Role of run-in parameters on the scuffing resistance of aluminum/steel area contacts

This paper summarises the effects of run-in procedures on the scuffing resistance of 390-T6 aluminium pins sliding on 1018 carburized steel disks. The area contact is lubricated by a base polyalkylene glycol (PAG) lubricant mist carried by a tetrafluoroethane (R134a) refrigerant gas under starved lubrication conditions. These material and lubricant/refrigerant combinations are found in automotive swash plate compressors. Run-in pressure, velocity and time as well as the effect of the friction coefficient during run-in are examined. Surfaces are traced before and after run-in to examine topographical modifications. In addition, SEM and Auger spectroscopy are used to monitor film formation due to run-in. Results show that the higher scuffing resistance after run-in is related primarily to film formation. Low friction conditions during run-in (f  0.1) are necessary to ensure the success of the run-in procedure. The value of the product between the apparent contact pressure and the sliding velocity (PV product) during run-in may be used as a guideline to distinguish between conditions of low and high friction.