Numerical and experimental investigations into microchannel formation in glass substrate using electrochemical discharge machining

Abstract

Microchannels formed in non-conductive substrates like fused silica, glass and quartz, etc, have wide applications in the field of micro-fluidic and lab-on-chip applications due to their optical transparency, chemical inertness, and biocompatible nature. Electrochemical discharge machining (ECDM) has emerged as a potential low-cost fabrication method to fabricate microfeatures in these materials, compared to conventional laser etching techniques. In this paper, numerical simulation and experimental fabrication of microchannels in a glass substrate using the ECDM based micromilling technique is demonstrated. Stainless steel needle as tool electrode is used in alkaline electrolyte medium. The effects of process parameters viz. tool feed rate, pulse frequency and machining voltage on material removal rate (MRR) and surface roughness (SR) of the microchannels were analysed. The experimental results showed that the MRR and SR increases with an increase in machining voltage and tool feed rate but reduces with an increase in the pulse frequency. Simulations using FEM-based model showed similar trends in MRR with that of experiments. A comparison between the cross-section profiles obtained by the experimental work and predicted profile by the numerical simulation showed some deviation between them due to the Gaussian heat flux assumption in the numerical model. Optical images showed that KOH performance is comparatively better than NaOH with respect to thermal damage and width of cut. Further, multi-objective optimization was performed using utility theory coupled with Taguchi’s method to optimize the process parameters. Moreover, the capability of the ECDM process was demonstrated in fabricating various other micro-features such as sinusoidal channel, letter engraving, etc in a glass substrate, which can be extended to other brittle materials like quartz, fused silica, ceramic, etc.

A Comprehensive Review on Modeling and Simulation Studies in Electro-Chemical Discharge Machining

“…Mishra et al [22] demonstrated numerical simulation and fabricated microchannels on the glass substrate. Machining voltage, pulse frequency and tool feed rate were considered as process parameters for analyzingsurface roughness (SR) and MRR of the microchannels as response parameters.…”

“…Mishra et al [22]presented the trend for variation of MRR with tool feed rate asincreasing based on simulation and experimental results. For electro-chemical discharge drilling (ECDD) of silica glass, Rajput et al [17] reported that the tool feed rate was the most governingprocessparameter for controlling TWR based on RSM analysis.…”

“…Owing to wide applications of glass, most of the studies employed glass as workpiece. Although most of the studies were based on drilling operation, very few simulation studies were carried out for microchannel and milling operation [22], [23], [30].…”

“…Three-dimensional Goud and Sharma [21] 2017 Hajian et al [30] 2018 Mishra et al [22] 2019 Mishra et al [23] 2019 Arab et al [31] 2019 Sharma et al [24] 2020 Rajput et al [26] 2020 Arab et al [33] 2020 Rajput et al [17] 2020 Arab et al [34] 2021…”

“…Uniform Jain et al [12] 1999 Kolhekar and Sundaram [25] 2019 Gaussian Bhondwe et al [18] 2006 Wei et al [27] 2011 Jiang et al [19] 2014 Behroozfar and Razfar [29] 2016 Paul and Korah [20] 2016 Goud and Sharma [21] 2017 Hajian et al [30] 2018 Mishra et al [22] 2019 Mishra et al [23] 2019 Arab et al [31] 2019 Sharma et al [24] 2020 Rajput et al [26] 2020 Arab et al [33] 2020 Rajput et al [17] 2020 Arab et al [34] 2021 [27] 2011 Jiang et al [19] 2014 Goud and Sharma [21] 2017 Mishra et al [22] 2019 Mishra et al [23] 2019 Arab et al [31] 2019 Rajput et al [26] 2020 Arab et al [33] 2020 Rajput et al [17] 2020 Arab et al [ [22] Melting temperature of glass substrate 1400 °C Behroozfar et al [29] Assumed critical temperature of glass 600 °C…”