Rolling noise analysis of NTN bearings

     The rolling sound is due to the rolling of the rolling elements in the raceway when the NTN bearing rotates to excite a smooth and continuous noise, which only attracts attention when its sound pressure level or tone is extremely large. In fact, the sound energy excited by the raceway sound is limited. For example, under normal conditions, the quality of the 6203NTN bearing raceway is 25~27dB. This type of noise is the most typical of single row deep groove ball NTN bearings that can withstand radial loads. It has the following characteristics:
a. Noise and vibration are random;
b. The vibration frequency is above 1 kHz;
c. Regardless of the change in the rotational speed, the main frequency of the noise is almost constant and the sound pressure level increases as the rotational speed increases;
d. When the radial clearance increases, the sound pressure level increases sharply;
e. NTN bearing housing rigidity increases, the lower the total sound pressure level, even if the speed increases, its total sound pressure level does not increase much;
f. The higher the viscosity of the lubricant, the lower the sound pressure level, but for grease lubrication, the viscosity and shape of the soap fiber can affect the noise value.
The source of the rolling sound is caused by the natural vibration of the ferrule after the load. Due to the elastic contact of the ferrule and the rolling body, a nonlinear vibration system is formed. When the lubrication or machining accuracy is not high, the natural vibration associated with this elastic characteristic is excited, and when it is transmitted to the air, it becomes noise. It is well known that even with the most advanced manufacturing techniques used to process NTN bearing parts, there are always small geometric errors in the working surface, which causes small fluctuations between the raceway and the rolling elements to excite the natural vibration of the vibration system.
Although the rolling noise of the NTN bearing is unavoidable, the working surface of the part can be processed with high precision, the NTN bearing is correctly selected and the NTN bearing is accurately used to reduce noise and vibration.

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