Which Metals Are Best for CNC Machining?

     In the world of CNC machining, the choice of metal materials directly affects machining efficiency, part accuracy and final cost. Although no metal can "take all" in all machining scenarios, some metals have become the "darlings" of CNC machining due to their excellent comprehensive performance. They are not only adaptable to a variety of machining processes, but also can show stable performance in the fields of auto parts, aerospace, etc.

Aluminum alloy is one of the ideal materials for CNC machining, especially in the fields of auto parts and aerospace.

In terms of processing performance, aluminum alloy has moderate hardness (the hardness of common 6061 aluminum alloy is about 95HB), low cutting resistance, slow tool wear, and can greatly improve processing efficiency. Its thermal conductivity is excellent, about 3 times that of steel, and the heat generated during processing can be quickly dissipated to avoid the accuracy of parts affected by thermal deformation. In addition, aluminum alloy has good plasticity, and smooth surface quality can be obtained whether it is milling, turning or drilling, without complicated subsequent processing.

In terms of cost, the price of aluminum alloy raw materials is relatively affordable, and the material utilization rate is high during processing, which is suitable for mass production. For example, engine brackets in the auto parts field and lightweight structural parts in aerospace are mostly processed with aluminum alloys, which can meet strength requirements and achieve weight reduction goals.

Brass has become a popular choice for precision parts processing due to its excellent cutting performance.

Brass has a low hardness (about 50-100HB) and a uniform internal structure. It is not easy to produce burrs and cracks during processing, and can easily achieve high-precision dimensional control (tolerance can be stabilized within ±0.01mm). It has good self-lubrication, is not easy to stick to the tool during cutting, and can reduce tool loss. It is especially suitable for processing parts with fine threads and complex holes, such as hydraulic valve components in auto parts and connectors in precision instruments.

In addition, brass has good conductivity and corrosion resistance. After processing, it can meet the needs of some scenarios without additional plating, further reducing production costs. However, brass has a high density and is relatively limited in its application in weight-sensitive aerospace parts.

Low carbon steel (carbon content <0.25%) is a "frequent visitor" in the industrial field and also occupies an important position in CNC processing.

Its strength and toughness are balanced, and the cutting force during processing is moderate, which is suitable for various conventional processing technologies. Low carbon steel is cheap and the raw material supply is sufficient, which is suitable for mass production of structural parts, such as chassis brackets in auto parts and gear blanks in mechanical transmission. After heat treatment, low carbon steel can also improve the surface hardness and meet the wear resistance requirements.

However, it should be noted that low carbon steel is easy to rust, and usually needs to be electroplated or painted after processing; and its thermal conductivity is not as good as aluminum alloy, so it needs to be cooled during high-speed processing to avoid deformation of parts.

In scenarios with high requirements for corrosion resistance, 304 and 316 stainless steel are the first choice for CNC machining.

304 stainless steel contains chromium-nickel alloy, has strong oxidation resistance and stable processing performance, and is suitable for making parts for food machinery and medical equipment; 316 stainless steel has better resistance to salt spray and high temperature corrosion due to the addition of molybdenum, and is often used in aerospace pipeline systems and exhaust parts in auto parts.

Although stainless steel has a high hardness (about 150-200HB) and the tool wears faster during cutting, high-precision parts can still be efficiently processed by selecting carbide tools and optimizing cutting parameters (such as reducing feed speed and strengthening cooling).

To determine whether a metal is suitable for CNC machining, the following factors need to be considered comprehensively:

• Machining efficiency: Material hardness and cutting resistance directly affect machining speed and tool life;

• Precision control: Thermal conductivity and plasticity determine whether the parts are easily deformed due to machining heat or stress;

• Cost adaptation: Raw material prices, machining energy consumption, and subsequent processing costs must match the project budget;

• Scenario requirements: The strength, corrosion resistance, weight and other properties of the parts must meet the special requirements of the application field (such as the requirements of aerospace for lightweight and high temperature resistance).

Different metals have their own advantages, and the selection needs to be combined with the drawing requirements, performance indicators and cost budget of the specific project. If you are struggling with the selection of parts, or want to know the feasibility of machining a certain metal, please contact us. Our team of engineers is familiar with the machining characteristics of various metals and can provide customized solutions according to your needs, from material selection to process optimization, to escort your project throughout the process.