A plasticating screw including a grating mixing section provided to
enhance mixing of incompatible materials. The screw includes a mixing
section including an inlet groove having a closed distal end, a discharge
groove circumferentially spaced from the inlet groove, the discharge
groove having a closed proximal end. Located between the inlet groove and
the discharge groove is a land region is including at least one grating
element that includes a plurality of grooves extending between the inlet
groove and the discharge groove.