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 ... Depth1.5mm-3.5mmWarranty period:2-4years(Depends on the plastic raw materials)Bimetallic: much longer lifetime.Nitriding timeOver 180 hours ...