Ultra-precision machining technology is an important way to improve the performance, quality, service life and reliability of electromechanical products, as well as saving materials and energy. For example: improving the machining accuracy of cylinders and pistons can improve the efficiency and horsepower of automobile engines and reduce fuel consumption; improving the machining accuracy of rolling elements and raceways of rolling bearings can increase the speed of bearings, reduce vibration and noise; improve flatness of processing of magnetic disks, thereby reducing the gap between it and the magnetic head, can greatly increase the storage capacity of the magnetic disk; improving the marking accuracy of the semiconductor device (reducing the line width, increasing the density) can improve the integration of the microelectronic chip, etc.