Lexan -Yes/No/Maybe?

[Scott Shepherd]

Bought a small piece of lexan yesterday, along with some plexiglass. Plexiglass did fine, but while it was cutting, I thought I would search the forum on Lexan. I quick search yielded few topics on it, and left me quite confused. One post that stuck in my mind was the one that said the MSDS sheet said it contained some form of a chloride, which would make it a no-no for burning.

Other posts mentioned it lightly in passing, with no real approval or disapproval. I looked up the MSDS sheet and darned if I can find anything that remotely mentions chloride it.

Anyone know the answer to this?

You can cut Lexan on the laser :

1) No problem
2) In moderation and be careful because repeated use will damage the machine
3) BIG PROBLEM, DON'T EVEN THINK ABOUT IT

[Joe Pelonio]

Material content can actually vary by brand, if there's no choride on the MSDS you have to assume it's correct. I have cut it up to 1/4" thick after verifying with Epilog that it was safe. Sometimes it does give off a yellow smoke which is not very comforting so I try to avoid it if I can.

[Rodne Gold]

Anything but the thinnest polycarbonate (which most lexan is) will not cut without major discolouration and a poor edge unless you have a LOT of power. We do often use the laser to cut the very thin lexan films that are used for press button panels for instruments etc , called membrane switches. We use Nitrogen as a gas assist to stop the minimal yellowing of the edge.
AFAIK , cutting lexan is not toxic and we have no signs of machine damage. But I could be wrong if there are various formulations as Joe mentions

[Scott Shepherd]

Thanks guys- it's made by GE Plastics, and darned if I can find any chemical composition of anything that's in it listed on the MSDS.

Bought it from Home Depot. I'll take it back and for a refund and it sounds like it's more trouble than it's worth.

[Mike Null]

Scott:

Lexan engraves quite well. It's hard and slower than acrylic but you get a nice finish. But forget about cutting it with the laser. You can't get a clean cut regardless of your settings.

[Joe Pelonio]

Scott:

Lexan engraves quite well. It's hard and slower than acrylic but you get a nice finish. But forget about cutting it with the laser. You can't get a clean cut regardless of your settings.
Mike, I have gotten nice clean edges on it with my 45 watt Epilog. Like Rodne I do membranes, often screenprinted prior to cutting but also on 1/8" and 1/4" I've gotten good cutting results. I remove the plastic film and replace it with transfer tape, and use air assist but just air. What I'm using is polycarbonate, Lexan is just a brand name but is polycarbonate. I buy it at Tap Plastics and the brand they sell is Makrolon GP by Bayer, distributed by Sheffield Plastic, Inc.

[Steve McKee]

Excerpts from a previous response on this subject, this information came from Wikipedia so you can take it for what it's worth.

It is a polycarbonate polymer consisting of chains of Bisphenol A alternating with carbonyl chloride, also known as phosgene.

(Definition: Phosgene (also known as carbonyl chloride, COCl2) is a highly toxic gas.)

[Joe Pelonio]

Excerpts from a previous response on this subject, this information came from Wikipedia so you can take it for what it's worth.

It is a polycarbonate polymer consisting of chains of Bisphenol A alternating with carbonyl chloride, also known as phosgene.

(Definition: Phosgene (also known as carbonyl chloride, COCl2) is a highly toxic gas.)

Looking up phosgene I see where the yellow smoke comes from. While the msds on the stuff I have used says "irritating fumes" from burning. I think I'll stop cutting it.

I also found this in an old press release from Bayer:

"Clearing up a misconception: The birth of Makrolon
In the beginning, it was primarily a misconception that slowed the rise of this multitalented plastic. Generations of chemistry students learned in college that carbonates are thermally unstable and readily decomposable. So why even try polycarbonates at all? The 37 year-old Bayer chemist Dr. Hermann Schnell was unimpressed by this prejudice as he worked in his Uerdingen laboratory in 1953. He sifted through the literature. "To my great surprise, I found that no work had been done at all in this area for almost 50 years", he later explained. Schnell then did something that characterizes a "true" scientist: he decided to put his trust in experiments alone. When he reacted bisphenol A and phosgene, the two building blocks of Makrolon, he instantly came up with a material that the plastics industry had been looking for for years: a transparent polyester that was dimensionally stable at high temperatures but still thermoplastic (i.e. moldable by applying heat)."

