Burn marks outside of cut on plastic

[Todd Mueller]

just got a new laser machine, 60watt, and got it set up, c02 laser, going to fine tune laser alignment tomorrow if it needs it, but couldnt resist at least seeing if the thing worked, well, it does.

I was cutting .07" plastic, and maybe 5 or 6mm above material, just eyeballed it figuring i will fine tune everthing tomorrow, and it cut through the material just fine anywhere between 50 and 60%power, and 15 to 25mm/sec speed, that is all i tried so far,

it cuts a nice fine line all the way through the material, but there are what i would call scorch marks off to the side of the cut and rubbing it down with rubbing alcohol doesnt make them go away,

any tips on what this could be, focus, power, speed? I definately need my material to be clean on each side of the cut

[Keith Downing]

When you say you're cutting plastic, do you mean acrylic, or actual sheet plastic?

If it's true plastic, that could be the culprit itself. Or you could be cutting a little too slow.

Are you using a metal honeycomb table? How much flash are you seeing off the metal as you cut? That flashback could be the cuplrit if you're cutting too slow or at too high of a power setting.

PS. Pictures always make trouble shooting 100x easier.

[Mike Null]

It appears that you didn't focus it accurately which could well be the issue. Did you use air assist when doing the cutting?

[tommy suriady]

Does happen on plastics. Suspect ur plastic is vinyls. Increase speed and we usually apply soapy water on the plastic. The soot will float on the soapy water and easily wipeable. I think i learnt it here...

Easy on the soap, it is just to reduce water tension on water so that water doesnt bead up, but coats the surface of the plastic. Excess soap will cause scummy surface that looks ugly and feels terrible to touch. Water clinging to plastic and creating protective layer is the key. Apply just before cutting. Use squirt to keep it wet for long cutting duration.

[Clark Pace]

If it is vinyl or pc based do not cut it.

[Keith Downing]

If it is vinyl or pc based do not cut it.

Believe he meant to type pvc based. And I was thinking the same thing.

The consensus here seams to be cutting pvc is extremely hazardous to your health. Part of the reason I was asking if you meant acrylic or if you were actually cutting plastic.