On-machine measurement with an electrochemical jet machine tool

Measurement of surface geometry is an essential activity in engineering, which is commonly performed by tracing the surface of interest with a mechanical or an optical probe. This is generally performed ex-situ in laboratories designed for metrology. However, inline measurement represents an opportunity to unlock significant efficiency gains throughout manufacturing. Here, a new approach is proposed for in-situ measurement of surface topography using an electrolyte jet as a scanning probe within a precision electrochemical jet machine tool. The electrical resistance of a cylindrical jet impinging on a metal surface is a direct measure of the distance between the surface and the electrified nozzle, allowing profiling of surface shape. This enables integrated on-machine measurement in the electrochemical jet apparatus with tuneable sensitivity and vertical resolution, achieving accuracy of 4.4% with the calibration proposed here. The developed measurement system provides an accurate and low-cost surface imaging approach that can be easily integrated with industrial manufacturing processes. • An electrolyte jet can be used as a probe for measurement of surface geometry. • The resistance of the impinging jet is dependent on the distance to the surface. • Accurate on-machine measurement within electrolyte jet machining is demonstrated. • Micrometric vertical resolution is achievable.