Drill 303 stainless steel with HSS at about 50 SFM: 382 RPM for a 1/2 inch drill, 764 RPM for 1/4 inch, feeding about 0.0030 in/rev at 1/4 inch.
What RPM and feed for 303 stainless steel?
| Drill | RPM | Feed (in/rev) | Feed (IPM, capped 2500 RPM) |
|---|---|---|---|
| 0.0625" | 3,056 | 0.0008 | 1.88 |
| 0.125" | 1,528 | 0.0015 | 2.29 |
| 0.1875" | 1,019 | 0.0023 | 2.29 |
| 0.25" | 764 | 0.0030 | 2.29 |
| 0.3125" | 611 | 0.0037 | 2.29 |
| 0.375" | 509 | 0.0045 | 2.29 |
| 0.5" | 382 | 0.0060 | 2.29 |
| 0.625" | 306 | 0.0075 | 2.29 |
| 0.75" | 255 | 0.0090 | 2.29 |
Tools for cutting 303 stainless steel
How does 303 stainless steel machine?
303 is the free-machining stainless and the one to choose for machined parts that do not need welding. It still work hardens, so keep the tool cutting at all times.
Why a HSS twist drill?
Twist drill speeds are set lower than turning speeds because the cutting edge is buried in the hole with no escape for heat. Peck deep holes (clear chips every one to two diameters), and use cutting oil in everything except cast iron, brass and plastics.
Adjust speeds with the RPM calculator and milling feeds with the feed rate calculator. The cutting speed chart compares every material.
Frequently asked questions
What SFM for 303 stainless steel?
A starting surface speed of 70 SFM with HSS and 250 SFM with carbide, and 50 SFM for HSS drills. These are conservative for hobby machines; raise them in steps if the chips come off clean and the tool stays cool. 303 stainless steel rates fair (about 78% of free steel) for machinability.
What happens if my machine cannot reach the RPM?
Run at your top speed. Running below the ideal surface speed only makes the job slower; it does not damage the tool. For milling and drilling, keep the chip load per tooth or feed per revolution the same so the edge keeps cutting instead of rubbing, which lowers the feed in inches per minute in proportion.
Other tools in 303 stainless steel
Other materials with a HSS drill
- 6061-T6 aluminum
- 7075-T6 aluminum
- 360 free-machining brass
- 932 bearing bronze
- 110 copper
- 12L14 leaded steel
- 1018 cold rolled steel
- 1045 medium carbon steel
- All