Inner hole roughness 0.1-0.8 um Inner hole size tolerance H8 Straightness 0.3-1.0/1000 UsageApplicable to hydraulic pressure, pneumatic cylinder,oil pump barrel, motor body, transmission shaft, etc.Quality Standard DIN 239, EN 10305 and ASTM A519 ProcessRaw materials- Cold drawn/rolled- Heat treatment(BKS)- Honed or SRB- packingSteel GradeST52/E355, ck20, ck45, 34CrMo4, SAE 1026, SAE4130,SAE4135, ...