The life cycle of a debris particle

Debris particles exist in most lubrication systems; they are frequently responsible for the early failure of tribological machine elements. Particles come from the surrounding environment, or may be generated within the machine components. As the lubricant circulates, these particles get flushed into the machine elements. Contact pressures are lugh and oil films are small, so that the relatively large particles damage even the hardest gear, bearing, or cam surface. This damage can lead to contact fatigue or wear, and thus premature failure of the whole machine. Further, one failure can result in the generation of further wear debris, often in very great quantities, that then can have a knock-on effect in other parts of the lubricated system. This paper gives an overview of important features of the life cycle of a debris particle; entrainment of debris particles into a contact, resulting surface damage, shortened component life, and debris particle procreation by fatigue and wear. The debris life cycle coincides with the early mortality of the machine element. The methods by which component life, under particulate contaminated conditions, can be determined are reviewed.