Electric Discharge Machining of Low Conductivity Materials
Thanks to advances in electronics and numeric controls, unconventional technologies such as Electric Discharge Machining (EDM) has recently evolved into a highly effective and reliable method for processing aerospace materials, independently of their hardness and mechanical resistance, and with the only requirement of having a good electrical conductivity. However, the present study shows that EDM can also be upgraded for the machining of low electrical conductivity materials by enhancing the EDM pulse generator sources so that, first, the spark ignition and sustaining conditions in the machining gap become close to those obtained in standard systems by compensating the resistive losses in the machined materials, and second, the machining pulse itself is designed to optimize the removal mechanism in the material, whether melting, evaporation or mechanical thermo-shock. The applications potential of such new adapted systems is shown by describing the process results of promising but challenging materials for high-efficiency aerospace component manufacturing, like ceramic matrix or carbon-fiber based composites, and through the analysis of removal rates, surface integrity and mechanical characteristics of the machined surfaces.