With the development of social industrialization, motors have been widely used in various fields (furniture, industrial machinery, aerospace), and 3.3 inch motor aluminum shell type are beginning to be used by more users because of their light weight, good heat dissipation, good thermal conductivity, die-casting, good plasticity and high elongation. In the process, the 3.3 inch motor aluminum shell type will inevitably produce noise. The following will take you into detail to understand the three causes of noise generated by 3.3 inch motor aluminum shell type.

1. Electromagnetic noise.

Electromagnetic noise is a low-frequency noise caused by the stator, rotor, and the whole motor structure vibration caused by the pulsation of the motor air gap magnetic field. From the influence of the magnetic field, electromagnetic noise is mainly caused by the asymmetry of the magnetic force wave and flux distribution. Therefore, when designing or machining, the roundness of the stator and rotor must meet the requirements, and the magnetic circuit must be symmetrical and even. The machining accuracy of the end cover of the aluminum shell motor and the assembly of the stator core die casting, and the frame is related to the coaxiality of the stator and the rotor. The accuracy requirement is important for the aluminum shell motor.

2. Mechanical noise.

The friction, impact, imbalance, and structural resonance of the running part of the aluminum shell motor will produce mechanical noise. The mechanical noise of 3.3 inch motor aluminum shell type is relatively high, generally accounting for about 10%-15%. Mechanical noise includes:

（1）Shaft starting noise.

（2）An unbalanced rotor causes noise.

（3）Noise caused by the eccentric assembly.

The noise value caused by the starting noise is closely related to the dimensional accuracy, surface roughness, shape, and position tolerance of the ball and inner and outer ring grooves.

3. Atmospheric dynamic noise.

The dynamic atmospheric noise of the 3.3 inch motor aluminum shell type is caused by the rotating rotor and the cooling fan rotating with the shaft and the motion caused by the ever-changing atmosphere. As the fan and rotor speed increases, the faster the flow and the stronger the change, the greater the noise. Dynamic noise is related to changes in speed, fan and rotor shape, roughness, unbalanced mass, duct cross-section, and duct shape.

These are the three causes of noise from3.3 inch motor aluminum shell type, and I hope it can help you to buy and use.