Nitriding process,Bimetallic layer of this single screw and barrel. Specifications of this single screw and barrel:diameter: Φ15mm~ Φ250mmlength:300mm~8000mmexternal ... single-screw types can be made.Scope of application:PP, PE, PS, EVA, ABS, PVC, APC, PMMA pelletizing, foaming,sheet and plate extruder ... etc. single screw and barrel