IJIRST –International Journal for Innovative Research in Science & Technology| Volume 3 | Issue 11 | April 2017 ISSN (online): 2349-6010
Review of Research Work in Nano powder Mixed Electric Discharge Machining Sachin Mohal Associate Professor Department of Mechanical Engineering Chandigarh Engineering College, Landran
Sandeep Singh Sangwan Associate Professor Department of Mechanical Engineering Chandigarh Engineering College, Landran
Abstract Nanopowder mixed Electrical discharge machining (NPMEDM) is a non-conventional machining process used to manufacture intricate profiles, complex cavities in dies and molds, machining of advanced materials that are extremely difficult to machine by conventional machining processes. In recent years, researches have emphasized on machining of workpiece material after the addition of nano particles into the dielectric fluid of EDM. This technology is termed as NPMEDM. This article presents a review of ongoing research and development in NPMEDM. The critical analysis of the use of powders for micro and nano machining is also presented. The last part of the article discusses the future research directions. Keywords: Electric discharge machining, Nano powder mixed EDM, Material removal rate, Tool wear rate, Surface roughness _______________________________________________________________________________________________________ I.
INTRODUCTION
Electric Discharge Machining (EDM) is the one of the most effective non-conventional machining method for machining of difficult to cut materials irrespective of their strength and hardness. The applications of EDM are tremendously increasing in aerospace, automotive components. It is a non-contact material removal process, therefore vibration and distortion problems do not occur. To enhance the process capabilities of EDM, one of the recent advancement is the addition of nanopowders in to the dielectric fluid of EDM. This technology is called as NPMEDM). In NPMEDM, the addition of nano powders i to dielectric results in an increase in MRR, corrosion and wear resistance of machined surface and further reduce SR, surface cracks, thickness of formed surface layers and porosity. Till date, no review paper is available on nanopowder mixed EDM. Therefore, authors have tried their best to critically analyze the NPMEDM process and presented the research works conducted in recent years in a collective and comprehensive manner. The first part of the paper discusses the principle of NPMEDM. Thereafter, extensive and exhaustive literature review is carried out with micro, nano powder as additive in to the dielectric of EDM. Finally the future directions and conclusions based on the review have been discussed. II. THE TECHNOLOGY AND PROCESS MECHANISM OF NPMEDM A schematic representation of NPMEDM experimental setup is shown in Fig.1. NPMEDM is entirely different from conventional EDM. In this process, nano powder particles were mixed in to the dielectric fluid of EDM in a separate tank. Stirring system is generally employed in this tank to achieve homogeneous dispersion and circulation of powder in to dielectric fluid. The tool and workpiece are supplied with a suitable voltage ranging from 80–320V leading to the generation of an electric field of 105–107 V/m. Spark gap is filled with additive particles supplied through flushing, thereby causing an increase in the gap distance between workpiece and tool from 25–50 µm to 50–150 µm. A large amount of energy is accumulated in the powder particles due to the influence of electric field resulting in charging up of particles. These accelerated particles move in zig-zag way and act as conductors promoting breakdown in the gap and widens the spark gap between the electrodes. The particles accumulate under the sparking area and move either in reciprocating motion, adhered to either electrode, gather in clusters or form a chain like structure connecting the electrodes. An irregularity in shape and size of powder particles result in interlocking and may lead to chain formation. The bridging effect reduces the insulating strength of the dielectric fluid leading to easy short circuiting and hence an early explosion in the gap. A ‘series discharge’ occurs under the electrode area due to early explosion. The workpiece erodes at a higher rate due to quick sparking under the electrode area. The striking effect of the particles and discharge transitivity increases MRR. At the same moment, the added powder enlarged and widened the plasma channel. Even distribution of sparking among the powder particles leads to reduction in electric density of the spark. Therefore, flat craters are formed on the workpiece surface. Hence the surface finish is improved.
