Tool flank wear monitoring using torsional–axial vibrations in drilling

In this paper, monitoring of amplitude variation in the torsional–axial frequency is proposed for evaluating drill flank wear. Vibration signals were captured from the experiments resulting to the drilling process and investigation was focused on the role of torsional–axial coupling on instability predictions arising as a result of drill flank wear in the frequency spectrum. The first and second modes of torsional axial coupling frequencies were found through use of finite element analysis (FEA) and verified using experimental modal analysis (EMA) by the resonance frequency test. The proposed strategy uses dominant peaks of torsional–axial first mode (T_p1) and second mode (T_p2) frequency. The ratio of torsional–axial amplitudes (T_P1/T_P2) was considered for the monitoring and the evaluation of drill wear and also to nullify process parameter variation. Drill frequencies verified through experimental study showed their capability of predicting drill flank wear. The validation showed the proposed methodology having 80% accuracy and its ability for effective use for monitoring tool wear.