Avoiding Melted Edges: Pro Tips for Laser Cutting Acrylic

Laser cutting acrylic is a popular technique for creating precise, clean designs, but achieving flawless edges without melting can be challenging. Melted edges occur when excessive heat causes the acrylic to soften or burn, resulting in uneven, cloudy, or wavy cuts. With the right techniques and settings, you can achieve professional-quality results. Here are pro tips to help you avoid melted edges when laser cutting acrylic.

1. Choose the Right Type of Acrylic

Not all acrylics are created equal. For laser cutting, cast acrylic is generally preferred over extruded acrylic because it cuts more cleanly and produces smoother edges. Extruded acrylic tends to melt more easily due to its lower melting point. Always check the material specifications before cutting and opt for high-quality cast acrylic for the best results.

2. Optimize Laser Settings

Adjusting your laser cutter’s settings is critical to preventing melted edges. The key parameters to tweak are power, speed, and frequency:

• Power: Use the lowest power setting that still cuts through the material. High power generates excess heat, leading to melting.
• Speed: Increase the cutting speed to reduce the time the laser spends on any one spot, minimizing heat buildup.
• Frequency: Lower the frequency (pulses per inch) for acrylic to reduce heat concentration. A range of 5,000–10,000 Hz is often ideal for most laser cutters.

Test your settings on a small piece of scrap acrylic to find the sweet spot for your specific machine and material thickness.

3. Use Air Assist

An air assist system blows a stream of air at the cutting point, cooling the material and removing debris. This reduces heat buildup and prevents molten acrylic from resolidifying on the edges. Ensure your air assist is set to a moderate pressure—too high, and it may disrupt the cut; too low, and it won’t be effective.

4. Apply Masking Tape or Transfer Tape

Covering the acrylic with masking tape or transfer tape before cutting can protect the surface and reduce edge melting. The tape acts as a barrier, absorbing some of the laser’s heat and preventing burn marks. Be sure to press the tape firmly to avoid air bubbles, and remove it carefully after cutting to avoid residue.

5. Focus the Laser Precisely

Incorrect laser focus can lead to uneven cuts and excessive heat. Ensure the laser is focused precisely on the acrylic surface or slightly below it, depending on your machine’s recommendations. Use a focus gauge or the manufacturer’s guidelines to set the correct focal distance, typically around 2–3 mm for acrylic.

6. Use Multiple Passes for Thicker Acrylic

For thicker acrylic (over 6 mm), consider using multiple low-power passes instead of a single high-power cut. This approach reduces heat buildup in one area, resulting in cleaner edges. Adjust the focus slightly deeper for each pass if necessary, and test on scrap material to confirm the settings