CO2 lasers are ideal for cutting and engraving acrylic workpieces with precision. They allow you to produce a variety of products such as illuminated signs, fashion accessories, displays, and home décor. Below are a few guidelines for selecting the right materials and laser settings to achieve optimal results.
Acrylic material is generally available in either cast (GS) or extruded (XT) versions. In principle, both types of acrylic can be easily cut or engraved using a laser. However, cast and extruded acrylics react differently to processing.
Cast Acrylic (GS)
Cast acrylic is created by pouring a liquid acrylic mass between two glass plates. The liquid is then polymerised, resulting in a homogeneous, tension-free material. Due to this manufacturing process, the thickness "tolerance" (i.e. variability) of cast acrylics is significantly higher (approx. ±15%) than that of extruded acrylics. Therefore, it is not uncommon for two seemingly identical cast acrylic sheets to have slightly different thicknesses. The cast acrylic production process is also costlier than that of extruded acrylic. Hence, the former tends to be more expensive.
Laser cutting a cast acrylic sheet creates burn-free edges on both of its sides. In addition, laser engraving this material yields exceptional results (see the image directly above). Notice the engraving clarity on the cast acrylic workpiece.
Extruded Acrylic (XT)
Extruded acrylic is produced through an extrusion process, in which an acrylic mass is pressed through a "die" (a mechanism that is similar to a nozzle). The process resembles how cake frosting is pressed through a piping bag tip.
This manufacturing method gives the extruded acrylic different mechanical properties across its surface. In addition, it has a lower thickness tolerance (±5%) than cast acrylic. When extruded acrylic is cut with a laser, flame polished edges are created, which tend to be sharper on one side of the material.
Extruded acrylic has a lower production cost, and is thus economical when produced in high volumes. As a rule of thumb, processing extruded acrylic requires less laser power than does equally thick cast acrylic material. Laser engraving extruded acrylic is not recommended due to the unclear, matte grey finishing (see the image above).
All Trotec CO2 laser models are well suited to processing acrylic. For instance, both the Speedy 100 and SP3000 systems can cut and engrave the material with a high degree of accuracy and efficiency. There is variation, however, in the processing speed and the quality of the results (depending on the specific lens and laser power employed).
Laser Power Level
The laser power required for cutting acrylic depends on the workpiece thickness and your desired productivity. To efficiently process acrylic sheets, we recommend a laser power of 60W or more.
To achieve a high-quality cut, the general rule for processing acrylic is 10W of laser power per 1mm sheet thickness (maximum thickness of 20-25 mm).
Selecting the Correct Lens
Selecting the correct lens is essential to efectively cutting acrylic. Generally, the thicker the material, the longer the required focal lens length.
|Material Thickness||Speedy Series||SP Series|
|thin acrylic sheets |
< 5 mm
|2" lens||2,5" lens|
|thick acrylic sheets |
> 5 mm
|2,5" lens||5" lens|
Move the Focal Point to the Material Interior
For acrylic materials thicker than 6 mm, we recommend moving the laser's focal point to the interior of the material. This adjustment will result in an even, homogeneous cut.
The following guiding values apply:
- Shift the focus level so that it is about 1/3 of the material's thickness
- For 6 mm acrylic, the z value would be -2 mm
Selecting a Nozzle and Adjusting the Air Assist Settings
When cutting acrylic, you should opt for a short nozzle with a large hole diameter and reduce the Air Assist settings to a maximum of 0.2 bar. That gives the material enough time to cool off - and glass-clear edges result. In contrast, if a nozzle with the small diameter is used or the air pressure is too high, the result is a dull, milky cutting edge because the material cools off too quickly.
Selecting the Correct Lens
Selecting the correct is essential to cleanly cutting acrylic. Generally, the thicker the material, the longer the focal length of the lens should be.
