Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Microfluidics is one of the rapidly growing markets in the present era of miniaturization. Microchannels have wide applications in various fields such as biomedical, mechanical, electrical, and chemical sciences. Machining microfeatures with high aspect ratio in metals is difficult by mechanical and lithography-based processes. Micro-electric discharge milling is a suitable process to machine microcavities and microchannels in all electrically conductive materials. The main disadvantage of this process is its very low material removal rate. Improving the machining performance of micro-electric discharge machining (μEDM) is a research area that attracts researchers and remains as an unfulfilled agenda. The aim of this study is to improve the machining performance of micro-electric discharge milling process by investigating the performance of cryogenically treated tool and workpiece materials. Since surface roughness determines the minimum feature size machinable by any micromachining process and also it is an important factor in determining the flow characteristics of microchannels, a detailed comparative study was conducted on the three-dimensional (3D) surface quality parameters along with machining performance while using all four different combinations of untreated and cryogenically treated tool and workpiece, and the roughness parameters are correlated with the erosion behavior. The study revealed significant change in material removal rate and erosion pattern due to cryogenic treatment. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

Mechanical

School of Mechanical Engineering

Chennai Campus

World University root node

Journal of Micro and Nano-Manufacturing

Correlation of Three-Dimensional Roughness Parameters with the Crater Dimensions in μeD-Milling of Cryogenic-Treated Tool and Workpiece

Micro-electric discharge milling (μED milling) has the potential to create micro-channels in metals. Since μED milling is a slow machining process, the requirement of strategies that can enhance the material removal rate (MRR) is always crucial in the field of micro-machining. Nano-powder-mixed micro-electric discharge milling (NPMμED milling) is least explored by researchers. Also, the behaviour of μED milling at various discharge energy regime (D.E.R) was not analysed extensively. The present study investigates the combined effects of nano-powder-mixed dielectric at three different regimes of discharge energies with respect to MRR and tool wear rate (TWR) while micro-machining of Ti-6Al-4V using cryogenically treated electrodes. There is significant difference in the machining behaviour at low, medium and high D.E.Rs. Also, the effects of transformation in cathodic streamers due to addition of nano-graphene powders in the dielectric fluid were extensively analysed. Cryogenic treatment of the tool electrodes gave better MRR. The addition of nano-powders in the dielectric has reduced the crater diameter significantly however increased the overall 3D roughness of the machined surface. © 2019, Springer-Verlag London Ltd., part of Springer Nature.

The International Journal of Advanced Manufacturing Technology

μED milling of Ti-6Al-4V using cryogenic-treated Wc tool and nano-graphene powder-mixed dielectricat different discharge energy regimes

Non-ferrous materials are widely used in industries, especially because of its corrosion resistance property. Among them Aluminium alloys are widely used because of its ease of machinability, good thermal Conductivity, less weight etc. Presently Aluminum is more used by industries than steel. Further Aluminium with alloy elements like copper, nickel, magnesium, tin etc. will enhance the properties of the materials and these alloyed elements have more industrial applications. Solution Treatment enhances the properties of these aluminium alloys. This work is focused on synthesis and characterization of hexenary aluminium Alloy (Al-Cu-Sn-Ni-Mg-Fe) by gravity die casting technique. The microstructure and wear behavior of as cast, solution treated alloys were elucidated by optical microscopy, pin-on-disc wear test. The mechanical properties were assessed by the tensile test, hardness test and compressive test. Solution treated aluminium alloy showed the remarkable improvement in wear resistance, hardness and tensile strength. The uniformly dispersed thermally stable θ and Ω phases in the aluminium matrix are one of the predominant factor in improving the hardness and tensile properties. The increase in hardness was achieved with solution treatment significantly reduced the wear rate. © 2006-2018 Asian Research Publishing Network (ARPN).

ARPN Journal of Engineering and Applied Sciences

Effect of solution treatment on microstructure, mechanical and wear characteristics of gravity die cast aluminium alloy

Machining of high aspect ratio micro-channels and cavities in metals is a challenging task. Micro-electrical discharge milling is a version of micro-electrical discharge machining process which is capable of micro-machining of all electrically conductive materials. The aim of this study is to analyze the effects of non-electrical parameters such as layer thickness (LT), horizontal tool feed rate (HTF), and tool rotational speed (TRS) on material removal rate (MRR) and relative electrode wear (REW) while micro-electrical discharge (μED) milling of stainless steel using tungsten electrode. The study revealed that layer thickness along with tool rotational speed and horizontal feed rate of the tool significantly influences the performance of μED milling. © 2015, Springer-Verlag London.

Effect of non-electrical parameters in μED milling: an experimental investigation

Micro-electric discharge milling (μ-EDM milling) is one of the micromachining processes which draw the attention of researchers in fabricating microcavities and microchannels. Improving the efficiency of this process remains challenging. There are publications that report the benefits of applying ultrasonic vibration to tool or workpiece and using magnetic fields to enhance debris removal. In almost all the literature, magnetic field and/or ultrasonic vibration were applied separately in micro-/macro-EDM. The aim of this study is to apply ultrasonic vibration and magnetic field simultaneously/separately, and compare the machining performance by analyzing material removal rate and tool wear rate (TWR) while fabricating microchannels on nonmagnetic materials using μ-EDM milling. From the results, it is recommended to use magnetic field or ultrasonic vibrations separately for achieving high MRR, but the combination of both gave poor results. © 2014 Copyright Taylor & Francis Group, LLC.

Materials and Manufacturing Processes

Effects of ultrasonic vibration and magnetic field in micro-EDM milling of nonmagnetic material

Micromachining processes have become more imperative in this modern era of miniaturization. Micro-EDM (μEDM) is an excellent micromachining process capable of producing microholes and microfeatures in all electrically conductive materials, irrespective of their mechanical properties. μEDM is a proven process for producing microholes. The quality of microholes is imperative in many applications. The aim of the present study is to investigate the role of capacitance and voltage in determining the perfection of microholes edges that machined using die sinking μEDM by applying image processing techniques. The experimental results reveal that the capacitance significantly influences circularity more than open circuit voltage. The quality of the microholes is also affected by flushing force of dielectric fluid and tool adhesion. Best circularity was achieved with capacitance values between 0.001-0.00001 μF and voltage between 80-100. Discharge energies greater than 50 μJ gradually reduce the quality of microhole edges. © 2013 Copyright Taylor and Francis Group, LLC.

Investigation of the quality of microholes machined by μeDM using image processing

Micro machining processes are becoming popular in this modern era of miniaturization. Microelectric discharge machining (MEDM) is one of the micromachining processes capable of machining all electrically conductive materials. The overall machining performance of electricdischarge machining (EDM) process depends on the electrical, thermal properties of both tool and workpiece materials. Cryogenic treatment has a history of improving mechanical, electrical, and thermal properties of materials. Recently, very few researchers applied cryogenic cooling in conventional EDM and found notable improvement in machining performance. In the present work, a comparative study on machining performance of both cryogenically treated and untreated micro electrodes in MEDM were analyzed alongwith electrical resistivity, crystallite size, microhardness and microscopic analysis. From the study, it is evident that there is significant reduction of 58% in tool wear rate (TWR) for Tungsten electrode followed by brass and copper electrodes with 51% and 35%, respectively. Electrical conductivity and microhardness of Tungsten electrodes exceptionally improved, while that of brass and copper electrodes also remarkably increased. Material removal rate (MRR) almost proportionally decreased with respect to decrease in TWR for all the three cryogenically treated electrodes. Copyright © 2013 Taylor and Francis Group, LLC.