twin screw barrel/parallel screw and barrel for pvc,upvc,pe. We supply various types of screw barrels according to customer' ... steel,etcTechnology:nitriding treatment,alloy coating sparying,heat-treatment,etcAppliance:PE,PVC,PP,etc Technical index:Depth of Nitrated Layer: 0.5 ... .4um Hardness of Cr-coating Layer: ≥950Hv Thickness of Cr-coated Layer: 0.03-0.08mmHardness of Bimetallic Layer: HRC55-72 ...