Influence of process parameters in electrostatic fluidized bed coating

Experimental analysis of the electrostatic fluidized bed coating process of carbon steel thin sheets was performed using two different mesh-sized epoxy - polyester powders. In particular, systematic analysis of the influence of the operative variables on coating and process variability in the field of low film thickness (below 100 μm), was carried out, which for electrostatic fluidized beds has previously not been considered feasible. In this context, the effect of varying both the electrostatic and fluidized bed setting on the amount of the powder layer coating the work-piece surface was studied. In particular, exposure time, applied corona voltage, and airflow rate were found to influence the performance of the coating process significantly. Experimental results produced coating thickness trends consistent with theoretic expectations. In particular, effects on the coating process of both electric and aerodynamic forces, which in turn affect the powder particles drawn up to the work-piece surface could largely be predicted by examining experimental data. A set of 3D maps of the coating thickness achieved are also reported as they provide a useful tool to monitor the process in a 5-15 s time range, applied voltage from 45 to 90 kV, and flow rate from 3 to 11 m3/h. © 2005 Elsevier B.V. All rights reserved.