screw and barrel for rubber machine 1.Technics: 1):Heat-treatment 2):Nitriding-treatment 3):Spray alloy coating 4):Hard-chrome electroplated 2.Technical parameter: 1):diamater:50mm-500mm 2):maxiumn screw length: 10000mm 3)barrel inner bore diamater:500mm 4)depth of nitration case:0.4-0.7mm 5)hardness of nitration :HV900-1060 6)roughness of the surface:Ra0.4 7)screw straightness:0.015mm