Investigations on quantification and replenishment of vaporized electrolyte during deep micro-holes drilling using pressurized flow-ECDM process

Electro-chemical discharge machining (ECDM) process has ability to drill micro-holes, nonetheless has limitation of lower depth with appreciable hole quality. The reason thereof is poor replenishment of vaporized electrolyte inside the machining zone with an increment in drilling depth. Few approaches have been reported to replenish the electrolyte in ECDM process. However, quantification of the vaporized electrolyte from the machining zone at different parametric conditions, and its replenishment with precise control is not revealed. In order to address these limitations of ECDM process, this article reports development of pressurized flow-ECDM (PF-ECDM) process. In this development fresh electrolyte is injected through a tubular electrode with precisely controlled electrolyte flow rate (EFR) into the machining zone during ECDM. Also, a novel approach is used to predict the range of EFR by quantifying the electrolyte vaporization rate at various thermal energy inputs. A comprehensive investigation is conducted to bring forth the effect of EFR on machining performance (i.e. depth and entrance diameter of the hole). The results of investigation reveal that the injected fresh electrolyte enhances the machining performance over conventional ECDM process. Also, the EFR is found to be dependent on provided thermal energy inside the machining zone. Hence, noticeable improvements in the process performance are realized at a particular value of EFR (i.e. adequate EFR) for specific parametric conditions. The multi criteria optimization is also performed using desirability function approach to obtain the optimum process parameters for PF-ECDM process. Eventually, a micro hole of 2478 mu m depth is achieved using PF-ECDM process.