The machine tool spindle refers to the axis on the machine that drives the work piece or the tool to rotate. The main shaft components are usually composed of a main shaft, a bearing and a transmission member (gear or pulley). In the machine, gears and pulleys are mainly used to support transmission parts,machine tool spindles are used to support transfer motion and torque, some are used to clamp workpieces, such as mandrels. Most machine tools have spindle components, except for planers, broaching machines, etc., where the main motion is linear. The motion accuracy and structural rigidity of the spindle components are important factors in determining the machining quality and cutting efficiency. The indicators that measure the performance of the spindle components are mainly the accuracy of rotation, stiffness and speed.