Acrylic is one of the most satisfying materials to cut with a laser — clean edges, smooth results, and great for signs, jewelry, and decorative pieces. But it's also the most punishing when settings are wrong. Too slow and it melts back together. Too fast and it doesn't cut through. Here's how to get it right.
This is the most important thing to understand about laser cutting acrylic: cast and extruded acrylic behave completely differently under a laser. Cast acrylic vaporizes cleanly and produces a frosted edge that looks polished. Extruded acrylic melts rather than vaporizes and will often fuse back together after cutting.
Always use cast acrylic for laser cutting. If you're not sure which type you have, test a small piece — cast acrylic cuts with a frosted white edge, extruded cuts with a clear or slightly yellow edge and often shows melt marks.
Diode lasers cut acrylic less cleanly than CO2 lasers because the 450nm wavelength is partially transmitted through clear acrylic rather than absorbed. Colored acrylic generally cuts better than clear on a diode laser because the pigment absorbs the laser energy more effectively.
| Material | Thickness | Mode | Power (10W) | Speed (mm/min) | Passes |
|---|---|---|---|---|---|
| Cast acrylic (clear) | 2mm | Cut | 80% | 200 | 2–3 |
| Cast acrylic (clear) | 3mm | Cut | 90% | 150 | 3–4 |
| Cast acrylic (colored) | 3mm | Cut | 80% | 200 | 2 |
| Cast acrylic | 3mm | Engrave | 25% | 4000 | 1 |
CO2 lasers are the preferred tool for acrylic cutting. The 10.6 micron wavelength is absorbed extremely well by acrylic, producing polished flame-cut edges on cast material. Even a basic 40W K40-style machine cuts acrylic better than a 20W diode laser.
| Material | Thickness | Mode | Power (40W CO2) | Speed (mm/s) | Passes |
|---|---|---|---|---|---|
| Cast acrylic | 3mm | Cut | 55% | 20 | 1 |
| Cast acrylic | 6mm | Cut | 70% | 10 | 1–2 |
| Cast acrylic | 3mm | Engrave | 20% | 200 | 1 |
Air assist is not optional when cutting acrylic. Without it, the vapors from cutting can ignite and burn back along the cut path. Air assist blows these vapors away, prevents flare-ups, and keeps the cut path clear so subsequent passes cut cleanly.
Even a small aquarium pump running through a nozzle pointed at the cut area makes a significant difference. Dedicated air assist compressors provide better results but the basic setup works well enough for most hobbyist projects.
If your acrylic is fusing back together after cutting, you are almost certainly using extruded acrylic. Switch to cast. If you have cast acrylic and it's still fusing, increase speed and reduce power — slower cuts with higher power cause more heat buildup and melting.
If you're getting a yellow or brown tint on your cut edges, you are running too slow. Speed up or reduce power. The ideal CO2 cut edge on cast acrylic is clear and slightly polished.
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