February '21

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If you want to use a CO 2 laser on metal, you need to first apply a metal-marking spray onto it. When the laser hits the coated surface, it creates a thermochemical reaction that bonds the spray to the metal, produc- ing a permanent black mark, says Dean. Other metals, like anodized aluminum, produce a nice white contrast when engrav- ing without applying a metal-marking spray first, Dean adds. Powder-coated metals can also be lasered. The laser vaporizes the paint and exposes the shiny subsurface beneath it. Most colored stainless steel mugs are pow- der coated. Leather is a great product for both cut- ting and engraving. Shops can laser engrave a logo onto leather for keychains or luggage tags and then cut them out. Set your laser to high speed, low power and it will produce a nice, charred mark on the leather which creates a high contrast, Dean states. Stone is yet another popular substrate for engraving. Granite and marble are used for headstones and monuments. Typically, the names of the deceased will be sandcarved onto the stone and then a photo or saying will be laser engraved onto it. It is much easier to engrave a picture or design with a laser than to develop a stencil for sand- carving, believes Smallwood. A 50- to 100-watt laser can engrave on granite and marble. Another big industry for engraving is bricks. Hospitals, schools, and even sports complexes sell engraved bricks to help raise funds for projects. In the past, those items were only sandcarved then painted. With a laser engraver, the intense heat turns the engraved area black, so the engraved area doesn't need to be painted or touched up down the road. "Bricks are a huge money- maker in the business," notes Smallwood. On the bigger side of things, Kern's lasers are used for many industrial purposes, like large point-of-purchase displays, shower and bathroom doors, lighting, and aero- space. Much of it is laser engraving UPC bar codes or parts numbers on ID tags, tools, and control panels. It's clear each substrate has its own set of 8 0 G R A P H I C S P R O F E B R U A R Y 2 0 2 1 G R A P H I C S - P R O. C O M If you want to cut materials or do more advanced techniques, such as 3D engraving, it is beneficial to have a laser with more power. (Im- age courtesy Kern Laser Systems)

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