About cast acrylic
Cast Acrylic is a thermosetting plastic with a superior surface finish, flatness and optical properties. It is also easy to break particularly if parts are small or thin.
Model making, point of sale, signs and display items, models, glazing, forming and fabrication and more.
Acrylic sheet is supplied with a protective plastic film on both sides. If only cutting then the film can be left on.
If cutting from, for example 3mm acrylic, try not to cut anything less than 3mm in width. It is of course possible to go smaller but this can make your components quite fragile which might not be suitable for the application.
Acrylic can be cut with a highly polished edge. To achieve this use a high PPI pulses per inch (high laser frequency) that melts the edges as it cuts. If you look closely at the edge and see vertical marks this may caused by the laser beam reflecting off the material support. Simply put spacers under the material to lift it of your support / honeycomb bed.
To cut materials thicker than 10mm it often helps to move the point of focus down by between a ¼ to a ½ of the thickness of the material This can also help reduce the angle on the cut edge.
All clear cast acrylic engraves with a milky white finish so if engraving an image you may need to invert it. Clear acrylic from Hobarts has the words “show face” on one of the protective films, for best results mirror your artwork and engrave on the opposite side. On one of our machines we get excellent results with a 50 watt laser using 20% power, 90% speed and 1000 PPI. Adjust the power proportionately for lower or higher laser power. The results achieved on solid colours will vary and won't have the same asthetic appeal as on clear.
If you just require vector engraving / scoring and cutting, it is possible to leave the protective film on both sides and mark through the film into the acrylic surface. Test first to make sure the film peels off cleanly and this helps to protect the top and bottom surface from marks.
Standard engraving settings for acrylic are very shallow, it is possible to engrave deeper but due to the slower speeds and higher power required. Deep engraving isn’t as aesthetically pleasing but can be useful to back fill with a variety of substances. Residues also tend to build up on the surface.
Raster engraving is not an absolute science in terms of depth specification so trial and error applies.
Engraving thinner acrylic
Heat from the laser can cause the sheet to warp during the engraving process on large sheets causing the focus of the beam to vary.
Cast PERSPEX is manufactured in accordance with ISO7823-1, this allow for the thickness range of 2 to 25mm to have a tolerance of + / -10% plus 0.4mm