Powder Coated Tough - Spring 2008 - (Page 28) Powder Technologies Photo courtesy Ford Motor Company The first U.S. auto body ES powder top coat attempt, based on a thermosetting polyester-melamine binder system, was made by Ford. erage and transfer efficiency based upon part type and geometry. By the mid1990s, further emphasis on controls technologies focused on more efficient material utilization and higher first-pass transfer efficiency through the use of part identification and gun triggering systems. Digital closed-loop flow control and monitoring systems followed, along with the use of color, and graphics-based user interface touch systems for ease of use. Also, special gun nozzles with digital valve and integrated pneumatic control designs have evolved from the continual need to simplify powder application. Today’s latest innovations are directed at coating faster with less effort, higher first pass transfer efficiency, and the capability of quickly changing colors. Examples of new cost efficient technologies include utilizing low velocity air to propel powder to the spray gun for depositing more powder on a part with less overspray. Another utilizes a twin air deck recovery concept providing a continuously clean floor and keeping the recovered powder flowing through the system so that very little is left when shut down for color change. Of early potential alternate delivery systems, ES powder bells and disks failed to provide sufficient powder velocity to effectively coat, for example, aluminum extrusions. Impact fusion on the edges of powder disks proved to be a detriment. The powder application potential for bells, along with radial fan and air horn gun nozzles, are actively being pursued today, and those that become commercialized are likely to be advanced versions of prior designs. Considerable effort was also devoted to powder coating cans at liquid coating speeds. The Weld-Arm system, shown in the photo above, was designed to ES powder coat the interior of three-piece tin-plated steel cans but required more powder material and equipment development to meet the very low coating weights and application cost requirements. Powder coating the welded side seam stripe of steel cans and easy open pull-tab lids has been commercialized world-wide for some time but powder's future in this industry appears limited due to the growing dominance of aluminum cans. 28 Powder Coated Tough http://www.wisconsininfraredsystems.com/pct http://www.wisconsininfraredsystems.com/pct
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