Abstract: A method is provided for the manufacture of record stampers having electroformed inner and outer edges of a predetermined configuration. In the disclosed method, a flat matrix is formed from a ductile metal. The inner and outer sections of the matrix are shaped into a form which is the mirror image of inner and outer edges desired be formed on the stamper. A metal, preferably a relatively hard metal, is then electroformed on the surface of the matrix in a preselected thickness required for the stamper. The resulting stamper is then stripped from the surfaces of the matrix. The stamper which is obtained will have electroformed inner and outer edges of the predetermined configurations.

Abstract: An improved cathode head is provided for use in the matrixing of masters, molds and stampers for use in the manufacture of molded records and discs. The cathode head of this invention has a disc shaped member on which a matrix to be replicated is to be mounted and an outer threaded ring which is screwed on the outer edge of the disc member to secure the outer edge of a matrix to be replicated to the surface of the disc shaped member. It has been found in accordance with this invention that the seal formed at the outer edge between the ring member, the matrix replicated and the disc shaped member can be substantially improved as compared to that of a prior art cathode head by using a seal having a right triangular shaped lead section which, in addition to providing a substantially improved electrolyte seal disc, allows the replica to be formed having a perpendicular outer edge.

Abstract: In order to provide an improved seal between matrixes and their replicas, as well as eliminating or substantially reducing the problem of premature separation of the replicas from the matrixes, a circumferential spiral groove of a substantially rectangular configuration is cut into the outermost circumferential area of the matrix. The rectangular spiral groove is cut beyond the portion of the matrix which will be used as the molding surface of the stamper. The rectangular groove is substantially larger than the V-shaped groove of audio records and is much larger than the V-shaped grooves used on high density information discs. Because of the larger size and the substantially rectangular geometric configuration of the grooves, the rectangular spiral groove forms a highly effective seal between the matrix and the replica.

Abstract: An improvement is disclosed in the matrixing process employed in the manufacture of molded records. The improvement consists of using an insert in the matrixing process which is secured to the center portion of the matrix to be duplicated prior to electroforming a replica on the surface of the matrix. Metal is then electroformed over the surface of the matrix and the insert to form the replica and the insert is thereafter used to apply force at the center portion of the replica to force it away from the matrix on which it is formed.