Abstract
Recent applications of heavy-duty gunmetal mechanical elements demand superior quality oil holes for extended service life and significant enhancement in functional aspects. In this work, through-holes of 10 mm diameter are machined by an electrical discharge machining process in LG-2 gunmetal blocks based on Taguchi L9 orthogonal array. The selected input factors are spark-on time, current, and gap voltage. The multi-criteria optimization technique Taguchi-gray relational analysis is used for optimizing the input factors for machining characteristic responses such as material removal rate, electrode wear rate, surface roughness, and form accuracy characteristics of holes such as circularity, cylindricity, radial overcut, and taper rate. The optimum cutting condition identified is the current of 30 A, gap voltage of 25 V, and spark-on time of 90 µs. Experiments carried out using the optimum cutting conditions with various copper electrode profiles such as cylindrical, conical, tapered, stepped, D-shaped, and curved electrodes reveal that the conical electrode profile is best suited for achieving the required machining and form accuracy characteristics. A comparison of the hole surface characteristics of the three holes machined using conventional drilling, traditional cylindrical electrode, and the conical electrode using salt spray corrosion test and scanning electron microscope reveals the hole machined using a conical electrode profile has minimum surface undulations resulting in better corrosion resistance.
Get full access to this article
View all access options for this article.