Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
6 results
Search Results
Item 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.Item Machining Parameter Optimization of Wire Electrical Discharge Machining for Ni50.3Ti29.7Hf20 Alloy Using TOPSIS and Grey Wolf Optimization Technique(Springer, 2025) Bhaskar, M.; Balaji, V.; Narendranath, S.; Sahu, R.K.Ni50.3Ti29.7Hf20 is an alloy with shape memory characteristics that can withstand high temperatures. It possesses remarkable strength, hardness, and exceptional corrosion resistance. SMAs are well-suited for various applications, including automotive sensors, automobiles, aerospace technologies, robotics, actuators, and MEMS devices. However, its unique properties make it difficult to machine using conventional methods. Wire EDM is an unconventional machining process suited for difficult-to-machine materials like Ni-Ti-Hf alloy, providing high accuracy and precision and minimizing the risk of material damage. This paper focuses on the optimization of machining parameters, namely Discharge time (PON), Pause time (POFF), Gap voltage (GV), and Wire travel speed (WS) during WEDM of Ni-Ti-Hf shape memory alloy utilizing the TOPSIS and GWO techniques. The aim is to obtain optimal machining parameters for improving the machined Ni-Ti-Hf alloy’s material removal rate (MRR) and surface roughness (Ra). The optimal machining parameters from GWO were PON = 123.8 µs, POFF = 50 µs, WS = 2, and GV = 25. The predicted values of material removal rate and surface roughness are 4.22 mm3/min and 3.62 µm, respectively. The experimental verification demonstrates the proposed optimization approach's effectiveness, as the predicted values correlate strongly with the actual values. © ASM International 2023.Item Optimization of measured mechanical characteristics of selective microwave hybrid heating processed Inconel 625/ SS 304 weldments using multi-objective JAYA algorithm coupled with multi-attributes decision making R-method(Elsevier B.V., 2025) Singha, B.; Kamble, D.L.; Sahu, R.K.; Narendranath, S.; Badiger, R.I.This work focuses on the joining of Inconel-625/SS-304 using selective microwave hybrid heating (SMHH) technique. Input power, filler powder particle size, separator, and susceptor size are considered for experimentation according to the Definitive Screening Design. The multi-objectives measured are UTS, FS, and microhardness. XRD results show the intermetallic/secondary phases, and FESEM micrographs show the metallurgical bonding occurs between base metal and filler. The joint and interface region had an average microhardness of 204 ± 10 HV and 342 ± 18 HV, respectively. The UTS and FS of the weldments measured to 550 MPa and 805 MPa. MOJAYA technique is utilized for multi-objective optimization, and R-method determined the optimal process parameters. The optimal process parameters found to 2.2 kW, 25 ?m powder, 120 grit and 0.804 mm separator. The confirmation test reveals UTS ? 566 MPa, FS ? 903 MPa, and microhardness ? 365 HV, which closely matched with predicted observations. © 2024 Elsevier Ltd