In turning, the applied forces have to be known as accurately as possible, especially in the case of difficult-to-cut materials for aircraft workpieces finishing operations. Traditionally, edge discretisation methodology based on local cutting laws is used to determine the cutting forces and results are usually considered suitable. Nevertheless, only the rake face is considered in most of studies and the cutting relations are determined by direct identification with a straight edge. This study deals with finishing operations of Inconel 718 alloy with one type of round insert. The main objective is to formulate a novel cutting forces model, taking into account the clearance face. First, a generic model based on a geometrical description using homogeneous matrix transformation is presented. Then, cutting coefficients are identified by inverse identification from experimental measurements distributed with an orthogonal design experiment including tool wear. Finally, modeling and experimental values of the cutting forces are compared and the identified model is analysed.