This paper concerns the tool wear in hard turning of AISI 52100 hardened steel by means of PCBN tools. The purposes of this work are the development of a tool wear model and its implementation in a FEM-based procedure for predicting crater and flank wear progression during machining operations for studying the influence of tool wear on the process in terms of tool geometry modifications and stress variation on the tool. Deform 2D FEM software has been utilized to simulate the orthogonal cutting process and the tool wear model has been implemented into the software by means of a dedicated subroutine able to estimate the wear rate and to update the geometry of the worn tool. Previous performed research showed the employment of analytical models for the evaluation of crater wear of flank wear separately, and FEM models only for the crater depth evolution without pointing their attention on the behavior of flank width. A new analytical model, concerning both crater and flank wear, has been proposed and validated by the authors. The validation of the model has been achieved by the comparison between experimental and simulated wear parameters. For doing this, an extended experimental campaign has been accomplished. The comparison results have shown good agreement. Once validated, the FEM strategy has been utilized for examining the influence of tool wear on the effective rake angle and the related tool stresses, individuating the excessive positive rake angle value as the final tool breakage mechanism.