Prediction of machined surface evolution in the abrasive jet micro-machining of metals

Surface evolution models have been used in the past to accurately predict the cross-sectional profile of micro-channels resulting from the abrasive jet micro-machining (AJM) of glass and polymeric substrates. In the present paper, the models are suitably modified and applied for the first time to the AJM of metallic substrates. The dependence of erosion rate on abrasive jet inclination angle was measured for aluminum 6061-T6, Ti–6Al–4V alloy, and 316L stainless steel using 50 μm Al2O3 abrasive powder launched at an average velocity of 106 m/s. For all three systems the peak erosion rate was found to occur when the jet was inclined between 20° and 35° relative to the surface. The AJM etch rate was found to be much lower than that found in glass and polymers, and it was found that a significant amount of particle embedding occurred in the 316L stainless steel. When the erosion data were used in an AJM surface evolution model, the resulting predicted cross-sectional profiles of unmasked and masked channels were in reasonable agreement with the measured profiles up to an aspect ratio (channel depth/width) of 1.25. The results demonstrate that surface evolution during the abrasive jet micro-machining of metals can be predicted using existing models, originally developed for glass and polymers.