The lifetime of a ball bearing is the number of revolutions completed by the bearing before the first signs of material fatigue appear on the ring raceways or on the ball
Even for ball bearings of the same type, size, and material, and which received the same heat treatment and other processing, the rolling contact fatigue
life varies greatly, even under identical operating conditions.
Therefore, a calculated lifetime is always understood as a statistical lifetime. It is based on the fact that a certain percentage of a large quantity of identical
ball bearings reaches or exceeds this lifetime.