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 ... on the screw's ridge,and uses different alloy and welding methods for the screw of different functions.Materials38CrMoAlA (JIS SACM645)SKD61 ...