Determination of process parameters for microchannel fabrication by microelectro-discharge machining

Abstract

Data for processing of micrometric geometric features via electro-discharge machining are not widely available. This article describes a methodology to produce microfeatures with a low-cost, open-architecture micro-electro-discharge machining setup using a Resistive–Capacitive oscillator as the power source. The goal of this work was to identify process condition parameter values to maintain a stable micro-electro-discharge machining process. The setup consists of a machine under development for the fabrication of two-and-a-half-dimensional microstructures on conductive materials, using 254-µm-diameter brass electrodes. Three performance parameters were defined to characterize the process: material removal rate, ratio of electrode to workpiece wear, and surface finish. Because of their relevance to the viability of the process, voltage and energy were selected as controllable parameters. The effect of controllable parameters on the mean and standard deviation of the performance parameters during machining of an A36 cold drawn steel workpiece was studied. Voltage and energy values that resulted in a stable process were identified from this exploratory study. Microchannels of 290 µm width (discharge over cut of 18 µm on lateral walls), 50 µm depth and various millimeters long were machined to test selected values. Microchannel depth was maintained constant by applying a sloped motion that compensated for electrode wear.