Maximum depth of cut and mechanics of erosion in AWJ oscillation cutting of ductile materials

The nozzle oscillation technique was shown recently to enhance the performance of Abrasive Water Jet (AWJ) cutting. However, the fundamental reasons behind these process improvements have not been well established. In addition, presently available models of AWJ cutting, which are used for predicting depth of cut and, in some cases, surface quality are not capable of tackling the nozzle oscillation technique. The paper presents a semi-empirical model that can be used for predicting the maximum depth of cut in both oscillation and normal cutting processes. The model was constructed by integrating the results of a visualisation and parametric experimental study of the AWJ cutting process that compares the nozzle oscillation technique with conventional AWJ cutting to the theoretical potential of the cutting process. The experimental results for ductile materials processing show that by oscillating the nozzle during cutting at relatively small angle and high frequencies of oscillation, the efficiency of the erosion process is appreciably increased. At the optimum, oscillation parameter settings, about 30% improvements in performance were obtained for oscillation cutting of mild steel compared to normal cutting samples, while the level of improvement that was found for aluminium samples were about 20%. Outside this optimum range, the process performance for nozzle oscillation was found to be worse than normal cutting.