Electrochemical machining - new machining targets and adaptations with suitability for micromanufacturing

Abstract

Electrochemical machining (ECM) is a non-conventional machining technique capable of machining any conductive substrate, regardless of its physical properties e.g. hardness. ECM became an attractive method due to its ability to machine substrates without creating a defective surface layer. ECM utilises electrolysis; a small gap is maintained between two electrodes whilst a favourable potential is applied between them to remove material from the workpiece. The parameters are adjusted to obtain the desired machining results i.e. surface finish, machining resolution and machining rate. Much work has been conducted for the anodic dissolution of stainless steels and brass but little work outside of these materials is available. This work demonstrates the applicability of ECM for a new range of materials; superconductors and semiconductors, along with the application of ECM for medical needle production and an alteration to the machine set up to anodically dissolve titanium metal at reduced potentials. Through a series of electrochemical techniques, namely polarisation curves, machining potentials were defined for a cuprate superconductor and a semiconductor. These were then demonstrated as suitable settings by completing tests on an electrochemical machine. Hypodermic needles were created on an electrochemical machine and polarisation curves of titanium with the addition of ultrasonic vibrations were used to demonstrate the anodic dissolution of titanium at much reduced potentials.