Abstract: An upper press block for a disc record press comprises a support member surrounding a mould member to which a stamper plate is fixed. Means for adjusting the axis of the stamper plate relative to the support member are provided by four lever arms evenly spaced around the mould member, each lever arm being pivotally mounted to the support member and engaging the periphery of the mould member. Each lever arm is disposed between two opposing cams which may be rotated to adjust the mould block position in a lockable manner.

Abstract: Stamper plates and backing plates in a tool for the pressing of video discs are recessed to permit the formation of an annular ridge which encircles the information region of a disc and is provided for use in the mechanical removal of a disc from its container. Apertures in an annular recess in a stamper plate are aligned with apertures in the associated backing plate to lead to a manifold which communicates with atmosphere. Air which may be present in the ridge of plastics material during the pressing operation thereby escapes to atmosphere, and blemishes in the ridge due to air entrapment are substantially avoided.

Abstract: An extruder control arrangement in which the time taken to deliver a known quantity of extrudate is maintained within closely controlled limits by feedback circuit which controls the rate at which plastics material is fed to the extruder.

Abstract: A record transfer press including an apparatus for trimming flash from a disc record, said apparatus having a relatively movable drive means and trimming head.

Abstract: A press element for a disc record press which is heated and cooled by the passage of hot and cold fluids is made from materials of different thermal conductivity so that parts of a surface on which a matrix is attached in use which are further from a fluid channel are related to material of higher thermal conductivity than those parts of the surface which are nearer to a fluid channel.