FEM-based optimum design of multi-stage deep drawing process of molybdenum sheet

Molybdenum, one of the refractory metals, has high heat and electrical conductivity while remaining strong, mechanically, at high, as well as low, temperatures. Therefore, it is a technologically very useful material, especially for high temperature applications. However, due to its very low drawability, a multi-stage process is necessary to make a deep drawn part from the molybdenum sheet. In this study, a multi-stage circular cup deep drawing process for a molybdenum sheet was designed by including ironing, which was effective in increasing drawability. A parametric study by finite element analysis of deep drawing was conducted to evaluate the effect of die design variables. From parametric study results, the design variables of the multi-stage deep drawing process were selected. Then, nonlinear process optimization, based on finite element simulation, was conducted to obtain the optimum multi-stage deep drawing process, using a global, as well as a local, optimum search algorithm.