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Best Plastics for Laser Cutting: What's Safe?

Best Plastics for Laser Cutting: What's Safe?

Best Plastics for Laser Cutting: What's Safe?

Plastic is a synthetic material that generally cuts smoothly with a laser.

However, these synthetic materials produce heavy smoke, which can, in some cases, be extremely harmful to the operator and the laser equipment.

So, it is important to know about the best plastics for laser cutting and also be wary of plastics that are not recommended to be processed under a laser.

This article provides a detailed guide on the best plastics for laser cutting while discussing their optimal parameters and the type of laser suitable for processing them.

In the end, I've also provided a list of plastic materials that should not be processed under a laser and discussed the safety precautions to be followed when laser cutting plastics.

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Types of Plastic Best Suitable for Laser Cutting

Acrylic, a thermoplastic, is the best plastic for laser cutting because it produces a flame-polished edge with no harmful fumes. Some other plastics suitable for laser cutting include fluoropolymers, Delrin, polypropylene, Mylar, etc. All these plastics can be laser-cut safely by maintaining good process control.

Plastic represents a broad category of synthetic materials with different mechanical properties and chemical compositions.

As a result, each type of plastic behaves differently when processed under a laser.

While some plastics produce a clean cut with no harmful fumes, others tend to melt or produce toxic fumes during the laser-cutting process.

Therefore, it is important to know the types of plastic best suitable for laser-cutting plastic projects.

Plastics are generally divided into two main categories: thermoplastics and thermosetting plastics.

Thermosetting plastics have a unique characteristic where they tend to harden when subjected to heat until the temperature reaches high enough to melt the material.

On the other hand, when a thermoplastic is subjected to heat, it tends to soften up and sometimes even turn into gooey material before reaching its melting point.

This makes thermosetting plastics comparatively more difficult to laser cut than thermoplastic materials.

Some of the popular types of plastics and their laser cutting, engraving, and marking quality are mentioned in the table below.

NameLaser CuttingLaser Engraving/MarkingSafety
AcrylicExcellentExcellent / GoodNo harmful fumes
PolypropyleneGoodPoor/FairProne to melting when <1mm thick
DelrinGoodFair/FairProduces fumes of formaldehyde
MylarGoodFair/FairNo harmful fumes
FluoropolymersFairGood/FairNo harmful fumes
PolycarbonatePoorFair/GoodProduces heavy smoke when cut
PolyimidePoorPoor/GoodNo harmful fumes

Types of plastics suitable for laser processing

Acrylic-Best Plastic for Laser

Laser cut acrylic
Laser-cut black acrylic

Acrylic is a thermoplastic material that produces clean, flame-polished edges when cut by a laser.

Laser cutting acrylic generally requires a moderately powerful laser, and a 60W CO2 laser can be used to cut up to 0.23" (6mm) thick acrylic workpieces.

Apart from that, acrylic also produces excellent results for laser engraving projects.

Laser cutting acrylic produces moderate to heavy fumes, which are not harmful to the operator, but using a good exhaust system is recommended to avoid the accumulation of fumes around the work area.

Based on its manufacturing technique, there are two types of acrylic: cast acrylic and extruded acrylic.

Cast acrylic has a more uniform structure, making it ideal for various applications that involve machining acrylic.

On the other hand, extruded acrylic is prone to internal stress, making it comparatively more prone to cracking or breaking during conventional machining operations.

Generally, extruded acrylic is comparatively cheaper and best suited for laser cutting, whereas cast acrylic is recommended for laser engraving due to its white frosting look when engraved.

Polypropylene

Polypropylene Sheets
Polypropylene Sheets

Polypropylene is also a thermoplastic material that is prone to melting and producing a gooey mess over the work table.

However, setting the optimal parameters and ensuring proper parameters will help you overcome the challenge and produce clean cuts with a high surface finish.

Generally, a CO2 laser with a power output of above 40W is recommended for industrial applications where a fast cutting speed is required.

It is also strongly recommended to use high-volume air assist during laser cutting polypropylene to reduce the heat-affected zone and the risk of melting the workpiece.

Laser cutting polypropylene generates fumes that can sometimes contain volatile elements, risking fire hazards.

Therefore, a ventilation system is strongly recommended to dispose of the fumes safely.

Delrin

Delrin sheets
Delrin sheets

Delrin, also known as polyacetal, is a polyoxymethylene polymer-based thermoplastic generally used for making seals, high-load mechanical components, etc.

Laser cutting Delrin requires around 80W CO2 laser to perform clean cuts with a high surface finish.

A lower-power laser with a slow cutting speed can successfully produce through cuts in Delrin but at the cost of quality.

Apart from that, a fiber laser can also be used for laser marking Delrin, but the produced mark lacks contrast, leading to poor visibility.

