Investigation of epoxy powder coated galvanized steel substrate through electrostatic powder coating system

Abstract

This research deals with the optimization of an electrostatic powder coating by optimizing the combination of total volume of air with the powder output. Generally, the coating's thickness and uniformity are not at the optimum level. A thicker coating does not necessarily provide a good surface quality. This phenomenon is caused by the insufficient volume of air to support the powder reaching the workpiece. Furthermore, too much air also causes the air to blow off the powder on the workpiece. This research aims to identify the optimum combinations of variable parameters to produce the optimum thickness with the best quality by improving the transfer efficiency and specifically to minimize the amount of powder usage. The evaluation methods used to determine the level of coating quality were thickness measurement, Buchholz indentation test, cross-cut test, color visual and surface structure analysis. The instruments used to evaluate the testing samples were a coating thickness gauge, Buchholz indentor, multi-blade cutting tools, spectrophotometer and Scanning Electron Microscope. The optimum level was found when using the optimum combination of powder output and total air volume, which produced a complete single layer of coating film, having good quality in terms of thickness, adhesion, uniformity, indentation resistance and surface structure.