The mechanical bearing of the motor produces vibration noise, which is generally caused by the imbalance of the rotor. 3.2 The vibration of the bearing forms resonance with the motor, or poor lubrication produces friction noise. 3.3 The brushes slide, causing vibration and noise of the motor. 3.4 The fluid vibration noise of the motor, the vibration noise of the ventilation motor caused by the fan or the rotor is difficult to avoid for the motor. In many cases, the vibration noise of the motor as a whole affects the whole motor. Except for the air whistle sound caused by the blades of the fan or the teeth of the iron core, it is also necessary to pay attention to the ventilation. resonance. The electromagnetic vibration noise of the motor is the motor vibration noise generated by the unbalanced or unbalanced magnetic force of the magnetic circuit and the electromagnetic force wave of the air gap, or the motor vibration noise caused by the saturation of the magnetic flux density or the eccentricity of the air gap. Abnormal bearing produces motor vibration and motor vibration noise Countermeasure: Replace the bearing. Properly preload the axial spring to avoid the change of the bearing axial clearance. Choose soft grease or grease with excellent low temperature, and the remaining clearance should be small (but pay attention to temperature rise). Main parameter table of bearings of various structural types for motors Reason: There may be damage inside the bearing. The axial abnormality of the bearing causes the motor vibration, which is caused by the excitation effect of the motor vibration system composed of the axial spring constant and the rotor mass. Friction noise: caused by poor lubrication and bearing clearance of cylindrical rolling bearings or large-diameter high-speed ball bearings.