Hydrodynamic wire coating using a tapered bore pressure unit

In the conventional process of wire coating, the wire is either dipped in the coating material or is coextruded along with the coating material. Apart from dipping or coextrusion methods, there is another innovative method called hydrodynamic coating in which the polymer melt is used as a pressure medium in a pressure unit. The wire size is less than the smallest bore of the pressure unit. The wire coating thickness and quality depend on the wire speed, polymer viscosity, polymer melt temperature and the gap between the wire and exit end of the die. In this paper, results of experimental investigation are presented by comparing the coating quality on galvanized mild steel wire using molten Nylon 6 is used as the coating material in a tapered pressure unit at different temperatures and backpressures. The coating thickness and quality are also discussed for different wire speeds of up to 12 m/s.