Machinability study and characterisation of holes machined using mechanical micromachining technique – micro drilling

Abstract

ABSTRACTMechanical Micro Drilling (MMD) is a high-speed micromachining process used to machine micro holes economically on engineering materials. In this paper, an attempt has been made to machine micro holes of ϕ500 microns using MMD process by varying tool type; solid carbide, tungsten carbide and Nickel phosphate coated carbide, workpiece materials; SS 316, Inconel 625 and Titanium Grade 2 and spindle speed; 2800 rpm, 4500 rpm and 7000 rpm at three levels as per Taguchi's L9 orthogonal array. Machined holes are characterized in terms of responses such as Material Removal Rate (MRR), roundness, taper angle and radial overcut. The results are analyzed using S/N ratios for the above-said responses and ascertained the optimal parameters. The maximum MRR is found to be 57.76 μg/s for workpiece: Inconel 625, tool: solid carbide and spindle speed: 7000 rpm. The maximum roundness is found to be 0.981 for workpiece: SS 316, tool: solid carbide and spindle speed: 2800 rpm. The minimum taper angle is found to be 0.248° for workpiece: SS 316, tool: solid carbide and spindle speed: 2800 rpm. The minimum radial overcut is observed to be 17.68 microns for workpiece: Inconel 625, tool: solid carbide and spindle speed: 2800 rpm.