... /0.4um -Helix Angle 35 degree -HRC60~68, Co9%~12% -High aluminum coating drill bit -For high speed ... Standard 2 flutes high speed drill bit, high speed 2 flutes short flute drill bit with cooled(3xd), 2 Flute ... Co, the better wear-resistance.6.ZHY-600 series drill bit, grain size 0.4um, Co12%, HRC60, AlTiN ... material, for high speed cutting.7.ZHY-650 series drill bit, grain size 0.2um, Co9%, HRC65~68, ...