Cage damage
      If, on examination of a failed bearing, the cage is found to be damaged,
      it may in many cases prove difficult to ascertain the cause. Usually other
      components of the bearing are damaged too and this makes it even more
      difficult to discover the reason for the trouble. However, there are
      certain main causes of cage failure, viz. vibration, excessive speed, wear
      and blockage.
      Vibration
      When a bearing is exposed to vibration, the forces of inertia may be so
      great as to cause fatigue cracks to form in the cage material after a time
      Sooner or later these cracks lead to cage fracture. 
      Excessive speed
      If the bearing is run at speeds in excess of that for which the cage is
      designed, the cage is subjected to heavy forces of inertia that may lead
      to fractures. Frequently, where very high speeds are involved, it is
      possible to select bearings with cages of special design.
      Wear
      Cage wear may be caused by inadequate lubrication or by abrasive
      particles. The idea with rolling bearings is of course to avoid sliding
      friction. However, where the cage is concerned, sliding cannot be
      eliminated in the contacts with the other components of the bearing. This
      explains why the cage is the first component to be affected when the
      lubrication becomes inadequate. The cage is always made of softer material
      than the other components of the bearing and consequently it wears
      comparatively quickly. As the cage pockets increase in size, due to wear,
      the rolling element guidance deteriorates and this also applies to the
      cage in cases where the cage is centred on the rolling elements. The
      resultant forces may lead to cage failure within a short space of time. 
      Blockage
      Fragments of flaked material or other hard particles may become wedged
      between the cage and a rolling element, preventing the latter from
      rotating round its own axis. This leads to cage failure. 
      Other causes of cage damage
      If the rings of a deep groove ball bearing are fitted out of alignment
      with each other, the path of the balls has an oval configuration. If the
      cage is centred on the balls, it has to change shape for every revolution
      it performs. Fatigue cracks then form in the material and sooner or later
      they lead to fractures. There is a similar case when a thrust ball bearing
      is fitted together with radial plain bearings. If clearance arises in the
      plain bearings, the washers of the thrust bearing become displaced in
      relation to each other. Then the balls do not follow their normal path and
      heavy stresses may arise in the cage. Cages in bearings subject to severe
      acceleration and retardation, in conjunction with fluctuations in speed,
      are affected by forces of inertia. These give rise to considerable
      pressure between the contacting surfaces, with consequent heavy wear.