What is the clearance of rolling bearing

May 18, 2023

Regardless of whether we are buying or using rolling bearings, we often hear a term, bearing clearance, which means that when the bearing is not installed on the shaft or bearing housing, one side of the inner ring or outer ring is fixed, and the unfixed side do movement when moving radially or axially. According to the direction of movement, it can be divided into radial clearance and axial clearance. According to whether the bearing is installed or not installed when moving, it can be divided into theoretical clearance and actual clearance. Clearance is also very important for the use of bearings, which is related to the service life of roller bearings.

When measuring the clearance of a bearing, in order to obtain a stable and accurate measurement value, a certain load is generally applied to the bearing. Therefore, the measured value obtained is larger than the theoretical clearance, that is, the amount of elastic deformation caused by the measured load is increased. For roller bearings, due to the small amount of elastic deformation, it can be ignored. The internal clearance of the bearing before installation is generally expressed by theoretical clearance. The clearance during operation is called the working clearance. The size of the working clearance has an impact on the service life, temperature rise, noise, vibration and other performance of the bearing, so the appropriate clearance is very important.

There is also a term called installation clearance, which is the theoretical clearance minus the expansion or contraction of the ring caused by the interference fit when the bearing is installed on the shaft. The clearance obtained by adding and subtracting the dimensional change due to the temperature difference inside the bearing to the installation clearance is called "effective clearance". Many customers choose inappropriate clearance values because they do not understand the clearance of bearings, resulting in poor bearing performance in actual use.

For bearings, when the working clearance is slightly negative, the fatigue life of the bearing is long, but the fatigue life decreases significantly as the negative clearance increases. Therefore, when selecting the clearance of the rolling bearing, it is generally advisable to make the working clearance zero or slightly positive. In addition, when the rigidity of the bearing needs to be improved or the noise needs to be reduced, the working clearance should be further taken as a negative value, and when the temperature rise of the bearing is severe, the working clearance should be further taken as a positive value, etc. The clearance of the bearing should be selected according to the use conditions are analyzed in detail.

If you don't know how to choose the appropriate clearance, please contact Luoyang FV Bearing, our engineers are always at your service.