# Conformity of inner and outer ring

> [HTML Version](conformity_of_inner_and_outer_ring.html)

The conformity is the ratio between radius of curvature of a race and the ball diameter. For geometric reasons, the value has to be larger than 0.5. The values used for the calculation of tables in [ISO 281](bibliography.md#iso_281) are fi=fe=0.52 for radial ball bearings and fi=fe=0.535 for thrust ball bearings as stated in [ISO/TR 1281-1](bibliography.md#iso_tr_1281-1).

According to [ISO 16281](bibliography.md#iso_16281) usual values are fi=0.52 and fe=0.53 for radial ball bearings and fi=fe=0.54 for thrust ball bearings. [ISO 76](bibliography.md#iso_76) also uses fi=fe=0.54 for thrust ball bearings.

For spherical or barrel roller bearings values of fi= fe=0.5 should be used. Here the diameter of the outer race de is used as reference. 

According to [ISO 281](bibliography.md#iso_281) and [ISO 76](bibliography.md#iso_76) a larger conformity reduces the load capacity and therefore a reduction of fc is required, but a smaller conformity does “not necessarily increase the load-carrying ability”. Therefore, the software allows to enter a limit for the conformity used for the calculation of load capacity. See the (./images/all_img3.png)-button behind the bearing type for ball bearings.

For spherical ball bearings, the diameter of outer race de is used as reference for fe. So fe=0.5 should be used as default. The  (./images/all_img4.png)-button allows to enter the radii and to optionally adjust the pitch diameter Dpw so that the outer race is a sphere with fe=0.5

Using the (./images/all_img4.png)-button behind the input field, the conformity can be calculated from a given radius. Ensure that you input the correct roller and pitch diameter before.