What is the most common reason for the noisy operation of electric motors?

Worn bearings are indeed a primary cause of noisy operation in electric motors. Bearings support the rotor and help it spin smoothly within the stator. Over time, due to stress, wear, and inadequate maintenance, these bearings can degrade, leading to increased friction and irregular movement. This degradation manifests as noise during operation.

When bearings become worn, they may develop play, leading to misalignment of the rotor, which can further exacerbate noise levels. This noise can range from a slight hum to a pronounced grinding or rattling sound, signaling that the motor's internal components are not functioning as they should. Regular maintenance and timely replacement of bearings are essential to prevent operational issues and maintain motor efficiency.