★ nitride layer Depth: 0.5 to 0.8 mm
★ nitride hardness: 900 ~ 1000 HV
★ nitride brittle: grade 1
★ surface roughness: Ra 0.4 μ m
★ entire hard screw (wear resistance, corrosion resistance, high temperature, high pressure, high speed resistance): HPT1, HPT2, HPT3
★ bakelite dedicated nitride Screw