Causes of bearing noise

There are many factors that cause bearing noise. The main reasons are briefly described below.

(1) Bearing raceway sound and its control method

When the bearing is running, the raceway sound is a continuous sliding sound emitted by its rolling elements rolling on the raceway surface. This unique basic sound occurs in all rolling bearings. The ordinary bearing sound is the raceway sound mixed with other sounds. The raceway sound of a ball bearing is irregular, the frequency is above 1000 Hz, its main frequency does not change with the speed, but its total sound pressure level increases with the speed of revolution. For bearings with loud raceway sound, the sound pressure level of the raceway sound decreases with the increase of viscosity; while for bearings with low raceway sound, when the oil viscosity increases above 20mm2/s or so, the sound pressure level has changed from a decrease to an increase. The greater the rigidity of the bearing seat, the lower the total sound pressure level of the raceway sound. If the radial clearance is too small, the total sound pressure level and main frequency of the raceway sound will increase sharply as the radial clearance decreases. The methods to control the raceway sound are: select low-noise bearings, that is, bearings with small waviness, and carefully choose the conditions of use. The noise of the raceway often affects the noise of the entire machine, and reducing the noise of the raceway can reduce the noise of the entire machine.

(2) Impact sound of rolling elements and its control method

When larger ball bearings or cylindrical roller bearings run at low speed under pure radial load, the rolling elements in the non-loaded area will impact the cage or raceway and cause noise due to the small centrifugal force of the rolling elements. But as the speed increases, this sound will disappear. The controlling methods for the impact sound of rolling elements include: appropriately reducing the radial clearance and selecting bearings with a reasonable structure and a flexible material cage.

(3) Bearing rolling noise and its control method

In all applications, cylindrical roller bearings are likely to produce harsh metal friction rolling noises, which are more likely to occur in larger grease-lubricated bearings, especially in greases with degraded base oil performance. It hardly occurs during oil lubrication. In addition, rolling noise is more likely to occur in winter. When bearing pure radial load, cylindrical roller bearings are prone to rolling noise when the radial clearance is large. Moreover, it is easy to produce continuous and intermittent rolling noise within a specific speed range, due to the different in sizes of the bearings. If necessary, a bearing with a special processing method for the outer ring raceway can be selected to prevent rolling noise, or to reduce the radial clearance of the bearing appropriately, or to adopt a grease with excellent performance, and improve the rigidity of the matched parts.