Surface damage effects caused by debris in rolling bearing lubricants, with an emphasis on friable materials

The influence of debris in concentrated surface contacts is reviewed in terms of the fundamental mechanisms of 3-body contact, and how subsequent surface damage effects relate to rolling contact fatigue life. Particular emphasis is placed on how friable debris causes surface damage; experimental evidence is presented to show how various forms and sizes of friable debris fragment in the inlet to EHD contacts. Although this can lead to significant wear and surface roughening of the rolling elements, the effects on fatigue life are not always seen to be as severe as with ductile debris. The reasons for these differences are examined and discussed in detail. (A