Selecting the Correct Work Table
Selecting an appropriate laser work table is an important criterion for achieving optimal acrylic cutting results. The recommended work table depends on the size of your application. For example, the Acrylic Slat Cutting Table for Trotec's Speedy series is ideal for cutting acrylics that are 0.2" or thicker and parts that have a 4" (or greater) width. The table design prevents kick-back when cuts are being made. For parts having a shorter width (less than 4"), we suggest either the Acrylic Cutting Grid Table or the acrylic grid overlay on the Vacuum Table, as the workpieces remain in a flat position after being cut.
On the other hand, the Acrylic Cutting Grid Table for Trotec's SP series is specially designed for cutting thin acrylics (1/3'' or thinner).
|Cutting Table||Material Thickness||Size of Parts|
|Acrylic slat cutting table||Acrylic sheets > 6 mm thick||Parts that are cut wider than 100 mm|
|Acrylic grid cutting table||Acrylic sheets < 8 mm thick||Parts that are cut smaller than 100 mm|
Adding an Exhaust System
Using an appropriate exhaust system is indispensable for cutting or engraving acrylic. Debris and vapours are often formed, and it is strongly advised that they be removed via exhaust suction to ensure high-quality processing. Furthermore, sufficient ventilation enhances laser operation safety, as debris can ignite and cause flames. Laser machines should never be left operating unattended.
Acrylic requires a higher frequency when being laser cutting compared to several other materials, such as wood. A higher frequency directs the laser beam's more energy evenly onto the material's surface. This causes an even melting of the cutting edges which creates a clear, flame-polished edge.
- For processing cast acrylic (GS), we suggest a frequency of 5,000-20,000 Hz
- For cutting extruded acrylic (XT), a maximum frequency of 5,000 Hz is suggested
If the cutting speed frequency is too low, fine ridges (so-called "chatter marks") become visible on the cut edges. To prevent this effect, adjust the frequency level accordingly. However, if the cutting speed is too slow, this can result in an increased risk of fire.
In short, determining the ideal parameters for your application is imperative to working with acrylic in a safe and efficient manner.
The saying "less is more" applies to engraving acrylic. When only the surface of the acrylic is scratched a solid white engraving is created. If an excessive amount of power is used, the etchings will be deeper, although they will not be as defined.
TIP: Engraving on the Reverse Side
Engraving the acrylic on the back gives the final result a higher quality and the engraving is better protected against external influences. Even with printed acrylic, the product looks better when engraved on the back.
NOTE: . You can do this either by using the "flip" function on your graphics program or by adjusting your printer settings when sending the job to JobControl®, SpeedMark®, or Rayjet Commander®.
Minimum Number of Nodes
The cutting contour should contain as few nodes as possible. This allows the laser to process the workpiece without making unnecessary stops.
Selecting the Cutting Start Point
The point at which a laser beam first hits a material's surface tends to be particularly notable, especially if this point is positioned on a straight line or on the centre of a curve. That is why a start point should always be situated in an unnoticeable corner. This point is also called a "lead-in."
The thicker the acrylic material used, the better it is to define the lead-in outside of the cutting or engraving area. The lead-in should be located roughly 3-8 mm outside of the finished contour, and it should be drawn so that the laser beam will move to the contour in a straight line. You can draw this lead-in easily using your graphic program. Alternatively, you can use Trotec's supplementary software package, TroCAM, to prepare your design lead-ins.
Defining the Cutting Sequence
If many small objects are being cut within a relatively small area, that portion of the acrylic material is excessively heated. In turn, there is an increased risk of flame formation. If you would like to cut many small graphics from one large sheet, we recommend that you arrange the individual parts so that the material can cool off in between cuts.
The cutting sequence can be reviewed on your graphic program (CorelDraw, Adobe Illustrator) in the level window and is always processed from down to up.
Trotec offers a large selection of cast acrylic materials, ranging from clear and transparent sheets to coloured sheets with various finishes (e.g., metallic, satin, frosted, matte).