Parallel double screw barrel for extruder Diameter 65-90mm Min.Order 1 set Materials 38CrMoAIA 42CrMo(JIS SCM440) 9Cr18MoV CW6Mo5Cr4V2 Discount Available Application PP,PS,PE Sheet,Profile,Pipe Payment Term T/T, L/C Technical Process 1.Rough Machining 2.Quenching and Tempering 3.Finish Machining 4.Nitriding 5.Spraying and welding with alloy power 6.Screw polishing Technological Parameter Roughness Ra 0.4um ...