GB550563A - Improvements in and relating to moulds for use in pressing, die-casting and injection moulding operations - Google Patents

Abstract

550,563. Moulds for injection-moulding, die-casting etc.; electrolysis. FRANKENTHAL, A. O., LONDON & SCANDINAVIAN METALLURGICAL CO., Ltd., and KOHNSTAMM, E. June 10, 1941, No. 7346. [Class 87 (ii)] [Also in Groups XXII and XXXVI] The mould comprises an electrodeposited shell which constitutes the working face, and a backing of high melting point metal of which the metal next to the shell is sprayed on the shell and the remainder is cast on the sprayed metal. The shell may be of nickel or nickel alloy, the sprayed metal may be steel and the cast metal steel or cast-iron. In one example the cast metal is applied by passing it into a cup-like frame containing the sprayed shell. The mould may be electrolytically polished, and may be finally chromium plated. In making the shell, a pattern of phenol-formaldehyde resin or cellulose acetate is prepared. (If cellulose acetate is used, the parts of the pattern may be separately machined and then built up and stuck together by softening their abutting surfaces with acetone. If the entire pattern is coated with acetone it assumes a high polish which is later found in the electrodeposited shell. If the article to be formed by the finished mould is to have holes such as can be formed by pins projecting from the mould, steel pins are inserted in the pattern.) The pattern is degreased, silver coated by applying a solution thereto, and those parts where no nickel is to be deposited are cleaned with nitric acid, to remove the silver, or covered with a lacquer. The pattern is suspended by lacquercovered copper wires and rotated in the bath. The pins which were inserted in the pattern are tightly gripped by the deposited nickel. The pattern may be removed from the shell by dissolving, melting, burning or by mechanical means. U.S.A. Specification 1,912,889 is referred to.