A 58 7. Bearing tolerances 7-1 Tolerances and tolerance classes for bearings Bearing tolerances and permissible values for the boundary dimensions and running accuracy of bearings are specified. These tolerances are prescribed in JIS B 1514-1, JIS B 1514-2, and JIS B 1514-3 (roller bearings - bearing tolerances part 1: radial bearings, part 2: thrust bearings, and part 3: permissible values for chamfer dimensions). (These JIS standards are based on ISO standards.) Bearing tolerances are standardized by classifying bearings into the following six classes (accuracy in tolerances becomes higher in the order described): 0, 6X, 6, 5, 4 and 2. Class 0 bearings offer adequate perfor- mance for general applications; and, bearings of class 5 or higher are required for demanding applications and operating conditions including those described in Table 7-1. These tolerances follow ISO standards, but some countries use different names for them. Tolerances for each bearing class, and organizations concerning bearings are listed in Table 7-2. n Boundary dimension accuracy items on shaft and housing mounting dimensions *Tolerances for bore diameter, outside diameter, ring width, assembled bearing width *Tolerances for set bore diameter and set outside diameter of rollers *Tolerance limits for chamfer dimensions *Permissible values for width variation *Tolerance and permissible values for tapered bore n Running accuracy (items on runout of rotating elements) *Permissible values for radial and axial runout of inner and outer rings *Permissible values for perpendicularity of inner ring face *Permissible values for perpendicularity of outer ring outside surface *Permissible values for thrust bearing raceway thickness Accuracies for dimensions and running of each bearing type are listed in Tables 7-3 through 7-10; and, tolerances for tapered bore and limit values for chamfer dimensions of radial bearings are in Tables 7-11 and 7-12. Table 7-1 High precision bearing applications Required performance Applications Tolerance class High accuracy in runout is required for rolling elements. Radar / parabola antenna slewing shafts Machine tool spindles Aluminum foil roll necks Multi-stage mill backing bearings Class 4 Class 5,4,2, ABEC 9 Class 5 Class 4 High speed rotation Dental spindles Superchargers Jet engine spindles and accessories Centrifugal separators LNG pumps Turbo molecular pump spindles and touch-down Machine tool spindles Tension reels Class 2, ABMA 5P,7P Class 5,4 Class 5,4 Class 5,4 Class 5 Class 5,4 Class 5,4,2, ABEC 9 Class 5,4 Low friction or low friction variation is required. Control equipment (synchronous motors, servomotors, gyro gimbals) Measuring instruments Machine tool spindles Class 4, ABMA 7P Class 5 Class 5,4,2, ABEC 9