... Nitriding process,Bimetallic layer of this single screw and barrel. single screw&barrel for injection machine or extruder diameter: Φ15mm~ Φ250mmlength: ... depth:0.45~0.7mm, surface roughness:Ra0.4, screw straightness:0.015mm, Chromium plated hardness:>900HV, Chromium layer thickness ... made. Scope of application:PP, PE, PS, EVA, ABS, PVC, APC, PMMA pelletizing, foaming,sheet and plate extruder etc.