Assessment of friction incorporating tool wear effect

This paper compares friction for orthogonal and non-orthogonal models developed for chamfered ceramic tools with a large negative rake angle. The new non-orthogonal friction model was tested for the machining of spheroidal cast iron (SCI) using coated nitride ceramic inserts. Friction coefficients were determined on the rake and flank face for fresh and worn ceramic inserts using the values of force components recorded during tool wear tests at different cutting speeds. In particular, the friction and normal forces acting on the rake and flank faces were computed. It was revealed that friction coefficients at the tool-chip and tool-workpiece interfaces change substantially with the tool wear progress and differ from that determined for orthogonal friction model.