On prolongation of discharge regime during ECDM by titrated flow of electrolyte

In electrochemical discharge machining (ECDM), the drilling of micro holes has been established through two regimes (i.e., discharge and hydrodynamic regimes). In discharge regime, the material removal mechanism is directly controlled by the number of spark discharges and it allows fast penetration of tool electrode inside the work material, whereas in hydrodynamic regime, the accumulation of bubbles at hole entrance and inadequate supply of electrolyte toward tool tip limit the penetration rate during deep hole drilling. In order to achieve consistent machining conditions, particularly during deep hole drilling, the prolongation of discharge regime is essential. Thus, in the present research endeavor, a ECDM with titrated flow of electrolyte was attempted. The application of titrated flow of electrolyte in ECDM process drilled micro through holes in 1350-μm-thick work material in approximately 30 s. In comparison to the conventional ECDM process, the presented method reduces the machining time by 7 times and also improves the machining accuracy by reducing the hole entrance diameter by 1.25 times. The consistency obtained in discharge characteristics as well as in penetration rate is evident in the prolongation of discharge regime during ECDM with titrated flow of electrolyte. The underlying material removal mechanism has also been presented. Multicriteria optimization (MCO) was also performed to predict the suitable parametric combination for higher penetration rate and low hole entrance diameter of the machined micro holes. The results obtained from the current investigation presents titrated flow of electrolyte as a one of the fastest machining strategy (that provides a penetration rate of 45 μm/s) to drill the micro holes by ECDM process.