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Review of Research Work in Nano powder Mixed Electric Discharge Machining (IJIRST/ Volume 3 / Issue 11/ 009)
1. Magnets, 2. Circulation pump, 3. Work tank, 4. Nozzle, 5. Machining tank, 6. Workpiece, 7. Electrode, 8. Stirrer, 9. Oscilloscope Fig. 1: Schematic diagram of PMEDM experimental setup [1].
III. PROCESS PARAMETERS OF NPMEDM The performance of NPMEDM depends upon electrical parameters, non-electrical parameters, nanopowder concentration and its type, material and size of electrode, workpiece material and their properties. All the possible process parameters for PMEDM are shown in fig. 2 on a Ishikawa cause and effect diagram.
Electrical parameters
Nanopowder parameters
Pulse on time
Peak Current Supply Voltage
Pulse off time
Nanopowder Type Nanopowder Concentration NPMEDM performance measures
Nozzle flushing Material Type
Lift time Working time
Non-Electrical parameters
Size
Electrode parameters Fig. 2: Process Parameters of NPMEDM
IV. RESEARCH DEVELOPMENTS IN NPMEDM Very few researches have been reported in the literature on nano powder as additive into the EDM dielectric. The influence of micro-powder (MoS2) suspension in ultrasonic vibration assisted dielectric fluid has been investigated by Prihandana and
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Review of Research Work in Nano powder Mixed Electric Discharge Machining (IJIRST/ Volume 3 / Issue 11/ 009)
coworkers [2]. They demonstrated that the ultrasonic vibration to powder-mixed dielectric tank avoided powder settling and provide more uniform suspension media which in turn accelerated the discharging efficiency. Furthermore, the use of nanographite powders in the dielectric fluid prevents the striking of electric discharges from the electrode to the workpiece and hence generate small discharges to the workpiece [3]. Tan et al. [4] investigated the effect of nano powder additives on SR. They reported that Al2O3 and silicon carbide nano powders decreased the SR during the micro-EDM of stainless steel. The effect of graphite nano powder on micro-EDM of SKH51 tool steel was explored by Jahan et al. [5]. In another work, Jahan et al. studied the influence of graphite, aluminium and Al 2O3 nano powders on surface topography, Ra, Rmax, MRR and EWR [6]. After the discovery of CNTs in 1991, academicians, scientists and researchers focused their attention towards this novel material. Few researchers have taken their interest towards the CNTs mixed dielectric fluid. Hocheng and Huang observed 70% improvement in SR and 66% improvement in machining efficiency with addition of CNT in to the dielectric of EDM [7]. The effect of adding MWCNT in to dielectric when EDMing titanium alloy was examined by Izman et al [8]. Prabhu and Vinayagam achieved nano level finish by adding MWCNT in EDM dielectric [9]. Mohal et al. optimized the process parameters of NPMEDM by adding multiwalled carbon nanotube into the dielectric fluid of EDM for the machining of Al-10%SiCp metal matrix composite [10-11]. The machining of AISI H13 tool steel material with MWCNT mixed EDM was performed by Sari et al [12]. They observed that the thickness of recast layer is reduced with the addition of CNTs in to dielectric of EDM Review of literature reveals that only few researchers have used nano powder as additive into the dielectric of EDM. Number of issues need to be addressed in future for successful implementation of this process. V. APPLICATIONS OF NPMEDM 1) PMEDM has promising application for achieving near mirror like surface finish. PMEDM can also be used for improving the corrosion resistance and surface microhardness. 2) Complex 3D shapes, intricate profiles, thin and fragile components utilized in numerous industrial applications can be successfully machined regardless of their strength and hardness. 3) The machining of micro components, micro-sized features, micro-engines, micro pumps, micro gears, micro holes, micro blades, micro turbine rotors, microball joints can be done by using NPMEDM. 4) NPMEDM can also be used for increasing the biocompatibility of materials, development and subsequent modification, machining of biomedical implants. 