In the past 30 years, the technical progress of the PDC bit and its important share in the market are far better than the roller bit. The development of cutting parts, water horsepower and dynamic stability has greatly increased the penetration rate and life of PDC bit. Previously, PDC drills only drilled soft formations. A great deal of technical breakthroughs have greatly enhanced the drilling speed and drilling quality of PDC bit.
       The PDC drill has no moving parts and is made of steel and tungsten carbide. The erosion resistance of the steel PDC bit is not as good as that of the mixed tungsten carbide bit, and is often used in soft to medium ground.
       The diamond is better than the three roller bit in the diamond bit; the contact surface shape of the polycrystalline diamond wafer and tungsten carbide disk is improved; the thermal stability limit is also improved.
       The mechanism of rock breaking is shearing. Shear action plays a major role in rock breaking.