Abstract: An apparatus useful for the extrusion of high melting slippery plastic resins comprising a screw element which operates rotatably within a close-fitting barrel having cut into the interior surface thereof a shallow and narrow groove of the same hand and substantially the same lead as the screw element.

Abstract: A two-stage single screw apparatus and process for the extrusion of plastic resins, the first stage positively advancing the resinous material while in a highly viscous state with minimum blow-back and the second stage, through the use of a screw having multiple lead threads with a high pitch adapted to allow substantial blow-back to provide mixing and ultimate discharge of the resin through die means, providing precise metering and discharge of the molten resin through the die over a wide variation of die pressures.