ELECTRIC-FIELD MODELING FOR ELECTROSTATIC POWDER COATING OF A CONTINUOUS FIBER BUNDLE

The application of electrostatic powder coating technology to the proc essing of thermoplastic composites is discussed. An electrostatic powd er spray gun is used to deposit polymer powder on a continuously movin g glass fiber bundle. The glass fiber bundle is locally spread in the region of powder deposition to expose the filaments. A three-dimension al finite element model is presented for predicting the electric field strength due to the applied corona electrode. The model provides the spatial variation of the electric field vector for the specific spray process geometry, Corona voltage, corona electrode height, fiber bundl e spreading, and space charge density were varied in the model to pred ict their effect on the electric field strength. The finite element re sults display the ''wrap-around'' effect of the electric field to the bottom surface of the fibers, Experimental results substantiate the el ectric field distribution along the length of the glass fiber bundle.