... Nitriding process,Bimetallic layer of this single screw and barrel. single screw&barrel for injection machine or extruder diameter: Φ15mm~ Φ250mmlength:300mm ... depth:0.45~0.7mm, surface roughness:Ra0.4, screw straightness:0.015mm, Chromium plated hardness:>900HV, Chromium layer thickness ... hardness: 60~70 Product types:almost all kinds of single-screw types can be made. Scope of application:PP, PE, ...