Laser Cutting and Engraving Plastic-Expert Guide

Laser Cutting and Engraving Plastic-Expert Guide

Laser Cutting and Engraving Plastic-Expert Guide

Plastics are synthetic or semi-synthetic polymer materials that can be molded into various complex shapes.

They are available in many forms, from extremely thin and flexible sheets to specially engineered plastics that offer high strength and durability.

Laser cutting can be used to cut almost every type of plastic, except for a few that produce toxic by-products when vaporized by the laser beam.

In this article, I discuss everything you need to know about laser cutting and engraving plastics.

Including the types of plastics that are suitable for laser cutting and ways to improve the quality of the cut while working with plastics.

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Laser Cutting Plastics

Laser cutting is a fast and economical process that can produce high-precision cuts in plastics.

Laser Engraved Plastic Product
Laser Engraved Plastic Product (Source: Etsy)

But selecting the right laser for the right process is very important to keep the process economical and efficient.

Although diode and fiber lasers can engrave plastics, they are not ideal.

For laser cutting plastics in a single pass, use a CO2 laser with a power rating of over 40W. This works for most types of plastics and a variety of thicknesses. Using low-powered diode and fiber lasers for cutting thick plastic will require multiple passes and thus the process will not remain economical.

Apart from the type of laser, selecting the right type of plastic for your application also plays an important role.

Types Of Plastics Suitable For Laser Cutting

While working with plastics, it is important to know which plastics are safe for laser processing.

NameLaser CuttingLaser Engraving/MarkingSafety
AcrylicExcellent Excellent / GoodNo harmful fumes
Fluoropolymers GoodGood/FairNo harmful fumes
DelrinGoodFair/FairProduces fumes of formaldehyde
Polycarbonate PoorFair/GoodProduces heavy smoke when cut
MylarGoodFair/FairNo harmful fumes
PolyimidePoorPoor/GoodNo harmful fumes

Types of plastics suitable for laser processing

Acrylic

Laser processing examples of Acrylic
Examples of laser processing on Acrylic (Source: Synrad)

Acrylic is a thermoplastic material with glass-like optical properties and is often used as an alternative to glass.

It is a laser-safe material and the fumes produced while laser cutting acrylic are not toxic to the health but on prolonged exposure, might cause irritation to the lungs.

Laser cutting acrylic produces a clean, flame-polished edge with a high surface finish.

A high-power CO2 laser with a wavelength of 10.6 µm and low cutting speed is recommended for best results with acrylics.

There are basically two types of acrylics: Cast acrylic and Extruded acrylic.

Cast acrylic is comparatively more costly than extruded acrylics and produces high-quality output to the laser engraving process.

Whereas extruded acrylic is comparatively cheaper and cuts smoothly with flame polished edges.

However, laser engraving extruded acrylic results in a lower quality output with a grayish shade.

If you are specifically interested in laser processing acrylics, then you can refer to the article - Laser Cutting Acrylic.

Fluoropolymers

Examples of laser processing on fluoropolymers
Examples of laser processing on Fluoropolymers (Source: Synrad)

Fluoropolymers are a class of polymers that are based on carbon/fluoride bonding.

These polymers show high resistance to harsh environmental factors and are known for their long life.

A CO2 laser with a wavelength of around 9.3 µm to 10.6 µm is best suitable for laser cutting and engraving fluoropolymers.

Laser cutting these polymers results in a clean cut with a good surface finish and no discoloration along the edge.

Some of the most commonly found fluoropolymers are Teflon, Kel-F, and Halar.

Delrin

Examples of laser processing on delrin
Examples of laser processing on Delrin (Source: Synrad)

Delrin is a thermoplastic based on polyoxymethylene polymer and is also known as polyacetal.

It is a high-strength plastic material with good rigidity and low friction which makes it an ideal material for various applications, such as bearings, pumps, gears, etc.

A CO2 laser with a wavelength of 10.6 µm can produce smooth cuts that do not require any additional finishing processes.

Whereas, a fiber laser with a wavelength of 1.06 µm can be used for the laser marking process.

Laser cutting Delrin produces fumes that contain a small quantity of formaldehyde gas, which although is not toxic but can be very unpleasant and requires a good ventilation system.

Polycarbonate

Examples of laser processing on polycarbonate
Examples of laser processing on Polycarbonate (Source: Synrad)

Polycarbonate is a thermoplastic material that contains carbonate content in its structure.

It is a durable material with high impact resistance which makes it difficult to laser cut intricate designs.

A CO2 laser with a wavelength of 10.6 µm can be used to make smooth cuts in polycarbonate but it leaves a yellowish discoloring along the edge with heavy smoke generation.

Due to this reason, it is not recommended for laser cutting, but it gives good results for laser engraving by a low-power laser.

