Investigation on a sustainable composite method of glass microstructures fabrication—Electrochemical discharge milling and grinding (ECDM-G)

Glass structures with microchannel morphology play an important role in the fields of biology, medicine and MEMS. The non-traditional machining methods currently used to machining glass have problems such as excessive energy consumption, poor sustainability, and harmful to operators and the environment. To achieve precision, efficient, green, sustainable production and save resources, a novel composite machining method of electrochemical discharge milling and grinding (ECDM-G) was proposed in this paper. Compared with tranditional electrochemical discharge machining, lower discharge energy is applied, and KH2PO4 solution is used as electrolyte instead of alkaline solution, thus realizing energy-saving and green machining. Compared with mechanical grinding, tool wear is reduced and the sustainability of machining is improved. In the theoretical part, the heat conduction process of electrochemical discharge was simulated and the softening effect of workpiece material was analyzed. Furthermore, the matching mathematical model between electrochemical discharge energy and material removal by grinding was established. So as to accurately control the energy and avoid waste. In the experiment part, the key parameters were determined through the Plackett-Burman experiment, and then the Box-Behnken experiment was conducted on the key parameters and the Response Surface Methodology (RSM) was used to obtain the optimal combination of machining parameters. Compared with mechanical grinding, the problems of edge collapse and breakage are solved. The overcut is reduced by 35.1%, the edge damage is reduced by 42.2%, the surface morphology is improved and the surface roughness value is reduced by 47.7%. Compared with ECDM, the problems of heat affected zone and thermal defects are solved. The overcut is reduced by 49.1%, the edge damage is reduced by 56.6%, the surface feather morphology is removed and the surface roughness value is reduced by 74.9%. The machining stability and consistency of ECDM-G method are analyzed by machining array microchannels. Finally, with the optimized machining parameters, the microfluidic chip with typical microchannel structure was fabricated by ECDM-G, and the tool electrode has no severe wear after machining the long path complex structure, which proves that ECDM-G can be an energy-saving, sustainable and effective method for machining precision glass microstructures with high quality, and further shows that ECDM-G has industrial application prospects in the manufacturing of key biological and medical components.