Laplacian fields of bell-type electrostatic painting systems

A Laplacian model (i.e excluding the space charge effect) for a bell-type electrostatic painting system has been developed using the charge-simulation technique. The study involved the evaluation of the electric field in the space between the bell and the paint target as well as at their surfaces. An investigation was also conducted to determine the variations that occur to the electrical parameters when: (1) the bell-to-target spacing is changed; and (2) the size of the target is varied. Finally, results are reported for incorporating the charge-simulation model in a routine that predicts the paint-droplet trajectories from the bell to the target. The results of the developed model predict that the field-dependent droplet charging mechanisms, which are required to ensure strong electrical forces on the droplets, will be insensitive to the size of the workpiece and the spacing between the bell and the target. However, the magnitude of the fields at the workpiece, which account for the enhanced deposition in electrostatic painting, are shown to be highly dependent on these parameters