Mill Delrin (acetal) with a HSS end mill at about 300 SFM: 2,292 RPM for a 1/2 inch cutter, 2 flutes, about 0.0060 inch per tooth.
What RPM and feed for Delrin (acetal)?
| Cutter | Ideal RPM | Chip load (in/tooth) | Flutes | Feed at ideal RPM (IPM) | Feed if capped at 2500 RPM |
|---|---|---|---|---|---|
| 0.125" | 9,167 | 0.0015 | 2 | 27.5 | 7.5 |
| 0.1875" | 6,112 | 0.0023 | 2 | 27.5 | 11.3 |
| 0.25" | 4,584 | 0.0030 | 2 | 27.5 | 15.0 |
| 0.375" | 3,056 | 0.0045 | 2 | 27.5 | 22.5 |
| 0.5" | 2,292 | 0.0060 | 2 | 27.5 | 27.5 |
| 0.75" | 1,528 | 0.0090 | 2 | 27.5 | 27.5 |
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 end mill?
HSS end mills are the forgiving choice on a light hobby mill: they tolerate chatter and interrupted cuts that chip carbide, they are cheap to replace, and they cut well at the modest spindle speeds benchtop mills offer.
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 end mill
- 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