Effect of Dielectric Fluid and Vibration on Performance in Electrical Discharge Machining of AlSiC Metal Matrix Composites

Abstract

Metal Matrix Composites (MMC) belong to a new generation of engineering materials that have desirable qualities such as high strength-to-weight ratio, high toughness, low value of coefficient of thermal expansion, high wear resistance, and thermal stability. They are therefore increasingly finding applications in the areas of aerospace, automotive, defense, biological and nuclear energy fields. Due to the nature of their application, these materials require to be machined to a high accuracy and to have a good surface finish. This requirement poses a challenge due to hard and abrasive nature of the materials. Mostly, grinding is the process used but the process is expensive and slow. Electrical Discharge Machining (EDM) can be used to address these challenges since it can be used to machine electrically conducting materials irrespective of their hardness. This paper investigates the effect of using oil and deionised water as the dielectric fluids as well as the effect of introducing low frequency vibration in EDM machining of Aluminium Silicon Carbide (AlSiC) MMC. Experiments were carried out on AlSiC (AMC225XE) material using Sarix-100 high precision micro-erosion machine. A series of experiments were carried out with and without workpiece vibrations. For the experiments with vibrations a vibration frequency of 900Hz was used. The results of this study indicate that introduction of vibration raises the material removal rate but results to an inferior surface quality. Using deionised water as the dielectric results in lower machining time as opposed to Oil. However, this also results in an inferior surface quality and geometry of bore.