CNC Material

What Material Do I Use for Machined Parts?

An overview of metal, plastics, carbon fiber and other material considerations for CNC Machining

One major advantage of precision CNC machining is the wide selection of materials mechanical engineers have at their disposal but narrowing down the choices to select the right material for your application can sometimes seem overwhelming. Better Molds is here to help make CNC material selection a little bit easier.

  • Determine Part Requirements

The first step is to prioritize your requirements the old phrase “Is it a need or is it a want?” is always useful when considering material selection.


One advantage of working with Better Molds is a DFM engineer will review your CAD files and having an experienced manufacturing engineer review your job (we have machined every kind of part you can think of for just about every industry) is always helpful.


Consider the conditions in which your part will function and whether it is intended to work as part of an assembly as a moving part or stationary.


  1. Environment: Environmental factors such as heat and cold, moisture, chemical tolerance, etc. are a key part to material selection. Especially if you need aerospace, medical grade or food grade. A part that will be going to space may need certain radiation tolerances while a part used in a medical device may need to go through extreme high heat of an autoclave chemical sterilization between uses.
  2. Electrical: Does your part need to conduct or insulate? Does it need to dissipate static. Are there any electrical considerations for your part?
  3. Mechanical Strength: How strong does the part need to be? Does it need to be rigid or flexible? Does it compressive or tensile strength, or be able to resist impact? Does it need to be water proof or resistant or lubricated like in a bearing?
  4. Cosmetics and Surface Finish: Is your part on the inside or outside and does it need to be aesthetically appealing and functional? Plastic materials can come in a variety of colors, while metals can be colored using secondary processes such as chromate plating, anodizing, painting. While specific surface texture from textured to non-slip to high polish also dictate what you need.
  5. Size: How big is the part? Are there limitations on stock size the material is available in? Can it fit in a standard CNC sized machine? How small or large should it be to optimize manufacturability while still maintaining the part’s intended functions?
  6. Cost: Always one of the most important considerations. At Better Molds, we encourage our customers to inquire about less expensive alternatives. Having an experienced team of CNC experts can help engineers understand how “low they can go” before the intended part functionality is compromised. Steel vs. Aluminum, Brass vs. Copper, etc.


Better Molds offers a range of metals to machine from including aluminum, brass, copper, steel and stainless steel. Plastic materials we machine include ABS, Acetal, PEEK, nylon, polycarbonate, polyvinyl chloride (PVC), high- and low-density polyethylene, and more.

ABS vs. Acetal

  • ABS offers high impact strength, low heat conductivity, and low coefficient of friction.
  • Acetal offers high mechanical strength, high dimensional stability, and low moisture absorption.

PEEK vs. Ultem

  • Peek provides high abrasion and wear resistance, low moisture absorption, and low coefficient of friction.
  • Ultem (PEI) offers extreme strength and rigidity, chemical resistance and high dielectric strength.

Aluminum 6061 vs 7075

  • 6061 offers excellent machinability, low cost, and versatility.
  • 7075 offers high strength, hardness, low weight, and heat tolerance.


Better Molds is your premier partner for 5-Axis and 3-axis machined parts. Upload your file today for a free quote and DFM review. We succeed by helping engineers succeed and we aim to provide the highest quality and precision at the best price and fastest delivery. Contact us today or upload your files here: (insert link to file upload)