Stainless steel is chosen for what it refuses to do: rust, corrode, react, or attract a magnet. The three grades we run most cover most of that ground, and the differences between them matter more than the price difference suggests.
Grades We Run
Stainless Steel Machining Capabilities
| Grades | 303 (free-cutting), 304, 316 |
|---|---|
| Machining tolerance | ±0.01 mm standard |
| Surface roughness | Ra 1.6 |
| Processes | CNC turning, turn-mill compound, Swiss-type turning, milling |
| Typical parts | Pins, shafts, bushings, medical instrument components, valve parts, fittings, spacers |
| Surface finishing | Passivation, polishing, sandblasting, electro-coating, PVD |
| Records | Material certificate, dimensional report, first article inspection (FAI), salt-spray and hardness tests |
| Medical | 304 and 316 components machined under our ISO 13485:2016 certified quality system |
Machining notes
303 is not a cosmetic choice. The sulphur that makes it free-cutting also makes it slightly less corrosion resistant than 304 and unsuitable for some welding. It is the right answer for a machined part in volume, and the wrong answer for a part that will be welded or exposed to aggressive chemistry.
304 and 316 work-harden. Cutting too lightly, or dwelling in the cut, hardens the surface instead of removing it — and the next pass gets harder still. It is why these grades machine more slowly and why the tooling and feeds matter more than they do in brass. We account for it in the quoted cycle time rather than discovering it on the machine.
Passivation is usually worth specifying. Machining leaves free iron on the surface. Passivation removes it and restores the oxide layer that makes stainless steel stainless — a small step that prevents rust appearing on a part that is supposed to resist it.