Electrical characterization of a charged workpiece grounded-sprayer electrostatic painting system

In situations where paint resistivity is low, as it is with waterborne paints, it is not possible to use conventional electrostatic painting systems without isolating the sprayer, the fluid handling system, and the paint containers. An alternative technique is to apply high voltage to the workpiece and ground the sprayer. The electrical characteristics of such a system are evaluated and compared with those of the conventional electrostatic spraying system using computer simulations. It is shown that a charged workpiece grounded-sprayer system can achieve a transfer efficiency that is comparable to 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 is no improvement in the paint deposition for recessed surfaces