The research to be carried out is directed toward a more fundamental understanding of the micro-electrical discharge machining (micro-EDM) process employed for high precision shaping and manufacturing.
Intellectual Merit: The specific objectives are to:(1) gain better control of the plasma used to remove debris and (2) achieve improved understanding of the physical mechanisms of debris formation and removal. These objectives will be realized through the execution of four principal tasks: (1) improve precision by stabilizing the plasma; (2) model the flow characteristics of the melt pool; (3) develop a magnetic field-assisted debris removal technique; and (4) experimentally validate the model used to predict the detailed heat transfer and fluid flow processes that ultimately drive the process. The model will also be used to develop new magnetic field-assisted debris removal configurations that will assist the experimental design. A micro-EDM test bed with optical emission spectroscopy and underwater acoustic emission sensor capabilities will be employed to characterize the plasma. Advanced material diagnostics will also be used for debris characterization. Novel magnetic field-assisted debris removal concepts will be developed and tested.
Broader Impacts: The project will result in new features of the micro-EDM process and, in turn, manufacturing precision that might not be achievable by other means. This will enable manufacture of high-precision, micro-scale components and devices characterized by complex geometries fabricated from a wide range of engineering materials. This will help meet a wide spectrum of current and future needs in applications including but not limited to: medicine and health care, communications, optics, and defense. The project will involve researchers from academic and research institutions in India and South Korea. Efforts will be made to boost the participation of members from underrepresented groups by leveraging programs such as the Women in Engineering Program, the Minority Engineering Program, and the McNair Scholar Program.
Major outcome of this research project has been the improved understanding of the physical mechanisms of the material removal through modeling of micro-EDM plasma and the role of magnetic field in assisting the crater formation and debris removal. The micro-EDM plasma model developed enables prediction of transient characteristics of the plasma, i.e., the number densities of different species in the plasma, temperature of the plasma, radius and velocity of the plasma bubble, pressure of the plasma bubble as well as the heat flux transferred to the workpiece during the discharge process. Further, the model predicts effect of the machining parameters such as applied electric field and inter-electrode gap on the plasma characteristics. A micro-EDM melt-pool model developed gives the temperature distribution and the melt-flow of the workpiece during a single micro-EDM discharge. The model also predicts the workpiece crater size and shapes in a single discharge micro-EDM process at different inter-electrode voltages and gaps. It is seen that the model accurately predicts the crater shapes at higher discharge gaps (>1 micron). Using the model, it is demonstrated that by using an external magnetic field, a morphological and dynamical modification of the micro-EDM melt-pool can be accomplished. Furthermore, magnetic field-assisted micro-EDM experiments show that an external magnetic field results in appreciable increase in the erosion volume and enhanced debris ejection causing more material removal in micro-EDM. This new, efficient process of magnetic field-assisted micro-EDM can offer unique capabilities not achievable by any other available methods for the manufacture of high relative accuracy micro-scale components and devices with complex geometries in a wide range of engineering materials. Also, expansion of the understanding of electro-discharge machining enables a more widespread use of the technology in the areas of medicine and healthcare, communications, optics and defense. The results of this research have been introduced as a part of theoretical study and laboratory exercise in a combined graduate/undergraduate course in ‘Micro-manufacturing Processes and Automation’ offered annually at University of Illinois at Urbana-Champaign. The physical and informational resources developed as a part of this project have been made a part of micro-manufacturing processes laboratory at University of Illinois at Urbana-Champaign, where they can be accessed for future research and educational purposes.
