Faculty Publications
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Item MOJAYA Coupled with R-method for Optimization of Machining Parameters Used in the Generation of Micro Holes on GFRP Composite Using an In-House Developed µ-ECDM System(Springer Science and Business Media Deutschland GmbH, 2023) Bhargav, K.V.J.; Shanthan, P.; Balaji, P.S.; Sahu, R.K.Glass fiber reinforced plastic is a highly versatile composite with properties such as high strength, flexibility, durability, stability, lightweight, and resistance to heat, temperature, and moisture. It is commonly used in automobiles, aerospace, construction, power generation, and manufacturing. Owing to these numerous applications, machining holes in GFRP composite has become the need of the day. This paper focuses on machining microholes in GFPR composite using an in-house developed µ-ECDM system. The process parameters selected for machining are voltage (V), concentration (wt%), and duty factor (DF), and the machining characteristics chosen are material removal rate (MRR) and overcut (OC). The machining parameters are optimized using the multi-objective JAYA algorithm coupled with the multi-attributed decision-making technique R-method to find the most favorable responses for machining GFRP composites. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Design and development of microneedle array-based electrode for bio-potential measurement(Inderscience Publishers, 2017) Balashanmugam, N.; Naveen, K.; Krishna, K.; Mohan Kumar, G.C.Conventional wet electrodes used in bio-potential measurement like EEG, ECG, etc., require the need for conductivity gel application on skin to wet the surface so that more contact area exist between skin and electrode resulting in better signal acquisition. Wet electrodes have certain drawbacks like the gel tends to underperform within one to two hours after application due to reasons like body heat. To overcome this drawbacks, dry electrodes are being developed which can be classified into two types; one penetrating skin and the other not. Both this type of electrodes has the advantages and limitations. The major drawback of filament type non-penetrating dry electrodes is that if the interest is in acquiring signals during motion, these electrodes tend to move relative to the skin resulting in noisy signal where as the microneedle can overcome this drawback by being continuously in contact with skin in all circumstances. In present work we have used micromachining technique to fabricate PMMA microneedle array. The study involves design of microneedle array, fabrication and mechanical testing of microneedles for skin insertion. It was found that for skin insertion upto 150 ?m microneedles 7.5 N load was required and microneedles were structurally stable at this load. © © 2017 Inderscience Enterprises Ltd.Item Investigation on the performance of valveless pump for microdelivery of the fluid, fabricated using tool-based micromachining setup(World Scientific Publishing Co. Pte Ltd wspc@wspc.com.sg, 2017) Veeresha, R.K.; Rao, M.; Rao, R.; Tauro, A.M.Micropump is an integrated part of microfluidic system and is a boon to the field of miniaturization, owing to its helping hand in numerous applications mainly in biomedical, electronic cooling, fuel cells, spacecraft, etc. In this paper, an attempt is made to design and fabricate valveless pump, with active and passive valves. The actuation element used is piezowafer, piezowafer was experimentally tested and compared with simulated values from ANSYS for its peak displacement and these displacements were used to find volume pumped by pump. The pumping volumes found by experimentation are in good agreement with the simulated results. Further fabrication of valveless pump is carried out by using tool-based micromachining center which is a novel type of fabrication technique in micromachining. Through experiments, the optimum frequency of the pump was found to be 60Hz at an actuating voltage of 150V. The maximum head that a pump could pump was found to be 0.051m with pressure of 500.13Pa. The flow rate of the pump had a decreasing trend with increase in head. © 2017 World Scientific Publishing Company.Item Performance evaluation of mechanical micro-drilling, electrical discharge machining and laser beam machining on nimonic 80A alloy(National Institute of Science Communication and Information Resources (NISCAIR) ijact.editor@gmail.com Dr. K. S. Krishnan Marg (Near Pusa Gate) New Delhi 110-012, 2018) Sudhakar, S.; Kumar, P.; Srinivas, G.; Ravishankar, S.; Dupadu, D.; Barshilia, H.C.Micromachining techniques such as mechanical micro-drilling, electrical discharge machining (EDM) and laser beam machining (LBM) play an important role in the manufacturing of micro-devices used in mechanical, electronics, aerospace and medical applications. In this paper, an effort has been made to compare the performance of these micromachining techniques with regard to tool wear, burr formation and surface integrity. This is done by producing 20 micro-holes of approximately 800 ?m diameter on a rectangular block (90×30×3 mm3) of Nimonic 80A superalloy. TiAlN coated WC micro-drills, Cu electrodes and CO2 laser beam are used to produce these holes in conventional micro-drilling, EDM and LBM, respectively. The quality of the drilled hole (diameter, surface roughness and micro-burr formation), tool diameter analysis, taper angle and material removal rate (MRR) are compared and reported. A comprehensive analysis is also carried out on overcut, which leads to hole inaccuracy. Results show that mechanical micro-drilling produces better results in the above mentioned characteristics in comparison to LBM and EDM techniques. The relatively better performance of mechanical micro-drilling is attributed to the usage of TiAlN coating on WC tool. © 2018, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.Item Damage Analysis of Tool-Based Micromachining Setup Using Electrical Continuity-Based Contact Detection System(Springer, 2021) Veeresha, R.K.; Rao, M.; Rao, R.; Sushith, S.; Karegoudra, M.K.Initial registration of tool with respect to workpiece is a critical requirement in tool-based micromachining setup. As the tool is in the order of few hundred micrometre diameter and rotating at very high speed, hence, the chance of tool breakage or workpiece surface damage during tool workpiece registration is more during micromachining. Initial tool registration of tool with respect to workpiece circuit was developed and incorporated with developed tool-based micromachining setup. The performance of the developed electrical continuity-based contact detection circuit was done by feeding the workpiece with different offset dimensions. From the experiments, it’s observed that there is more damage in workpiece when tool workpiece offset distance is more in both milling and drilling tools. © 2021, ASM International.Item Development of titanium nitride thin film microheaters using laser micromachining(Elsevier Ltd, 2022) M.a, M.A.; Lakshmi Ganapathi, K.L.; Ambresh, M.; Nukala, P.; Udayashankar, N.K.; Mohan, S.In this paper, we report the fabrication and characterization of titanium nitride (TiN) thin-film-based microheaters. TiN thin films have been optimized on Si and SiO2 substrates for their optimum electrical resistivities by controlling the process parameters, including argon:nitrogen (Ar:N2) ratio in reactive pulsed DC magnetron sputter (PDCMS) deposition technique. An optical emission spectroscope (OES) was used for monitoring the plasma characteristics at various nitrogen flow rates. The microstructural and surface properties of the TiN films have been investigated and correlated with the electrical properties. It has been observed that the amount of nitrogen flux in the TiN plasma plays an essential role in the microstructural, surface, and electrical properties of the TiN thin films. Micro-heaters have been fabricated with TiN thin films with low electrical resistivity using laser engraving techniques instead of conventional lithographic and micromachining techniques. The TiN microheater has shown excellent performance. A temperature of 406 °C has been achieved by applying an input power of 8 W. This work paves the path for developing scalable and economic TiN microheaters using laser micromachining techniques. © 2021Item Multi-response optimization and effect of tool rotation on micromachining of PMMA using an in-house developed µ-ECDM system(Elsevier Ltd, 2022) Bhargav, K.V.J.; Balaji, P.S.; Sahu, R.K.; Katiyar, J.K.Poly-methyl methacrylate (PMMA) is a lightweight and transparent thermoplastic material which is commonly used as an alternative for high-cost and resilient glass. PMMA has potential applications in the fields of microfluidics because of its high strength, low weight, optical transparency, and biocompatibility. Therefore, in this study, in-depth experimentation was carried out to generate microchannels on PMMA using an in-house developed micro Electrochemical Discharge Machining (µ-ECDM) system. The µ-ECDM process parameters used for the experimentation include voltage (V), electrolyte concentration (wt%), and duty factor (DF) (%). Experiments were designed at three levels of process parameters for the parametric study. The microchannels were machined on a 2.5 mm thick PMMA workpiece using a titanium tool of diameter 0.7 mm. The optical microscope images, along with SEM images, are used to characterize the machined channels. The machining characteristics such as material removal rate (MRR), tool wear rate (TWR), channel width, surface roughness (SR), and depth of the channel were studied using the process parameters. Individual response optimization is carried out using S/N ratios, but confounding of factors at different factor level settings is observed for each response. Therefore, to overcome this problem, multi-response optimization using the JAYA algorithm coupled with the multi-attributed decision-making (MADM) R-method has been adopted for maximizing MRR and depth of the channel and minimizing TWR, channel width, and surface roughness at single factor level settings. The optimal process parameters are obtained by multi-response