Modeling the effect of tramp oil contamination on selective component depletion in metalworking fluid systems

Functional component depletion and physical interaction of contaminants with the machining process are thought to be the primary determinants of metalworking fluid useful life. An oil/water partition coefficient and mass balance based model is derived that is capable of accounting for the effect of tramp oil induced extraction of metalworking fluid components. After developing general expressions for the predictive model, the magnitude of extraction for a synthetic metalworking fluid is investigated. The model is then used to predict system concentrations over time in the presence of such metalworking fluid contaminants and is verified via laboratory experimentation and an industrial case study. The partition coefficient/mass balance modeling procedure is further utilized to determine the amounts and frequency required for tankside addition of metalworking fluid components, while accounting for depletion by the tramp oil mechanism.