MICRO ELECTRIC DISCHARGE DRILLING IN CARBON FIBER REINFORCED POLYMER COMPOSITES

Abstract

Carbon fiber reinforced composites are widely used in many engineering applications because of their superior physical and mechanical properties such as high strength, high stiffness, corrosion resistance, high temperature resistance, light in weight etc. As the constitution of CFRP is inhomogeneous in nature, its machining is quite difficult. It is more difficult to conduct micro feature machining in CFRP. Micro Electric Discharge Machining which is a non conventional machining technique can be used to machine micro features in CFRP because of the presence of electrically conductive carbon fibers in CFRP. Machining through this technique leads to the development of a product which has a high surface finish, high accuracy and aspect ratio. In this report, fabrication of micro electrode using micro wire electric discharge grinding and drilling micro hole in CFRP using micro electric discharge machining technique have been discussed. In this research work, micro holes of 130 micron diameter were drilled in CFRP using micro electric discharge machining. For drilling, tungsten carbide was used as tool material. Tool of three different geometries (solid cylinder, single slotted and double slotted cylindrical shape) were fabricated using micro wire electric discharge grinding technique. Experiments were conducted on CFRP to find out the effect of voltage, capacitance, tool speed and tool geometry on tool wear rate, material removal rate and aspect ratio. Scanning electrode microscope (SEM) images of micro holes in CFRP and tungsten carbide micro electrode were taken. Response surface methodology (RSM) has been used as design of experiments technique. The experimental results indicate that given process parameters has influence on material removal rate, tool wear rate and aspect ratio. Though drilling micro hole using μEDM is a time consuming process, it is used to produce holes of high accuracy and high aspect ratios.