Friction modelling in metal cutting

This paper reviews the experimental evidence for what is the nature of the friction contact between chip and tool during continuous chip formation and the historical development of friction models. It considers three separate circumstances of turning: at low speeds when lubricants can reduce friction by partial penetration of the chip–tool contact; at high speeds when thermal softening can provide self-lubrication; and at intermediate speeds when in some cases solid-lubricating inclusions from the work material can segregate in the chip–tool contact. It demonstrates, through numerical simulation of the turning process, shortcomings in a commonly used friction model and proposes an improved formulation.