PREMIUM HSS MILL SPEED & FEED Stainless Steels RPM CHARTS Hardened Steels 430-550 Bhn Hardened Steels ... (High Speed Cutting) Non-Alloyed Steels Alloy Steels Cast Iron <430 Bhn Diameter RI /64 x 1/32 ... PREMIUM HSS MILL SPEED 4-Flute - Ball Nose - Long & FEED CHARTS Alloy Steels Tool Steels 285-430 Bhn RPM Material Hardness