... plastic injection machines, 15-300mm single screw extruders, 30-130mm tapered and parallel double screw extruders, rubber machinery, and petroleum ... .015mm/m 5)hardness of the double alloys:HRC56-65 6)Fully hard screw(wear-proof, corrosion-proof, heatproof ... plastic injection machines, 15-300mm single screw extruders, 30-130mm tapered and parallel double screw extruders, rubber machinery, and petroleum ...