Process simulation of micro electro-discharge machining on molybdenum

Micro electro-discharge machining (micro-EDM) is an ideal process for obtaining burr-free machined micron-size apertures in many materials. Molybdenum is one of the most attractive high energy and power aperture materials due to its mechanical and physical properties, mainly its high melting temperature and relatively high thermal conductivity. In this paper, process simulation and residual stress analysis for the micro-EDM machining on molybdenum is presented. Material removal is analyzed using a thermo-numerical model, which simulates a single spark discharge process. Using the numerical model, the effects of important EDM parameters such as the pulse duration on the crater dimension and the tool wear percentage are studied. Experimental single-spark crater sizes are investigated using scanning electron microscopy and optical evaluation methods and the results compared to the model. Results from a coupled thermal-structural finite element analysis are also presented to show how the thermal action of the micro-EDM process affected the surface integrity of machined workpiece.