Mylar cutting problem - melting + irregular edges

Community Laser Talk
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1

Hi everyone,

I’m having a double problem cutting mylar on my CO2 laser and could use your advice.

My machine:

  • Omtech Max-1615

  • CO2 laser

Material:

  • 190 micron mylar

My current settings:

  • Speed: 400 mm/s

  • Power: 12-15% (already very low)

  • Single pass

  • Precise focus at mylar surface

The problems:

  1. The mylar melts instead of cutting cleanly

    • I think it’s an air assist problem (not enough air or poorly directed)

    • The material heats too much and melts instead of vaporizing

  2. The edges are not clean/regular

    • I wonder if the laser beam is hitting the inside edge of the laser head

    • That would explain why the cut is irregular despite good parameters

Any thoughts on what might be causing this?

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2

Two problems:

  • Despite the 400 mm/s layer speed, the laser head cannot reach that speed while following the intricate curves.
  • A CO₂ laser can’t fire at the low power required to prevent overcooking the corners where the head moves slowest.

Assuming the machine has a Ruida controller, Dot Mode may produce a series of fine perforations that come Close Enough™ to a continuous cut:

Dot Mode kiss-cut polyurethane film to leave the paper backing (mostly) intact:

It produces a nice trench in sheet of PETG (similar-ish to Mylar = PET):

Producing a complete cut, rather than a trench, will require some tweaking, but it seems feasible.

3

A couple of things to check would be to make sure you are in focus and also to make sure that your air assist is working. The power setting should also be about 10% difference between the two as well.