Perfect Laser Settings for Cutting Acrylic, PETG & More (Cheat Sheet)

Laser cutting offers unparalleled precision for plastics, but achieving a flawless cut requires more than just pressing “start.” The wrong settings can lead to melted edges, discoloration, or weak cuts. This cheat sheet breaks down the ideal laser settings for popular materials like acrylic and PETG, empowering you to achieve professional results every time.

A Crucial First Step: KNOW YOUR LASER

The numbers provided are a starting point. Always perform a test cut on a small scrap piece! Power and speed are interdependent and vary significantly between different laser machines (e.g., 40W vs. 100W CO2 lasers). The golden rule:

• Too much power / Too slow speed: Causes melting, burning, and wide kerfs.
• Too little power / Too fast speed: Results in incomplete cuts and a sticky, melted surface.

Safety Note: Always use adequate ventilation. Cutting plastics can release harmful fumes. NEVER cut PVC or Vinyl, as they release chlorine gas, which is toxic and corrosive to your laser machine.

The Cheat Sheet

1. Acrylic (PMMA) – Cast vs. Extruded

Acrylic is the superstar of laser cutting, known for its perfectly polished, flame-like edges.

• Best For: Signs, displays, models, and decorative items.
• Lens Choice: Use a 2.0″ or 2.5″ lens for a clean, vertical edge.
• Key Tip: Use CAST ACRYLIC whenever possible. It laser cuts to a stunning, transparent finish. Extruded acrylic is cheaper but can leave a slightly hazy edge.
• Air Assist: Use high-pressure air assist to blow molten material away and prevent flaming.

2. PETG (Polyethylene Terephthalate Glycol)

PETG is a tough, durable plastic popular for functional parts and prototypes. It’s more challenging than acrylic.

• Best For: Machine parts, containers, protective shields.
• Key Challenge: PETG tends to string and melt rather than vaporize cleanly. The goal is to cut it quickly before heat spreads.
• Air Assist: CRITICAL. Use the highest air pressure possible to cool the material and blow away molten strings.
• Result: You will not get a polished edge like acrylic. Expect a slightly frosted, but clean, cut edge.

3. Wood (MDF & Plywood)

While not a plastic, it’s a common laser material. Settings vary wildly based on wood type and resin content.

• Best For: Puzzles, boxes, architectural models.
• Key Tip: Use masking tape on the surface to prevent smoke and burn marks on the top surface.
• Air Assist: Use medium to high air assist.

4. Polypropylene (PP) & Polyethylene (PE)

These common plastics are notoriously difficult to laser cut cleanly. They melt at a low temperature and can be a fire hazard.

• Best For: Specialized applications (e.g., living hinges).
• Key Challenge: They melt and drip, often re-welding behind the laser. Success is limited.
• If you must try: Use very high speed, low power, maximum air assist, and a honeycomb bed that allows melted material to fall through.

Advanced Tips for a Perfect Cut

1. Focus is Fundamental: An incorrectly focused beam will ruin your cut. Always ensure your laser is focused to the material’s surface before starting a job.
2. Frequency/PPI (Pulses Per Inch): For acrylic, a high frequency (5000+ PPI) gives a smooth edge. For wood or PETG, a lower frequency (500-1000 PPI) can help vaporize material more effectively. Experiment!
3. Test Grids: The best way to dial in settings is to create a test grid. Design a grid of small squares and assign different power/speed combinations to each. This visually shows you the perfect setting for your specific machine and material batch.

Print this cheat sheet, keep it by your laser, and remember: test, test, test! Happy cutting