Richard Rumancik
03-29-2008, 12:48 PM
One more point on the burning of acrylic. If you take a match and burn acrylic the composition of the smoke is different from what comes out when you laser it. When acrylic is burning the smoke is black + it smells different and worse . . Kim
I thought that I would respond to this as a separate thread. Kim, your point is well taken. Perhaps I should have found a better reference. I understand that burning acrylic in a fire will probably be more severe than laser cutting it, as laser cutting acrylic turns the plastic into a vapor and there is no smoke. Sometimes laser cutting can be similar to physical burning, if it cuts by decomposition, such as cutting fibreglass or polycarbonate, because you are effectively "torching" the material to cut it.
In my file I have a copy of a magazine article from Industrial Laser Systems magazine Sept 1998. Unfortunately, the archive is no longer available at their website. It states:
"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 would go further and add that not all toxic vapors have a smell, so I would tend to exhaust when cutting any polymer, ablating paint, engraving composites like MDF, etc.
It is difficult to find conclusive evidence as to the toxicity of laser cutting a particular material. A lot of people on this forum suggest that users should get the MSDS for a material before cutting it. Rarely have I found the MSDS useful to decide whether or not to cut a material. The reason is that either it is very superficial, or lists so many toxic elements and health concerns that there is no real way for the average user to assess the risk.
When I did a quick search on acrylic, I found one MSDS that suggested that the most serious hazard for acrylic was cuts due to sharp edges on the sheet. Since you can't ingest sheet plastic or breathe it, they made it sound like it was inert. No comments on dust from sanding or polishing, or outgassing during heating for bending, laser cutting, sawing etc. So by looking at this MSDS you would have to assume it was 100% safe. If you don't process it in any way, it may well be inert.
I try to find information more directly related to laser cutting if possible. The plastic manufacturers often do not have much information. I have had them refer me back to the laser system manufacturers, who of course understandably decline to comment on any unusual materials. I have tried the Laser Institute of America, but so far have found very little information that can be applied to laser engravers. Many of their publication need to be purchased. NIOSH has some toxicity info at their website, but application of the information is difficult. They will tell you how many parts-per-million of methyl methacrylate will kill a rat, but this is not useful information to the laser fabricator as we want to know "safe" levels for people. Also, we do not have equipment to measure ppm of a chemical in the air.
There may be some materials that can be cut or marked without exhausting. I have never investigated marking marble or granite, for example. But in general I would also err on the side of caution.
I thought that I would respond to this as a separate thread. Kim, your point is well taken. Perhaps I should have found a better reference. I understand that burning acrylic in a fire will probably be more severe than laser cutting it, as laser cutting acrylic turns the plastic into a vapor and there is no smoke. Sometimes laser cutting can be similar to physical burning, if it cuts by decomposition, such as cutting fibreglass or polycarbonate, because you are effectively "torching" the material to cut it.
In my file I have a copy of a magazine article from Industrial Laser Systems magazine Sept 1998. Unfortunately, the archive is no longer available at their website. It states:
"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 would go further and add that not all toxic vapors have a smell, so I would tend to exhaust when cutting any polymer, ablating paint, engraving composites like MDF, etc.
It is difficult to find conclusive evidence as to the toxicity of laser cutting a particular material. A lot of people on this forum suggest that users should get the MSDS for a material before cutting it. Rarely have I found the MSDS useful to decide whether or not to cut a material. The reason is that either it is very superficial, or lists so many toxic elements and health concerns that there is no real way for the average user to assess the risk.
When I did a quick search on acrylic, I found one MSDS that suggested that the most serious hazard for acrylic was cuts due to sharp edges on the sheet. Since you can't ingest sheet plastic or breathe it, they made it sound like it was inert. No comments on dust from sanding or polishing, or outgassing during heating for bending, laser cutting, sawing etc. So by looking at this MSDS you would have to assume it was 100% safe. If you don't process it in any way, it may well be inert.
I try to find information more directly related to laser cutting if possible. The plastic manufacturers often do not have much information. I have had them refer me back to the laser system manufacturers, who of course understandably decline to comment on any unusual materials. I have tried the Laser Institute of America, but so far have found very little information that can be applied to laser engravers. Many of their publication need to be purchased. NIOSH has some toxicity info at their website, but application of the information is difficult. They will tell you how many parts-per-million of methyl methacrylate will kill a rat, but this is not useful information to the laser fabricator as we want to know "safe" levels for people. Also, we do not have equipment to measure ppm of a chemical in the air.
There may be some materials that can be cut or marked without exhausting. I have never investigated marking marble or granite, for example. But in general I would also err on the side of caution.