G. Lundberg and A. Palmgren in 1947 established the primary relation between rolling-element bearing geometry and bearing life. For ball and roller bearings, their analysis did not consider the life of the bearing’s set of rolling elements independent of race life. The analysis reported herein reassess the effect of ball-race conformity on ball bearing life and considers the life of the ball set independent of the lives of the races. The related changes in ball bearing life are incorporated in life factors that can be used to modify the bearing predicted life using the Lundberg-Palmgren equations and the ANSI/ABMA and the ISO Standards. Two simple algebraic relationships were established to calculate life factors (LFc) to determine the effect of inner- and outer-race conformity combinations on bearing L10 life for deep-groove and angular-contact ball bearings, respectively. Depending on the bearing type and series as well as conformity combinations, the calculated life for deep-groove ball bearings can be over 40 percent less than that calculated by the Lundberg-Palmgren equations. For deep-groove ball bearings, the life can vary from a positive 16 percent to a negative 39 percent difference from that calculated by the Lundberg- Palmgren equations. Comparing the two ball bearing types, the life factors LFc for the deep-groove bearings can be as much as 34 percent lower than that for angular-contact ball bearings.
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