How to Select a Material for CNC Machined Parts

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Selecting the optimal material is a foundational step in the CNC machining process, directly impacting the part's functionality, durability, cost, and lead time. A wellinformed material choice ensures your project's success, while a poor one can lead to premature failure or budget overruns. As a professional onestopshop for CNC machined parts, we guide our clients through this critical decision by evaluating three key factors.


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1. Functional and Mechanical Requirements
The primary driver for material selection is the part's intended application. Ask these critical questions:
Strength & Hardness: Will the part endure high stress, impact, or wear? For highstrength applications, metals like 4140 Steel or Stainless Steel 304/316 are excellent. For a superior strengthtoweight ratio, Aluminum 6061 is the industry standard.
Operating Environment: Will the part be exposed to moisture, chemicals, or extreme temperatures? Stainless steels offer excellent corrosion resistance, while Titanium (Ti6Al4V) provides strength and corrosion resistance in demanding environments. For hightemperature stability, PEEK or other engineering plastics are ideal.
Weight Constraints: Is minimizing weight critical? Aluminum and its alloys, along with POM (Acetal), offer significant weight savings without sacrificing too much strength.

2. Manufacturing and Cost Considerations

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The machinability of a material significantly affects production time and cost.
Machinability: Materials like Aluminum and Brass are known for their excellent machinability, allowing for faster machining speeds, better surface finishes, and reduced tool wear. Harder materials like Stainless Steel or Titanium require more specialized tooling and slower processes, increasing cost.
Material Cost: The raw stock price varies greatly. While plastics like Nylon (PA66) are generally inexpensive, advanced composites like PEEK command a higher price. Aluminum offers a great balance of cost and performance.



3. PostProcessing Needs
Consider the final appearance and properties you require.
Aesthetics & Protection: Aluminum and Stainless Steel are highly suitable for anodizing, which adds color and corrosion resistance. Steel parts often require plating or painting to prevent rust.
Special Properties: Some applications may require additional treatments like heat treatment (to increase hardness) or passivation (for stainless steel to enhance corrosion resistance).

Partner with Experts
Navigating this landscape can be complex. Our expertise lies in helping you balance performance requirements with budget and timeline constraints. By understanding your project's full scope, we can recommend the most efficient and costeffective material—be it a common alloy like Aluminum 6061 or a specialized plastic like Ultem (PEI)—ensuring your CNC machined parts meet the highest standards of quality and performance. Let us help you make the right choice from the start.