Improving the electrochemical discharge machining (ECDM) process for deep-micro-hole drilling on glass by application of the electrolyte-air injection

The electrochemical discharge machining (ECDM) process is a popular technology for drilling holes in ceramic materials (including glass), particularly in the microdomain. The ECDM process and its variants have been continuously investigated and augmented to fabricate deep micro-holes on glass. ECDM with electrolyte injection was recently utilized to fabricate the deepest micro-hole in borosilicate glass. However, the drilling capability is still limited to a certain depth of micro-hole due to poor flushing of the machined by-products (i.e., salt, sludge, and debris). In order to resolve this issue, the present work uses the application of electrolyte and air injection, which improves the flushing action during ECDM drilling without compromising the advantages of electrolyte injection. This is achieved by providing electrolyte-air injection into the machining zone using a novel multiphase injection system with the ECDM facility. The underlying material removal mechanism in the conventional ECDM, ECDM with electrolyte and electrolyte-air injection, is also established based on analytical models and extensive experimental characterization. Additionally, a parametric investigation is conducted to compare the drilling performance of the ECDM with novel electrolyte-air injection and the ECDM electrolyte injection at various parametric conditions. The experimental results clearly showed the advantages of the ECDM with electrolyte-air injection over the previously benchmarked ECDM with electrolyte injection. Eventually, a through-micro-hole is drilled on a 3500 mu m thick glass work material using the ECDM with electrolyte-air injection. Concurrently, a 22.73% lower entrance diameter and 37.36% higher hole depth are realized compared to the ECDM with electrolyte injection.