Machinability and characterisation of machined hole on quartz using developed µ-AJM set-up

Micro-abrasive jet machining (µ-AJM) is one of the novel machining processes used for machining brittle materials wherein the mechanism of erosion is brittle fracture and for ductile materials wherein the mechanism of erosion is due to shear fracture on the materials. In the current work, an attempt has been made to find the material removal rate (MRR) and characterisation of micro-holes produced on quartz using silicon carbide abrasives of various grit sizes. The process parameters selected are air pressure, stand of distance (SOD) and abrasive grit size and output responses measured for the experiments are MRR, radial over cut (ROC) and taper angle. Taguchi L 16 orthogonal array has been selected to conduct the experiments. Grey relation analysis (GRA) was utilised to optimise the process parameters to increase the MRR and at the same time reduce the taper angle and ROC. From the GRA, the obtained optimum parameters are 4 bar air pressure, 0.5 mm SOD and Mix 1 (50% of 320+ 50% of 220) for maximum MRR of 3.96 mg/min, minimum ROC of 85 µm and minimum taper angle of 5°. An improvement method has been adopted to overcome the chipping at the bottom edge of the workpiece.