Experimental Determination of Parameters to Avoid Arcing in Electrical Discharge Machining of Titanium Diboride Particulate Reinforced Ferrous Matrix Composite

Titanium diboride (TiB₂) particles are most popular reinforcement along with tungsten carbide for ferrous matrices for developing composites with high specific modulus, improved wear resistance and hardness while providing good fatigue properties as well. The hardness of such composites poses a problem in conventional machining in terms of very fast wear rates of tools and very high cutting forces. Non-conventional processes like electrical discharge machining (EDM) are very popular for machining of conductive composites like TiB₂ reinforced ferrous matrix composites. However, there are a large number of process parameters for EDM which need to be selected and controlled carefully for satisfactory machining performance. Parameter settings which lead to arcing are specifically investigated and avoided as this phenomenon leads to uncontrolled machining through short circuit conditions and large energy discharges. In this paper, an experimental approach to determine the parameter settings which will lead to arcing during EDM machining of TiB₂ particulate reinforced ferrous matrix composite is discussed. Values of major EDM process parameters are selected in roughing, intermediate and finishing domains. Experimental trials using L27 design of experiment are conducted and parameter combinations leading to arcing are recorded and the zone of parameters that can lead to arcing is identified.