Analysis of Micro Fin Deformation Due to Micro EDM

This work describes deformation of fin machined by micro electrical discharge machining (EDM). First, temperature distribution in a workpiece due to micro EDM single discharge was calculated using finite element method, and the result was used to calculate residual stress. It was found that the residual stress in the radial direction, σ r ( z ) along the centre axis of the single discharge crater was distributed non-linearly in thickness direction from top surface of the workpiece. Then, in structural analysis, the result of σ r ( z ) was imposed within micro fin model. Here, thermal stress field due to series of sequential discharges was considered. The summation of calculated deflections after three sequential discharges was almost equal to the measurement result. To explain the deformation of fin, additional models of uniform rectangular beam were built. As a result, the non-linear distribution of σ r ( z ) was found to be the main reason that causes the non-uniform curvature of micro fin.