Computer numerical control (CNC) machining is a flexible, high-precision manufacturing process that enables a quick and efficient production of parts, prototypes, and components for specific applications. It is also well suited for manufacturing intricate details in medium to high-volume production runs.
One significant advantage of CNC machining is that it allows using various raw materials to produce finished parts. This provides design engineers and manufacturers with an array of plastics and metals to choose from when undertaking a machining project. However, having too many options can make the task of selecting the best materials challenging.
This article will provide an overview of CNC materials, their benefits, common industrial applications, and important factors to consider when selecting the best material.
Common CNC Machining Materials
Most CNC machined parts are made of metallic materials due to their strength and rigidity. However, plastic resins are excellent substitutes because they are strong, easily machinable, and capable of producing long-lasting parts and components.
Let’s start with the most commonly used metals beneficial for CNC machining.
Stainless steel is widely used in CNC machining due to its strength and resistance to corrosion, distortion, and wear. These characteristics allow for the availability of various stainless steel alloys and grades, which are frequently used in the automotive, marine, and aerospace industries.
The best stainless steel alloys and grades for CNC machining are as follows:
- Stainless Steel 303: This grade contains sulfur, making it the most easily machined stainless steel, but it also slightly reduces corrosion resistance. Moreover, 303 is generally utilized for stainless nuts and bolts, fasteners, bearings, and gears.
- Stainless Steel 304: Also called 18/8, this grade contains 18% chromium and 8% nickel in its alloy. It is the most common type of stainless steel used for various industrial and consumer products because it is particularly tough and nonmagnetic.
- Stainless Steel 316: This grade has molybdenum added and is thus more corrosion-resistant. It is frequently used in structural and marine fittings for industrial pipes and tanks, automotive applications, and kitchen cookware.
Carbon Steel 1045
Carbon Steel 1045 is a popular mild steel grade that is less costly than stainless steel but significantly stronger and tougher. It is simple to machine and weld and can be hardened and heat-treated to achieve various hardness levels. In addition, this material is suitable for strong small parts, such as nuts, bolts, gears, bearings, and other mechanical components.
Aluminum alloys are simple to work with in large quantities. They are also naturally corrosion-resistant, have excellent thermal and electrical conductivity, and have a good strength-to-weight ratio.
Here are some of the best aluminum alloys for CNC machining:
- Aluminum 6061: This alloy contains magnesium, silicon, and iron. It has good mechanical properties and machinability. Furthermore, it is commonly found in bicycle frames, automobile parts, aircraft components, sporting equipment, and RC vehicle frames.
- Aluminum 7075: This is a higher-grade aluminum alloyed primarily with zinc. It has excellent strength-to-weight characteristics and is one of the strongest aluminum alloys in machining. It is also used in panels and other parts for automobiles and aircraft.
Despite its higher cost than other CNC materials, titanium is frequently used to produce parts for the most stringent aerospace, military, and industrial applications. In addition, this material is also biocompatible and appropriate for use in the production of medical devices.
Next, here are the most commonly used plastic materials for CNC machining:
Acetal- (homopolymer and copolymer) Often referred to by the brand names, Delrin and Acetron GP, they are two of the strongest unreinforced plastics. They both machine well, are scratch resistant, low friction, and have excellent resistance to hydrocarbons and have a high fatigue endurance. These materials are dimensionally stable and offer excellent moisture resistance. They are both FDA and USDA compliant for use in Industrial Food Processing Equipment along with many other industries and applications.
Nylon is a versatile, low-friction thermoplastic frequently used as a substitute for metal in CNC-machined parts. It is elastic, strong, and resistant to impact and chemicals. Moreover, it can be manipulated and modified to generate the desired properties as it reacts well to additives and fillers.
Acrylonitrile butadiene styrene (ABS) is a tough, impact-resistant material that is also resistant to chemicals and electric current. It is commonly used for rapid prototyping and can be found in automotive parts, machine tools, toys, and sporting equipment.
Polyether ether ketone (PEEK) is a high-strength, stable construction plastic that you can use in place of metal. It is an excellent material for lightweight fixtures but is more prevalently used in advanced medical, aerospace, and electronic parts.
Also known as acrylic or acrylic glass, PMMA is a rigid, clear resin used to replace glass or make other optical components. It is scratch-resistant and is used in screens, light pipelines, lenses, enclosures, and food storage.
Other Considerations When Selecting the Best CNC Materials
Aside from comprehending the distinctions between CNC materials, it is also critical to consider the following factors:
Consider how and where the part will be used, as these aspects significantly impact the material selection. For instance, using the wrong steel grade or aluminum alloy for a particular application might jeopardize the part’s durability.
If you need a lightweight part — common in automotive and aerospace applications — you should look into low-density CNC metals, such as aluminum and magnesium. Also, consider using plastic materials to reduce weight if strength is not required.
You should consider your budget before finalizing any decisions because costs often affect material selection. Most product teams want to choose a material that maximizes desired mechanical properties and performance while reducing expenses.
Solutions Manufacturing: Your Trusted Source for Precision Machined Components
Since 1994, Solutions Manufacturing has provided innovative solutions for our customers’ machined products and value-added services to meet their products requirements. We specialize in precision CNC milling and turning, and our competent manufacturing organization enables us to consistently provide our customers with high-quality products and services.