The rock breaking action of diamond drill bits is completed by diamond particles. To understand the rock breaking effect of a drill bit, it is necessary to understand the rock breaking effect of a single diamond. In hard formations, a single diamond under drilling pressure puts the rock in an extremely high stress state (about 4200-5700MPa, some data suggest it can reach 6300MPa), causing the rock to undergo a lithological transformation from brittle to plastic. A single diamond enters the formation and, under the action of torque, cuts and breaks the rock, with a cutting depth basically equal to the depth of diamond particle penetration. This process is like plowing the land, hence it is called the plowing cutting effect of diamond drill bits.

In some brittle rocks (such as sandstone, limestone, etc.), diamond particles on the drill bit, under the simultaneous action of drilling pressure and torque, break the volume of the rock much larger than the volume of diamond particles ingested and rotated. When the pressure is not high, small grooves can only be formed along the direction of diamond movement. Increasing the pressure will cause the deep part of the small grooves and the rocks on both sides to break, exceeding the cross-sectional size of diamond particles.

The rock breaking effect of diamond drill bits is not only related to lithology and external factors that affect lithology (such as pressure, temperature, formation fluid properties, etc.), but also to the size of drilling pressure. It, like a roller drill bit, has three ways of breaking rock: surface crushing, fatigue crushing, and volume crushing. The ideal rock breaking effect can only be achieved when diamond particles have sufficient specific pressure to feed into the formation rock, causing the rock to undergo volume fragmentation.