Laser-cutting Delrin can produce mild fumes of non-toxic formaldehyde that can be unpleasant if inhaled.

Mylar

Mylar sheet
Mylar sheet

Mylar is a type of polymer that is made from polyethylene terephthalate (PET).

It is a durable material generally available in thin-flexible sheets, making it ideal for making stencils.

These thin Mylar sheets are easy to cut under a laser, and a budget-friendly k40 laser cutter can be used for cutting, marking, or engraving them.

However, when cutting stencils from very thin sheets of Mylar, a high-powered laser can overheat the material, leading to dimensional accuracy in the stencil due to melting.

Therefore, it is recommended to use the raster engraving technique and perform multiple passes until you achieve the desired cut with minimal heating of the material.

The fumes produced during the process are harmless, but a good exhaust system prevents the accumulation of smoke and enhances the quality of the cut.

Fluoropolymers

Teflon sheets
Teflon sheets

Fluoropolymers are organic polymers that contain fluorine as one of their major components.

Their distinctive properties, such as temperature resistance, friction resistance, flame resistance, etc., make them popular for various applications.

Teflon is one of the popular Fluoropolymers used in household utensils to provide a non-stick coating.

These plastics require moderately high laser power to perform clean cuts with a high surface finish and minimal edge burns.

Polycarbonate

Polycarbonate sheets
Polycarbonate sheets

Polycarbonates are thermoplastic materials that are generally transparent and have high strength and impact resistance.

Laser cutting these plastics results in the discoloring of the material, leading to a yellowish hue along the cut edge.

As a result, polycarbonates are not recommended for laser cutting projects but can be used for laser engraving applications.

Polyimide

Polyimide labels
Polyimide labels

Polyimide is a thermosetting plastic with excellent mechanical properties and the ability to resist harsh temperatures.

Laser cutting these plastics results in poor quality cut with charred edges and is therefore not recommended for laser cutting.

Apart from that, laser engraving polyimide produces good results, but being a thermosetting plastic, it tends to harden when engraving a very thin sheet of polyimide, making it brittle and easy to break.

Some common uses of laser engraving polyimide include barcode and serial number tags on electric equipment and other goods.

Type of Laser Suitable for Laser Cutting Plastics

The ability of a laser cutter to make clean cuts in plastics also depends upon the type of laser used in that cutter.

Generally, CO2 lasers and diode lasers are best suited for laser cutting plastics.

CO2 lasers have a wavelength of around 10600 nm, readily absorbed by plastics, making them the best suitable laser for laser cutting or engraving plastics.

Diode lasers have a wavelength varying from 450 nm to 950 nm, which is also readily absorbed by plastics.

However, diode lasers cannot be used to cut transparent plastics, as the laser beam passes through the transparent surface without significantly affecting the material.

Although fiber lasers cannot be used for laser cutting plastics, a Ytterbium Fiber Laser, with a wavelength of 1062 nm, can be used for marking various types of plastics like acrylic, Delrin, Polycarbonate, etc.

Types of Plastics Not Suitable for Laser Cutting

Plastics are relatively easy to cut by a laser.

However, certain plastic can be dangerous to process under a laser, even when maintaining good process control.

Laser cutting these plastics can be dangerous for the operator as well as the laser machine.

Therefore, it is important to be wary of the types of plastics not suitable for laser cutting.

PVC

PVC pipes and cables
PVC pipes and cables

Polyvinyl chloride, commonly known as PVC, is a thermoplastic that is used in various applications.

It is a durable material with high flexibility and has the ability to withstand extreme environments, making it ideal for applications such as plumbing pipes, wire cables, PVC wall panels, etc.

Despite being a versatile material with various applications, it is not safe for applications involving laser processing.

This is because the vinyl content present in PVC produces harmful fumes of chlorine when burnt under a laser.

Although laser cutting vinyl is relatively easy, the chlorine fumes produced are toxic if inhaled by the operator.

Moreover, these chlorine fumes react with the atmosphere and release hydrochloric acid which can damage the laser cutting equipment.

Therefore, it is strongly advised to always verify the material for chlorine content before processing under a laser.

An easy test to check the presence of chlorine in your work material is to perform the Beilstein test.

It involves heating a metal wire and pressing it against the workpiece to get a sample for the test.

This wire (with a sample of work material) is then placed in a flame, and if the flame turns green, the workpiece contains chlorine.

It is a simple test that helps you identify chlorine content and prevent any harm to the operator or your laser equipment.

ABS

ABS filament for 3D printing
ABS filament for 3D printing

ABS or Acrylonitrile Butadiene Styrene is a thermoplastic that produces toxic fumes of hydrogen cyanide when processed under a laser.

