When drilling extra-hard, compact and weak-abrasiveness formation, diamond bit is oftenpolished and slipping. The drilling efficiency, run and the mean life are very low.

• 金刚石钻头在坚硬致密弱研磨性岩层钻进时,经常出现钻头抛光和打滑现象,钻头时效、使用寿命都非常低。