Help with Laser Cutting PET Film without Smoke Marks

[John Kang]

Hi everyone,

I've been rummaging through as many posts as I could for the last 3 months in the hopes of finding a way to cut through PET film without smoke marks. We've tried just about everything that's been suggested for film, paper, acrylics, etc. We've tried raising the film about 1/2 and inch above the honeycomb, tried laying a sheet of paper on top and on the bottom, tried transfer tape, and played with as many settings as were available on our ULS 30 watt machine, yet nothing seems to guarantee a smoke-free cut. We've got it to cut through many times without the marks or to an acceptable level, but the results were not consistent. :(

Transfer tape seems to work, but it was latching on to the protective liner when we tried to peel it off after the cut.
One of our last resorts before giving up is to try air assist or come up with a way to clean the material after it's been cut. Do you guys have any suggestions?

BTW, i'm as newbie as one can be when it comes to this machine. But i've been learning quite a bit by playing around with it for several months.
I've been amazed at how creatively genius the members of this forum are and am hoping to chime in after i get some more experience. Thank you for your help.

The film is PET that measures about 0.008 in. with a Polyethylene liner and the project is on-going and not a one-time deal.

[Dan Hintz]

Did you wet the transfer tape before trying to peel it off? When wet, that stuff practically falls off on its own...

[John Kang]

That's a good idea, however, we're trying to touch the material as little as possible, it attracts fingerprints and we're afraid that once it touches water, it'll be a nightmare to get watermarks off.
I'll give it a shot though, thank you.

[Kim Vellore]

PET with plastic protective liner is a pain to remove. The PET and the protective plastic fuse at the cut point and also bead up in a small scale, so when you peel the protective plastic it leaves some at the edge and you also cannot pick a point on the edge to peel the plastic. If you have protective plastic the smoke should not bother it anyway. The way I did it was to remove all protective plastic, now it becomes a static dust magnet. Then cover it with transfer tape in a clean work area, then cut. You will even get better edges with this method.

Kim

[Dan Hintz]

Use deionized water... no water spots.

[John Kang]

I'll try deionized water and see if it'll clear up clean. Thank you Dan.

Kim, how did you manage to get it to work when you removed the backing piece? For me the dust doesn't even wait till it's peeled off before settling there permanently. Does the transfer tape help pull some of it off after the cut?

[Ernie Balch]

You can use a UV laser like a tripled YAG at 355 nm. PET cuts beautifully and very clean. A fiber laser might work as well.

[John Kang]

Is it possible to change a CO2 laser to a UV one? Will it void our warranty with ULS?

[Ernie Balch]

Possible, yes, but a major task with all new optics and electronics, not something that people do.

UV lasers are very expensive but are a much better choice for clean micro machining tasks. All the UV systems I have used were galvo or rotating polygon based and several orders of magnitude more expensive than our cheap laser engravers.

ernie

[John Kang]

Darn, there goes this possible solution. Our budget is pretty restricted with this project. Thanks you anyways Ernie.

[Kim Vellore]

John,
The tape pulls off all the dust and it has very little static after that but with water application it might be even better. Depending on the volume it should be OK to wipe off water. DI should work well as long as it does not pick up dirt that can dissolve from the tape and leave it as a residue on the PET. Let us know which process works the best.
Kim

[John Kang]

I've been testing this for a few weeks now, and it seems like the post clean-up method is our best hope. We got pretty close with spraying DI water on the transfer tape, but for some reason, it still left smoke marks on the film. Cleaning with DI and a little solvent after the cut was the only way we got it to be completely clear. Hope this helps someone.