Plain bearing failure - Fatigue - Fatigue of White Metal Journal Bearing

PLAIN BEARING FAILURE

Plain bearing failure index

Fatigue

3.1 Fatigue of White Metal Journal Bearing

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	Photograph "a": Initial stages of fatigue showing 'bruising' of the white metal surface.
	Photograph "b": More advanced stage of fatigue showing cracking and formation of loose pieces of white metal.
Main Characteristics	Both photographs show the characteristic crazy cracking of the white metal surface. Where loose pieces are formed these may remain in the bearing (photograph 'b') or come away and get trapped so that they melt and wipe, but this is a secondary effect, not the primary damage. The loose pieces tend to have an aspect ratio (length / thickness) of about 5:1, so that on thick wall bearings the fatigued areas are large. For further details see Fatigue failure summary.
Cause	Excessive alternating loading (e.g. reciprocating machinery).
Note	Photograph 'b', where the fatigue damage is on one side of the bearing suggests that there may have been slight misalignment.
Possible Confusion with Other Types of Damage	It is necessary to determine whether the fatigue is "normal" or due to poor bonding (see Premature fatigue of white metal journal bearing ).
Comment	Reduce load or change to a stronger bearing material (but check that shaft hardness is at least 3 times the hardness of the new bearing material otherwise shaft damage could occur in the event of a further failure).