Bearings are important basic components in mechanical equipment, requiring high performance and accuracy. The fit between bearings is also very important. In order to ensure that bearings do not undergo excessive deformation after installation, it is necessary to:
(1) The roundness of the shaft and seat hole, as well as the perpendicularity of the shoulder, should be required according to the corresponding accuracy of the bearing
(2) It is necessary to accurately calculate the interference fit of the rotating ring and the appropriate fit of the fixed ring. The interference fit of the rotating ring should also be minimized within the possible range. As long as the thermal expansion effect at the working temperature and the centrifugal force effect at the highest speed are effectively ensured, it will not cause creep or sliding of the tight fitting surface. The fixed ring is selected with extremely small clearance or interference fit according to the working load size and bearing size. Being too loose or too tight is not conducive to maintaining the original precise shape.
(3) If the bearing operates under high-speed conditions and the working temperature is high, special attention should be paid to the fit of the rotating ring not being too loose to prevent eccentric vibration, and the fit of the fixed ring should not have gaps to prevent deformation and vibration of the ring under load.
(4) The condition for adopting a small interference fit for the fixed ring is that both sides of the matching surface have high shape accuracy and small roughness, otherwise it will cause installation difficulties and disassembly difficulties. In addition, the influence of spindle thermal elongation also needs to be considered.
(5) The main shaft using paired double angular contact ball bearings has a lighter half load, and if the fit interference is too large, the axial preload inside will be significantly increased, causing adverse effects. The main shafts using double row short cylindrical roller bearings and tapered roller bearings have relatively high loads, so their fit interference is also relatively large.

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