CNC machining is one of the most common manufacturing methods used to manufacture metal parts. Computer digital control (CNC) uses processes that allow the use of a high degree of automation to manufacture parts and has advantages over many traditional manufacturing methods in terms of speed, productivity and accuracy. Choosing the right materials for CNC machining can be a daunting task, and many factors should be considered when selecting materials for parts, including machinability, price, corrosion resistance, strength, weight and appearance.
As one-stop CNC machining shop in China, CFS is very professional on CNC machinining. Here we would like to introduce the 6 main types of CNC machining metal materials in below:
Aluminum alloy has excellent strength-to-weight ratio, high thermal & electrical conductivity, and natural corrosion protection. They are easy to process and have low mass production cost, so they are often the most economical choice for manufacturing custom metal parts and prototypes.
Aluminum alloys are generally less strong and hard than steel, but they can be anodized to form a hard protective layer on their surface.
Aluminum 6061 is the most common and universal aluminum CNC machining alloy with good strength-to-weight ratio and excellent machinability.
Aluminum 6063 has similar composition and material properties to 6061. It is more commonly used in Europe for CNC Machining because it meets British standards.
Aluminum 7075 is the most commonly used CNC Machining alloy in aerospace applications, where weight reduction is critical because it has excellent fatigue properties and can be heat treated to a high strength and hardness comparable to steel.
Aluminum 5083 has higher strength and excellent seawater resistance than most other aluminum alloys and is therefore commonly used in construction and Marine applications. It is also the best choice for welding.
- Typical density of aluminum alloy: 2.65-2.80 g/cm³.
- Can be anodized.
2. Stainless Steel
Stainless steel alloys have high strength, high ductility, excellent wear and corrosion resistance, and are easy to weld, process and polish. They can be (basically) non-magnetic or magnetic.
Stainless steel 304 is the most common stainless steel alloy in CNC machining process, with excellent mechanical properties and good machinability. It is resistant to most environmental conditions and corrosive media.
Stainless steel 316 is another common stainless steel CNC machining alloy with similar mechanical properties to 304. Although it has higher corrosion and chemical resistance, especially to salt solutions (such as seawater), it is often preferred for harsh applications.
2205 Duplex stainless steel is the highest strength stainless steel alloy (twice that of other ordinary stainless steel alloys) with excellent corrosion resistance. It is used in harsh environments and has many applications in the oil and gas industry.
Compared with 304, 303 stainless steel has excellent toughness, but lower corrosion resistance. Due to its excellent machinability, it is commonly used in high-volume applications such as manufacturing nuts and bolts for aerospace applications.
Stainless steel 17-4 (SAE class 630) has similar mechanical properties to 304. It can precipitate and harden to very high degrees (comparable to tool steel) and has excellent chemical resistance, making it suitable for very high performance applications such as the manufacture of turbine blades.
- Typical density: 7.7-8.0 g/cm3
- Non-magnetic stainless steel alloy: 304, 316, 303
- Magnetic stainless steel alloy: 2205 Duplex, 17-4 ph.
3. Mild Steel
Mild steel has good mechanical properties, good machinability and weldability. Due to their low cost, they can be used in general purpose applications, including the manufacture of machine parts and fixtures. But mild steel is susceptible to chemical corrosion and erosion.
Mild steel 1020 is a general purpose alloy with good machinability and weldability, as well as excellent toughness, strength and hardness. It is the most commonly used low carbon steel alloy.
Mild steel 1045 is a medium carbon steel with good weldability, good machinability, high strength and impact resistance.
Mild steel A36 is a common structural steel with good weldability. It is suitable for a variety of industrial and architectural applications.
- Typical density: 7.8-7.9 g/cm3
4. Alloy Steel
Alloy steels contain other alloying elements in addition to carbon, resulting in increased hardness, toughness, fatigue and wear resistance. Like mild steel, alloy steel is vulnerable to corrosion and chemicals.
Alloy steel 4140 has good comprehensive mechanical properties, good strength and toughness. The alloy is suitable to machine components for many industrial applications but is not recommended for welding.
Alloy steel 4340 can be heat treated with high strength and hardness while maintaining good toughness, wear resistance and fatigue strength. This alloy is weldable.
- Typical density: 7.8-7.9 g/cm3
5. Tool steel
Tool steel is a metal alloy with extremely high hardness, stiffness, wear resistance and heat resistance. They are used to make manufacturing tools (hence the name), such as molds. They must be heat treated for good mechanical properties.
Tool steel D2 is a wear resistant alloy that maintains its hardness up to 425 ° C. It is usually used to make tools and molds.
Tool steel A2 is an air hardened general purpose tool steel with good toughness and excellent dimensional stability at high temperatures. It is often used to make injection moulds.
Tool steel O1 is an oil hardened alloy with hardness up to 65 HRC. Often used with knives and cutting tools.
- Typical density：7.8 g/cm3
- Typical hardness：45-65 HRC
Brass is a metal alloy with good machinability and excellent electrical conductivity, ideal for applications requiring low friction. It is also commonly used in architecture to create parts with a golden appearance for aesthetic purposes.
Brass C36000 is a CNC machining material with high tensile strength and natural corrosion resistance. It is one of the easiest CNC machining materials to work with and is therefore usually used for large volume applications.
- Typical density: 8.4-8.7g /cm3