If the spindle speed is abnormal, that is, after the spindle is given a command speed, the response speed on the CNC machining center is not consistent with the command speed (usually less than the command speed). Perhaps the spindle of the CNC machining center is not smooth and there are abnormalities. The sound is loud and slow, and in some cases, the motor may even trigger an overcurrent alarm. For the spindle of a CNC machining center, in response to the encoder, the speed command "S" given by the CNC machining center machine is followed by a number, which will reflect the same value on the system flash.