In this type of extruder the screw/barrel/pin combination gives great flexibility due to very good mixing & dispersive action on the compound being transported down the extruder barrel. The arrangement of the pins in the barrel divides the material being transported in the rotary laminar flow along the screw flights. The material undergoes flow division and shifting with only low shear rate, providing mixing and homogenizing without excessive thermal overstressing. The repeated division and rejoining of the material streams constantly creates new surfaces, to give intensive mixing and breakup of the laminar flow, and provides heat interchange between the rubber particles. Energy absorption is claimed to be low and the machine is self cleaning. If necessary a mixing zone portion can also be machined into the screw to improve the productivity when difficult natural rubber stocks are being processed