Drill Delrin (acetal) with HSS at about 200 SFM: 1,528 RPM for a 1/2 inch drill, 3,056 RPM for 1/4 inch, feeding about 0.0050 in/rev at 1/4 inch.
What RPM and feed for Delrin (acetal)?
| Drill | RPM | Feed (in/rev) | Feed (IPM, capped 2500 RPM) |
|---|---|---|---|
| 0.0625" | 12,223 | 0.0013 | 3.13 |
| 0.125" | 6,112 | 0.0025 | 6.25 |
| 0.1875" | 4,074 | 0.0037 | 9.38 |
| 0.25" | 3,056 | 0.0050 | 12.50 |
| 0.3125" | 2,445 | 0.0063 | 15.28 |
| 0.375" | 2,037 | 0.0075 | 15.28 |
| 0.5" | 1,528 | 0.0100 | 15.28 |
| 0.625" | 1,222 | 0.0125 | 15.28 |
| 0.75" | 1,019 | 0.0150 | 15.28 |
Tools for cutting Delrin (acetal)
How does Delrin (acetal) machine?
Acetal machines beautifully with sharp, polished, positive rake tools. The limit is heat: rubbing melts it. Use a sharp tool, a real chip load, and air to clear chips; it does not need cutting oil.
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 Delrin (acetal)?
A starting surface speed of 300 SFM with HSS and 600 SFM with carbide, and 200 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. Delrin (acetal) rates excellent 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 Delrin (acetal)
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