What plastics are safe to laser cut?

Plastic is a versatile material, which gives it a wide range of applications. One of these applications is laser cutting. With a laser cutting machine, you can cut or engrave nearly any plastic. But not every plastic should be cut with a laser machine because it is not safe to cut some. So, what plastics are safe to cut?

The five plastic materials that are safe to laser cut are:  

  • Acrylic
  • Delrin
  • Mylar
  • Kapton tape
  • Polycarbonate sheeting

In this article, we will take a detailed look at each plastic material, uses, tips for cutting, and (if any) possible hazards or issues to watch out for.  

Acrylic

Acrylic (lucite/plexiglass/PMMA) is one of the top materials for laser cutting. It cuts nice and safely, producing a fine polished edge.

There are two types of acrylic materials: extruded and cast. Both are ideal for laser processing, but they respond differently to laser cutting. Extruded acrylic cuts smoothly and leaves a clean, flame-polished edge. In addition, it is less expensive than cast acrylic. It is therefore the best acrylic type for laser cutting.

Cast acrylic also cuts nicely under a laser beam, but it does not produce a polished edge. It produces a white frosty color under laser processing. It is therefore more suitable for laser engraving.

When cutting acrylic, high power and slow speed produce the best result. This ensures that the laser beam melts the edges and creates a smooth edge. The process is perfectly safe, but you should wear protective gear to protect against any fumes.

Delrin

Delrin is the name used for acetal resins, a type of semi-crystalline thermoplastic polymers. These plastics are also known as polyoxymethylene (POM). It is used in a wide range of applications such as pumps and water valve components, gears, rollers, electrical insulators, bearings, and more.

Delrin is strong, has low friction, and maintains high rigidity. It is also more ductile (compared to acrylic and wood), which allows for easier and more accurate cuts. On top of that, the laser creates a smooth, sharp-less edge that requires no additional finishing.

That said, laser cutting Delrin does come with some drawbacks. First of all, the material tends to warp, especially if stored improperly. It also produces fumes that, though not toxic, are very pungent. Furthermore, it can catch fire, especially under a powerful laser beam. It is therefore advisable to use low cutting speed and low power when laser cutting Delrin.

Mylar

Mylar is another name for polyester film polyethylene terephthalate. It is mostly used to make stencils, as it is easy to stencil with, clean, and durable.

Mylar is a versatile plastic material that possesses high strength, durability, and high tensile properties. It is therefore an excellent material for laser cutting as it allows for a precise and clean cut.

However, while Mylar is safe and ideal for laser cutting, it does pose some challenges. First of all, the edges of the plastic can melt as you cut, resulting in burred edges. If the laser beam is too powerful, the material may catch fire. As a result, a low-power laser beam at low speeds is recommended.

Another issue with laser cutting Mylar has to do with the thickness. If the sheets are too thick, they will warp, curl, or bubble as you are cutting. On the other hand, if they are too thin, they will not hold together.  So you may have to do a lot of testing before you find your sweet spot.

Kapton

Kapton (also known as polyimide) is a type of high-performance plastic polymer. The material is characterized by properties such as high electrical resistance, high thermal conductivity, and excellent tensile properties. This makes it ideal for laser cutting.

Kapton tape can be laser cut to make solder masks or stencils. It can also be used in laser marking. The material is usually cut using CO2 lasers as polyimides have excellent CO2 laser energy absorption capacity. However, UV lasers can also be used.

One major drawback of laser cutting Kapton is that the edges tend to char. Thermal damage can also occur under a too powerful laser beam. However, this can be overcome by using medium power laser beams (with thin sheets). Any charring that occurs can be easily cleaned using isopropyl alcohol.

Polycarbonate sheeting

Polycarbonate refers to a group of thermoplastic polymers that feature carbonates in their structure. There are several trademark names for these plastics, including Lexan, Lupoy, Makrolon, and others. They are durable and lightweight, which makes them ideal for laser cutting.

However, while it is ideal for laser cutting, polycarbonate is not the best choice of material. It is hard (even harder than acrylic), making it trickier to cut complex designs. It also absorbs high levels of infrared energy and can easily catch fire (If it is too thick). Furthermore, it usually produces discolored (yellowed) edges that are not smooth.  

Which plastics cannot be laser cut?

Even if you have a powerful laser cutter, there are some plastics that you shouldn’t use for your laser cutting projects. These are;

  • PVC
  • Coated carbon fiber
  • ABS plastics

Let’s have a look at each of these and why you shouldn’t laser cut them.

PVC

PVC (polyvinyl chloride) is the name of a versatile plastic material with numerous applications. Examples include making water pipes, drainage pipes, sewer pipes, plastic cables, floors, roofing membranes, synthetic leather, and more.

 Despite having a wide range of applications, PVC is not safe for laser cutting. Under a laser beam, the material releases chlorine gas (and can possibly release hydrochloric acid). Apart from damaging the laser cutter, these by-products can also result in serious physical injury.

Coated carbon fiber

Carbon fiber is a plastic material that is not ideal for laser cutting due to its high absorption of laser energy. It also possesses a very high energy diffusivity. As a result, it can easily catch fire, which can spread to large parts of the material during the cutting process.

Cutting coated carbon fiber is an even worse idea, and should not be attempted. With the coating (usually epoxy), the material produces toxic fumes. The fumes can be especially dangerous in closed spaces.

ABS plastic

ABS (Acrylonitrile Butadiene Styrene) is an amorphous thermoplastic polymer. It is another material not ideal for laser cutting as it tends to melt, leaving behind a gooey mess. Furthermore, it produces hydrogen cyanide, which is toxic even in small amounts.

Final thoughts

Plastic materials offer a wide range of applications in laser cutting due to their versatility and unique properties. However, not all materials are ideal. Some will give you unnecessary troubles, while others are unsafe as they can harm you or your laser machine. That being said, several plastics are not only safe but will deliver excellent laser cutting results. You just need to find them and choose the most appropriate for your project.