Metal Finishing Guide Book

2013

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The ability of dense phase powder application to reduce gun-topart distance stands out as being more transferable to robot painting than all other benefits. Due to the lower velocity and relatively shorter "throw" of the powder as compared to conventional venturi pump technology, the gun-to-part distance for dense phase powder coating guns becomes shorter. Please note: this does not mean that the effective fan pattern width is reduced as there is a wide range of nozzle configurations for dense Figure 1. In this schematic, a dense phase technology phase guns that allow them to pump illustrates alternating cycles of the two chammatch, and in some case, exceed bers, each containing two valves. the maximum fan pattern width of powder guns using conventional venturi pumps. Similarly, the same features and benefits of dense phase delivery pumps that make them useful with robots also makes them perfect for use with automatic guns. Dense phase technology and robotics—a perfect marriage of advanced technologies. As more and more powder coaters adopted dense phase technology for use with manual guns and fast 20 second color changes, it was a natural evolution to adapt this same technology to automatic guns. This was done not only for use in spray-to-waste systems, but also for use in reclaim systems that recovered the over-spray and reused it. It was determined during this evolution that the decreased gunto-part distance that applied to the manual guns, not only applied to the automatic gun as well, but also lent itself very well to the combination of an dense phase gun on a robot. Because of the almost infinite movement and longer reach of a robot (as compared to a manual operator), the dense phase gun could track very close to the part at a high speed, resulting in exceptional powder uniformity, better standard deviation of film build, reduced over-spray, and reduced cycle time. Coupled with AFC (automatic feedback control) current limiting technology, this Figure 2. The gun-to-part distance of a dense phase allowed the robot to not only congun is much closer to the part, making it the perfect tour the part quickly, but to reach powder coating tool for use with robotics. back into cavities and coat them 162

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