Different Methods for Zinc Electroplating Process

Different Methods for Zinc Electroplating Process

Zinc electroplating of parts of fixed dimensions is carried out by different methods of handling - barrel and rack plating. In barrel plating, parts are handled in bulk, while in the rack method, pieces are handled separately by attaching them to a conducting fixture in the form of a wire, hook, or clip.

In practice bolts, nuts, nails, screws, washers and small articles in general are commonly zinc plated by the barrel method. After the perforated barrel, which is made of non-conducting material, is immersed in the electrolyte, enough of the articles, properly cleaned, are loaded in the barrel to fill it partially. The parts are in contact with the flexible metal conductors on the inside of the barrel and together they form the cathode of the cell. The anodes are suspended in the electrolyte outside the barrel and occasionally positioned partially to encircle it. The barrel is arranged so that it turns about its longitudinal axis. As it slowly rotates, the parts are tumbled over one another continually thus exposing fresh surfaces to the plating current and thereby assuming a uniform coating.

For larger parts that have to be individually handled, where volume is large enough, conveyor equipment is used to reduce costs. With this arrangement, products are moved by an endless chain or screw conveyor through all operations so that the only handling operations are those necessary to attach and remove them.