Dry friction model of percussive drilling

It is postulated that the main mechanism of the enhancement of material rem oval rate (MRR) in percussive drilling is associated with generating impact forces, which act on the workpiece and help to develop micro-cracking in t he cutting zone. The inherent non-linearity of the discontinuous impact pro cess is modelled as a frictional pair, to generate the pattern of the impac t forces. A novel formula for calculating the MRR is proposed, which explai ns the experimentally observed fall in MRR at higher static forces.