Can acrylic be laser cut?
Yes. Acrylic is the standard plastic for CO2 laser cutting: edges come out clear and flame-polished. Cast sheet engraves and bonds better than extruded.
Acrylic (PMMA) is the plastic CO2 lasers are best at. Under the beam it breaks down into methyl methacrylate vapour instead of charring, and the cut edge re-solidifies as a clear, glossy, flame-polished surface that needs no further finishing. Signs, displays, light guides, covers, fixtures and enclosures are cut this way. Most laser shops cut up to about 20-25 mm (0.75-1"), with the best edges under about 10-12 mm; thicker sheet shows more taper and some striation. Kerf is roughly 0.1-0.3 mm, and a profile tolerance of about ±0.1-0.2 mm (0.004-0.008") is typical. Fiber lasers do not cut clear acrylic, because their 1 µm wavelength passes through it.
Cast and extruded sheet both cut with a polished edge, but they behave differently. Cast acrylic engraves to a frosted white that shows up well, has lower internal stress and tolerates solvent bonding better. Its thickness can vary by 10% or more from nominal, which matters for slot-and-tab designs. Extruded acrylic is cheaper and more uniform in thickness, but it engraves clear rather than frosted, carries more orientation stress from extrusion and is more prone to edge crazing after cutting. Specify cast sheet for engraved, bonded or display-quality parts, and extruded for cost-driven parts cut to profile only.
The laser leaves stress in the cut edge. If the part will be solvent cemented, cleaned with alcohol or loaded in bending, that stress shows up as fine edge cracks (crazing) days later. Annealing after cutting, typically at 70-80 °C (160-180 °F) for a time scaled to thickness per the sheet maker, prevents it. Keep the masking paper or film on through cutting to avoid smoke haze and flashback marks. Remember that acrylic is brittle: it suits covers and displays, not guards or parts that take impact, where polycarbonate (routed, not laser cut) is the right choice.
Laser Cutting for acrylic parts: where to send them
What to specify
- Sheet type: cast or extruded acrylic, with thickness and colour (clear, tinted, opal)
- Sheet specification if one is required: ASTM D4802
- Profile tolerance of ±0.1-0.2 mm (0.004-0.008"), and whether kerf taper on thick sheet matters
- Edge: laser-polished edge accepted as cut, or diamond-polished for optical edges
- Anneal after cutting for parts that will be solvent bonded, cleaned with alcohol or loaded
- Masking kept on through cutting and shipping, and the show face named
- Engraving depth, and whether frosted contrast (cast sheet) is required
Pitfalls
- Edge crazing days later when laser-cut parts meet solvent cement or alcohol; anneal first
- Designing slots to nominal thickness when cast sheet varies enough that tabs will not fit
- Using acrylic for guards or impact covers; it cracks where polycarbonate would not
- Smoke haze and flashback marks on the back face; keep masking on and cut on a pin or honeycomb table
- Taper and a slight bulge on the edges of thick sheet when a square edge is needed
- Choosing extruded sheet for engraved parts and getting clear, low-contrast engraving
Frequently asked questions
- Cast or extruded acrylic for laser cutting?
- Both cut with a polished edge. Cast engraves frosted white, bonds better and has less stress. Extruded is cheaper and more uniform in thickness but engraves clear and is more likely to craze at cut edges.
- How thick can acrylic be laser cut?
- High-power CO2 lasers cut up to about 20-25 mm (0.75-1"). Most work is 3-12 mm, where the edge is clearest and taper is smallest.
- Can a fiber laser cut acrylic?
- Not clear acrylic. The 1 µm fiber laser wavelength passes through it. Acrylic is cut with CO2 lasers at 10.6 µm, which it absorbs strongly.
