Feed & Speed Calculator for Stainless Steel 304
Machinable, but unforgiving of hesitation — keep the tool cutting continuously or 304 hardens right where you needed it soft.
304 stainless starting ranges
| Tool | Cutting speed (SFM) | Chip load, 1/2" 4-flute (in) |
|---|---|---|
| Carbide (coated) | 200–350 | 0.002–0.004 |
| HSS | 40–70 | 0.0015–0.003 |
Keep chip load toward the higher end of the range rather than the lower end — a light chip load that lets the edge rub is exactly what triggers work hardening.
Work hardening is the defining problem, not raw hardness
304 isn't especially hard to start, but it work-hardens fast wherever a tool rubs instead of shearing cleanly — a light pass, a dull edge, or a tool dwelling in one spot all leave a hardened skin that's much harder to cut than the base material. That hardened layer is exactly what the next pass has to fight through, which is why one bad pass in stainless tends to compound into a worse one.
Constant feed matters more than the exact chip load number
Keep the tool feeding continuously and consistently rather than pausing, backing off, or taking an overly light finishing pass — a steady, adequate chip load that shears cleanly does far more for tool life and finish in 304 than chasing a lighter cut for a "better" surface.
Sharp edges and rigid setups matter more here than in mild steel
A dull tool is worse in 304 than in 1018 for the same reason light chip loads are: any rubbing accelerates work hardening. Replace tools sooner than you would in mild steel, and minimize deflection and chatter (check the Tool Deflection Calculator for long stickouts), since any inconsistency in the cut invites hardening right where the finish matters most.