This paper presents a model for on-line prediction of a drill flank wear using changes in vibration amplitude in the drilling process. Prediction of wear-time and wear-amplitude ratio relationships during the drilling process is enabled by this mathematical model through variations in vibration amplitude signals. An empirical method for an in-process approach for quantifying tool wear, and failure following it, is the outcome of the measurement of variations in the ratio of amplitude between torsional-axial dominant first mode (T P1) and the second mode (T P2) frequency. Performance of a series of cutting tests has been undertaken to study the effect of drill flank wear and other independent cutting parameters on the vibration amplitude signals. The objective is extended to finding the relationship between amplitude signals, drill flank wear and various other independent parameters. Details of the flank wear of drill and the ratio of amplitudes seen at various working conditions were determined and collected through experimental procedures. Verification of the model was done through comparison of the experimental values with the predicted values.