The Effects of ZDDP Additive and Running-in Process on Scuffing and Vibration Behaviors of a Lubricating Oil

Scuffing is a surface failure phenomenon observed in sliding-rolling contacts due to high loads and high sliding speeds. Preventing scuffing is essential for improving operational efficiency and longevity of mechanical systems. Therefore, this study investigates the effect of zinc dialkyl dithiophosphates (ZDDP) additive, the running-in process, and their combined impactImpact on the tribological performance, scuffing resistance, surface damage characteristics, and vibration behavior of a lubricatingLubricating oil using the four-ball wear test method with varying applied loads and rotating speeds. The obtained results show that the addition of ZDDP additive effectively enhances scuffing resistance at various speeds. Notably, lubricants containing 1.5 wt% ZDDP exhibit lower pitting and better anti-scuffing characteristics among the tested ZDDP concentrations. The running-in process proves to be highly effective in enhancing scuffing resistance. The vibration behaviour exhibits a consistent trend with variations in the friction coefficient for all tests. Finally, the onset of scuffing is predicted using the true frictional power intensity criterion.