Adapting ‘tool’ size using flow focusing: A new technique for electrochemical jet machining

Electrochemical jet manufacturing methods exploit the localised interaction of an electrified jet with a conductive workpiece. This has been exploited by numerous researchers to deposit and remove material. In recent studies, the same approach has been used as an analysis tool to measure and evaluate engineering components. The capability of this manufacturing method is limited by the resolution, which is governed by the diameter of the jet. Although approaches have been taken to reduce the kerf or interaction volume in the process, it is the jet diameter still provides the fundamental limit. In this study, a new method is proposed which takes advantage of a constriction effect to reduce the jet diameter through flow focusing, which occurs in coaxial two-phase flows. A novel nozzle arrangement is presented which demonstrates jets can be constricted by 79% leading to 54% reduction in machined kerf width. The limitations of this method are investigated in the context of fluid dynamic constraints, identifying optimum operating regions to utilise the approach in a computer numerical control machine tool arrangement. This enables continuously varying tool size in-process, which is analogous to other energy beam processes where spot size can be adjusted with a corresponding response in fluence.