In Situ Measurement of Fluid Film Thickness in Machining

A novel method using luminescent molecule sensors is described for in situ measurement of fluid film thickness along the tool rake face in machining. The method uses an optically transparent sapphire tool to access the rake face, and measurement of radiation emitted by luminescing molecules dispersed in a machining fluid. By measuring the intensity of the emission, the film thickness is estimated. Implications for tool-chip contact boundary conditions and near-dry machining are discussed.