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When we use the miniature bearing raceway, often hear there is noise, the reason we do not know, in order to understand how the 6921LLU EDA bearings knowledge through the experiment, we draw the conclusion, the following will help you to cause analysis.
A. noise and vibration is random;

B. vibration frequencies above 1kHz;
C. No matter how changes in speed, noise frequency and sound pressure level is almost the same with the speed increase;
D. when the radial clearance increases, the sound pressure level increases sharply;
E. miniature bearing rigidity increases, the lower the total sound pressure level, even if the speed increased, the overall sound pressure level increases slightly;
F. lubricant viscosity is high, the sound pressure level is lower, but the grease, the shape and size of the viscosity, the soap fiber can affect the value of the noise.
Due to the elastic contact rings and rolling elements of nonlinear vibration system. When the lubrication or machining precision is not high it will inspire the vibration associated with the elastic characteristics, transfer into the air into a noise. It is well known that even the manufacturing technology of fabricating micro bearing the highest contemporary parts, its work surface there are not a small degree of geometric error, so that the raceway and rolling body produce tiny wave excitation vibration vibration system.