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