Effect of different dielectric fluids on material removal rate, surface roughness, kerf width and microhardness

Abstract

In microelectro discharge machining, dielectric plays prime role in the machining performance. The performance of machining is highly affected by dielectric fluid used in the micro-EDM. This paper discusses the influence of various different dielectric fluids such as demineralised (DM) water, oxygenated DM water, mixture of ethylene glycol and DM water, alumina suspension in DM water, alumina suspension in oxygenated DM water and alumina suspension in mixture of ethylene glycol and oxygenated DM water on the performance criteria such as material removal rate (MRR), surface roughness, kerf width and microhardness during the machining of stainless steel. The results show that the use of DM water as a dielectric gives high MRR. Also when non-conducting alumina powder is mixed with dielectric, the MRR is decreased. Surface roughness is best for DM water. Surface roughness is found to increase with other dielectric fluids. Kerf width is improved after mixing alumina powder and ethylene glycol to DM water. A comparative study for microhardness has also been done for different dielectric fluids. Further study is done using microscope to analyze the microstructure. Further investigation is performed on surface integrity in each type of dielectric with the help of microstructure. Hence, micro-EDM is performed on stainless steel with different dielectric fluids. It is noticed from the results that there is significant impact of mixing non-conducting alumina powder and oxygen in DM water which increased the kerf width and microhardness of machined surface in micro-EDM of stainless steel.