Executive Summary : | The objective of this proposal is to improve the efficiency of the electrical discharge machining (EDM) process and achieve desired machining performance for machining superalloys that are of particular interest to space technology, viz. Titanium Ti6AlV, Inconel 600/718, Hynes-25, Molybdenum, Columbium 103. To achieve the research objective, this proposal seeks to, (1) develop a 2D multi-physics model EDM process; (2) experimentally validate the EDM model; (3) optimize EDM machining parameters for improved efficiency via parametric studies. The modeling work will be carried out on two fronts. Firstly, a 2D axisymmetric model for EDM plasma will be developed to gain a spatial and temporal description of the plasma characteristics. The plasma model will also incorporate the mathematical description of dielectric flow during and after the discharge. Secondly, a fluid and heat transfer model will be developed to model the flow of melt-pool on the electrode surfaces and the debris formation. The multi-physics model of the plasma and material removal will be solved together numerically at each time step to obtain a complete mathematical description of a single discharge operation in EDM. Systematic experiments will be carried out to validate the predictions of the model. Diagnostic tools such as optical emission spectroscopy, high-speed imaging, and electrical measurements will be used for validation of predicted plasma characteristics, while 3D surface measurement and debris characterization will be used to validate the material removal. Finally, an extensive parametric study will be carried out with different materials to improve the understanding obtained by the model-predictions. This will narrow down the range of parameters that result in desired machining performance in terms of surface finish, material removal rate (MRR) and tool wear, etc. The quantitative understanding of EDM obtained through both experimentation and multi-physics mathematical modeling will be superior to a simple empirical approach, leading to significant process improvements in EDM of superalloys that have critical applications in space technology. |