Abstract: An apparatus for simultaneously anodizing the heads of several aluminum pistons includes a plating tank with an array of apertures extending through one side wall, one aperture for each piston; a fixture on the wall providing a cylindrical bore aligned with each aperture adapted to receive a piston; and a plurality of actuators which, when pivoted and locked into alignment with the fixture bores, operate to secure individual pistons in their respective apertures. A masking/sealing assembly within each fixture bore ensures that each aperture is sealed upon the securing of a piston therein, with only the piston's head and peripheral land being placed in fluid communication with the interior of the plating tank. A remote storage tank provides a supply of an electrolyte which is circulated by a fluid supply network between the storage tank and the thus-sealed plating tank during electrolysis. After the desired coating is achieved, the electrolyte is drained from the tank.

Abstract: An apparatus and method for simultaneously anodizing the heads of several aluminum pistons includes a plating tank having an array of apertures extending through one of its side walls, one aperture for each piston; and means for securing the head of each piston in its respective aperture. A seal disposed in each aperture ensures that the aperture is sealed upon the securing of the piston therein, with only the piston's head being placed in fluid communication with the interior of the plating tank. An acid electrolyte is directed into the plating tank through electrically-conductive sparging nozzles positioned therein opposite the heads of the pistons, thereby forming an electrolytic cell with the pistons as anodes and the sparging nozzles as cathodes. A power supply simultaneously applies a current to the cell, i.e., across the electrolyte via the pistons and sparger nozzles, to effect electrolytic coating of each piston's head.

Abstract: An improved electrical power control apparatus and method for use in an aluminum anodizing system includes a pulsed DC power supply and an automatic switchable shunt discharge unit connected in parallel across the anodizing cell. The cell, consisting of an anode, the aluminum part or workpiece being anodized, the electrolyte bath of sulfuric acid or the like and the cathode, forms and inherent capacitance that retains charge when pulsed with positive current flowing into the workpiece through the anode from the power supply. Between positive current pulses produced by peridoic firing of the SCRs in the power supply, the automatic discharge unit shunts the accumulated charge from the anode to cathode, thereby discharging the inherent capacitance. This markedly lowers average DC processing voltages, reduces the chance of damage to the workpiece due to overvoltage, reduces processing time, and can improve the quality of the anodized coating.