... ! Harden steel with HRC50-67, Cutting speed, 50-150 m/min; Feed, 0.05-0.12 mm/rev; Cutting deepth, about ... gray cast iron with HB about 200, Cutting speed, 500-1000 m/min; Feed, 0.1-0.5; Cutting deepth, about 3 ... cast iron with HRC50-64, Cutting speed, 50-100 m/min; Feed, 0.1-0.3 mm/rev, Cutting deepth, about ...