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Laser Cutting and Engraving Plastic-Expert Guide

Laser Cutting and Engraving Plastic-Expert Guide

Laser Cutting and Engraving Plastic-Expert Guide

Laser cutters can be used to cut and engrave 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 cut plastic workpiece
Laser cut plastic workpiece

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

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, using a CO2 laser with a power rating of over 40W is recommended.

Using diode lasers for cutting thick plastic will require multiple passes, and moreover, diode lasers cannot be used to cut clear plastics.

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

Step 1: Prepare the Design

When preparing the design for laser cutting plastics, it is important to understand that plastic is a heat-sensitive material that has the tendency to melt upon heating.

As a result, laser cutting intricate designs can increase the localized heat in an area, thereby causing the workpiece to melt.

Therefore, it is advised to minimize intricate details in the designs and set the cut order in such a way that allows the workpiece to cool down in between the cuts.

When using the multi-pass technique for a diode laser, it is advised to allow the laser to perform once complete pass before executing the second pass instead of performing multiple passes individually on each element.

This allows the workpiece to cool before beginning the second pass.

Step 2: Set Optimal Parameters

You can use a 40W CO2 laser to cut and engrave plastics. Apart from that, you can also use a diode laser to make clean cuts in a variety of plastics.

However, diode lasers are not suitable for cutting thick plastics, as they will require multiple runs, causing the plastic to melt and deform.

With my 55W CO2 laser, I was able to get clean cuts in 2mm thick plastic at 10mm/s and 60% power.

I was also able to cut through 8mm thick acrylic at 5 mm/s and 100% power.

Apart from that, you can use a fiber laser to engrave plastics, but it is not suitable for cutting them.

The optimal parameters for laser-cutting plastics will vary depending on the type of plastic used. Therefore, it is advised to perform test runs and identify the optimal parameters for your setup.

Step 3: Execute the Cut

Once you prepare the design and set the optimal parameters, you can execute the cut.

However, it is important to monitor the process as plastic can melt and cause a fire.

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.

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

1. 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 and low cutting speed are 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.

2. 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 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.

3. 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 can produce smooth cuts that do not require any additional finishing processes.

Whereas, a fiber laser is preferable for laser marking Delrin.

Laser cutting Delrin produces fumes that contain a small quantity of formaldehyde gas, which, can be harmful and requires a good ventilation system.

4. 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 is best suited 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 fiber laser produces excellent results with a high level of detail.

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

5. 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 is best suitable for laser cutting and marking mylar, but you can also get good results with a diode laser.

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.

6. 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.

While polyamides are easy to laser cut, they 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 suitable for laser cutting and engraving, 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.

However, if your application demands precise cuts on these plastics, you can use a Cricut to cut these plastics safely.

When compared to laser cutting, Cricut does not involve heating the workpiece. This eliminates the risk of generating harmful fumes.

1. 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, flooring, some synthetic leather, 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 the hydrochloric acid can damage the laser cutter equipment.

2. ABS Plastic

ABS or Acrylonitrile Butadiene Styrene is a thermoplastic that does not require a high laser power to be cut.

But laser cutting ABS produces harmful fumes of cyanide, and is therefore not suitable for laser cutting.

Apart from it, laser cutting ABS tends to melt the material and leave behind a gooey mess, which can be difficult to scrape off the work table.

However, with proper laser parameters and right setup, you can mark ABS plastics. This process involves heating the material just enough to oxidize and change its color rather than to vaporize it.

As a result, the mark is formed without releasing any harmful fumes or melting the workpiece.

3. 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 during laser processing.

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

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
PlasticLaser Cutting and Engraving Plastic
PolypropyleneLaser cutting polypropylene
BrassLaser Engraving Brass
FeltLaser Cutting Felt
FabricLaser Cutting Fabric
FoamLaser Cutting Foam
PlywoodLaser Cutting Plywood
Glass (cutting)Laser Cutting Glass
Glass (engraving)Laser Etching and Engraving Glass
Wood (cutting)Laser Cutting Wood
Wood (engraving)Wood Laser Engraving
GraniteLaser Engraving Granite
VinylLaser Cutting Vinyl
FoodLaser Engraving Food

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 Abraham

Hey I'm John. I write about Manufacturing, Metalworking, 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 Abraham

Hey I'm John. I write about Manufacturing, Metalworking, 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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