5) Machining of advanced and difficult to cut materials such as MMCs and Insulating ceramics like Si 3N4, ZrO2 and TiO2have been successfully machined by dispersing various powders in to the EDM dielectric 6) NPMEDM can also be used as a surface treatment/modification process. VI. FUTURE DIRECTIONS AND CONCLUDING REMARKS Since the inception of EDM many advancements in the machining process has been made. It has been concluded that NPMEDM has the capability to achieve mirror like surface finish. After a thorough scrutiny of the published work, the following main conclusions can be drawn: 1) Research is mainly focused on NPMEDM of conventional materials such as die steels, alloys etc. Only few researchers have worked on nanpowder mixed EDM of MMCs, alloys etc. 2) Few researchers have focused their attention towards non-electrical parameters such as workpiece rotation and electrode rotation. Hence, more studies on the effect of process parameters are needed. 3) Surface modification with micro and nano powders has not been tried yet. 4) No published research work on Finite element modeling and simulation of process parameters in NPMEDM. REFERENCES [1] [2] [3] [4] [5] [6] [7]
Sachin Mohal, Harmesh Kumar and S.K. Kansal, “Nanofinishing of materials by powder mixed electric discharge machining (PMEDM): A review”, Science of Advanced Materials, 7 (10), 2234-2255, 2015. G. S Prihandana, M. Mahardika, M. Hamdi, Y. S. Wong and K. Mitsui Effect of micro-powder suspension and ultrasonic vibration of dielectric fluid in micro-EDM processes—Taguchi approach, International Journal of Machine Tools and Manufacture 49, 1035-1041, 2009. G. S Prihandana, M. Mahardika, M. Hamdi and Y. S. Wong, Study of workpiece vibration in powder-suspended dielectric fluid in micro-EDM processes, International Journal of Precision Engineering and Manufacturing, 14 (10), 1817-1822, 2013. P. C Tan, S. H. Yeo and Y. V Tan, Effects of nano-sized powder additives in micro-Electrical Discharge Machining, International Journal of Precision Engineering and Manufacturing, 9, 22-26, 2008. M. P Jahan, M. M Anwar, Y. S. Wong and M. Rahman, Nanofinishing of hard materials using micro-electrodischarge machining”. Proceedings of the Institution of Mechanical Engineers Part B-Journal of Engineering Manufacture, 223 (9), 1127-1142, 2009. M.P Jahan, M. Rahman and Y. S. Wong, Study on the nano-powder-mixed sinking and milling micro-EDM of WC-Co”. International Journal of Advanced Manufacturing Technology, 53 (1-4), 167-180, 2011. C. Mai, H. Hocheng, S. Huang, Advantages of carbon nanotubes in electrical discharge, International Journal of Advanced Manufacturing Technology., 59 111-117, 2012.
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Review of Research Work in Nano powder Mixed Electric Discharge Machining (IJIRST/ Volume 3 / Issue 11/ 009) [8]
S. Izman, D. G. Hodsiyen, T. Hamed, R. Rosilza and M. Rezazadeh, Effects of Adding Multiwalled Carbon Nanotube into Dielectric when EDMing Titanium Alloy, Advanced Materials Research, 463 - 464, 1445-1449, 2012. [9] S. Prabhu, B. K. Vinayagam, Analysis of surface characteristics of AISI D2 tool steel material using Electric Discharge Machining process with Single wall carbon nano tubes, International Journal of Engineering and Technology, 2 (1), 35-41, 2010. [10] Sachin Mohal and Harmesh Kumar, “Parametric optimization of multiwalled carbon nanotube assisted electric discharge machining of Al-10%SiCp metal matrix composite by response surface methodology”, Materials and Manufacturing Processes, 32(3), pp263–273, 2017 [11] Sachin Mohal and H.K. Kansal, “Experimental investigation and optimization of process parameters of multiwalled carbon nanotubes mixed EDM using response surface methodology”, Journal of Nanoengineering and Nanomanufacturing, 5 (2), pp132–140, 2015 [12] M. M Sari, M. Y. Noordin and E. Brusa, Evaluating the electrical discharge machining (EDM) parameters with using carbon nanotubes. International Conference on Structural Nano Composites (NANOSTRUC 2012), IOP Conf. Series: Materials Science and Engineering 40, 012019 U.K, 2012
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