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Bob Davis
05-03-2009, 12:33 PM
I recently ordered several sheets of various thickness clear acrylic, one of them being the 2mm variety.
After it was delivered I discovered the 2mm was much more flexible than the usual 2mm. The label on this particular sheet seems to indicate it is PET (it's a bit unclear) and I'm guessing that it was dispatched in error.
A search of the net disclosed that it PET is short for Polyethylene Terephthalate, and it is the material used to make plastic soft-drink bottles.
It was pretty cheap and would appear to be suitable for the job at hand, so I'm wondering whether anyone has any experience of this material in a laser. Does it cut and mark in a similar fashion to acrylic? Any problems of note?
If it's not suitable I'll have to send it back and obtain the regular item, and that means delays and mucking around. If it has similar characteristics I'd just as soon keep it.

Martin Reynolds
05-03-2009, 1:02 PM
We cut a lot of PETG, which is probably what you have. It is much tougher than acrylic, more like polycarbonate. On the other hand, the surface is softer, but marks polish out with a flame.

Tooo much power and you will get a yellowed edge. Also, it is more susceptible to flashback.

The cutting leaves a white residue, and the smell hangs around for longer than acrylic. You will have to ckean the laser or the residue re-evaporates from the beam and leaves white marks on the masking.

We use it precisely because it is tough.


It melts easily, so getting a nice clear edge can be tricky.
Get it too hot, and it goes like rubber - very good for vacuum molding.

Mike Null
05-03-2009, 3:16 PM
If you wanted acrylic send it back. PETG will not produce the detail the edge or the perfectly clear surface of acrylic. It is durable and good for fixtures etc.

Scott M Smith
05-03-2009, 4:27 PM
Is lexan the same as acrylic? If it is not how would it differ from acrylic?

Dave Johnson29
05-03-2009, 5:11 PM
Is lexan the same as acrylic? If it is not how would it differ from acrylic?

Lexan is brand name for Polycarbonate.

Polycarboinate is much tougher than acrylic but it has limitations in that it does not like to be bolted to anything or it will stress crack. It needs to be clamped gently fand evenly from both sides.

I have not cut it with the laser so cannot comment on that side.

Also I believe Polycarb cannot be glued to itself very successfully unless using some very expensive Mil-spec adhesives.

Allen Isakson
05-03-2009, 5:57 PM
Dave not sure what kind of lexan you use. I fabricate with it all the time in makeing machine gaurds. It bolts up great. are you sure your not thinking of plexiglass

Dave Johnson29
05-03-2009, 6:57 PM
I fabricate with it all the time in makeing machine gaurds. It bolts up great. are you sure your not thinking of plexiglass

Hi Allen,

Nope, Lexan brand actually. I forgot to add that with some liquids it will harden and crack away at the pressure points. I also use it for machine guards but with some coolants the bolted areas only last a matter of weeks before they harden, crack around the bolt holes and then fall apart.

If I edge-clamp it using thin sheet rubber it is fine. It just seems to be around bolt holes for some reason.

Michael Hunter
05-03-2009, 7:31 PM
Rowmark "LaserLights" is PET, so it should not present any particular problems.
Lights are very thin (0.1mm??), so although that cuts well it is not an indication of how a sheet 20 times thicker would vector.

Michael Simpson Virgina
05-03-2009, 7:56 PM
LEXAN is the trademark of SABIC Innovative Plastics. They used to be owned by GE. It is a form of Polycarbonate. It was discovered accidentally by GE in 1953 while researching a coating for wire.

Plexiglas is one of the many trade names for Acrylic. Acrylic or PMMA is unique in its behavior in that it ignights at 460C and burns completely ( Vaporizes ) giving off carbon dioxide and water.

Acrylic seems like it was specifically invented for lasers but has been around since 1843.




Wikipedia is our friend :)