PP,PE,PVC,PET,ABS,PPR for Plastic Extruder Machine Conical Twin Screw and Barrel material: bimetallic layer PP,PE, ... PVC,PET,ABS,PPR for Plastic Extruder Machine Conical Twin Screw and Barrel Zhejiang Bohai Conical twin screw ... Nitriding Technology 2.Anti-corrosion and Wear-resisting Duplex Metal Spraying Technoloy3. we uses special alloy powders being sprayed and welded ...