Prediction of the erosive footprint in the abrasive jet micro-machining of flat and curved glass

A computational fluid dynamics (CFD) procedure is presented for the prediction of the erosive footprint size in abrasive jet micro-machining (AJM). The CFD-obtained footprints were in good agreement with those measured experimentally. The footprint was found to be due to both primary particle impacts in the conical plume emanating from the nozzle, and secondary particle impacts driven by the flow. The footprint depended on target curvature because the spread in lateral particle rebounds differed, depending on the target radius. It thus follows that footprints obtained from shallow channels machined on flat targets cannot be used to predict channel shape on curved surfaces. Since the footprint must consider secondary impacts, this has important implications for surface profile modeling of curved surfaces.