November '20

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7 6 L A S E R E N G R A V I N G R E P O R T 2 0 2 0 G R A P H I C S - P R O. C O M PROCESSING TIPS When it comes to processing, there are a couple things to focus on: preventing burn and achieving a flame-polished edge. Before you begin processing, it is important to consider the capabilities and functions of the laser machine, most importantly, the power and velocity of the motion system during cutting. Slower is always better when processing acrylic, so reduce the speed and power if necessary to ensure that you do not overpower the material. It is also critical that the motion system can correctly interpret curves and change its direction smoothly so that your application's borders are precise. The focal lens used also plays a major role in your application's edge quality, in addition to laser power. Ideally, a 2.5-inch lens will work with thicknesses up to 3/8 to 1/2 of an inch. Anything thicker may require a lens with a longer focal length. As the focal distance increases, the amount of energy the laser provides will seem to decrease. Not having enough power means slowing the laser down sig- nificantly to cut through the material. Eventually, cutting slower no longer works because it increases the chance of flare-ups. With enough power, the acrylic can be cut at an optimal and production-friendly speed and still end with a polished edge. Focal point is also a major factor in producing pristine acrylic edges, primarily with thicker acrylics. Rather than focusing your laser on the surface of the material, as you would with other substrates or thin- ner acrylics (anything under a 1/4 inch), the focal point should be compensated so that it is one-third of the total distance. This can be done by adjusting the Z-offset in your printer driver. The laser head will be much closer to the surface of the material, but it will prevent any angular cuts and ensure a straight cutting path through the acrylic. Air assist, or the added flow of compressed air, optimizes acrylic cutting. It does not take much air pres- sure: 5 PSI or more depending L A S E R E N G R A V I N G R E P O R T 2 0 2 0 The focal lens used plays a major role in your application's edge quality, in addition to laser power.

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