The following procedure uses nine basic steps to be followed in looking for the causes of a failed bearing, and within each of the steps are numerous questions to be asked. It starts with an inspection of the housing and surroundings so as to better understand the bearing's operating conditions, then looks at the exterior of the bearing (to understand the heat transfer and supporting forces) and, the internals (to see the actual operating forces).
The nine steps we use in finding physical causes of the bearing failure are:
1) Understand the background, i.e. the bearing's history
2) Inspect the contact surfaces of the inner and outer rings, i.e., the inner- and outer-race fits.
3) Next look at the sides of of both ring exteriors.
4) Remove the seals and/or shields and visually examine the lubricant.
5) Look at the application, determine the loads, understand what the ball and rollers paths should look like, and separate the rings in such a way that those paths can be inspected. Then place the rotating ring on a "Lazy Susan" and slowly rotate the bearing while watching the ball/roller path.
6) Continuing with the physical inspection, place the fixed ring on a lazy Susan and slowly rotate it while watching the ball/roller path.
7) Test the rings and roller elements for hardness.
8) Inspect the cage, paying careful attention to the surfaces that the elements come into contact with.