Sliding wear characteristics and wear constitutive equation of lead-free white metal under various lubricating liquids

In the present study, sliding wear experiments are conducted on lead-free white metal under three types of lubricating fluids, that is, two types of lubricating oils and water, and the sliding wear characteristics and friction coefficient of the sliding surface of the white metal are investigated. Lubricating fluids were selected with viscosities varying widely from 1.0 × 10⁻³ to 409.7 × 10⁻³ Pa s. Based on the experimental results, the constitutive equations of sliding wear, the coefficient of friction, and the effects of lubricating oil viscosity η and compressive stress σ are investigated. The coefficient of friction is proportional to σ^0.5 and η^−0.5. Therefore, as η increases in the low σ region, the coefficient of friction decreases and the amount of wear decreases. Conversely, as η decreases in the high σ region, the coefficient of friction increases; thus, the amount of wear increases and the sliding surface seizes. Furthermore, a method for quantitatively predicting the sliding wear life of white metals is devised from the perspective of machine maintenance. The wear life required to achieve a certain wear depth can be estimated using the wear constitutive equation proposed by the authors, which is expected to facilitate the safety management of bearings and the extension of their operating life.