Precision ECM by Process Characteristic Modelling

Abstract

Electrochemical machining (ECM), which is not normally considered as a precision process, is used to achieve accuracy better than 5 urn and surface finish 0.03 μm R a by using pulsed power of relatively short durations (1–10 ms) and narrow inter-electrode gaps (10–50 μm). The narrow gaps, however, make the control and prediction of the process much more complex than normal ECM. An empirical model is developed based on the characteristic relationships of ECM to predict and optimise the process parameters such as dissolution efficiency, current density, electrolyte concentration and pulse duration, in narrow gaps. This model is then used to facilitate new applications of high precision ECM without recourse to the lengthy trial-and-error approach, by predicting selective dissolution of the workpiece and tool design.