Abstract: A method of molding a disc substrate, includes the steps of: fitting a movable die and a fixed die for a disc substrate onto a movable platen and a fixed platen of a molding machine, respectively; bringing the movable die and the fixed die in close contact with each other through a mold closing operation where the movable platen moves through a mold clamping cylinder; filling a given quantity of melting resin into a cavity of the movable and fixed dies for the disc substrate from a nozzle of an injection unit through a screw within a heating cylinder in a state where a mold clamping hydraulic pressure is zero; and after the completion of the injection process, implementing a mold clamping pressure control of one stage or a plurality of stages by application of a mold clamping pressure, and simultaneously conducting a process of cooling a melting resin.

Abstract: An injection mold for disc molding such as in the manufacture of video or audio discs. The mold has a stamper removably clamped to one mold half by a rotating stamper holding ring. Both mold halves contain a plurality of clamping pins which selectively engage and hold slots in the holding ring. By rotating the holding ring, disengagement of the ring with the pins of the mold half carrying the stamper occurs simultaneously with engagement of the ring with the pins of the other mold half. Thereby, the stamper is released and may then be replaced.