INVESTIGATION ON INFLUENCE OF PROCESS PARAMETERS OF ELECTRO DISCHARGE MACHINING OF AI-7075-SiC COMPOSITE

Abstract

Fuelled by a growing need for high strength materials in technologically advanced industries and supported by the advances in the field of material science, there has been an increase in the availability and use of difficult-to-machine materials. Composites are being seen as the replacement of the existing materials in aerospace and manufacturing industries. They have better properties than their constituting elements. Metal Matrix composites (MMCs) are composed of a metal (e.g. Al) which forms it's matrix and reinforcement is formed by an inexpensive material to induct properties like better abrasion resistance, light-weight and high stiffness, improved high temperature properties, good thermal shock resistance, excellent stability to radiation damage and low activation characteristics in the metal matrix. This makes them extremely useful in high-tech structural and functional applications including aerospace, defense, automotive, and thermal management areas in walls of fusion reactors, as well as in sports, recreation, and manufacturing of track shoes in advanced military tanks. In the light of high tool wear and high cost of tooling with conventional machining, unconventional material removal processes like Electrical Discharge Machining (EDM) offers an attractive alternative. The AMC discussed here is Al-7075matrix with SiC (15%) reinforcement. Its high hardness makes its machining economical through a non contact process like Die Sinking EDM. However, due to high heat generated in the discharge channel, the Heat Affected Zone appears, thereby rendering the composite hard to machine, and degrading its physical properties. Through studies it is established that Heat Affected Zone (HAZ) depends on applied parameteric values. The project aims to study the HAZ and tries to establish some optimum parameteric values through experimental investigation. In the end, a trial case study on difficult to machine hard material like Inconel 718 is intended to be taken up for understanding purpose.