Investigations into the mechanics of metal cutting

The nature of the contact at the chip-tool interface and its evolution in the low speed cutting of pure metals has been studied using transparent tools and high resolution optical microscopy. The observations show that the chip slides over the tool rake surface in a region close to the cutting edge, where the normal stress is high, whereas it sticks to the tool near the edge of contact where the normal stress is low. The chip-tool interface has also been studied at higher speeds and initial results of some unique high speed photographic observations are described. An accurate finite element simulation of the metal cutting process has been developed by drawing upon similarities to the wedge indentation process. This has been implemented using commercially available FEM packages and has been used to study the mechanics of chip formation with blunt as well as sharp cutting tools. The role of friction along the chip-tool interface has been analyzed in detail. Novel experiments to measure the tool-chip interface temperatures in the machining of metals by making use of transparent tools and multi-wavelength infrared pyrometry are proposed. The experimental configuration has been designed and the necessary equipment are being assembled together. Implications of this work on our understanding of the nature and origin of the frictional interactions at the chip-tool interface and their effects on the mechanics of machining are discussed