They are mostly used for engraving works and can work on wood, plastics, acrylic, jewelry, and PCBs. Some have strong enough motors and quality rails that permit them to also work on aluminum.

Some are also fitted with laser engraving modules while others generally have the provision but require the user to separately buy and attach the laser engraver. 

Examples of Desktop CNC Routers include the CNC 3018 Pro Max 3 Axis Desktop and the Sainsmart Genmitsu PROVer.

Hobby CNC Router Machine

Figure 3. Shapeoko CNC Machine (Source: inventables.com)

These types of CNC machines were recently developed following the rise in demand for small affordable CNC machines by hobbyists.

They are generally used for cutting and engraving and can work on PCBs, plastic, wood, and aluminum. Some can also handle brass and steel.

Examples of CNC machines within this category include the X-Carve CNC, Shapeoko CNC Router.

Small CNC Lathe Machines

These are more advanced and can be used not only for engraving but also for machining and they can comfortably handle steel and titanium.

However, their production speed is still too low for high-volume production work.

Examples of CNC machines within this category include the Shopbot PRS Alpha CNC and the Tormachs CNC machines.

Entry-Level 2-axis Lathe Machines

Figure 4. Tormach 8L Lathe (source)

These CNC machines are generally used by small shops.

Examples of CNC machines within this category include the Tormach 8L and Tormach 15L Slant Pro lathe machines.

They are used for medium production volumes and can generally handle most of the materials.

Other Costs Associated with CNC Machines

Besides buying the CNC machine of your costs and having it shipped to your location, there are things that you will require to purchase to be able to work with the CNC machine.

Some of the things that you will require include:

• Work holding devices
• Tool Holding devices
• Inserts and Insert cutter bodies
• Cutting tools (carbide, etc.)
• Equipment for inspection
• Measuring tools like calipers, micrometers, pin gauges, and thread gauges
• Somewhere to store your cutting tools
• Coolant mixer
• Fasteners, HSS Drills, and wrenches
• Computer setup with the appropriate OS, and well-networked with the machines and team members

Conclusion

This post should help you choose a good affordable CNC machine depending on the CNC machine cost.

As shown in the post, it is possible to get a good CNC machine especially for engraving purposes with a budget of less than $10,000 especially if you are just starting and do not need a machine for a high production volume.