Material for CNC parts
The right material decides function, production cost and lead time. We compare the most important materials and show what matters in the choice.
Material selection for CNC parts: aluminium (light, corrosion resistant), stainless (high strength, food safe), steel (load bearing, hardenable), brass (conductive, decorative) and plastics (chemically resistant, light).
Materials compared
Every material has a characteristic property profile. Aluminium scores on machinability and weight, stainless on corrosion resistance and strength.
For CNC production, machinability is the decisive factor. It sets the cycle time and the tool wear, and with them the production cost.
The most important CNC materials
| Material | Material no. | Typical application | Machinability | Practical tip |
|---|---|---|---|---|
| Aluminium 6082 | 3.2315 | Housings, plates, lightweight | ★★★★★ | High cutting speed possible (300+ m/min) |
| Aluminium 7075 | 3.4365 | Aerospace, high strength parts | ★★★★☆ | Harder chip, more tool wear |
| Free cutting steel | 1.0718 | Turned parts, bolts, bushings | ★★★★★ | Ideal for bar feeder series |
| Structural steel S355 | 1.0570 | Machine building, structures | ★★★★☆ | Standard material, welds well |
| Stainless 1.4301 | 1.4301 | Food, medical, chemical | ★★★☆☆ | Avoid built-up edge, run cool |
| Stainless 1.4571 | 1.4571 | Chemical, offshore, seawater | ★★☆☆☆ | Molybdenum alloyed, stickier chip |
| Titanium grade 5 | 3.7165 | Medical, aerospace, implants | ★★☆☆☆ | Low cutting speed, high tool cost |
| PEEK | - | Medical, semiconductor, insulation | ★★★★☆ | Risk of melting, use sharp tools |
Material drives the price
Material cost is only part of the equation. Machinability sets the cycle time and the tool wear, and with them the greater part of the production cost.
Free cutting steel (11SMnPb30) turns three times faster than stainless 1.4571, at a fraction of the tooling cost. So always check whether a more machinable material meets the requirement just as well.
Choosing the material well
Function before prestige
Not every part needs stainless. Galvanised structural steel or anodised aluminium is often enough, at half the production cost.
Prefer stock material
Standard materials (6082, S355, 1.4301) are available from stock. Special alloys carry 4 to 8 weeks lead time and minimum quantities.
Watch the machinability
On turned parts, free cutting steel instead of tempered steel saves up to 30% cycle time. On aluminium, 6082 instead of 7075 when the strength is sufficient.
Think about certificates
3.1 certificates (works issued) are standard. 3.2 certificates (independent inspection) cost extra and lengthen the lead time. Only ask for them when they are needed.
Frequently asked questions
For series turned parts, free cutting steel (11SMnPb30 / 1.0718) is ideal: short breaking chips, high cutting speeds, low tool costs. For corrosion resistant parts: stainless 1.4301.
Stainless runs around 30 to 50% more expensive to produce than aluminium at similar geometry. The higher price comes less from the material itself than from the two to three times longer machining time and the higher tool wear.
Yes, but titanium needs specific cutting data: low cutting speed (30 to 60 m/min), heavy coolant and coated carbide tooling. Machining costs run two to three times those of aluminium.
POM is the standard plastic for mechanically loaded parts: cheaper and easy to machine. PEEK is for extreme requirements: up to 260 °C, chemically resistant, biocompatible, but 10 to 20 times the price of POM.
The material number (1.4301 for example) is the European designation to EN 10027-2. The first digit gives the material group (1 = steel, 2 = copper, 3 = aluminium). The number is unique and internationally standardised.
CNC machined we reach Ra 1.6 µm. For smoother surfaces: polishing down to Ra 0.1 (mirror finish), electropolishing for an even surface, or glass bead blasting for a matt look.
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