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Six major things about bearing clearance

The so-called bearing clearance refers to the amount of movement when the inner ring or outer ring is fixed when the bearing is not installed on the shaft or the bearing box, and then the unfixed side moves radially or axially. According to the direction of movement, it can be divided into radial clearance and axial clearance. Clearance is also very important for the use of bearings, so China Bearing Network tells you that you must not ignore this.

Six matters of bearing clearance:

1. The size of the clearance (called the working clearance) during operation has an impact on the bearing's rolling fatigue life, temperature rise, noise, vibration and other properties.

2. When measuring the bearing clearance, in order to obtain a stable measurement value, generally a specified measurement load is applied to the bearing. Therefore, the measured value obtained is larger than the real clearance (called the theoretical clearance), that is, the elastic deformation caused by the measured load is increased. For roller bearings, since the amount of elastic deformation is small, it can be ignored.

3. The internal clearance of the bearing before installation is generally expressed by theoretical clearance.

4. The clearance after subtracting the expansion or contraction of the ferrule caused by the interference fit when the bearing is installed on the shaft or in the housing from the theoretical clearance is called "installation clearance". The clearance obtained by adding or subtracting the dimensional change caused by the internal temperature difference of the bearing to the installation clearance is called the "effective clearance".

5. The bearing is installed with a mechanical clearance when it is placed under a certain load, that is, the effective clearance plus the elastic deformation caused by the bearing load so as to be called "working clearance".

6. 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 bearing clearance, it is generally appropriate 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 negative, and when the bearing temperature rises sharply, the working clearance should be further positive, etc., and specific analysis must be made according to the conditions of use. .