You are heading into a blind alley

This paper analyses that tip angle of drill bit influences on cutting capability and life of twist drill, when the material and shape of work piece is different.

分析了工件材料、形状不同时 ,钻尖顶角的大小对麻花钻切削性能及寿命的影响 ,介绍了麻花钻的钻尖顶角的选择 。