... 35 degree -HRC60~68, Co9%~12% -High aluminum coating drill bit -For high speed cutting 2 Flute High Speed Tungsten Carbide Drill ... .6.ZHY-600 series drill bit, grain size 0.4um, Co12%, HRC60, AlTiN coating, Kennametal material, for high speed cutting.7.ZHY ... -650 series drill bit, grain size 0.2um, Co9%, HRC65 ...