Metal Finishing Guide Book

2012 Organic Finishing Guidebook Issue

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application methods POWDER COATING WITH ROBOTS AND DENSE PHASE TECHNOLOGY—A CRITICAL BLEND OF ADVANCED TECHNOLOGIES BY JOHN BINDER, MARKETING MANAGER, NORDSON POWDER COATING SYSTEMS, NORDSON CORP., AMHERST, OHIO The efficiencies of robotics designed specifically for painting—coupled with ad- vances in powder coating application and delivery technology through the use of dense phase technology guns, pumps and controls—provides greater pro- ductivity, higher repeatability and savings in daily powder coating operations. There was a time when powder coaters would adapt large welding robots to powder coating applications. The result was costly over-sized machines that did not lend themselves well to powder booths or precise powder paint applications. Often the window or opening for the robot would need to be sized to accom- modate the robot's painting motion. This caused higher than desired open booth area and up-sized collectors to allow for the necessary booth airflows to contain powder. Since then, robot technologies have progressed at a rapid pace. Today, there are robots designed specifically for powder painting that are smaller, more cost ef- fective and more precise with advanced part identification and controls that com- municate between the powder application equipment and the robot. As a result, powder coaters achieve higher productivity, greater repeatability – and savings! Robotics and powder coating—for greater process control and efficiency. Because of their virtually unlimited range of motion, robots are more flexible than fixed axis machines–be they single, dual or even triple axis machines. Since robots can maintain a gun-to-part distance that is more precise and flexible than fixed axis machine, they are able to contour a part as well as reach into hard-to-reach areas. This allows for more uniform coverage of the powder coating on all coat- ed surfaces. Additionally, a robot makes the same motion every time for each and every part, translating into less variability of the coating than if coated with a man- ual powder gun. Some might ask, then–what if the part is not hung correctly or the same way every time? Fortunately, there are robots available with sophisticated part iden- tification that can sense if a part to be coated is misaligned. In fact, robot controls when combined with powder system controls cannot only sense part orientation but can also sense part type and shape. This makes it possible for both the robot to know what motions to make and the powder gun to know what application parameters to use. In other words, part identification information can be sent to the powder gun controller such that the correct pre- sets for powder flow and electrostatic control match the part to be powder coat- ed. This same sophisticated part identification technology allows the robot to then powder coat the same parts with precise robot arm speed, repeatable motion and consistent gun-to-part distance parameters that are both optimized and harmonized with the powder coating equipment application settings. This trans- lates into consistent and repeatable part quality that eliminates powder waste, 102

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