Apart from that, ABS plastics melt easily, leaving behind a gooey mess on the work table, making it ideal for 3D printing applications.

As a result, it is not recommended to process ABS under a laser.

Coated Carbon Fiber

Coated Carbon fiber on a safety head gear
Coated Carbon fiber on a safety head gear

Carbon fiber is a lightweight and durable material with applications in a wide range of industries.

It readily absorbs laser energy making it easy to cut but results in frayed edges along the cut.

However, the high energy absorption rate produces a risk of fire hazards, and a coated carbon fiber consists of a coating of epoxy resin.

When laser cutting coated carbon fiber, the epoxy material releases toxic fumes with volatile particles that can cause fire hazards.

Therefore, it is not recommended to laser-cut coated carbon fiber.

Polypropylene Foam

Polypropylene foam is a type of plastic that is used for various packaging and insulation applications.

It is a durable material with high resistance to impact loads.

Laser cutting of polypropylene foam results in the dripping of hot melts on the work table, which then continue to burn until they harden and stick to the table.

Thereby making polypropylene foam not suitable for laser cutting applications.

Safety Precautions to Follow When Laser Cutting Plastics

Although laser cutting plastic does not require very high laser power, it is important to follow laser safety precautions during the process to minimize the risk of health and other hazards.

Laser Safety Glasses

Saftey glasses provided with of laser master 2
Laser Saftey glasses

Lasers are high-energy beams of light that can be dangerous when handled carelessly.

A reflected beam of a high-power laser can cause severe injuries if it comes in contact with the eyes.

Therefore, it is strongly advised to wear laser safety glasses when operating a laser.

Especially when working with a CO2 laser because CO2 lasers fall under the infrared region of the UV spectrum, making it invisible to the human eye.

Safety Enclosure

Snapmaker Original with safety enclosure
Safety enclosure of Snapmaker Original

Laser cutting of any plastic produces fumes that may not necessarily be toxic.

However, being exposed to these fumes on a regular basis can have an adverse effect on health in the long run.

Therefore, it is recommended to use a safety enclosure that not only prevents stray laser radiations but also helps to entrap the fumes.

Good Exhaust System

Exhaust fan
Exhaust fan for disposing of the fumes

The exhaust system is one of the most important accessories for laser cutting plastic.

Laser cutting plastic produces mild to heavy smoke, which causes unease to the operator and also affects the quality of the cut.

The smoke diffuses the laser beam and reduces its ability to perform a clean cut.

Therefore a good exhaust system not only prevents smoke from harming the operator but also improves the quality of the cut.

Generally, the smoke from plastics contains carbon content which is harmful to the environment, so it is recommended to use an exhaust system with a carbon filter to purify the smoke before disposing of it in the atmosphere.

Air Assist

Air assist is the use of high-pressure air that facilitates the cutting process by blowing the molten material out of the kerf.

It also prevents the optical system of the laser cutter from hot molten deposits by blowing them away from the laser head, enhancing the life of the equipment.

Furthermore, the air assist also blows the smoke away from the operator and minimizes the risk of inhaling harmful fumes.

Therefore, it is recommended to use an air assist when laser cutting plastics.

Final Thoughts

Plastics are excellent materials for laser cutting and depending upon their behavior under a laser, each plastic is used for different applications.

Acrylic and polypropylene are the most commonly used plastics for laser cutting applications because they produce clean cuts with flame-polished edges.

Mylar is commonly used for laser cutting stencils, while Delrin is used for making mechanical components.

Whereas plastics like fluoropolymers, polycarbonate, and polyimide are not best suitable for laser cutting but can be used for laser marking applications.

Frequently Asked Questions (FAQ)

Can we use a fiber laser to cut plastic?

No, a fiber laser is not suitable for lasrr cutting plastics, but it can be used for laser marking on various plastics.

What type of plastic can a 10W diode laser cut?

A 10W diode laser can laser cut almost any type of thin plastic workpiece. As the thickness increases, its ability to make clean cuts decreases. A low-powered diode laser is best suitable for laser engraving and marking applications.

Can we laser cut Polyethylene?

Yes, you can laser cut Polyethylene. It produces a clean cut with a slightly built-up edge due to melting. Laser engraving polyethylene produces a dark engraving with good contrast. High-density Polyethylene (HDPE) is the best suitable Polyethylene for laser applications.

About John

Hey I'm John. I talk about CNCs and Lasers at Mellowpine. If you have any questions related to CNCs or Lasers, I'd be happy to answer them. Reach me at mail@mellowpine.com

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John

Hey I'm John. I talk about CNCs and Lasers at Mellowpine. If you have any questions related to CNCs or Lasers, I'd be happy to answer them. Reach me at mail@mellowpine.com

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