There are three different types of motors used in the industry today. These three types are General Purpose, Servo, and Spindle motors. Each of these types of motors is similar but also unique at the same time and that is why you would need to send your motor to a specialized repair shop.
General Purpose motors are your standard motor type. These motors can be used in many applications. Most General Purpose motors do not use feedback and run at a single speed. This means that they have a line fed voltage and are basically turned on and then off whenever they are needed.
Servo motors are a little more specialized than General Purpose motors. Servo motors are used in applications typically where they are axes of a CNC machine where they move a chuck or a table in certain directions. These motors are specialized because of their use of feedback (encoder) to know what position the shaft is at. This feedback also allows the motor the ability to hold the position. Servo motors are also characterized by their use of permanent magnets as their stator. Most General Purpose and Spindle motors have a winding or a bunch of wires coiled around to help create the magnetic field that spins the rotor in a specific direction. This is different in Servo motors because permanent magnets are used to create the field.
Spindle motors are similar to General Purpose motors but like Servo motors, they are more specialized. Spindle motors application in CNC machines is the machine tool. It is the motor that controls the speed at which the machine tool spins to do the cutting or boring. These motors are specialized like the Servo motor because they also use feedback in most applications. This feedback is used for orientation of the motor shaft. This means that when given an orientation command the shaft will move itself to a specified position. These motors are also characterized by the high speeds that they can run at and the ability to stop on a dime when given the stop command.
The differences that Servo and Spindle motors have over the General Purpose motors is why we recommend you send these motors to a specialized repair shop. The feedback portion of both the Servo and Spindle motors is one of the main reasons to do so since it requires the repair of encoders and for Servo motors specifically if the encoder is not aligned properly with the permanent magnets then the motor can draw excessive load and ultimately damage the motor. Another reason to send to a specialized repair shop is maintenance. At a shop like ours when the motor leaves here, it looks like it is brand new. We make sure all bearings are good and use the original manufacturer bearings. We inspect all housings to make sure they fit correctly and are not damaged. We re-paint all motors and create new nameplates for them as well. We also can test the Servo and Spindle motors on the drives that they typically run on in their respective CNC application. So the next time you need any repair work done on your Servo or Spindle motor remembers that these are specialized motors and we recommend that they are looked at by a specialized repair shop.