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 visibl e and infrared wavelengths using transparent tools, measurements of the var iation of forces with flank wear and microstructural changes produced in st eel surfaces during machining and perturbation of the tool-chip interface u sing low-frequency modulation. The application of these techniques has prov ided new insights into the motion of the chip relative to the tool along th e rake face, enabled measurement of the full-field temperature along the ra ke face and suggested avenues for modifying friction conditions along the t ool rake and flank faces. It is shown that important differences as well as similarities exist between the rake face and flank face boundary condition s. The implications of these results for the theoretical analysis of machin ing are discussed.