Exploration of contact conditions in machining

The contact conditions along the tool-chip and tool-work interfaces in the machining of metals are analysed and discussed. The principal experimental techniques used are direct optical measurements of the interfaces at visible and infrared wavelengths using transparent tools, measurements of the variation of forces with flank wear and microstructural changes produced in steel surfaces during machining and perturbation of the tool-chip interface using low-frequency modulation. The application of these techniques has provided new insights into the motion of the chip relative to the tool along the rake face, enabled measurement of the full-field temperature along the rake face and suggested avenues for modifying friction conditions along the tool rake and flank faces. It is shown that important differences as well as similarities exist between the rake face and flank face boundary conditions. The implications of these results for the theoretical analysis of machining are discussed.