Laser Cutting and Engraving Acrylic: Tips and Tricks

Whether you're a seasoned professional or embarking on your journey into the realm of CO2 laser technology, engraving and cutting acrylic can be both exciting and challenging. In this guide, we've compiled our top tips to help you navigate every aspect of working with acrylic, from mastering the art of cutting thick Perspex to refining your engraving techniques and sourcing the best acrylic for your projects. Additionally, if you have any cutting or engraving tips for acrylic, we'd love to hear them!

What plastics can be laser cut?

Several types of plastics can be laser-cut or engraved using a CO2 laser cutter. Some suitable plastic types include:

Acrylic: Acrylic stands out as a top choice for processing thanks to its remarkable versatility, transparency, and ease of cutting. Available in an array of colours, thicknesses, and finishes, this material is ideally suited for an extensive range of applications.

Polyethylene: Polyethylene can be cut with a CO2 laser to produce a clean, non-discolored cut. However, due to polyethene's relatively low melting point, cutting and engraving can lead to localised melting around the laser beam path.

PVC: PVC is a widely used plastic known for its durability and chemical resistance. While PVC can be laser cut, it's important to note that cutting PVC releases chlorine gas, which is hazardous to your health when inhaled, and can cause damage to your laser machine, so PVC is NOT something we recommend laser cutting.

Polypropylene: Polypropylene is lightweight, flexible, and resistant to moisture. It can be cut and engraved, but similar to Polyethylene, the low melting point can result in localised melting around the laser beam path. When in doubt, test, test and test again. 

What is the difference between cast acrylic and extruded acrylic?

Cast acrylic is produced through a casting process by pouring liquid acrylic into moulds and curing it through heat treatment. This process results in sheets with uniform thickness and better optical clarity. Extruded acrylic, however, is made by continuously pushing acrylic polymer through a form and then passing it through rollers to achieve the desired thickness. This process produces sheets with inconsistent thicknesses of 0.4mm-/+ and minor differences in clarity and surface finish.

What is the difference between Perspex and acrylic? 

Perspex and acrylic are often used interchangeably. However, Perspex is actually a trademarked brand name for a type of acrylic sheet manufactured in Lancashire. Perspex® acrylic has been a leading brand in plastic since 1934. Acrylic, on the other hand, refers to the general category of thermoplastic. 

What is the best acrylic for laser cutting? 

The best acrylic for laser cutting depends on your specific needs and preferences, but cast acrylic is generally considered the top choice due to its uniform thickness and optical clarity. Additionally, we recommend sourcing acrylic with low chlorine levels. A tell-tale sign that you're laser cutting or engraving acrylic with high chlorine levels is that the laser beam will emit a green flame. Not only are the gases released toxic, but the acrylic tends to melt rather than vaporise, resulting in an unsightly finish.

Tips for Laser Cutting Acrylic

We've teamed up with our laser technicians to share our top tips for laser cutting acrylic: 

Enhance exhaust flow to cut thick acrylic effectively.

When laser cutting acrylic, we recommend turning your extraction system to the max. This airflow prevents flames from forming on the underside of the acrylic, which can result in unsightly discolouration around the cutting path. Additionally, to maximise the airflow from underneath the acrylic, we recommend blocking off any areas of the laser bed that aren't covered by your material.

Selecting the correct lens

Selecting the correct lens is essential when laser-cutting acrylic. The thicker the material, the longer the focal length of the lens should be.

If the laser machine's standard 2 inch focal length lens is being used, the maximum recommended thickness of acrylic is under 6mm. We would then recommend a 2.5 inch focal length lens for cutting acrylic between 6mm - 10mm. And for even thicker acrylic, above 10mm we would recommend using a 4 inch focal length lens to get the best results with the least amount of taper on your cut edge. 

The ideal laser bed for laser cutting acrylic

Choosing the appropriate laser-cutting bed is crucial for achieving flawless acrylic processing outcomes. Based on the size of your application, we suggest considering either a slat or cutting grid bed for optimal results.

Using a slat-cutting bed offers a notable advantage by effectively preventing flashback during the laser-cutting process. This feature makes it particularly well-suited for cutting thicker acrylic sheets, typically 6 mm or more in thickness.

Tips for Laser Engraving Acrylic

Our laser technicians' top tips for laser engraving acrylic: 

Engrave in layers

Engraving in layers enables you to capture finer details in your designs and helps to minimise heat buildup, which can otherwise cause melting or warping of your material. Additionally, although this will increase your processing time, engraving in layers will allow you to reduce the power of the laser, minimising localised melting around the edges of your design, resulting in a cleaner, crisper finish. 

Engrave on the reverse. 

Engraving acrylic on the reverse side of clear acrylic, also known as reverse engraving, will appear more eye-catching and impactful. Additionally, the engraving is better protected against external influences. 

How do you remove residue from engraved acrylic? 

It's common to observe an unsightly discolouration around the edges of your engraved design, especially when engraving clear acrylic. This residue can easily be removed with a cloth and an alcohol-based solvent, such as white spirit or sticky label remover. We recommend using a microfibre cloth, as unlike other cloths, the microfibre cloth will not scratch the acrylic. 

Do I leave the plastic film on acrylic when laser engraving?

For optimal results, we advise removing the protective adhesive film from the side of the acrylic you plan on engraving while leaving the film intact on the back to prevent scratching during handling.

We hope our cutting and engraving tips for acrylic will empower you to proceed with confidence on your journey into the world of CO2 laser technology. And remember, if you have any suggestions or tips of your own, we'd love to hear them!

Are you looking to buy an acrylic laser cutting machine? 

When choosing a suitable acrylic laser cutting machine, you'll want to take into consideration the following:

• Your budget

• The power of the laser

• The size and weight of the materials you're looking to process 

• What training is provided with the laser system? 

• Safety features

• Maintenance, repairs and replacement parts.

We have a brilliant guide to buying the best laser machine for your needs, where we explore each of these points in more depth. 

When uncertainty arises, don't hesitate to consult with our team of laser technicians. At Focused Laser Systems, we proudly stand as the UK's foremost laser machine supplier and repair specialist, prioritising affordability and reliability above all else. Our laser cutters embody decades of industry expertise at their core. Whether you're in need of a laser engraving machine for beginners or a large-format laser cutting machine, our laser systems are available in an array of bed sizes and power levels, ideally suited for various applications and industries, ranging from creatives and hobbyists to schools, universities, small businesses and manufacturing.