CNC machining center is a high-efficiency automatic machine tool which is composed of mechanical equipment and CNC system and is suitable for machining complex parts. CNC machining center is one of the most widely used CNC machine tools with the highest output in the world. Its comprehensive processing capacity is strong, the workpiece can complete more processing content after a clamping, the processing accuracy is high, on the batch workpiece of medium processing difficulty, its efficiency is 5 to 10 times that of ordinary equipment, especially it can complete many ordinary equipment can not complete the processing, the shape is more complex, the precision requirements of high single-piece processing or small and medium-sized batch multi-variety production is more suitable. It concentrates the functions of milling, boring, drilling, tapping and cutting threads in one device, so that it has a variety of processing processes. Machining centers are classified according to the spatial position of the spindle machining: horizontal and vertical machining centers. According to the classification of process use: boring and milling machining center, composite machining center. According to the special classification of functions: single table, double table and multi-table machining center. Machining centers for single shaft, double shaft, triple shaft and replaceable headstock. According to the guide rail classification: line rail machining center, hard rail machining center machine.