Laser marking on polycarbonate using a 1.06 µm fiber laser produces excellent results with a high level of detail.

Some of the most commonly found polycarbonates are Lexan, Lupoy, Makrolon, etc.

Mylar

Examples of laser processing mylar
Examples of laser processing on Mylar (Source: Synrad)

Mylar is a form of durable polyester, with a high tensile strength that, can be laser cut, marked, or engraved.

Laser cutting mylar produces a precise cut with a good surface finish and is mostly used for making stencils.

A CO2 laser with a wavelength of 9.2 µm is best suitable for laser cutting and marking mylar.

Laser marking mylar produces white frosty markings on the surface without damaging its structural integrity.

Using a high-powered laser beam for cutting mylar can result in edge burns and melts, therefore a low-powered laser beam with a low cutting speed is recommended.

Polyimide

Examples of laser processing polyimide
Examples of laser processing polyimide (Source: Synrad)

Polyimides are thermosetting polymers with good chemical and electrical resistance, high thermal conductivity, and good mechanical properties.

Kapton is one of the most popular polyimides that is primarily used in making solder masks and stencils.

This material readily absorbs the energy from a CO2 laser with a wavelength of 10.6 µm and thus can be cut easily.

However, polyimides are not recommended for laser cutting because they tend to leave a brown/black charring along the edge of the cut which requires a secondary process for cleaning.

A low-powered laser beam can be used for marking the surface of polyimide without any substantial damage to its structural integrity.

Types Of Plastics Not Suitable For Laser Cutting

Although most of the plastics are compatible with laser processing, there are some that can be dangerous if brought in contact with a laser beam.

So, it is always recommended to make sure that the material used for laser cutting does not contain any of the following plastics.

You must also be aware of the laser safety risks, hazards, and control measures before you start working with laser equipment.

PVC

PVC, also known as Polyvinyl chloride, is one of the most commonly used thermoplastic materials.

It has high strength and finds its application in various fields such as healthcare, electronics, plumbing, etc.

Some of the common examples of PVC materials used in daily life are pipes, wire insulation, blood storage bags, flooring, some synthetic leathers, etc.

Despite being such a widely used plastic material, it is not suitable for laser cutting.

When brought in contact with a laser beam, vinyl content present in PVC vaporizes and produces harmful fumes of chlorine and hydrochloric acid.

These fumes are highly toxic if inhaled and can even damage the laser cutter equipment.

ABS Plastic

ABS or Acrylonitrile Butadiene Styrene is a thermoplastic that can be suitable for laser cutting under a low-power laser.

But the laser cutting ABS requires careful monitoring as it has the tendency to melt and leave behind a gooey mess.

Furthermore, the fumes produced during the melting of ABS plastic can cause irritation to the eyes, skin, and lungs.

Carbon Fiber

Carbon fiber is a lightweight polymer with good strength and stiffness.

It has the tendency to readily absorb laser energy which makes it prone to catching fire while laser processing.

Most carbon fibers usually have a layer of epoxy coating which produces harmful fumes when burned under a laser.

Laser Cutter Setup for Plastic Cutting and Engraving

Performing clean cuts in plastic requires a capable laser cutter with good process control.

Laser Power

The amount of laser power required depends upon the type of material and its thickness.

Generally, a CO2 laser with a power rating of 30W or above is recommended for cutting or engraving plastics.

Fiber lasers, on the other hand, cannot be used for cutting or engraving but can be used for laser marking certain plastics.

Laser Wavelength

A laser with a wavelength in the range of 9.5 µm to 10.6 µm is best suitable because plastics have a high absorbing property for laser energy in this range.

A CO2 laser with a wavelength of 9.5 µm to 10.6 µm can be used for engraving and cutting almost all the plastics that are safe for laser processing.

Whereas, a fiber laser with a wavelength of 1.06 µm is only suitable for laser marking certain plastic materials.

Cutting Speed

The cutting speed of a process depends upon various factors such as laser power, thickness of the material, and type of material being cut.

A slow cutting speed for plastics results in a smooth cut with a good surface finish.

Generally while cutting a 1/5" (5mm) thick plastic material with a 30W CO2 laser, a cutting speed of 0.2 inches/sec (5mm/sec) gives good results with a smooth edge.

Similarly, the recommended laser power for engraving is around 15% with a speed of around 12 inches/sec (300mm/sec).

Working Table

Laser-cutting transparent plastics can sometimes lead to a 'flashback'.

These flashbacks can cause unwanted defects in the back of the workpiece and a honeycomb table can be used to overcome this problem.

A honeycomb table reduces the surface area of the work table, thereby reducing the chances of a flashback.

