Nitriding process,Bimetallic layer of this single screw and barrel. Specifications of this single screw and barrel:diameter: Φ15mm~ Φ250mmlength:300mm~8000mmexternal diameter ... , twin-alloy hardness: 60~70Product types:almost all kinds of single-screw types can be made.Scope of application:PP, PE ... , EVA, ABS, PVC, APC, PMMA pelletizing, foaming,sheet and plate extruder etc. single screw and barrel