Application of an Electrostatic Spray Process to Filament Winding

Manufacture of thermoplastic composites is expensive due to the use of pre-impregnated materials. Powder processing shows promise as an impregnation technique for a cost-effective manufacturing process. The overall objective of this study is to develop a continuous process for impregnating and consolidating thermoplastic composites using powder polymers in a filament winding process. A negative corona electrostatic spray gun is used to charge and direct the powder to adhere to both sides of a spread fiber tow. The tows are then pulled through ceramic heaters to coat the fibers, and then consolidated via filament winding using hot nitrogen gas heaters. A novel on-line consolidation apparatus with opposing steel rollers mounted on air cylinders is used to consolidate via filament winding. A frame construction isolates the filament winder from the large consolidation forces in addition to allowing smaller diameter and longer tubes to be wound. A preliminary finite element thermal model tracks heat transfer mechanisms in the composite cylinder during processing and heating.