Workpiece material / Stainless
Stainless Steel 303 (free-machining) speeds and feeds
Starting surface speeds and chip loads for milling Stainless Steel 303 (free-machining). Every value below is cross-checked against published sources and linked, so you can re-verify it yourself. Starting points, not limits.
- Hardness
- 160 HB
| Value | Used | Provider readings (each linked) |
|---|---|---|
| Surface speed, HSS (estimated) | 60 SFM | |
| Surface speed, carbide (estimated) | 250 SFM | |
| Chip load @ 0.25" | 0.0013 in/tooth |
| 0.125" | 0.25" | 0.5" |
|---|---|---|
| 0.0006 | 0.0013 | 0.0026 |
| Constant | Value | Readings |
|---|---|---|
| Kc1.1 (specific cutting force) | 1,850 N/mm2 | ISO group-typical - see notes |
| mc (chip-thickness exponent) | 0.21 | ISO group-typical - see notes |
| Unit power | 1.40 HP/(in3/min) | ISO group-typical - see notes |
The power-model constants (Kc1.1, mc, unit power) are class-typical values for the ISO material group, used only for a rough spindle-power estimate. Only their relative ordering and internal consistency are verified, never tuned to match any vendor.
Notes
303 adds sulfur for machinability and cuts more freely than 304, though it still work-hardens and prefers a positive, uninterrupted chip load with coolant. Power-model constants: Kc1.1 and mc are class-typical values; unit HP is derived from Kc, not independently published.
Verify this yourself
Every number above links to the provider that publishes it. Open two or more and confirm they agree with what is shown here. Full source list:
Take these into the feeds and speeds calculator for RPM, feed and power. Start a little under these numbers on a light or flexible setup.