Japanese cover developed tap of AU+SP coating helix with the place that make completely, because used the appearance design that already obtained patent protection, the performance discharging bits that improved tap of coating of this kind of TiN considerably, its characteristic is: ① was used withhold several complete teeth only in whorl part, the original figure that the others is half tooth (patent protection) ; ② has the effect that avoids blade of complete tooth collapse; ③ reduced tap torque and attrition to fight force; ④ can maintain whorl in tap oriented action, make tap stability undertakes; ⑤ can maintain the good performance that discharge bits. CNC Milling