Modeling and analysis of the rapidly resolidified layer of SG cast iron in the EDM process through the response surface methodology

The rapidly resolidified layer is formed by the re-solidification of residual molten material on the machined surface during the electric discharge machining (EDM) process. This paper presents a systematic methodology for modeling and analysis of the rapidly resolidified layer of spheroidal graphite (SG) cast iron in the EDM process using the response surface methodology (RSM). The factors of second phase considered are the quantity, diameter, and area fraction of spheroidal graphite particle. The performance of rapidly resolidified layer in terms of the layer thickness and ridge density are response variables investigated. Experimental plan is performed by a standard RSM design called a central composite design (CCD). The results of analysis of variance (ANOVA) indicate that the proposed mathematical model obtained can adequately describes the performance within the limits of the factors being studied. The conclusions reveal that the quantity and area fraction of graphite particle are the most influential factors on the layer thickness and ridge density. The formation of ridge is chiefly related to the quantity and area fraction of graphite particle. In addition, the layer thickness reduces as the diameter of graphite particle increases.