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Stainless Steel Speeds and Feeds
Guide · Updated October 28, 2026
Stainless is tough, gummy and work hardens when the tool rubs. The rules are simple: slower speeds than mild steel, a feed heavy enough that the edge always cuts under the hardened layer, sharp tools, and plenty of coolant.
Use the formula
RPM = 3.82 × SFM ÷ diameter. Feed (IPM) = RPM × flutes × chip load.
Step by step
- Know the grade: 303 machines easiest; 304 and 316 are gummier and work harden more.
- Pick a starting SFM: HSS: about 40–60 SFM for 304/316, up to about 80 for 303. Carbide: about 250–400 SFM turning, 200–350 milling.
- Compute RPM: RPM = 3.82 × SFM ÷ diameter in inches.
- Set a real feed: Never let the tool dwell or rub; light feeds cause work hardening.
- Flood coolant: Use flood coolant or a good cutting oil to control heat.
- Keep tools sharp: Replace or regrind at the first sign of wear; a dull edge hardens the surface.
- Adjust by the chips: Straw to light blue chips are fine; dark blue chips and smoke mean slow down.
Worked example
A 1/2 in 4-flute carbide end mill in 304 at 300 SFM: RPM = 3.82 × 300 ÷ 0.5 = 2,292 RPM. At 0.002 in per tooth, feed = 2,292 × 4 × 0.002 = 18.3 IPM. Drilling a 1/4 in hole with an HSS cobalt drill at 50 SFM: RPM = 3.82 × 50 ÷ 0.25 = 764 RPM, feeding steadily about 0.003 in/rev.
Work hardening
Austenitic stainless (304, 316) hardens right under the tool if it rubs. Once hardened, the next pass dulls the tool faster, which rubs more. Break the cycle with a positive feed, sharp edges and depth of cut deeper than the previous pass’s hardened skin.
Compared with aluminum
Aluminum wants high speed and big chip room; stainless wants low speed, heavy steady feed and heat control. See the aluminum guide for the opposite end of the scale.
Tips
- Opposite case: aluminum speeds and feeds.
- Basics: feeds and speeds basics.
- Coolant: cutting fluid and coolant basics.
FAQ
What SFM for 304 stainless with HSS?
About 40–60 SFM as a starting point.
What SFM for stainless with carbide?
About 250–400 SFM turning and 200–350 SFM milling.
Why does stainless work harden?
The tool rubs instead of cutting, often from too light a feed or a dull edge.
Is 303 easier than 304?
Yes; 303 has added sulfur and machines much more easily.
Should I use coolant on stainless?
Yes, flood coolant or cutting oil helps a lot.
Related guides and calculators
- Aluminum Speeds and Feeds
- Feeds & Speeds Basics
- Milling Speeds and Feeds
- Turning Speeds and Feeds
- Drilling Speeds and Feeds
- Cutting Fluid and Coolant Basics
- Cast Iron Speeds and Feeds
- Titanium Speeds and Feeds
- All free machinist calculators
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