Micro Electro-Chemical Machining

Micro Electro-Chemical Machining (ECM) (ESR4, ESR5). State-of-the-art

Scanning droplet cell, as an electrochemical analysis technique, has been widely used in various electrochemical surface investigations in recent decades. Before the invention of microcapillary cell or scanning droplet cell, the electrochemical analysis was usually conducted in a container full of some kind of electrolyte and the specimen surface had to be treated in advance considering the reaction performance.

Most microcapillary cell setups use the same principle as the original developed by Böhni. Recent research at KULeuven has proven that it is feasible to realize controlled supply of small electrolyte to 100μm in diameter to carry out micro-ECM processing. Jet ECM, as a promising method, can realize complex structures without immersing the workpiece surface in the electrolyte. Some research groups have done much work, such as M. Hackert et al., W. Natsu and M. Kunieda et al.

TU Chemnitz has developed closed-electrolytic-free Jet (Jet-ECM) to manufacture microstructures. Well-defined metal material volumes can be ablated by encasing direct electric current in an electrolyte jet, ejected from a solid metal micro nozzle. Working distances workpiece/nozzle with a minimal size down to 25% of the nozzle diameter between can be applied. The technology’s flexibility could be shown by Jet-ECM Turning and inverse Jet-ECM.

Fingerprint concept implementation
Both ESR4 and ERS5 will focus on the development of micro-ECM processing as a micro-structuring and polishing technique through the implementation of the process fingerprint concept. The process fingerprint of the micro-ECM processing techniques of ESR4 and ESR5 will be realized by process simulation in multi-physics tool of COMSOL®, monitoring of process parameters (e.g. current, flow-rate, density and temperature of the electrolyte etc.) and on-machine metrology for fingerprint verification. This will allow for real-time process control aiming at zero-defect micro structuring.

Expected progress beyond current state-of-the-art
As result of ESR4 and ESR5 projects two micro-ECM approaches at two different institutions based on micro-printing ECM and jet-ECM respectively will be developed for micro-structuring and polishing applications as requested by industrial applications of ESR8 and ESR12. Once the manufacturing fingerprint for these two micro-ECM structuring processes are experimentally established in combination with simulation and in-line/on-machine characterization, optimal process window will be defied to enable micro-structuring and polishing of dies and moulds. Two applications will be targeted by the ESRs to validate the manufacturing fingerprint research: micro structuring and polishing for micro injection moulding (ESR4), surface structuring for metal forming (ESR5).