A key factor affecting the operation of bearings is the working clearance of bearings. The main factors affecting the working clearance of bearings include the fit between the inner ring of the shaft and the shaft, the fit between the outer ring of the bearing and the bearing chamber, the clearance of the bearing itself under non-assembly conditions, the operating status of the motor and the turnover environment and other objective factors. The same motor may have different fates under different use conditions. To ensure the guarantee effect of the bearing during the operation of the motor, comprehensive considerations should be made from the selection of bearings, determination of the fit relationship, understanding of working conditions, lubrication and maintenance.

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1 Whether the bearing ring rotates

When the inner ring or outer ring of the bearing is a rotating ring when working, a slightly tight fit should be used, and the size of the interference should be such that the matching surface does not "crawl" (commonly known as running circles) under the working load, because once crawling occurs, the matching surface will wear and slide, and the higher the ring speed, the more serious the wear. When the bearing is working, if its inner ring or outer ring is a non-rotating ring, in order to facilitate disassembly and adjustment, a looser fit should be selected.

4 The influence of other factors on the fit

● Operating temperature - When the bearing is working, due to the influence of frictional heat and other heat sources, the temperature of the ring is higher than the temperature of the matching parts. The thermal expansion of the inner ring will cause the fit between it and the shaft neck to loosen, while the thermal expansion of the outer ring will cause the fit between it and the housing hole to tighten. Therefore, when the operating temperature of the bearing is high, the selected fit should be adjusted appropriately.
● Rotational accuracy and rotational speed - For bearings that bear heavy loads and require high rotational accuracy, clearance fits should be avoided in order to eliminate the effects of elastic deformation and vibration. For lightly loaded bearings of some precision machine tools, clearance fits are often used to avoid the effects of shaft shape errors on bearing accuracy. It is generally believed that the higher the rotational speed of the bearing, the tighter the fit should be.