Awards & Engraving

June '18

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8 • A&E JUNE 2018 Thank you, readers, for the positive input from the first installment of "Plastic Fan- tastic!" about plastic engraving sheet. The first article published in the February issue of A&E (page 20) covers the many varieties, colors, textures, and applications that this popular laser substrate has in our industry. This article focuses on best practices for engraving and cutting plastic sheet and how to produce professional results for your customers. ENGRAVING PLASTIC SHEET CONSTRUCTION Reviewing the basics of plastic sheet materials starts with understanding their construction. Comprised of two parts, a base and a cap material, plastic engraving sheet stock is engineered for optimum engraving and cutting results. An important fact about these plastic sheets is that they are thin. The cap material is super thin, measuring just a few thou- sandths of an inch thick. It is a combina- tion of the thin gauge and plastic formula- tion that gives this substrate the flexibility and durability that make it ideal for so many applications including plaque plates, awards, name badges, and signage to name just a few. These thin plastic substrates also have a downside: They are susceptible to the heat of the laser, which can generate undesirable distortion and warping. THE HEAT AFFECTED ZONE If you have worked with a laser system for any length of time, you are familiar with the focused heat energy it produces. By Mike Fruciano Mike Fruciano recently accepted the position of Market Develop- ment Manager at Coherent. Mike brings over 24 years of laser and laser materials expertise to the aerospace, automotive, and industrial markets he covers for Coherent. He can be contacted by email at mike.fruciano@ or by phone at 480-294-8859. Plastic Fantastic! Part 2: Best practices Heat Affected Zone It is this focused heat energy that produces the ability to vaporize the cap layer of the plastic sheet to reveal the base color. Cut- ting is also accomplished using the focused heat energy to completely vaporize all the way through the plastic sheet. The illustration to the left shows the cone-shaped laser that creates the small focus point. This is a similar effect to using a mag- nifying glass in the sun to burn onto wood. Most of us experimented with a magnifying glass and know that the smaller the focused spot is, the more intense the spot becomes, and soon smoke and fire appear. Modern lasers have accurate beam and focus control but also create heat energy near the focus spot called the Heat Affected Zone (HAZ). The key to creating profes- sional results with thin plastic sheet mate- rials is controlling the Heat Affected Zone. Controlling the HAZ is done using laser settings for resolution (DPI), pulse rate (PPI, rate, frequency), laser power, and speed. Working in concert and tuning of these settings reduces or eliminates melting, warping, and distortion from too much heat from the focused laser energy. Laser settings in general are always a compromise of productivity (speed) and quality. Take a scientific approach to tuning laser settings and only adjust one setting at a time and then evaluate the result. Adjusting multiple settings at one time can counteract each other and lengthen the settings tuning process. Keep a log of settings with notes on the results so you can easily see trends in the results and fine- tune settings. A graphic showing the cone-shaped beam profile with focus spot and Heat Affected Zone. ALL IMAGES COURTESY MIKE FRUCIANO

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