Evaluation of recast layer and parametric optimization of EDM process on aluminium based HMMCs using grey relational analysis

Metal Matrix Composites (MMCs) have a distinct property such as superior strength, higher elastic modules, augmented wear resistance, decreased weight, and high thermal conductivity as compared to the unreinforced alloy. Due to these superior properties MMCs are difficult for machining in conventional process. Hence, an advanced machining process namely Electrical discharge machining (EDM) process was utilized. In this existent work, an optimization technique called grey relational analysis is employed by optimizing the input process parameters to expose the optimal condition for enhancing the machinability and surface quality of aluminium based hybrid metal matrix composites (HMMCs) during Electrical Discharge Machining (EDM) process. The HMMCs is machined by EDM technique by scrutinizing the input parameters such as peak current (A), pulse on time (μs) and gap voltage (v) under L27 orthogonal array. A response table was exposed to indicate the optimum conditions of the individual parameter. The ANOVA results designates that peak current is the most contributing parameter for all the samples. Finally, a verification test is conducted to authorize the optimal conditions which were derived from the response table. Further the surface effects of the machined surface such as recast layer and machined surface at the circumferential area are analysed. The recast layer is developed on the machined surface at high peak current and pulse on time. At high pulse on time, extreme heat energy was generated which increases the irregular surface on the circumferential area.