22. Performance Analysis of ECDM Process Using Surfactant Mixed Electrolyte

With rapid escalation in the utilization of glass materials in microelectromechanical systems (MEMS) applications, need is generated to develop more sophisticated process for machining these materials at a higher machining speed with excellent features. Electrochemical discharge machining (ECDM) is proven to be a successful method for machining glass materials with ease which utilizes the thermal heat of the sparks and chemical etching action of electrolyte for material removal simultaneously. However, low material removal rate and thermal cracks at the micro-hole entrance edges are some of the concerns which need to be enhanced. Several parameters influence the ECDM process but gas film formation and its thickness is the key determinant for obtaining higher quality machined surface. This present paper investigates the effect of surfactant addition, i.e., cationic surfactant cetyltrimethylammonium bromide (CTAB) in three different concentrations, into the 20 wt% alkaline solution of NaOH electrolyte for improving the material removal rate and thermal cracks during micro-drilling operation. Moreover, a transient thermal model based upon finite element modeling (FEM) is developed to analyze the material removal rate (MRR) with and without the presence of surfactants in the ECDM process. Simulation results are compared with the previously reported experimental results. Surfactant addition affects the electrochemical properties of the electrolyte and leads to the increase in tool electrode wettability which produces thin and stable gas film at the tool vicinity. As a result, more current densities are produced and hence faster material removal rate. Experimental results revealed that a significant increase in removal rate and reduction in thermal cracks were observed during micro-drilling process in the presence of surfactants. An increase of 39.31% was observed in material removal rate of soda–lime glass in the presence of CTAB surfactant at critical micelle concentration (CMC). Simulation results exhibit good similarity in the trend of the material removal rate with the experimental results. The developed thermal model can be effectively utilized to determine the removal rate of surfactant mixed ECDM process. Based on the observation of present investigation, a more reliable and effective surfactant mixed ECDM process with improved removal rate and surface quality is inferred.