Material selection is a decision that affects not only the durability of the part, but also the machining time and the final price. The same shape made in aluminium and in stainless steel can differ in cost several times over. Below is a practical overview of the materials we most often machine in CNC machining.
What material selection depends on
- How does the part work? — loads, motion, friction, temperature
- In what environment? — moisture, seawater, chemicals
- What is the priority? — strength, weight, corrosion resistance, cost, appearance
Steel and stainless steel
Structural/tool steel — high strength and stiffness, good material price; requires corrosion protection. Stainless steel — corrosion resistant (humid, marine, food, medical environments), but harder to machine, so the part costs more.
Aluminium
Light, highly machinable, corrosion resistant, easy to anodise. The most common choice when weight and fast, economical machining matter — machine parts, housings, prototypes.
Brass, copper, bronze
Brass — excellent machinability and finish (fittings, connectors). Copper — excellent conductivity (electrical). Bronze — wear resistance and sliding properties (bushings, bearings).
Engineering plastics
POM, PA (nylon), PTFE, PEEK — light, chemically resistant, self-lubricating, insulating. Chosen where metal is unnecessary or gets in the way.
In short — what to choose
- Low weight, economy → aluminium
- Maximum strength → structural steel
- Corrosion / marine / food resistance → stainless steel
- Easy machining + fittings → brass
- Sliding, bushings → bronze
- Lightness + chemical resistance → engineering plastics
Frequently asked questions (FAQ)
Which material is cheapest to machine?
Usually aluminium. Stainless steel is the most expensive to machine due to its difficult machinability.
I don’t know which material to choose — can you help?
Yes. Just describe how and where the part will work — we will select the material for the application.
Not sure about the material? Describe the part’s application — we will advise and quote. Send an enquiry or see the CNC turning offer.
