Bearing Failure Analysis
Bearing Failure Analysis
Bearing Failure Analysis
BEARING FAILURE
(ROLLING CONTACT BEARING)
Inner Race
Cage or Separator
True Brinellilng
Using hammer to
install.
Dropping a
bearing.
Pressing a bearing
onto a shaft by
applying force to
the non-rotating
ring.
Contamination
It includes airborne
dust, dirt or any
abrasive substance
that gets into the
bearing.
Contamination
results in bearing
vibration and wear
Electrical Fluting
It occurs when a current
is passed through the
bearing.
Frequently seen in
electric motors can be
eliminated by ceramic-
coating the OD of the
bearing
Misalignment Failure
Bent shaft
Burrs or dirt on the
shaft or housing
shoulders.
Shaft threads are
not square with the
shaft seats.
Reverse loading
Occurs when loads
shift direction in
bearing that can
only take axial load
in one direction
The thrust load
applied to the
wrong bearing face
result in a wear
band on the balls
Corrosion Failure
It result from the
chemical attack on the
bearing materials by
hostile fluids or
atmospheres.
It increased vibration
followed by wear, with
subsequent increase in
radial clearance.
Excessive load failure
Excessive load
normally causes
premature bearing
failure.
It show heavier ball
wear paths and
more widespread
and deeper
spalling.
Loose fit failure
Caused by relative
motion between
parts which, in turn,
causes fretting
This normally occurs
through outer ring
slippage in the
housing due to
improper fits
Lubrication failure
Restricted lubricant
flow or excessive
temperatures that
degrade the
lubricant property
cause failure
It lead to excessive
wear, overheating
and subsequent
bearing failure.
Overheating
It discoloration of the
ring, balls/rollers and
cages from gold to blue
Temperatures in excess
of 400 degrees C.
Result in deformation of
balls and ring.
Preload failure
If interference fits
exceed the internal
radial clearance,
the rolling become
preloaded.
Continued
operation can lead
to rapid wear and
fatigue
Fatigue failures
Metal fatigue is caused by repeated
cycling of the load.
Variation in the stress ratios can
significantly affect fatigue life.
The most commonly used stress ratio of
the minimum stress to the maximum
stress.
Preventing fatigue failure
To improvement in design.
Avoid sharp surface tears.
Prevent the development of surface
discontinuities.
Reduce or eliminate tensile residual
stresses caused by manufacturing.
Improve the fabrication procedures.
Installation damage
Occurs when a
sharp impact is
applied incorrectly
to a bearing during
mounting or
dismounting
To prevent it use
proper method.
Reducing bearing failure
Proper bearing selection.
Bearing handling and storage.
Bearing installation and handling.
Ongoing bearing lubrication.
Bearing maintenances and care.
Conclusion
By examining a
damaged bearing, it is
possible, in the
majority of cases, to
form an opinion on the
cause of the damage
and to take the
requisite action to
prevent a recurrence.