Abstract:By adding the circular grating full closed loop function in C axis positioning of CNC turning center, the stability of the system was increased by positioning damping. In order to improve the overall performance of the machine processing, the main servo motor (main drive) output shaft was increased with ZF speed reducer. Then in the turning process, not only C axis as the linkage axis had high torque at low speed, but also the machining accuracy of machine tool was greatly improved. At the same time, by using Siemens 828D CNC system, the machine performance was more perfect through the intelligent, accurate and precise control.