Identification method of simple rolling NTN bearings

For centripetal ball bearings in normal technical condition, the inner and outer race raceways should be free of spalling and serious wear marks, and show a bright arc groove; All balls shall be kept round, and the surface shall be free of spots, cracks and spalling; The cage is not loose, broken or worn through. When using one hand to hold the inner ring and the other hand to quickly push the outer ring to rotate, it is required to rotate smoothly. Only the slight sound of the ball rolling on the raceway is heard, and there is no vibration; Slow down gradually when stopping, and there is no reverse phenomenon after stopping.
The clearance between the inner and outer rings of the normal radial ball bearing and the rolling element is 0.005-0.010mm. When shaking the inner and outer rings along the radial direction, there should be no clearance. For the used NTN bearing, you can hold the inner ring by hand and shake it along the axial direction for several times. When there is an obvious sound between the outer ring and the ball, it indicates that the fitting clearance exceeds 0.03mm and should not be used anymore.

After the NTN bearing is used, check whether the rolling element and the inner race are peeled off, whether the cage is too loose, whether the front and rear edges of the inner race are complete, and whether the outer race race is cracked. After the inner ring and roller assembly are installed into the outer ring, the roller should fall into the middle of the raceway, and the forward displacement should not exceed 1.5mm. One of them is unqualified, that is, it cannot be used.

The outer ring of this type of NTN bearing is separable. Under normal conditions, the inner and outer race raceways and rollers should be free of breakage, pitting and deep wear marks; The cage shall be free of deformation and can fold the roller on the inner ring; The fit clearance between inner and outer race raceways and rollers shall not exceed 0.06mm.

Under normal conditions, the two raceways should be free of peeling damage and serious wear, and the ball should be free of breakage and pitting; The cage shall be free of deformation, not collide with the two raceway washers, and the balls shall be firmly folded together.

Maintenance and overhaul methods for simple rolling NTN bearings noise

Good results can be obtained by using vibration absorption or isolation devices to reduce or isolate the noise of NTN bearings, but this often costs a lot economically. Sometimes, it makes the mechanism larger, the heat dissipation condition worse, or it is easy to rust. It should be fully considered when using. This method can be used only after other measures are taken and the low noise index cannot be reached.
Another example is to add an intermediate sleeve between the NTN bearing and the seat hole, which can attenuate the vibration force transmitted by the rotating system to the simple rolling NTN bearings seat, but this requires proper allocation, otherwise the opposite effect may occur.
Here, glass fiber or foam plastic is used to eliminate higher frequency noise, the inner surface with small holes is used to eliminate lower frequency noise, and the thick steel plate on the outer surface is used to isolate the external transmission of noise.

In order to reduce the noise of the oil pump system,
The noise of simple rolling NTN bearings are not very sensitive to load, but it is very sensitive to speed. If conditions permit, the same working purpose is achieved by reducing speed and increasing torque, but the noise is reduced.

Adding some chemical additives to the lubricant of simple rolling NTN bearings can reduce the noise of NTN bearings, which can reduce the noise of NTN bearings by 3.9 ~ 9.2db from the original basis. It is suitable for use in micro or small NTN bearings.