I have a CNC spindle motor from the store and i found it is a better one, high quality. Two weeks ago, I bought a CNC spindle motor in another place, I equipped with it on machine and I found it had much overheating, I checked the load, the motor cooling system, the motor cooling fan, and the connection between the motor and the control unit.

However, I still failed to find out the real reason of its overheating. I want to know what else will lead spindle motor overheating so that I would take some actions to extend its service life.