Experimental investigation and modelling of the kerf profile in submerged milling by macro abrasive waterjet

Towards achieving control over the kerfing through abrasive waterjet submerged milling, there is a need to (i) understand the influence of the water column height on the kerf quality and (ii) develop a model for the prediction of the kerf characteristics. This study performs detailed experimentation to assess the kerf quality enhancement in submerged milling relative to the in-air on Al6061. From the modelling perspective, there are very limited efforts in developing a comprehensive model that includes both the jet flow dynamics and material removal models - this is the missing link. Towards this, a comprehensive model is proposed and validated for the prediction of kerf in in-air and submerged conditions by considering (i) jet dynamics and (ii) jet-material interaction. From the experimental results, it is observed that by adopting the submerged milling, the damaged region, top kerf width and edge radius got reduced by 20.3%, 13.53%, and 22.7%, respectively. However, this enhancement in the kerf quality is associated with a reduction in the centreline erosion depth (hmax) by 12.33% and a material removal rate by 24.52%. The material removal mechanism is more uniform and directed in the submerged milling, whereas in-air is random. The proposed model predicted the kerf cross-sectional profile in submerged milling and in-air with a mean absolute error of 60 μm and 57 μm, squared Pearson correlation coefficient of 0.97 and 0.99, and the hmax with a maximum error of 1.3% and 1.4%.