December 14, 2023
The material selection of your project might seem like a small concern, but it’s actually more important than the design itself. The wrong material will only waste your time and money, while potentially leading to safety concerns and functional failures. In an effort to get the most out of your parts, our team put together this guide.
We’ll teach you how to pick the perfect CNC material for your next CNC-machined project. You’ll learn why the material choice matters and what to consider. We’ll also give you a list of materials, with a quick explanation of why you might choose one material over another.
Why Your CNC Materials Choice Matters
It’s not an exaggeration to say that the functionality of your part largely revolves around the material that you choose. Choosing the wrong material can lead to a useless part that fails the second that it’s used. In most applications, this can lead to safety issues, performance problems, and efficiency concerns across your operation.
At the same time, material options also come with a wide variety of costs, turnaround time, and feasibility when it comes to machining. Identical parts made out of two different materials could come with price tags that are different by orders of magnitude — one part could be $100 while the other is $1,000.
Finally, the material choice will decide whether or not your part can be manufactured in the first place. Designing a very intricate and complicated part out of ABS allows us to easily 3D print the part, while designing the same part out of copper would require specialization that only a few machine shops in the country possess.
Considerations for Selecting the Right CNC Materials
Now that you understand why your material choice matters so much, let’s look at some specific considerations that you should make. These will help you fine-tune your material selection.
Machining Environment: Consideration of temperature, humidity, and contaminants is crucial. Different materials behave distinctly under varying machining conditions, such as cutting speed and coolant use.
Part Weight: Lighter materials like aluminum or magnesium can be more cost-effective and enhance performance in industries like aerospace and automotive.
Heat Resistance: Important for materials undergoing intense heating and cooling cycles. We use materials like aluminum for heat sinks and stainless steel for high-temperature applications.
Electrical Conductivity and Magnetism: Essential for parts requiring heat dissipation, with non-magnetic materials like titanium ensuring a cleaner cut.
Hardness and Machinability: Balancing material hardness is key for efficient machining and achieving precision components.
Surface Finish and Aesthetics: We choose CNC materials based on the required surface finish, ensuring both functional and aesthetic quality.
Application-Specific Needs: From temperature resistance to chemical reactivity, your material choice hinges on the final application of the product.
Budget Considerations: Ensure your material selection considers costs, balancing quality with affordability.
Metal Options for CNC Machining
In our line of work, metal manufacturing makes up a vast majority of the projects that our team handles. Metals are incredibly strong and relatively easy to manufacture with. Within the world of metals, aluminum and steel are two of the more popular options, but there are plenty of other metals to choose from:
Aluminum (6061, 7075)
This option offers strength, lightweight nature, and corrosion resistance. Aluminum is commonly used in aerospace, automotive, and consumer electronics — but truthfully, there’s an application for aluminum in nearly every industry.
Stainless Steel (316, 303, 304)
Known for strength, corrosion resistance, and use in marine and medical applications, stainless steel is a much stronger metal than aluminum, though it also weighs a lot more.
Carbon and Alloy Steel
This provides strength and machinability, commonly used in industrial and manufacturing applications. Typically, you’ll add a coating to carbon steel since it’s more likely to rust and fatigue over time.
Brass
Brass is favored for its machinability, corrosion resistance, and electrical conductivity.
Copper
Copper is renowned for electrical and thermal conductivity, but challenging to machine. Copper is common in plumbing and electrical applications, but not as common in CNC machining.
Titanium
Titanium offers a high strength-to-weight ratio and corrosion resistance, suitable for aerospace and biomedical applications.
Magnesium
Known for its strength and lightweight properties, this option is ideal for high-temperature environments.
Plastics and Other CNC Material Options
Modern machine shops can also work with materials outside of metals. Plastics and “other” options are especially useful when you want to keep weight down in applications that don’t see a lot of loading or cyclic stresses.
Acetal (POM)
Known for fatigue resistance and moisture resistance, POM is used in the automotive and aerospace industries.
Acrylic (PMMA)
A glass substitute with good rigidity and optical clarity, PMMA is used in lenses and transparent enclosures.
Polycarbonate (PC)
PC is valued for transparency and heat resistance, but sensitive to UV light. It is a really strong plastic that is often used in bulletproof glass and safety glasses.
Polypropylene (PP)
PP offers high chemical resistance and is used in medical applications. It is one of the more common plastics used, especially in bulk containing.
ABS
Cost-effective, ABS is often used in automotive components and rapid prototyping. ABS can be 3D-printed, making it a versatile option for your next project.
Nylon
Nylon is excellent for parts requiring protection from friction, especially over long periods of time.
UHMW-PE
Noted for its hardness and abrasion resistance, UHMW-PE is ideal for high wear applications.
Foam
Foam is often utilized for its lightness and versatility in protective packaging and insulation.
Wood
Wood offers aesthetic appeal and environmental friendliness. It’s also a low-cost way to make prototypes or for checking real-world fitments.
Composites
Including carbon fiber and fiberglass, composites are used in automotive, aviation, and sports industries.
Get a CNC Machining Quote From Rapid Axis
As you just learned, CNC material selection is a critical step in making high-quality parts that fit within your application. We covered some of the more common metals, plastics, and ancillary materials that a well-run machine shop might use. If you need more help deciding on the right material, leverage our experts at Rapid Axis.
We are a full-service machine shop that can fabricate your parts in a wide variety of materials. We have plenty of CNC machinery and material options that can ensure you get the right quality, strength, and material properties on your next project. Get a free quote today.