VARIATIONS IN SPARK DISCHARGE AREA FOR DIRECTIONAL OVERCUT IN PRECISION ELECTRICAL DISCHARGE MACHINING

Abstract

The Electrical Discharge Machining (EDM) is established as a precision machining process when micron tolerances are required to be produced in components. For the tool makers, dimensional accuracy becomes a prime concern when complex designs and profiles are produced in the dies and moulds. In spark erosion process, sparking along the edges of tool leads to overcut in particular direction, resulting in directional overcut. In EDM, lower direction overcut is preferable to achieve higher dimensional accuracy. Therefore, optimization of directional overcut is a key concern to limit the dimensional deviations in EDM machining. The area of the tool imposed in spark erosion plays a prime role so that change in an area of the tool affects the directional overcut. The objective of present work is to investigate the influence of variations in spark discharge area along with other process parameters for optimizing the directional overcut. The variations of spark discharge area are analysed through Taguchi orthogonal array (L16×4) and sequential Analysis of Variance (ANOVA) approach. The current intensity is observed as a prime parameter in precision finish-cut machining. The second order regression analysis model predicts the coefficient of correlation (R 2 value) as 94.73%, which indicates good dimensional accuracy.

Keywords

• Dimensional accuracy
• Directional overcut
• Finish cut
• Orthogonal array