Modelling the vibratory drilling process to foresee cutting parameters

The poor removal of chips in deep drilling of small diameter is often the cause of tool breakage and poor quality surface. The vibratory drilling enables the chip to be split thanks to the axial vibrations of the drill self-maintained by the cutting energy. Therefore chips are then evacuated easily. A specific tool holder with a variable axial stiffness was developed by the authors. The amplitude of the vibrations is greater than the feed rate. Vibratory drilling has been modelled to predict the cutting conditions and the adjustment of the stiffness of the tool holder. The models and the performances of the self-excited vibratory drilling process were validated by an experimental study.