Let’s discuss the use effects of small-size roller drill bits and PDC drill bits. The roller cone drill is composed of three tooth palms, and the rotation of the roller cone relies on bearings during operation. In actual work, cone drill bits with a diameter of less than 5 7/8 inches have smaller bearing diameters and often break during operation. The PDC drill bit welds PDC to the steel body or carcass. There is no weakness in small-sized drill bits, and the cutting speed is fast.