Modelling of Wire Electrochemical Micromachining (Wire-ECMM) process for anode shape prediction using finite element method

Abstract

In the present work, the principle of electrochemical dissolution was used to generate precise micro slits (kerf) on a flat stainless steel 304 workpiece, using a thin copper wire of diameter 30 μm as a tool. This variant of conventional electrochemical machining is called as Wire Electrochemical Micromachining (Wire-ECMM). The process was modelled in two dimensions with weak field formulation using finite element method (FEM) and the algorithm was implemented using a code in MATLAB (R2016a). Prediction of anode profile was done and this predicted profile was compared with the experimentally obtained profile. For this purpose, the distribution of iso potential contours in the domain of simulation was obtained by solving 2-D Laplace's equations for potential function in Cartesian coordinate system which was further used for quantitative assessment of current density at different points on the anode boundary. For experimental validation of the developed model, a setup for Wire-ECMM was designed and fabricated. Experiments were conducted to capture the variation of kerf width with three key process parameters namely, applied potential (V), electrolyte concentration (mol/L), and tool feed rate (μm/s), all varied one at a time. Each parameter was varied in four discrete equally spaced steps and width of kerf for each set of input parameters was obtained. Predictions from the developed model agreed well with the experimental results with a minimum error of 3.00%. On superimposing the kerf profile outline obtained experimentally on the simulated kerf profile outline, a close match between the two was observed.