Roughness modelling and optimisation in EDM using response surface method for different work piece materials

Influence of machining parameters, viz., pulse current, pulse on time and pulse off time on the quality of surface produced in electrical discharge machining (EDM) is investigated. Experiments are conducted for three different work piece materials to see the effect of work piece material variation in this respect. Five roughness parameters, viz., centreline average roughness, root mean square roughness; skewness, kurtosis and mean line peak spacing have been considered. The second order mathematical models have been developed for each of these five-roughness parameters predictions using response surface methodology. The roughness models, as well as the significance of the machining parameters, have been validated with analysis of variance. The response surface models are found to be specific to work piece materials. An attempt has also been made to obtain optimum machining conditions using response optimisation technique.