Identification of Friction Coefficients when Drilling Titanium TiAl6V4

This paper investigates the friction behaviour around a carbide drill when drilling titanium with an oil mist lubrication. It questions whether friction is constant along the cutting edge and along the margins. The application of specially designed tribometer reveals that tribological conditions on margins are fully different that the ones on rake and flank faces. Friction coefficients are quantified for both tribological conditions (open and closed tribosystem). The influence of contact pressure and of an AlCrN coating are also investigated. It is shown that friction varies a lot between both tribosystems, and that a closed tribosystem (i.e. margins) leads to much higher friction, adhesion and wear rate than an open tribosystem (i.e. flank faces).