accessories of screw and barrel 1)Depth of nitration case:0.5-0.8mm 2)Hardness of nitration:HV900-1060 (HRc56°-65°) 3)Roughness of the surface:Ra 0.4μm 4)Screw straightness: 0.015mm/m 5)Chrome plating thickness: 0.01-0.1mm 6)Fully hard screw(wear-proof, corrosion-proof, heatproof, high-pressure proof and high-speed proof):HPT1 HPT2 HPT3 7)Suitable plastic material: PP,PE,ABS,AS,PS etc 8)Material: SACM-645, SCM440, 38CrMoALA