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CNC Machining Materials

 If you have the opportunity to stop by a CNC or computer numeric control shop, I would say 4 out of the five senses would be active. A word of caution, unless you are part of the production team, no one should ever venture unescorted in any industrial machining service area.  While walking through with your guide of a well-run CNC shop, you will hear machines humming, the smell of the coolant, the feel of the machined parts (please ask first!) and the sight of various materials being processed. It is common for CNC machine shops to produce multiple jobs at once and out of multiple materials. This not only takes coordination and planning, but also requires expertise in manufacturing and material knowledge to produce CNC machined components. Five materials that are commonly machined are: 

  1. Stainless Steel: There are numerous alloys under stainless steel category and some of the more popular ones are 303/304. 17-7, 16-6. Stainless steel machined precision parts are produced for countless industries. They have strength and durability. Often stainless-steel machined components go through a finishing process.
  2. Aluminum: One of the most widely used materials by CNC component manufacturers. It also comes in numerous grades, and some are: 6061, 7075, and MIC-6. Aluminum is ductile and machines extremely well. One popular finishing process used is anodizing. 
  3. Titanium: Because titanium has a high strength to weight ratio and is 40% lighter than steel it is used in industries like aerospace, medical, automotive, and so many more. 
  4. Brass: Grades machined are C-260, C-360, C-646 and C-280. Having durability and corrosion resistance, brass parts are machined for bushings, bearings, gears, compression fittings, for example. 
  5. Copper: Available in grades of pure copper like c10100, c13000, electrolytic copper at c11000 and oxygen free copper at 10100 and c10200. Examples of machined components are busbars, heat exchangers, heat shields, fuel lines and many other applications. 
  6. Plastics: With many choices of materials, it is important to list this non-metallic category. Plastic like Peek, HDPE and polycarbonate are also used to produce machined components. You will fine plastic machined parts used for the medical, food, semiconductor, laboratory research industries for example. 

Before any material is used, CNC machining companies will ask the following questions to select the best material options: 

  • What is the purpose of the component? Does the use require high strength or corrosion resistance or both? Will it be subject to wear? 
  • What industry will it serve and what environmental conditions will it be subjected to? Will the machined component get wet or be exposed to harsh chemicals?  
  • Temperature ranges required. Parts used in jet engines for example, need a high temperature range as opposed to a medical implant. 
  • What tolerance is needed. Many industries require very stringent tolerances to be held of any CNC machined components. Some projects no not have this requirement and can be produced faster and possible at less cost. 
  • How machinable is the desired material for this project? Easier cut and machined materials generally will take less time and less cost to produce. Hardened materials will take longer and may wear down the tools used by the CNC manufacturer. This can add cost. 
  • The cost of the material? Many standard grades of materials are used and thus produced at lower cost. Some materials are made through longer chemical processes and the available stock is in lower supply. While some materials are only available by custom manufacturing and the cost and minimum requirements will add up greatly.  

Once the appropriate material is selected, CNC machining specialists may also recommend post-finishing processes, depending on the parts use. This is to protect and prolong the life of the machined part. It also can add functionality to allow parts to move smoothly without friction. Some examples of a finishing process are tumble or barrel deburring, anodizing, passivation, and powder coating. When considering your next project, it is crucial to speak with your CNC machined components manufacturer to learn of the options for materials and the best CNC manufacturing method. Their expertise will be the foundation for a quality machined component.