Metal Finishing Guide Book


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time of the corona charge. In other words, more powder at a lower velocity means that more powder has a greater time to attract a charge as it passes through the corona field in front of the powder gun. When compared head-to-head with a manual spray gun and a venturi pump, the dense phase technology gun and pump will apply more powder, with fewer strokes, in a shorter amount of time. The ability of dense phase powder application to reduce gun-toFigure 1. In this schematic, a dense phase technolpart distance stands out as being ogy pump illustrates alternating cycles of the two more transferable to robot painting chambers, each containing two valves. 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 phase guns that allow them to match, and in some case, exceed 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. Figure 2. The gun-to-part distance of a dense phase gun is much closer to the part, making it the perfect powder coating tool for use with robotics. 196 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 sprayto-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 gun-to-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 oper-

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