Cutting acrylic glass is an art form in itself. It is not just cleanliness at the processing station or reworking of the cut edges that makes the task challenging, there are also two completely different versions of acrylic glass that are relevant for laser cutting: extruded and cast.
Purely mechanical processing often reaches its limits here, for example, due to vibrations or unclean cut edges. eurolaser from Lüneburg, therefore, recommends for all those who process the thermoplastic to cut with a laser. The advantages of laser processing and the resulting non-contact cutting: clear, smooth cut edges without reworking, no breakage or waste and no dirt. Therefore there is no subsequent cleaning effort.
Acrylic glass, polymethyl methacrylate (PMMA), is a synthetic, transparent thermoplastic material. Since PMMA can be thermoformed, it is ideal for laser cutting and engraving. The main areas of application are in the advertising industry. But the CO2 laser machines from eurolaser are also used for signage and labels. The laser cutters process clear, coloured, structured, silicate-coated, and even mirrored acrylic glass. eurolaser also cuts and engraves both extruded and cast PMMA. With cast PMMA, the laser produces optimum cutting edges and particularly well visible and high-contrast engravings due to a significant colour change in the engraved areas.
Setting the cutting parameters for smoke-free edges
The challenge, especially with solid-colored acrylic glass, is clean cutting without any smoke traces on the edges. eurolaser, therefore, offers its customers a large number of parameter settings so that the cut edges do not have to be further processed afterward. The fine adjustability of the parameters for the machine control is a unique selling point of eurolaser. The setting options range from the lower beam diameter to adapting the laser frequency and the excess power required for the acrylic ut to adapting the processing speed for corners. Also, with the help of eurolaser’s control software, so-called lead-ins, including approach flags, can be programmed for particularly smooth and smoke-free edges. In this way, the user ensures that the laser does not laser twice or even several times at an interface. Last but not least, the software, which eurolaser always supplies, has a special acrylic mode with which these parameters can be set up.
Cast versus extruded PMMA
Thomas Armbruster, Marketing Manager at eurolaser: ‘We can cut or engrave both types of material excellently. It should be noted, however, that the two variants sometimes behave differently. Therefore, a basic understanding of the differences is useful. Especially when it comes to choosing the right acrylic material for the specific application.’
Acrylic glass is manufactured in two different processes, whereby the manufacturing method creates different material properties. For cast acrylic, the manufacturers run the PMMA as a liquid mass between two glass plates. The result is a very homogeneous, stress-free material with constant mechanical properties. The other material variant of PMMA is produced by extrusion. In this process, the acrylic mass is pressed through a nozzle. The nozzle opening determines the desired thickness of the material after solidification. Thomas Armbruster explained, ‘Extruded acrylic is generally cheaper than its cast counterpart, which makes it particularly attractive for large batch sizes and series production.’
Acrylic glass cutting with laser: “Only advantages”
‘Our laser cutting systems for cutting and engraving PMMA are designed for both manual and industrial use,’ says Armbruster. ‘With different processing surfaces to match the application or standard panel sizes. We have very special table mats for optimal acrylic cutting without reflections.’ The laser machines are also characterised by a very high level of precision that could hardly be achieved with mechanical processing. The contactless cutting and engraving means that the acrylic glass does not have to be fixed on the workbench. Vibrations in the material as in mechanical processing are avoided so that the risk of breakage is excluded. And to be even more careful with the acrylic, it can be processed with protective film. The laser simply cuts through it.
‘The quality of the cut edges is unsurpassed. And that without the further refinement step of flame polishing, which is necessary, for example, when sawing. Besides, there is practically no tool wear with our lasers, which ensures a consistently high cutting quality over the entire lifecycle of our machines.’
As final features of the laser cutting systems, Armbruster also lists the practically radius-free cutting of inner contours for all material thicknesses, automatic position detection with already printed acrylic glass by a camera and the problem-free extraction and filtering of PMMA vapors directly in the machine. ‘Ultimately, laser cutting only offers advantages over conventional processing methods,’ summarised Marketing Manager Armbruster.