坚硬及最坚硬岩层（Ⅸ～Ⅻ级）采用钢粒是提高钻进效率的主要途径，而中硬及硬岩层Ⅷ级）提高钻进效率还是以扩大合金钻进范围较为优越。近年来，许多国内外技术资料广泛地介绍了自磨式合金钻头中硬及硬岩层中钻进能获得较高的机械速度和较好的经济效果。对此我们不但从理论上有一致的看法，而且在实践中也得到了证实。 The hard and the most hard rock (Ⅸ ~ Ⅻ grade) using steel is the main way to improve drilling efficiency, and medium and hard rock Ⅷ level) to improve the drilling efficiency or to expand the scope of alloy drilling is superior. In recent years, many domestic and foreign technical data extensively introduced the self-grinding alloy drill bit hard and hard rock drilling can get higher mechanical speed and better economic results. In this regard, we not only have a consistent view of the theory, but also in practice has been confirmed.