Effects of surface texturing and kind of lubricant on the coefficient of friction at ambient and elevated temperatures

Abstract

Abstract Tribological tests were conducted using a pin-on-disc tester in unidirectional sliding under starved lubrication. A specimen of 25.4 mm diameter with a hardness of 50 HRC and a counter-specimen of 5 mm diameter with a hardness of 40 HRC were made from 42CrMo4 steel. Specimens were textured by abrasive jet machining. An average depth of oil pockets was 10 μm, a mean diameter was 0.5 mm and a pit-area ratio was 17%. Tribological behavior of sliding pairs with textured and untextured (polished) discs were compared. Friction tests were conducted at normal loads of 10, 20, 30, 40, 50 and 60 N increased in a stepwise manner, a sliding speed was set to 0.6 m/s. Friction behaviors were evaluated at room temperature and at elevated temperature (80 °C). The tested assemblies were lubricated by different oils. Surface texturing always led to beneficial performance of sliding pairs. However the best effect of surface texturing was observed at smaller loads and elevated temperature. Under these conditions, the effect of kind of oil on tribological behavior was negligible.