Then of their brochures says:

"Makrolon parts can be welded by means of vibration, friction, heated tool,
or hot gas welding.....the melt temperatures employed during processing are between 280 and 320C....the specified processing temperatures must not be exceeded by a significant extent in order to prevent greater partial decomposition of the polymer and splitting off of volatile breakdown products."

[Dave Jones]

From the Wikipedia:

"Phosgene is an insidious poison as symptoms may be slow to appear. Like many reactive chlorides, gas combines with water in the tissues of the respiratory tract to form hydrochloric acid."

[Scott Shepherd]

Excerpts from a previous response on this subject, this information came from Wikipedia so you can take it for what it's worth.

It is a polycarbonate polymer consisting of chains of Bisphenol A alternating with carbonyl chloride, also known as phosgene.

(Definition: Phosgene (also known as carbonyl chloride, COCl2) is a highly toxic gas.)
Steve, that's the post I had read and mentioned above, where one thread said it releases a chloride gas, and then other posts where people said they had used it, hence the confusion.

Glad I asked for clarification because good information has been posted on this thread. Not just for me for right now, but for those who may search in the future.

Thanks to all who have contributed. I must admit, it's about 3 pay grades over my head, so I'll just skip it and say "because they told me not to" (they, being the smart guys on this thread) :)

[Mike Null]

Joe:
My stuff is a 1/4" and is an ugly stinky cut.

With all the info others have added I'll be re-thinking my use of this material and in doing so want to thank those who have taken the time to do the reading and providing the cautions on this material.

[Larry Bratton]

No Lexan!:eek: Epilog distributor Roy Hatley was here yesterday for training and the subject of Lexan came up. He said due to what was in it, they didn't recommend use of it in the machine. End of conversation. (Scott, he's your guy also and must not have come up when you did your session with him.)

[Mark Winlund]

Isn't the material recommended by Bits & Bits for doing seals Lexan? I know from personal experience that it is difficult to cut with my laser (rated at 120 watts) but is engraving different than cutting? Seems to be the same process to me. Why would B&B sell it for seal dies if it were hazardous or un-workable? (I have not made any seals with the laser, just with rotary equipment.)

Mark

[Carol VanArnam]

So if you say no to Lexan (it's a poly carb material) are you saying NO to all poly carb material being cut and rastered in the laser. I have a customer who wants me to do a job and I'm holding off because I'm seeing all of these postings.


So let me get this right:
YES ok to laser ABS and acrylic
NO do not laser Lexan, Poly Carb material, and PVC

Any other suggestions you can give me would really help stop my head from hurting.

[Dave Jones]

I'm not familiar with Bits & Bits, but are they selling it for laser engraving seals, or for CNC milling seals? Doing it with CNC wouldn't burn it like a laser.

The material I've seen usually suggested for seals using a laser is Delrin.

[Larry Bratton]

Lexan is what is commonly used for bulletproof glass. It's toughhh stuff! I used to live next to a golf course and kept getting my window next to the fairway busted. I replaced it with Lexan and that was that. Did the same with my glass top table on the deck that kept getting balls dropped on it. It will sandblast OK but I don't think I would want to burn it due to it's chemical makeup.

[Mark Winlund]

Dave, You are correct. I was confusing the two. A "senior moment!"

Mark


Quote:

I'm not familiar with Bits & Bits, but are they selling it for laser engraving seals, or for CNC milling seals? Doing it with CNC wouldn't burn it like a laser.

The material I've seen usually suggested for seals using a laser is Delrin.
__________________
Dave Jones --

[Jeff Brewster]

Just wanted to set the record straight on this (I'm a chemist with a laser engraver).

Phosgene is used to synthesize polycarbonate, but the chlorine is eliminated as a byproduct. See the Wikipedia article for details: http://en.wikipedia.org/wiki/Polycarbonate#Chemistry

Heating polycarbonate may something nasty, but it won't be phosgene, hydrochloric acid, or anything of that nature.

[Larry Bratton]

:confused: So Jeff, do you laser Lexan? Yes or no?

[Martin Reynolds]

If you want something like lexan that cuts well, go for PETG.

[Joe Pelonio]

Just wanted to set the record straight on this (I'm a chemist with a laser engraver).

