The recommended standard mounting hole tolerance for CSB plastic plain bearings is H7, and the shaft tolerance is h9. These are general tolerance recommendations, and reflect the interference fit and the effect of the sleeves' thermal expansion coefficient during operation on the gap. Changes in the dimensional tolerance of the shaft or mounting holes will affect the size of plastic plain bearings' working surface contact area (Pact), which will cause the sleeves' actual load-bearing area to change. As soon as the Pact changes, this will directly affect the service life of the plastic sleeve.We ordinarily believe that the smaller the fit clearance between the shaft and plastic sleeve, the larger the plastic sleeve's contact area, and the longer the sleeve's service life, as well as the converse, which is that a large fit clearance will reduce plastic plain bearings' actual service life. Of course, when reducing the fit clearance between the shaft and plastic sleeve as much as possible, we must also consider that a certain amount of clearance is needed for sleeves to operate normally.