Current Research Trend in Wire EDM: An Overview

Transcription

1 Current Research Trend in Wire EDM: An Overview Chanchala, Navdeep Malhotra, P.G Student Mechanical Engineering Department, YMCAUST, Faridabad Professor, Mechanical Engineering Department, YMCAUST, Faridabad Abstract: Wire electric discharge machining is a non-conventional metal removal process as well as one of the best manufacturing processes available for hard material for producing jigs, fixtures and dies. This paper projects the main research areas of WEDM machine. Whenever there is a need of high precision in dimensions WEDM is used. WEDM is influenced by many variables, the effect of different variables on MRR, cutting speed (CS) and surface roughness (SR) is presented in this paper. The present paper also projects the major current research areas in field of WEDM and the application area of WEDM. Key Words: Surface roughness (SR), Wire electro discharge machining (WEDM),Material removal rate (MRR),Cutting speed (CS). 1. INTRODUCTION The rapid developments in the field of materials have given an impetus to the non-conventional manufacturing (NCM) technology to develop, modify and discover newer technological processes with the view to achieve results that are far beyond the scope of conventional manufacturing processes. Needs of future manufacturing technology is sustained productivity in face of rising strength barrier, Higher accuracy consistent with the increasing demand for better tolerances, versatility of automation. Advanced material have attractive properties i.e. high strength, high bending stiffness, good damping capacity, low thermal expansion, better fatigue characteristics which make them more reliable for defence, aero-space and nuclear industry. It is difficult to machine the advanced material. It has become a challenge to manufacturing engineers to develop new processes and tool materials that are necessary for meeting the desire higher metal removal rate, better surface finish and greater dimensional accuracy, with less tool wear [1]. action The WEDM process is particularly suitable for machining hard materials as well as complex shapes. 2. HISTORICAL BACKGROUND Year Development made 1943 Boris and Natalya Lazarenko invention of EDM principle and developed the first EDM machines 1950 industries produced the first EDM machines but performances of the machines were limited at this time due to the poor quality of Electronic components wire-cutting machines were at their very beginning 1970 Computer numerical control (CNC) system was initiated into WEDM that brought a major evolution of the machining process 1974 D.H. Dulebohn applied the optical line follower The conventional machining processes normally involve the use system to automatically control the shape of the of energy from electric motors, hydraulics, gravity, etc and rely component to be machined by the WEDM on the direct physical contact between tools and work piece. On process1980applications in micro-machining the contrary, NCM processes utilize energy such as that from electromagnetic force, electrochemical reactions, high 1990 EDM process control arose by using fuzzy control, temperature plasma, high velocity jets and loose abrasives neural networks response surface methodology, mixed in various carriers etc. According to the type of energy Taguchi optimization etc. used to remove material NCM processes are classified. The various forms of energy have been identified to classify these 3. PRINCIPLE OF WIRE ELECTRICAL processes, such as mechanical, thermal, electrochemical and DISCHARGE MACHINING chemical. Based upon these types of energy, a large number of NCM processes have been developed in the past. The Spark Theory on a wire EDM is basically the same as that of Wire-electrical-discharge machining (WEDM) is one of the the vertical EDM process. In wire EDM, the conductive modification of electro-discharge machining (EDM) and has materials are machined with a series of electrical discharges been widely used for cutting punches, dies, shaped pockets and (sparks) that are produced between an accurately positioned other machine parts on conductive materials. WEDM erodes moving wire (the electrode) and the work piece. High frequency work piece materials by a series of discrete electrical sparks pulses of alternating or direct current are discharged from the between the work piece and dielectric performs the flushing wire to the work piece with a very small spark gap through an 37

