CO2 — EVO · LS · HP
Acetal, POM, polyoxymethylene
Operator
Formaldehyde fumes
Delrin — acetal, or POM — is the engineering plastic that laser-cuts best. It produces crisp edges with good dimensional stability, so cut parts hold their designed size instead of needing fettling, which is why it’s a standard choice for gears, bushings, cams, fixtures and jigs. Edges come out matte rather than glossy; it isn’t a display material. The one thing to take seriously: acetal decomposes to formaldehyde under the beam. That’s not a PVC-class prohibition — no acid, no machine damage — but it does mean extraction is mandatory, not advisory.
1 · Why it makes good parts.
| Property | What it gives you |
|---|---|
| Dimensional stability | Cut parts stay the size you drew — the reason acetal is chosen for mechanical work |
| Stiffness and strength | Parts function under load rather than flexing out of engagement |
| Low friction, self-lubricating | Excellent for gears, bearings and sliding surfaces |
| Cuts crisply | Little melting or slumping compared with most thermoplastics |
| Machinable afterwards | Tapping, drilling and finishing all behave predictably |
The practical upshot: a laser-cut acetal gear tends to mesh. That sounds mundane until you’ve tried the same part in a material that melts at the edge and comes out a fraction oversize in a way that varies around the profile.
2 · The fume caution, stated plainly.
Acetal decomposes to formaldehyde
Under the beam, acetal breaks down and releases formaldehyde — a strong irritant to eyes, nose and throat, and a recognised carcinogen. You will smell it: a sharp, pungent, unmistakable odour. Effective extraction is a requirement for cutting Delrin, not a general good practice. Don’t lean over an open machine straight after a job, and let extraction run on after the cut finishes.
To keep this in proportion: this is a manage-it hazard, not a prohibition. Delrin is cut routinely and safely in properly ventilated shops every day. It belongs in a different category from PVC, where no amount of extraction makes the material acceptable. The difference between the two categories →
3 · Cutting notes.
- Expect a matte edge. Unlike acrylic, acetal doesn’t flame-polish. That’s normal, not a settings fault.
- Black and natural grades differ. Natural (white) acetal is translucent to the beam differently than pigmented black; don’t assume settings carry across colours.
- Air assist matters for keeping the cut clean and suppressing flame.
- Copolymer vs homopolymer acetal exist and behave slightly differently — if you’re holding tight tolerance, prove settings on the grade you actually buy.
- Thicker stock needs proportionally more care, as always — test rather than extrapolating.
Boss publishes CO2 settings by material as the right starting point rather than a generic figure — CO2 settings by material →
4 · What it’s genuinely good for.
Delrin earns its place where the part has to work mechanically: gears and sprockets, bushings and bearings, cams and followers, jigs and fixtures, wear strips, and prototype mechanisms that need to be tested rather than looked at. It’s a poor choice where appearance is the point — that’s acrylic’s job.
5 · FAQs
Frequently asked
Delrin / AcetalQCan you laser cut Delrin?
Yes, and it cuts well — crisp edges and good dimensional stability, ideal for mechanical parts. The caveat is fumes: acetal decomposes to formaldehyde, so extraction is essential.
QIs it toxic?
It needs respect. Formaldehyde is an irritant and a recognised carcinogen. That’s a manage-it hazard with proper extraction, not a prohibition like PVC — no corrosive acid, no machine damage.
QWhat is it used for?
Gears, sprockets, bearings, bushings, cams, fixtures, jigs and wear surfaces — anywhere dimensional accuracy and low friction matter.
QDoes it melt?
Much less than most thermoplastics. It cuts crisply rather than slumping, with a matte edge rather than a polished one.
6 · Related in this series.
Part of Materials & Safety:
- Which plastics cut well — Delrin in context
- Acrylic — the display material by contrast
- What must never go in a laser — and why Delrin isn’t on it
Keep exploring
One idea leads to the next.
Knowing how a material behaves under the beam is most of the job. Follow the rest of the series, or talk it through with someone who runs these systems.