CO2 laser, PVC cutting?

[vdKroon]

Hi,

I've read several times that PVC cannot be cut/engraved by a CO2 laser due to high toxic fumes created. Can anyone explain this? What's the subproduct so toxic? I assume chloride related?

Is there any way to accomplish this with high volume exhausts or something?

Thanks in advance,

Lucas

[MacGyver]

Where are you going to exhaust the fumes? Just because you get it out of your shop doesn't mean it's not dangerous stuff for someone hanging around outside your shop. You might get away with small pieces once in a blue moon, but it's not pretty stuff, and it will corrode just about any metal surface in your laser.

[vdKroon]

Hi MacGyver,

Thanks for your prompt reply. I'm not trying to be into 'this can't be that toxic' point of view, because every written reference I found, states clearly that fumes are toxic/corroding.

I'm trying to understand where/why toxicity comes from, and if can't be handled by high volume exhaust/vacuum, maybe through some HEPA or carbon filters before the air leaves the shop.

My shop is also located in a spot where no human being (apart of me) is located in 6 km radius, but I assume that this behaviour can not be 'environmetal friendly' anyway..

Lucas

[lamicron]

You can use the exhaust but your machine is going to corrode, get rust...

[StickChick]

I (once) tried cutting Lexan which is a nightmare...I immediately almost dissolved a lens, and researched and found out that hydrochloric acid is the result of laser cutting polycarbonate;
My exhaust is from the bottom, and I lost my beam partway through a cut, got this huge baffling *poof* of yucky thick yellow smoke that went right up to the lens, and just melted it. I guess that was maybe the beam couldn't even penetrate it, and maybe it deflected, combined withthe acid, not sure exactly what caused that... I do know I will never cut that stuff again; also, you will ruin your exhaust system; my customer had no problem switching to acrylic; I would have refused the job otherwise. Hope this helps

[LaserImage]

Originally Posted by vdKroon I'm trying to understand where/why toxicity comes from, and if can't be handled by high volume exhaust/vacuum, maybe through some HEPA or carbon filters before the air leaves the shop.

When PVC is heated it releases chlorine gas, this mixes with the moisture in the air and the result is hydrochloric acid. It is toxic to humans and corrosive to most anything it comes in contact with. I am sure you could filter it out of the air and everything would be fine... except everything between the source and the filter that is. Even a very high volume exhaust would probably just lengthen the time it takes to do damage but it won't stop the damage from happening. You are much better off mechanically cutting pvc instead of lasering it.

Gary

[LaserImage]

Originally Posted by StickChick I (once) tried cutting Lexan which is a nightmare...I immediately almost dissolved a lens, and researched and found out that hydrochloric acid is the result of laser cutting polycarbonate;

Polycarbonate absolutely does not produce hydrochloric acid. Here is an excerpt from an msds for polycarbonate:
Section 5 Fire Fighting Measures
Flash ignition temperature: 630°C / 1166°F
Unusual fire, explosion hazards: None known.
Hazardous combustion products: Hazardous combustion products may include intense
heat, dense black smoke, carbon monoxide, carbon dioxide and hydrocarbon fragments.
Special fire fighting instructions: Fire fighters and others exposed to products of
combustion should wear full protective clothing including self-contained breathing
apparatus. Fire fighting equipment should be thoroughly decontaminated after use.

You are right about the thick yellow smoke, but it's nothing more dangerous than anything else you laser. Your problems were not a result of the fumes, more than likely they were from soot build up on the lens.

Gary

[vdKroon]

Thank you all for your comments, I'll stick with my cnc router to do PVC.. Which other plastics besides acrylic can be laser cut?

[lamicron]

polystyrene, polypropylene, etc, the forbiden is PVC .
I heard some warning about kevlar.

[KTP]

Nah, kevlar only produces cyanide gas...shouldn't be too harsh on your optics...

[GWEIKE-LASER]

we have ever engraved on the PVC cards before. It's workable, although the smell is not good

[LaserImage]

Originally Posted by GWEIKE-LASER we have ever engraved on the PVC cards before. It's workable, although the smell is not good

If you smell it enough the problem goes away - that's the good news... The bad news is that it goes away because you are dead...