Materials Most Frequently Used by Precision CNC Machine Shops
Aluminium alloys
6061-T6 – balanced strength, corrosion resistance and the shortest machining cycle of any engineering metal; 7075-T6 when higher strength-to-weight is mandatory. Both alloys deliver ≤ 1.6 µm Ra as-milled and hold ± 5 µm dimensional tolerance without post-processing .
Stainless steels
304 L and 316 L for food, medical and marine environments; 17-4 PH for hardened fittings up to 40 HRC. All grades are machined with through-spindle coolant and carbide tooling to avoid work-hardening.
Titanium – Ti-6Al-4V
High strength-to-weight and bio-compatibility, but low thermal conductivity demands rigid fixtures, low feeds and high-pressure coolant. Typical accuracy: ± 10 µm, Ra 0.4 µm.
Nickel-based super-alloys
Inconel 718, 625 and Monel for aerospace and chemical plant; cut with ceramic or whisker-reinforced carbide at reduced speeds to maintain ± 0.01 mm tolerance.
Copper alloys
Oxygen-free Cu-101 for electrical contacts, 360 free-cutting brass for valve bodies and 110 copper for heat sinks. All give excellent chip control and surface finishes down to Ra 0.2 µm.
Low- and medium-carbon steels
1018, 1045 and 4140 (quenched & tempered) for shafts, gears and fixtures; magnetic, weldable and cost-effective while still able to meet IT 7 tolerances.
Engineering plastics
PEEK (250 °C service), PTFE, Acetal and Nylon for medical and electronic housings; hold ± 0.02 mm and Ra 0.4 µm when machined with sharp carbide and compressed-air cooling.
Tool steels & pre-hardened mould steels
A2, D2, H13 (48–62 HRC) used for injection-mould inserts and punches; profile-ground after hard machining to final tolerances of ± 2 µm.
Across these materials modern shops maintain certified traceability (ISO 9001, AS9100, ISO 13485), supply full chemistry and mechanical test reports, and match the grade to the required environment, strength, weight and cost targets.
