Awards & Engraving

March '20

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40 a-e-mag.com • A&E MARCH 2020 flashback effect that can leave tick marks on your acrylic piece. Raising the acrylic away from the hon- eycomb bed by placing it on standoffs while cutting helps reduce this problem. Stand- offs should be roughly 3/4 to 1 inch tall. If you still see flashback when using standoffs, apply additional layers of masking to the acrylic to help absorb the reflected beam before it hits the acrylic surface. Another issue that may occur during laser cutting is that the acrylic piece may have stick marks on the cut edges. Stick marks appear as matte spots on an other- wise flame-polished edge and are caused by the acrylic sticking together at the cut line as it cools down. Stick marks typically occur when the space between parts is too thin and flexes toward your piece from the heat of the cutting process. Another cause of stick marks is that the cutting speed is too fast. Ensuring proper spacing and reducing the cut speed of the laser should eliminate or significantly reduce the stick marks. Another issue that you hopefully have not encountered is a laser fire. Acrylic is flammable, and when not laser cut at the correct settings, it can easily catch on fire. Running your laser at the optimal settings is the best way to reduce your chances of fire, but fires are something that you should always be prepared for. It is crucial to always watch your mate- rial when laser cutting acrylic. Once the acrylic is on fire, there is not much you can do to salvage that piece, but catching it right away can save the rest of your sheet stock or even save your laser. LASER ENGRAVING ACRYLIC Just like cutting, when engraving acrylic, consider the power of your laser. Raster engraving is typically done at 300 DPI, and increasing the DPI can increase the level of detail that you can achieve with your engravings. When engraving clear acrylic, you can engrave the front or back of the piece, but I prefer the back for the depth it gives to those viewing your work. For the best results, make sure that you use cast acrylic. The carrier sheet should be pulled before engraving, but masking can be applied and engraved through if you need to paint-fill your engraving. Again, the recommendation is to start with the manufacturer's settings and then modify to achieve the desired result. Above: An example of flashback. Below: The standoff setup. Raising the acrylic away from the honeycomb bed by placing it on standoffs while cutting helps reduce the problem of flashback. Stick marks appear as matte spots on a flame-polished edge and are caused by the acrylic sticking together at the cut line as it cools down. Acrylic is flammable, and when the proper settings aren't followed, a laser fire can occur. Once the acrylic is on fire, there is not much you can do to salvage that piece, but catching it right away can save the rest of your sheet stock or even save your laser.

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