Boundary Dimensions and Bearing Number

ISO Dimensional system for Bearings
Standardized dimension system is adopted worldwide for dimensioning the rolling bearings, as bore diameter, outer diameter, width and chamfer dimensions. The ISO dimensional system defines the nomenclatures for the following dimensions for rolling bearings: bore diameter: d, outside diameter: D, width: B and height: T and chamfer dimension: r.

The table 5.1 shows factor fD and bore diameter d, from which the outer diameter of the bearing can be obtained. Symbols 9,0,2,3 are the common diameter series symbols. The diameter series helps to determine the thickness between the bore and the outer diameter of the bearings. Fig 5.1 shows the increasing order for the outer diameter series and same bore size i.e. 7, 8, 9, 0, 1, 2, 3, and 4. The factor fB combines with the diameter series to classify the width series of the bearing. The combination of the diameter series and width series is the dimensional series.

The boundary dimensions of the thrust bearings are given same as the dimensions of the radial bearings as, outside diameter: D=d+ f Dd0.8, and height: T= fT · (D–d)/2. Minimum chamfer dimension: rs min, should be selected from ISO table.

To know more click on the below link ..

White Paper – Boundary Dimensions and Bearing Number