optimization are 51 V, 24 wt%, and 55% DF, and the MRR, TWR, channel width, surface roughness, and depth of the channel are found to be 21.5 µg/min, 5.5 µg/min and 804.33 µm, 5.2412 µm, and 238.22 µm, respectively that are in close pact with the predicted observations. Further, the optimal machining parameters have been used along with tool rotation (in RPM) to observe the effect on machining features. The findings show that with increment in tool rotation rate improved the MRR, TWR, and depth of the channel decreased the channel width and surface roughness. © 2022 CIRPItem Exemplary approach using tool rotation-assisted µ-ECDM for CFRP composites machining(Taylor and Francis Ltd., 2023) Bhargav, K.V.J.; Balaji, P.S.; Sahu, R.K.; Katiyar, J.K.Carbon fiber-reinforced polymer (CFRP) composites are an advanced composite material class due to their remarkable properties such as high load-carrying capacity and low density. CFRP composites have enormous applications in aerospace, biomedical, automobile, etc. Machining the CFRP composite is need of the day, but issues like delamination, fiber pullouts, workpiece damage, etc. have made it difficult. These limitations can be surpassed by the micro-electrochemical corona discharge machining (µ-ECDM) process. Although the process has showcased high process capability and great versatility in machining conducting and non-conducting materials, the process has limitations in machining holes deeper than 300 µm because of insufficient electrolyte supply at the machining zone. Aiding assistance to the process can overcome the limitation by enhancing electrolyte availability. Therefore, an experimental analysis is carried out by generating through holes on the CFRP composite using a tailor-made rotating tool-assisted micro-electrochemical corona discharge machining (RT-µ-ECDM) system. The process parameters, voltage, concentration, duty factor, and tool rotation rate are taken at three levels. The materials removal rate and overcut as machining characteristics were analyzed. The multi-response optimization using JAYA algorithm and R-method is used to obtain the optimal process parameters. The experimental investigation suggests RT-µ-ECDM system can machine through holes on CFRP composite. © 2022 Taylor & Francis.Item Micromachining of borosilicate glass using an electrolyte-sonicated-µ-ECDM system(Taylor and Francis Ltd., 2023) Bhargav, K.V.J.; Balaji, P.S.; Sahu, R.K.Glass has become an integral part of today’s world. This is because of its wide range of applications owing to its various potential properties. Though it has enormous applications, processing or machining glass is a challenging task. The present study focuses on the generation of microholes on borosilicate glass (thickness: 1000 µm) using an in-house developed in-situ electrolyte-sonicated (ES)-micro electrochemical discharge machining (µ-ECDM), i.e. ES-µ-ECDM system. The experiments revealed that the sonication of electrolytes had increased the electrolyte flushing, which enables the basic µ-ECDM process to push its limits and machine the materials beyond 300 µm (hydrodynamic regime). The process parameters selected for the experimentation are voltage, concentration, and duty factor with sonication of electrolyte at 36 kHz frequency throughout the experiments. Material removal rate (MRR) and overcut (OC) are identified as the machining characteristics in this study. To acquire enhanced machining characteristics, the process parameters are further optimized using the MOJAYA algorithm in conjunction with the R-method which is a multi-attribute decision-making method (MADM). The detailed experimentation revealed that using electrolyte sonication through-holes was achieved at a higher level of parameter settings. © 2022 Taylor & Francis.Item Micromachining of Al7075 alloy using an in-situ ultrasonicated µ-ECDM system(Taylor and Francis Ltd., 2023) Bhargav, K.V.J.; Pyla, K.R.; Balaji, P.S.; Sahu, R.K.Al7075 is a lightweight metal alloy essentially used in various engineering sectors possessing applications in aerospace, military, missile, etc. Miniaturized machining operations have placed a great deal of pressure on the conventional machining capabilities of Al7075 alloys as they possess certain challenges due to their ductile and unique adhesive nature, which must be overcome. The present study focuses on generating through-holes on Al7075 alloy using an electrolyte ultrasonication-assisted µ-ECDM system. The FCC-RSM factorial-based design is chosen at three levels to carry out experimentation with process characteristics voltage (V), concentration (wt%), and duty factor (%DF). The material removal rate (MRR), top hole overcut (TOC), bottom hole overcut (BOC), and circularity (CIR) are the machining responses. JAYA algorithm, a multi-objective optimization is performed, and optimal process parameters are obtained using the R method. Further, RSM based desirability approach is also used to obtain optimal process parameters and compared them with results obtained from R-method and found to be relatively close. © 2023 Taylor & Francis.