Phosgene is used to synthesize polycarbonate, but the chlorine is eliminated as a byproduct. See the Wikipedia article for details: http://en.wikipedia.org/wiki/Polycarbonate#Chemistry

Heating polycarbonate may something nasty, but it won't be phosgene, hydrochloric acid, or anything of that nature.
In view of your comments, I have submited a question on it to the University of Washington Chemical Engineering Department. I'm not sure they will know or will answer, but with all the requests I get for cutting polycarbonate and the controversy (and yellow smoke) I though it best that we find out for sure.

Interesting that the Wikipedia article says: "extrusion with calenders into sheet (1-15 mm) and film (below 1 mm), which can be used as such, or manufactured into other shapes using thermoforming or secondary fabrication techniques, such as bending, drilling, routing, laser cutting etc."

Meanwhile I'm going to pass on those jobs just to be safe.

[Dave Jones]

One thing about Wikipedia that people forget, or never knew, is that it is not the same as a researched encyclopedia. Anybody can put anything they want into the Wikipedia. It is basically a reader written encyclopedia. Most of the contents are copied from web pages and articles on the web, not all of which might be accurate. So use info found at Wikipedia with caution. You never know where it came from.

[Jack Harper]

In view of your comments, I have submited a question on it to the University of Washington Chemical Engineering Department. I'm not sure they will know or will answer, but with all the requests I get for cutting polycarbonate and the controversy (and yellow smoke) I though it best that we find out for sure.

Interesting that the Wikipedia article says: "extrusion with calenders into sheet (1-15 mm) and film (below 1 mm), which can be used as such, or manufactured into other shapes using thermoforming or secondary fabrication techniques, such as bending, drilling, routing, laser cutting etc."

Meanwhile I'm going to pass on those jobs just to be safe.

Joe,

Have you received any further information on cutting polycarbonate? Also, when you were cutting it, what setting did you use for 1/4 and/or 1/8 material? Thanks for your help.

[Richard Rumancik]

It is certainly prudent to check out unfamiliar materials before attempting to cut them with the laser. However, if we base our decision on whether the material generates hazardous or toxic fumes I doubt that there will be much left to cut. Virtually all of the materials commonly cut will generate toxic fumes.

Even acrylic, which is generally accepted here as a laserable material, generates toxic fumes. In another thread, I posted this excerpt from a copy of a magazine article from Industrial Laser Systems magazine Sept 1998 which I will repeat:

"One consideration with vaporization cutting is removal of the cut byproducts. In the case of Plexiglas, this is methyl methacrylate, a dangerous vapor when breathed, even in minute concentrations. Caution should be observed when cutting all non-metals, but especially polymers. It is prudent to exhaust vapors out of the plant where the concentration is reduced. A simple rule of thumb: if you can smell it, exhaust it."

I have cut polycarbonate film (.030) and up to .094" sheet for "windows" in control panels. When I cut .030" the edge turn gold colored. When I cut .094 the edge is rough and dark, but for the application the edge is entirely hidden so the customer is not concerned. I remove loose carbonization and sometimes lightly sand the edge. It does create yellow smoke when cut. It would not be a good idea to breathe it. An engraved mark on polycarbonate may be suitable for identification such as a part number but is not very suitable in decorative applications. Thin films of polycarbonate cut well.

You need to have a satisfactory ventilation system. If a smell lingers and/or you think you are being affected by the fumes by all means do not continue. It is best to run the exhaust for some time after opening the lid or finishing a job, and keep your out face out of the enclosure when removing or exchanging material.

I am not saying that health issues should be treated lightly, but virtually ALL the materials that we regularly laser mark and cut are giving off toxic fumes. Is polycarbonate more toxic than acrylic? I don't know, but I do not find that an MSDS is helpful in making this decision. Generally I survey industry practices to make a decision. The prerequisite in all cases is having proper exhaust, adequate fresh air intake, and good work practices.

As an observation, I did notice that ULS, Trotec, and GCC LaserPro all list polycarbonate as suitable for laser cutting. Not sure what the other manufacturers say. Larry reported that Epilog does not support it. Synrad indicates that polycarbonate will laser cut, noting that there is some edge quality issues.

[lee maisel]

I have been cutting it just fine, and with a nice clean edge I might add.. But got scared and looked here to see if it's a safe material. I have a good ventilation system to the outside, so it's not bad in here...