ELECTRICAL CHARACTERIZATION OF A CHARGED WORKPIECE GROUNDED-SPRAYER ELECTROSTATIC PAINTING SYSTEM

In situations where paint resistivity is low, such as water-borne paints, it is not possible to use conventional electrostatic painting systems without isolating the sprayer, the fluid handling system, and the paint containers. An alternate technique is to apply high voltage to the workpiece and ground the sprayer. The work reported here evaluates the electrical characteristics of such a system and compares it with that of the conventional electrostatic spraying system using computer simulations. The results of the analysis show that a charged workpiece grounded-sprayer system will achieve a transfer efficiency that is comparable with that of a conventional electrostatic system. The results also predict an enhancement in the film build along curved surfaces and strong wraparound. These predictions have been confirmed experimentally. Furthermore, the analysis indicates that there will be no improvement in the paint deposition in recessed surfaces.