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Eric Ucci
04-05-2012, 11:23 AM
Hello All,
We've been cutting some complex shapes in clear .093" acrylic. The quality of the cut is great, however, we're finding that the acrylic tends to be very brittle and cracks. We've experimented with some clear .093" polycarbonate and the results are unacceptable (too much smoke & discoloration). Has anyone found a clear (colored is ok, too) plastic sheet of a similar thickness that cuts well on a co2 laser and is more durable (less brittle)? Perhaps one of the many formulations of Plexiglass shown here on their website?

http://www.plexiglas.com/acrylicsheet/acrylicsheetfamily/

I have a call in to the Plexiglass company, however, the one guy who can answer the question is on vacation for the next week. I was also told by one laser reseller that certain formulations of Plexiglass can be very toxic and should be avoided.
Any insight would be greatly appreciated.

Thanks
Eric

Michael Hunter
04-05-2012, 11:35 AM
The Romark "Laser-XXXX" materials are based on "modified" acrylic which is much less likely to crack than Perspex/Plexiglass, but at the cost of being a bit flexible.
Easy to get hold of, so it might be worth a try.

Eric Ucci
04-05-2012, 1:12 PM
I have an order in for "Romark ADA modified acrylic sheet". Judging from what I've heard, it should cut very well. Unfortunately, at $100 per 24"x48" sheet, its VERY expensive.
One supplier I spoke with mentioned ABS plastic as a laser-able substitute that is very durable. She stated that you'll see burn marks in white sheet, but that you can cut black sheet and you won't see the burn marks. the big plus is that it costs $31 per 4'x8' sheet.
Does anyone have experience with ABS plastic sheet?

Michael Hunter
04-05-2012, 2:00 PM
Some of the Chinese copies of Romark materials are ABS based and they do cut well.

ABS can absorb moisture from the air and this boils, expanding the plastic and causing a raised lip along the line of the cut.
The Chinese stuff doesn't do this, perhaps because of the capping coat.

Do you need the ADA stuff for the thickness? If not, then the ordinary laserable sheets are much cheaper.

Richard Rumancik
04-05-2012, 4:10 PM
Eric, two possibilities come to mind. Whether either one is suitable depends on the application . . .

The first is PETG. It will cut okay, but you will not get an acrylic-like flame polished edge. It may be a bit whitish along the cut edge and you might find some ridges.

The second possibility is impact modified acrylic. I use Acrylite Resist 65. It won't snap as easily as regular acrylic. It cuts fine but there is a bit of a stickiness to the cut edge. Depending on what you are doing it might be suitable. I am sure you can remove the stickiness - in my case I don't need to. It is of course more expensive than Acrylite FF. There are other flavors of Resist with different properties.

Martin Boekers
04-05-2012, 4:55 PM
Some of the Chinese copies of Romark materials are ABS based and they do cut well.

ABS can absorb moisture from the air and this boils, expanding the plastic and causing a raised lip along the line of the cut.
The Chinese stuff doesn't do this, perhaps because of the capping coat.

Do you need the ADA stuff for the thickness? If not, then the ordinary laserable sheets are much cheaper.


Thanks Michael, I never new why on some plastics made a lip.

Ya learn something new everyday, if, you listen!

Marty

Joe Pelonio
04-05-2012, 5:00 PM
Depending on the thickness, thinner ABS cuts great but 1/4" does leave a raised edge. I do a job regularly cutting up 20+ sheets into parts (black with sandblast finish) that's .06

Eric Ucci
04-05-2012, 8:21 PM
Hey Guys,
That's a lot to go on. thanks a bunch


Some of the Chinese copies of Romark materials are ABS based and they do cut well.



Michael,
do you have a source for the Chinese copies of Romark?

The main reasons I was looking at the ADA modified acrylic were that it was both clear and 1/8" thick. I could alter my designs to accommodate a thinner, not clear material. I will do this if I don't find a cost effective, not-so-toxic solution.
I'll have to post some photos of what we're working on once I have some relative successes :)

Richard,
I'll look into the PETG that you mentioned. Also the modified acrylic from sources other than Romark.

Thanks all for the insight!

Richard Rumancik
04-06-2012, 11:18 AM
Rowmark specializes in added-value products; they laminate, texture, coat, add adhesive etc. They are not a primary manufacturer of basic sheet materials, so if you just want uncoated extruded materials there may be better options.

You might check out Vivak PETG for more info. It is often used in lieu of acrylic for POP applications (store displays, racks, etc.) Maybe you can get a small piece from a POP fabricator to test on before you buy a sheet.

I haven't looked at the specs but I think PETG is less stiff than acrylic. Again, without knowing your application, I don't know which parameters are important.

Michael Hunter
04-09-2012, 2:15 PM
Michael, do you have a source for the Chinese copies of Romark?

Sorry Eric - I get it (very cheaply) from a UK supplier : not much help to you in the States.

dave standing
05-09-2012, 8:00 PM
Sorry Eric - I get it (very cheaply) from a UK supplier : not much help to you in the States.

I've read this thread with great interest as I too am looking for alternatives for Romark acrylics. Any chance you could share your UK supplier's details as I'm in Herts. Thanks

Michael Hunter
05-09-2012, 8:09 PM
Hi Dave

HPC Laser. You can buy from their website. Minimum order 5 sheets, but not much more in cost than two sheets of Rowmark.

The quality is not up to Rowmark standards - the cap layer seems to be painted on and there are blemishes.
The finish is more shiny than Rowmark and that suits my customer for switch panels as the Rowmark sheets picked up dirt very easily and looked second-hand by the time they had finished installing the panels. The Chinese stuff is much easier to keep clean.

Mike Null
05-10-2012, 6:39 AM
You may have already experimented with this but I find cast acrylic to be far more user friendly than extruded. That includes cutting and engraving but also from a durability standpoint it's better. I suspect the .093" stock you have may be the extruded version from one of the home supply stores.

I recently bought a 4' x 10' x .116" cast acrylic from a local plastic supplier for just over $100. (ACI Plastics)

I would also advise carefully tuning your settings to each material. That will take some time since you have two new machines but settings can make a significant difference in the behavior or performance of the material. I would test the .093 material you have with different settings looking particularly at slower and lower speeds and power.

Rodne Gold
05-10-2012, 8:04 AM
If you need the look of clear acrylic with a springy bendy characteristic , then the impact modded acrylic suggested by richard is the way to go , if you can live with the blueish tinge and need something like a flap that doesnt go white when bent and can bend a zillion times and you have a limited budget , then PETG is the way to go.

I import all my acrylic - approx 5 tons PA and all my engraving lams circa 1500/2000 sheets of 1200 x 600mm ex china. I have a really small rejection rate with the lams , maybe 3-4 sheets out of 2000 where there is a small surface blemish or a scratch or dimpling - otherwise they great. They use an acrylic base which is what you want for lasering and have a well printed cap , huge variety but we mainly use brushed gold/silver and common colours, you can get with or without UV protection. Brushed Gold/Black FOB China is like $8 a sheet , the abs based engraveable versions is FOB $6 a sheet. The Rowmark/IPI equivalent is $70 a sheet locally. I had to deal with constant price rises , poor service , always out of stock situations with the local agents here , I decided to DIY.
Minimum order qtys are 200-500 sheets , but you can mix and match with most suppliers.

PS I live in South Africa , where we don't have many competing firms to make choices from or to keep margins reasonable in respect of the suppliers - so mostly if you cant get joy from the local agents , you can go direct to parent Co and get referred back to to agent and so on or just find your own alternative supplier.

dave standing
05-10-2012, 7:45 PM
Thanks Michael

I'll contact HPC