Making parts processing as easy as online shopping! If the material is wrong, all efforts are in vain! There are many materials suitable for custom CNC machining parts, but selecting the right one for your product depends on various factors. A fundamental principle is that the material’s properties must meet the product’s technical and environmental requirements. When choosing materials for mechanical parts, consider the following five aspects:

1. Is the Material Rigid Enough?

Rigidity is the primary factor to consider when selecting a material, as products require stability and wear resistance in practical applications. The material’s rigidity determines the feasibility of the product design.

Based on industry characteristics:

• For non-standard tooling designs, 45 steel and aluminum alloys are commonly chosen.
• For tooling designs in mechanical machining, 45 steel and alloy steel are used more frequently.
• In the automation industry, aluminum alloys are often preferred for tooling designs.

2. How Stable is the Material?

For products with high precision requirements, material stability is critical. An unstable material may deform during assembly or use, constantly changing with environmental factors like temperature, humidity, or vibration. This is a nightmare for any product.

3. How is the Material’s Machinability?

Machinability determines how easily a part can be processed. While stainless steel is rust-resistant, it’s challenging to machine due to its high hardness, which can wear down tools quickly. Machining small holes, especially threaded ones, in stainless steel often leads to broken drills or taps, significantly increasing processing costs.

4. How is the Material’s Rust Resistance?

Rust prevention affects both the product’s stability and appearance. For instance, 45 steel is typically treated with “blackening” for rust protection, or parts may be painted or coated with plastic. Depending on environmental requirements, protective measures like sealing oil or rust inhibitors can also be used during operation.

There are various rust-prevention methods, but if none are suitable, you may need to switch to a material like stainless steel. Regardless, rust prevention is a critical consideration.

5. What is the Material Cost?

Cost is a significant factor in material selection. Titanium alloys, for example, are lightweight, have high specific strength, and excellent corrosion resistance, making them widely used in automotive engine systems for significant energy savings.

Despite their superior performance, the primary barrier to widespread use of titanium alloys in the automotive industry is their high cost. If not absolutely necessary, opt for more cost-effective materials.

Common Materials for CNC Machining and Their Key Properties

There are numerous metal CNC machining materials. Below are some commonly used materials for machined parts and their key characteristics:

Aluminum 6061

This is the most widely used material for CNC machining, offering medium strength, good corrosion resistance, weldability, and excellent anodizing results. However, Aluminum 6061 has poor corrosion resistance when exposed to saltwater or certain chemicals. It’s less strong than other aluminum alloys for high-demand applications but is commonly used for automotive parts, bicycle frames, sporting goods, aerospace fixtures, and electrical fittings.

Aluminum 7075

Aluminum 7075 is one of the strongest aluminum alloys. Unlike 6061, it offers high strength, easy machinability, good wear resistance, strong corrosion resistance, and excellent anodizing properties. It’s ideal for high-strength recreational equipment, automotive, and aerospace frameworks.

Brass

Brass boasts high strength, hardness, chemical corrosion resistance, and excellent machinability. It also offers superior electrical and thermal conductivity, ductility, and deep-drawing properties. Brass is commonly used for valves, water pipes, air conditioner connectors, radiators, complex stamped parts, small hardware, mechanical and electrical components, and musical instrument parts. Different brass types vary in corrosion resistance based on zinc content.

Copper (Red Copper)

Pure copper, also known as red copper, has electrical and thermal conductivity second only to silver, making it ideal for conductive and heat-conducting components. It offers excellent corrosion resistance in atmospheric conditions, seawater, certain non-oxidizing acids (e.g., hydrochloric acid, dilute sulfuric acid), alkalis, salt solutions, and organic acids (e.g., acetic acid, citric acid), commonly used in the chemical industry.

Stainless Steel 303

Stainless Steel 303 offers excellent machinability, resistance to burning, and corrosion resistance, making it suitable for applications requiring easy cutting and high surface finish. It’s commonly used for stainless steel nuts and bolts, threaded medical devices, pump and valve parts, but it’s not suitable for marine-grade applications.

Stainless Steel 304

Stainless Steel 304 is versatile, with good machinability and high toughness. It’s more corrosion-resistant in most non-chemical environments, making it an excellent choice for industrial, architectural, and automotive decoration, kitchen accessories, water tanks, and piping.

Stainless Steel 316

Stainless Steel 316 offers excellent heat and corrosion resistance, with good stability in chlorine-containing and non-oxidizing acid environments, earning it the title of marine-grade stainless steel. It’s tough, easy to weld, and commonly used for architectural and marine fittings, industrial pipelines, storage tanks, and automotive decoration.

45 Steel

45 Steel is a high-quality carbon steel and the most commonly used medium-carbon quenched and tempered steel. It offers good mechanical properties but low hardenability, with a tendency to crack during water quenching. It’s mainly used for high-strength moving parts like turbine impellers, compressor pistons, shafts, gears, racks, and worms.

40Cr Steel

40Cr Steel is one of the most widely used steels in mechanical manufacturing, offering excellent comprehensive mechanical properties, low-temperature impact toughness, and low notch sensitivity.

• After quenching and tempering, it’s used for medium-speed, medium-load parts.
• After quenching, high-frequency surface hardening is applied for high-hardness, wear-resistant parts.
• After quenching and medium-temperature tempering, it’s used for heavy-duty, medium-speed impact parts.
• After quenching and low-temperature tempering, it’s used for heavy-duty, low-impact, wear-resistant parts.
• After carbonitriding, it’s used for larger transmission parts with high low-temperature impact toughness.

Plastic Materials for CNC Machining

In addition to metals, there are a lot of plastic materials for CNC machining services. Below are some of the most commonly used plastic materials for CNC machining:

Nylon

Nylon is wear-resistant, heat-resistant, chemically resistant, and somewhat flame-retardant, making it easy to machine. It’s an excellent substitute for steel, iron, or copper. Common CNC-machined nylon applications include insulators, bearings, and injection mold components.

PEEK

PEEK is another plastic with excellent machinability, offering outstanding stability and impact resistance. It’s commonly used for compressor valve plates, piston rings, seals, and various aircraft and rocket engine components. PEEK is also the closest material to human bone, making it a viable substitute for metal in manufacturing human bones.

ABS Plastic

ABS offers excellent impact strength, dimensional stability, dyeability, and machinability. It has high mechanical strength, stiffness, low water absorption, and good corrosion resistance. It’s easy to connect, non-toxic, odorless, and provides excellent chemical and electrical insulation properties. ABS is heat-resistant, tough, scratch-resistant, and resistant to deformation.