Acrylic is a durable material available in a wide range of thicknesses and colours. It can be used to produce a variety of objects such as illuminated signs, fashion accessories, product displays, and home décor pieces.
Below are a few guidelines to achieve exceptional laser cutting and engraving results.
Cast Acrylic (GS)
Cast acrylic is created by pouring a liquid acrylic mass between two glass plates. The liquid mass is then treated to produce a homogeneous, tension-free acrylic sheet. 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 comparatively costlier, and hence cast acrylics tend to be more expensive.
Laser cutting a cast acrylic sheet produces burn-free edges on both of its sides. In addition, laser engraving this material yields high-quality results (see the image directly above). Notice the engraving clarity on the cast acrylic sample.
Extruded Acrylic (XT)Extruded acrylic is created by pressing an acrylic mass through a "die" (a mechanism similar to a nozzle). The process resembles how cake frosting is pressed through a piping bag tip. This production method gives the extruded acrylic different mechanical properties than cast acrylic. In addition, it has a comparatively lower thickness tolerance (±5%). 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. When extruded acrylic is cut with a laser, flame polished edges are created, which tend to be sharper on one side of the material. Laser engraving extruded acrylic is not recommended due to the unclear, matte grey finishing (see the image above).
All Trotec CO2 laser systems are well suited to processing acrylic. For instance, models in the Speedy SP series can cut and engrave the material with a high degree of precision and efficiency. Depending on the specific lens and laser power employed, however, there is variation in the processing speed and the quality of the results.
The laser wattage required to cut acrylic depends on your specific workpiece thickness and production volume. At the very least, we recommend a laser power level of 60W.
To achieve a high-quality cut, the general rule for processing acrylic is 10W of laser power per 1 mm of sheet thickness (maximum thickness being 20-25 mm).
An appropriate focal lens is essential to making clean cuts on acrylic. Generally, the thicker the acrylic, the longer the required focal lens length.
|Material thickness||Speedy Series||SP Series|
|thin acrylic sheets |
|2" lens||2,5" lens|
|thick acrylic sheets |
> 5 mm
|2,5" lens||5" lens|
We recommend moving the focal point to the interior of the material when it is more than 6 mm thick to achieve an even, homogeneous cut.
The following guiding values apply:
- Move focus to about 1/3 of the thickness of the material.
- For 6 mm acrylic, it would be a z value of -2 mm.
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.
Your laser's work table has a large impact on your acrylic cutting results and workflow. The "best" work table choice 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 > 6mm 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|
Having a high-quality exhaust system is essential to laser cutting and engraving acrylic. Debris and vapours are often formed when acrylic sheets are processed, and immediately suctioning residue from the work area ensures optimal results. More importantly, sufficient ventilation enhances laser operating safety, as debris can pose a risk to the user and bystanders. 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's energy evenly onto the material's surface. This causes the cutting edges to melt simultaneously. The result is 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 chatter marks from forming, adjust the frequency level accordingly. However, if the cutting speed is too slow, this can result in an increased fire risk.
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.
Engraving on the Reverse Side
As opposed to processing the front side of a transparent acrylic sheet, engraving a design on the reverse side has two main benefits: the design appears to be of a higher quality, and the engravings are better protected against damage (e.g., scratches). Trotec's TroLase Reverse allows you to incorporate different colours into your reverse-engraved design.
NOTE: Don't forget to horizontally flip your design. 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®.
Keep the Number of Nodes to a Minimum
The cutting contour should contain as few nodes as possible. This allows the laser to execute the design without making unnecessary stops.
Create a Lead-In
The point at which a laser beam first hits a material's surface tends to be particularly noticeable, especially if this point is positioned on a straight line or on the centre of a curve. Hence, the starting point should be situated in an unnoticeable corner. This distantly-positioned point is called a "lead-in."
The thicker the acrylic material used, the better it is to position the lead-in outside of the cutting or engraving area. The lead-in should be located roughly 3-8 mm outside of the design 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 graphics program. Alternatively, you can use Trotec's supplementary software package, TroCAM, to prepare lead-ins for your designs.
Define the Cutting Sequence
If many small objects are to be cut within a relatively small area, that portion of the acrylic sheet is excessively heated. In turn, there is an increased risk of flame formation. If you would like to cut many small pieces 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 graphics program (e.g.,CorelDraw, Adobe Illustrator).
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).