... )Roughness of the surface:Ra 0.4mm Bimetallic barrel barrel wall in a layer of 2-3mm welding ... plastic injection machines, 15-300mm single screw extruders, 30-130mm tapered and parallel double screw extruders, rubber machinery, and petroleum ... plastic injection machines, 15-300mm single screw extruders, 30-130mm tapered and parallel double screw extruders, rubber machinery, and petroleum machinery ...