Of the 4 groups, plastics is probably the group with the highest risks. There seems to be some confusion in the community as to which plastics are safe to process with a laser and which must be avoided at all times.
After researching a number of sites, including laser manufacturers and laser users. I have come up with the following three suggestions relating to plastics;
- Avoid all materials that contain Fluorine (F), Chlorine (Cl), Bromine (Br) and Iodine (I), also known as the Halogens. While everyone is agreed that laser cutting PVC (PolyVinyl Chloride – Chemical formula (C2H3Cl)n) is a bad idea. Mainly due to Hydrogen Chloride gas (HCl) being released, which subsequently reacts with water to form Hydrochloric Acid. Some sites are suggesting that it is acceptable to laser process PTFE (Polytetrafluoroethylene – Chemical Formula (C2F4)n). While I am not a Chemist, I would be concerned that a similar reaction would occur, producing Hydrogen Fluoride. One to be avoided!
- Avoid all materials containing a CN bond, i.e. a Nitrogen atom bound to a Carbon atom. Plastics containing this CN bond will form Hydrogen Cyanide Gas (HCN) when laser cut. This gas is highly toxic and can be absorbed through both the skin and lungs. ABS (Acrylonitrile Butadiene Styrene – Chemical Formula C8H8·C4H6·C3H3N)n) is an example of a plastic containing a CN bond. Performance wise, ABS is not a great material to cut or engrave with a CO2 laser.
- Avoid all materials that are claimed to have a flame retardant, the additive used often contains Bromine. See item 1 above.
Polyvinyl Chloride PVC (C2H3Cl)n
PVC is to be avoided at all times. Not only will it damage your machine by corroding metal parts the fumes generated are extremely bad for your health. Avoid at all costs. Kydex and Foamex both contain PVC.
Polycarbonate PC C16H18O5
Polycarbonate is also known by various trade names such as Makrolon and Lexan. It can be cut at thicknesses below 1mm but the quality is poor and generates excessive sooty smoke. It is also a significant fire hazard and needs to be closely supervised. Best avoided.
Acrylonitrile Butadiene Styrene ABS C8H8·C4H6·C3H3N)n
ABS does not cut or engrave well with a CO2 laser source. It melts easily and does not cut cleanly. Engraving performance is poor with little contrast and leaves behind deposits on the workpiece and the laser work chamber. It also gives off Hydrogen Cyanide gas, which is highly toxic. NB: If you are looking to mark ABS, you are better off using a fibre laser source which will leave a high contrast mark in most cases. Best to avoid, even if you have great fume extraction.
High-Density Polyethylene HDPE (C2H4)n
HDPE doesn’t cut very well, easily melts into a sticky mess and catches fire. The same goes for Polyethylene PE. Two to avoid.
Polystyrene Foam PS / Styrofoam (C8H8)n
Styrofoam/Polystyrene is highly flammable and should never be cut with a laser, it is not self-extinguishing and can continue to burn when the heat source is removed. Solid styrene (also known as ethenylbenzene) can be cut, but note that it will release Benzene gas which is a highly toxic gas. So full, effective extraction would be needed, but best to avoid when possible. Both Depron Foam and Gator Foam are types of Polystyrene.
Acrylic Poly (methyl methacrylate) PMMA (C5O2H8)n
Commonly referred to Acrylic or Plexiglas®, this is a mainstay material for the laser cutting and engraving industry. Please note that there are two types of acrylic: Cast and extruded. Even though they have the same chemical formula, they perform differently. Cast acrylic gives a beautiful engraved finish but can be very difficult to get a decent polished edge. Extruded acrylic gives a great polished cut edge but is not as good as cast acrylic when engraving.
Polyester PES – C27H38O14
Polyester is also known by the brand name Mylar. Great when cutting thin sheets, but take care on thicker sheets as there is a tendency for the material to warp and curl. As with Styrene, polyester gives off Benzene Gas, so effective extraction is required.
Nylon (C12H22N2O2)n
Nylon is another material that has the CN bond and should be avoided. If you are looking for an engineering plastic, I would suggest you consider Delrin.
Delrin – Polyoxymethylene POM (CH2O)n
Delrin is another great material for laser cutting but significantly more expensive than acrylic. However, it’s very stable and not as brittle as acrylic.
PETG – Polyethylene Terephthalate Glycol (C10H8O4)n
Yes, you can laser cut PETG, but it is a dirty material to process, giving off a significant volume of white particulates. Your laser machine will need regular cleaning and fume extraction filters will soon clog up unless you have a sacrificial pre-filter to take the strain. Your fume extraction needs to be good as the smell given off is extremely bad. Thin sheets should cut fine with sufficient power and speed, but thicker sheets will just melt and reform after the laser has passed. It is also possible to get a reasonable engraved finish.
Polypropylene PP (C8H8)n
Yes, polypropylene cuts well, although the kerf (the amount of material removed by the laser) tends to be wider than you would expect. You need to take this into account if you need accurate dimensions or if you are cutting detailed profiles.
Polypropylene Foam PP (C8H8)n
It’s best not to try and laser cut Polypropylene foam, it melts, easily catches fire and does not self-extinguish. The melted residue becomes rock hard and can be very difficult to remove.
Coroplast (polypropylene)
Coroplast is a “Fluted or Corrugated Polypropylene Sheet” used in the signage industry. It will laser cut but can prove difficult at larger thicknesses, leaving tags at the bottom where there are vertical corrugations.
Corflute (polypropylene)
Corflute is a “Fluted or Corrugated Polypropylene Sheet” used in the signage industry. It will laser cut but can prove difficult at larger thicknesses, leaving tags at the bottom where there are vertical corrugations.
Kapton Tape Polyimide C22H10N205
Polyimide, also known as Kapton does not cut well with a CO2 laser as it chars significantly.
Rubber (thin no chlorine) (C5H8)n
There are a wide variety of rubbers available and you will need to check the composition before laser cutting as some, such as Neoprene will contain Chlorine. Many rubbers will cut and engrave fine but can generate a significant amount of smoke. Other rubbers will just melt and reseal once the laser has passed. It is possible to purchase laser friendly rubber sheets, generally used for in the production of rubber stamps. Some are even perfumed!