Air Assist

A low-pressure air assist is recommended for laser-cutting plastic that keeps the temperature under control while providing enough time for a flame polished edge to form.

Exhaust System

Almost all plastics generate unpleasant fumes when vaporized by a laser cutter.

Depending upon the type of plastic, these fumes can sometimes be harmful to humans, especially when exposed to them for a long time.

In some cases, like acrylics, the vapors produced by the burning of material can be inflammable and catch fire.

Therefore, a good exhaust system is necessary to keep these vapors away from humans and the workpiece.

Best Laser Cutters for Plastics

Depending upon the laser power, performance, and material capability, here are some of the best laser cutters that give good results with plastics.

Glowforge Plus

The Glowforge Plus offers a work area of 19.5” x 11” with a 40W CO2 laser that can cut, mark or engrave a variety of plastics.

High power CO2 laser combined with a high precision of 0.001 inches makes it ideal for cutting and engraving intricate designs on various plastic materials.

The built-in air assist feature improves the overall performance of the Glowforge Plus and enables it to give good engraving results.

It also offers features like auto-focus and built-in cameras that help in the easy adjustment of the cutting layout.

OMTech DF0812-40BG

Orion Motor Tech (OMTech)-40BG has a comparatively smaller work area of 8” x 12” and can work on workpieces with a maximum thickness of 2.5”.

It offers a 40W CO2 laser with a water cooling system that enables continuous usage for long period without any overheating issues.

The dedicated exhaust system facilitates the safe disposal of harmful fumes away from the operator and workpiece.

Depending upon the type of plastic, it offers a maximum engraving speed of 1000 ipm.

OMTech provides a 2-year general warranty, which ensures a good build quality. However, the laser tube and power supply have a warranty period of only 6 months.

Beamo-FLUX

Beamo is a desktop laser cutter/engraver from FLUX that provides a work area of around 12" x 8".

It offers a comparatively low-powered, 30W CO2 laser that can perform through cuts on about 2" thick plastics.

The easy-to-use interface and built-in camera setup makes it a very handy device for beginners.

It comes with the Beam Studio software for computers and the Beam Go app that can be used to directly start the engraving/cutting from a smartphone.

Final Thoughts

Plastic, with its high durability and availability in different colors, has become extremely popular in laser cutting industry.

Most plastic industries have switched to laser cutting because of its ability to perform highly precise and complex cuts quickly.

To perform laser cutting safely, it's important to know about the nature of the plastic being used and its reaction to the laser process.

Irrespective of the type of plastic used, make sure to wear laser safety glasses when near a working laser machine.

With a good laser cutter and a proper exhaust setup, you can start making plastic projects that you can sell for a profit.

Laser Cutting and Engraving other Materials

Check out these guides on laser cutting some popular materials.

MaterialLink to Guide
PaperLaser Cutting Paper
AcrylicLaser Cutting and Engraving Acrylic
AluminumLaser Cutting and Engraving Aluminum
LeatherLaser Cutting and Engraving Leather
PolypropyleneLaser cutting polypropylene
BrassLaser Engraving Brass
FabricLaser Cutting Fabric
FoamLaser Cutting Foam
PlywoodLaser Cutting Plywood
GlassLaser Cutting Glass
VinylLaser Cutting Vinyl

Laser Cutting Guides for other Materials

Frequently Asked Questions (FAQ)

What is a flashback?

Flashback is the phenomenon wherein the laser passes through the material being cut and reflects back off the work table and burns the underside of the workpiece. This can cause the workpiece to get welded onto the work table and form a defective surface.

What is the difference between laser engraving and marking?

The major difference between laser engraving and marking is that laser engraving removes some layers of the material in order to make a visible mark or design on the material surface. Whereas, laser marking is a process in which only the surface layer is affected. It does not necessarily involve the removal of material, in some cases, laser marking takes place just by decolorizing the surface of the material.

Can diode laser be used to cut plastics?

Yes, a diode laser can be used to cut plastics. Although low-powered diode lasers are more suitable for engraving plastic materials, they can also be used to cut very thin sheets of non-transparent plastics in multiple passes.

About John

Hey I'm John. I talk about CNCs and Power Tools at Mellowpine. I'm a CNC hobbyist who has been making CNCs and writing about CNCs for a while. I currently also work as a consultant for business owners and hobbyists setting up their own CNCs. If you have any questions related to CNC, I'd be happy to answer them. Reach me at john@mellowpine.com

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John

Hey I'm John. I talk about CNCs and Power Tools at Mellowpine. I'm a CNC hobbyist who has been making CNCs and writing about CNCs for a while. I currently also work as a consultant for business owners and hobbyists setting up their own CNCs. If you have any questions related to CNC, I'd be happy to answer them. Reach me at john@mellowpine.com

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