Experimental study on micro electrical discharge machining of porous stainless steel

Porous metals and alloys are ideal lightweight and damping materials which have garnered significant research attention owing to their superior mechanical and metallurgical characteristics. Micro electrical discharge machining (micro EDM) is an alternative method for machining porous metals. In this study, experiments on porous stainless steel (PSS) were conducted to determine the micro EDM performance of austenitic stainless steel (AISI 304) and PSS samples with various porosities and pore sizes. The results were analyzed based on the thermal conduction theory of porous materials. PSS achieved better machining performance overall compared to AISI 304 due to its porosity; further, porosity and pore size were shown to have a significant influence on the machining characteristics of PSS. The larger the porosity and pore size, the higher the material removal rate (MRR) and the lower the relative tool wear ratio (RTWR). Thermal conductivity decreases due to the existence of pores, causing less heat to be lost by heat conduction and more energy to be consumed in order to remove the material. High capacitance in the experimental circuit proved suitable for machining PSS, while high open circuit voltage appeared to be more suitable for machining AISI 304.