Anyone else seeing a flame on the trailing edge of the laser when cutting acrylic? I’m cutting basic 1/8" Inventables opaque blue acrylic (using PG settings) and when the gantry moves from front to back, i’m seeing a faint elongated flame on top of the acrylic.
Anyone else see this at all? It’s not leaving a mark on the masking, so (to me) it doesn’t seem intense enough to affect my cuts. But figured it’s worth an ask.
I saw it tonight when cutting some Proofgrade clear acrylic.
I don’t remember seeing it before, but the last time I cut acrylic was around a month ago, so perhaps I’m just not remembering. But it’s also possible that they’ve changed the Proofgrade settings since then.
Hazardous Decomposition Products: In case of thermal decomposition, combustible vapors are formed, which are irritating to eyes and respiratory system, mainly consisting of: methyl methacrylate.
I had no idea what methyl methacrylate was so another MSDS search shows it as a liquid used for making of plastics and it has an amazingly low flash point.
(Not sure these numbers are valid when it is a vapor, but I would think that, as a rule, a vapor flashes easier than a liquid form).
Flash Points: CLOSED CUP: 13°C (55.4°F). OPEN CUP: 19°C (66.2°F)
Easy to connect the dots. As the plastic melts//burns it is gassing a potentially flame producing byproduct.
Interesting, but overall this looks//appears harmless since no danger of it becoming concentrated with the fans running. An added plus. Since the methyl methacrylate vapor is irritating, then having it burn off is probably a good thing.
Picked up some 3/16 and 1/4 clear cast acrylic locally. Between the thickness and the paper covering, it is not uncommon to get a flame. I have seen it suggested to play with the speed and power settings in order to minimize the ignition of the vaporized acrylic.
Here are some examples (best flames at the last 15 seconds of video 3)