... HRC60~68, Co9%~12% -High aluminum coating drill bit -For high speed cutting 2 Flute High Speed Tungsten ... (3xd), 2 Flute High Speed Tungsten Carbide Drill Bit With Cooled(5xd).2.AlTiN coating, black, high ... , the better wear-resistance.6.ZHY-600 series drill bit, grain size 0.4um, Co12%, HRC60, AlTiN coating ... for high speed cutting.7.ZHY-650 series drill bit, grain size 0.2um, Co9%, HRC65~68, AlTiN ...