Laser materials · Acrylic

Laser cutting and engraving acrylic

On a CO₂ laser, acrylic cuts with a glossy, flame-polished edge and engraves to a frosty white. On a diode laser it is a different story, and which kind of acrylic you buy matters as much as which laser you own.

Which laser can cut acrylic?

A CO₂ laser cuts and engraves every colour of acrylic, including clear. Its infrared wavelength is absorbed by the plastic.

A blue diode laser can’t cut or engrave clear, blue or translucent acrylic. Its 455 nm light passes straight through. It can engrave black and many opaque colours, and cut thin opaque sheets with several passes. If you have a diode and need clear parts, this is a job for a CO₂ machine or a laser-cutting service.

UV lasers mark the surface of clear acrylic and plastics, which is useful for fine detail and inside-surface marking, but they are not cutting tools for thick sheet.

Cast or extruded?

If a supplier doesn’t say, ask. For anything engraved, buy cast.

Cutting tips

• Leave the protective film on while cutting to keep the surface free of scratches and residue, unless you are engraving the face.
• Low air assist for cutting acrylic. High air cools the edge and loses the flame-polished finish; you still want enough to keep flames down.
• Raise the sheet off the bed (on pins or a honeycomb) so reflections don’t leave marks on the back.
• Don’t leave it. Acrylic can catch fire if the cut is too slow. Stay with the machine.

Engraving tips

Peel the film from the face you are engraving. Engraving clear acrylic on the back, with the design mirrored, makes it read correctly from the front and protects the engraving; the photo engraving studio has a preset for mirrored acrylic. Edge-lit signs work best with cast acrylic engraved on the back, lit from below with an LED base.

Two-colour engraving laminate

Laminate sheets have a thin coloured cap over a contrasting core, for name badges, labels and signs. Engrave just deep enough to expose the core colour; too much power melts the edges. Many lasers, including diodes, handle laminate well.

Fit and kerf

Acrylic doesn’t give like plywood, so press-fit parts need a precise fit. Measure your kerf in acrylic separately from wood with the kerf test, and for boxes start slightly looser than you would in plywood.

Safety

Acrylic (PMMA) is a standard laser material, but it does produce fumes and can ignite, so vent the machine and never leave it running. Make sure what you have really is acrylic: polycarbonate (Lexan) looks similar but burns and discolours with harmful fumes, and PVC sheet releases chlorine gas. If you can’t confirm the plastic, don’t laser it. See the full list on the materials page.

Settings

Starting values for black and clear cast acrylic are on the xTool settings page and the other brand pages under laser settings. Dial them in with a test card on an offcut from the same sheet.