... 4nitriding,spray coating,etc. Specification of this parallel twin screw and barrel:Length-diameter ratio:L/D=18~ ... 25The screw compression ratio should be decided based on ... depth:0.5~0.8mm, surface roughness:Ra0.4um, screw straightness: 0.015mm, Chromium plated hardness: >900HV, ... by the machine set which is with this screw and barrel. The pelletizers are alsocan be fitted ...