Abstract: A method of increasing the output of a mixing and kneading machine consisting essentially of a casing of fixed length having a screw shaft arranged in the casing and at least four mixing and kneading vanes; the casing being provided with kneading elements equal in number to said vanes and projecting radially inwardly on the inner wall of said casing and means for simultaneously rotating and reciprocating at least once per rotation the screw shaft within said casing; the method steps comprising the steps of doubling or tripling the diameter of the casing while simultaneously increasing the core diameter of said screw by an amount to maintain unchanged the difference between the casing diameter and the diameter of the screw and simultaneously reducing the screw speed about one half or about one third, respectively.