On the running-in behavior of lubricated line contacts

The first operating period of machine elements is subject to a running-in phase. Thereby, stresses applied on the contacting surfaces are influenced by the running-in conditions including the lubricant used and can strongly affect the frictional behavior and load-carrying capacity of lubricated contacts after running-in. This study investigates the influences of operating conditions and lubricant additives on the running-in behavior of lubricated line contacts of discs and gears. Results show a strong influence of the lubricant additive on the coefficient of friction during running-in as well as on the surface roughness and surface condition after running-in. The specific boundary friction power, supplemented by considering load carrying capacity limits, has been introduced as a criterion for defining the running-in conditions of gears.