The spindle end structure usually adopts the short cone method flange type. The spindle shaft end is used to install fixtures and tools. The positioning accuracy of fixtures and tools at the shaft end is required. The loading and unloading process is simple. At the same time, the overhang length of the spindle can be shortened. Because of the long-term use of the belt-driven spindle of the CNC machining center, the belt of the spindle box will have abnormal sound. This situation is mostly caused by belt problems. 1) The belt tension of the spindle connected to the servo motor is too tight: Too tight will easily lead to aggravation of belt wear, slipping, and abnormal noise. 2) The belt tension of the spindle connected to the servo motor is too loose: Too loose will easily cause slipping during heavy cutting, and the belt spindle of the CNC machining center will make abnormal noises when slipping. 3) The belt of the spindle connected to the servo motor is damaged: Under normal circumstances, if the CNC machining center runs for a long time, problems will inevitably occur. For example, after a long period of use, the transmission belt will wear out, which directly makes the belt "wailing". 4) The tooth profile of the transmission belt does not match the tooth profile of the servo motor and the spindle: The transmission belt of the CNC machining center will definitely experience some wear after long-term use. Therefore, many customers will purchase and replace it by themselves in order to save costs. It was found that the tooth profile of the transmission belt did not match the completion of the servo motor and spindle tooth profile, which would cause abnormal noise during use. Therefore, professionals recommend that when purchasing a transmission belt, customers must pay attention to whether the purchased transmission belt is the same model as the disassembled worn belt. The mechanical structure of the main drive system has been simplified to a large extent. The belt drive and gear drive have been eliminated. The spindle of the CNC machining center is directly driven by the built-in motor, which shortens the length of the main drive chain to zero, thereby allowing the machine tool to realize The "zero transmission" process has been implemented.