Mould obtd. by electroforming on workpiece - using alternate electroplated layers of copper and nickel to form strong laminated mould, which is then removed from workpiece

摘要

A workpiece is used as a pattern onto which alternate thin layers of different metal are electroplated, followed by removing the laminated coating. Each metal layer is pref. 0.25 mm thick; and the coating or mould pref. consists of alternate Cu and Ni layers. The Cu is pref. obtd. from an acid bath contg. 90 g/l Cu and used at 2.2-2.4 V and 4 A/cm2. The Ni bath pref. contains 60 g/l Ni, and is used at 60 degrees C and 4 V with 8 A/dm2. The electroplating time in each bath is pref. 2-2 1/2 h. Conventionally electroformed moulds are made using only very thin coatings which must then be reinforced, e.g. by casting a material onto the rear surface of the moul. The invention provides strong moulds with adequate rigidity so no reinforcement is required.