On the Elastohydrodynamic Film-Forming Properties of Metalworking Fluids and Oil-in-Water Emulsions

Abstract Oil-in-water (O/W) emulsions are water-based lubricants and used as fire-resistant hydraulic fluids metalworking (MWFs) in industry. The (elasto-)hydrodynamic film-forming properties of O/W have been studied extensively literature. Typical elastohydrodynamic lubrication (EHL) behaviors revealed at low rolling speeds followed by a starved EHL regime elevated speeds. These self-prepared mostly stable only for limited time ranging from hours to several days. By contrast, the behavior water-miscible commercial MWFs (long-term emulsions) has rarely reported. This restricts understanding status many tribological interfaces manufacturing processes, e.g., chip-tool contact cutting. In this work, property two is investigated measuring film thickness on ball-on-disc test rigs using different optical interferometry techniques. For comparison, simple with known formulation also investigated. Experimental results agree well show that typical reported However, MWFs, there almost no ability over whole range study. could be explained cleaning re-emulsification effects MWFs. mechanism mainly boundary rather than hydrodynamic lubrication. Graphical