2 insulated dielectric fluid. Fluid is continuously flowing in the machining zone. 4.1 EFFECT OF ELECTRICAL PARAMETERS 1. Pulse on time - During this time the voltage, VP, is applied across the electrodes. Many sparks can be observed at one time. This is because actual discharges can occur more than one hundred thousand times per second with discharge sparks lasting in the range of 1/1,000,000 of a second or less. A plasma channel exist between cathode and anode due to supplied electric current, that get finally converted into thermal energy of range 80,000-12,000 C [3] that melt the metal. The volume of metal removed during this short period of spark discharge depends on the desired cutting speed and the surface finish required. 2. Pulse-off time - The voltage is absent during this part of the cycle. 3. Peak current - The peak current is represented by IP and it is the maximum value of the current passing through the electrodes for the given pulse. 4. Spark gap set voltage -The spark gap set voltage is a reference voltage for the actual gap between the work piece and the wire used for cutting. The heat of each electrical spark, estimated at around 15,000 to 21,000 Fahrenheit, erodes away a tiny bit of material that is vaporized and melted from the work piece. (Some of the wire material is also eroded away) These particles (chips) are flushed away from the cut with a stream of de-ionized water through the top and bottom flushing nozzles. The flushing process occurs as pulsating DC power supply occurring between 20,000 and 30,000Hz [4] is turn-off, then plasma channel break down. Due to this sudden break down temperature reduction occurring between the work piece and electrode allows circulating dielectric fluid to enter the zone and flush the removed particles from the machining zone in the form of small debris. From the machine zone ejected material is flushed away whereas portion of molten material resolidify on to the work surface which is termed as recast layer. The dielectric used also prevents heat build-up in the work piece. Without this cooling, thermal expansion of the part would affect size and positional accuracy. Keep in mind that it is the ON and OFF time of the spark that is repeated over and over that removes material, not just the flow of electric current. In WEDM deionised water is used as dielectric but in conventional EDM process it cannot be used because of its low viscosity and faster cooling rate. 5. Servo feed - Servo feed setting decides the servo speed; the servo speed, at the set value of SF, can vary in proportion with the gap voltage (normal feed mode) or can be held constant while machining (with constant feed mode). Table 2: Effect of Electrical Parameters S. NO Electrical Parameters 4. FACTORS EFFECTING PERFORMANCE MEASURE OF WEDM Effect on cutting speed 1 Pulse on time Increases with increase in peak on time 2 Pulse off time Increases with decreases in pulse off time 3 Peak current Increases with increase in peak current 4 Servo feed Decreases with increases in servo feed 5 Spark gap set voltage No variation is recorded with increase in spark gap set voltage 4.2 EFFECT OF NON ELECTRICAL PARAMETERS 1. Wire feed - Wire feed is the rate at which the wire-electrode travels along the wire guide path and is fed continuously for sparking. 2. Wire tension - Wire tension determines how much the wire is to be stretched between upper and lower wire guides. Table 3: Effect of Non Electrical Parameters S. NO Electrical Parameters Fig 1.1: Factors Effecting Performance Measure of WEDM 38 Effect on cutting speed 1 Wire feed No variation with increases in wire feed 2 Wire tension No variation with increase in wire tension

3 4.3 EFFECT OF WORK PIECE RELATED PARAMETERS Die cost reduced by 30-70% Cuts hardened material Intricate shapes can be cut with ease Height Height of work piece show the thickness of work piece. 6. MAJOR AREAS OF WEDM RESEARCH Material Material properties like its melting point, electrical properties, magnetic condition of material is Research work done by the various authors in the area of wire EDM some of the authors had done in the field of optimization of considered under material properties. process variables and some are worked on monitoring and Table 4: Effect of Work Piece Related Parameters control of the process of wire EDM. Many of the authors also completed their research work on the performance measures to improve the performance of the process. A few of the authors also did their research work in the field of development of wire Parameters EDM to enhance its applications to meet the industrial requirements. Figure 1.2 shows the major research are of wire EDM MONITORING & CONTROL THE PROCESS OPTIMIZATION OF PROCESS VARIABLE 4.4 EFFECT OF ELECTROD PROPERTIES 1. Wire tension The wire tension force between the two wire guides present on WEDM machine. 2. Wire size The wire diameter show the wire size used. 3. Wire feed Feed of wire shows the speed with which wire is supplied for cutting operation. 4. Wire material The wire composition is considered in wire material. S. NO Electrical Parameters Effect on cutting speed Wire tension With increase in wire tension cutting speed increases 2 Wire size Not much variation is observed 3 Wire feed With increase in feed not much variation in speed 4 Wire material On greater the wire tension a wire can work higher the cutting speed Here is the list of advantages of WEDM. [6] No electrode fabrication required No cutting forces Unmanned machining Process Modelling Pulse Duration, Discharge Current Intensity, Discharge Frequency Etc. FUZZY CONTOL Ultrasonic vibration Assisted, WECT, WECG, WEDG 5. Advantages of Wire EDM WEDM DEVELOPMENT FUZZY LOGIC, WIRE BREAKAGE, SELF TURNING ADAPTIVE CONTROL Table 5: Effect of the Electrode 1 Process Parameter Design IMPROVING PERFORMANCE MEASURE Fig 1.2: Major Research Areas of WEDM Some of the research work done by various authors is studied and listed below along with the techniques and material used in table 6. 39

4 Table 6: List of Experiment Down on WEDM YEA Authors R MATERIAL USED 2009 A. Noorul Haq, et. al. [19] TECHNIQUE OUTPUT USED PARAMETERS STUDY Co2 casting Taguchi component Casting defects 2012 S.Y. ASSAB Martowibowo, A. 760 Wahyudi [7] Taguchi L18 MRR,SR 2009 Esme.U, et.al. [20] Neural Networks 2012 S Sivakiran, et. al. [8] En31 Taguchi L16 MRR, 2008 Aminollah Mohmmadi [21] Taguchi L18 MRR 2011 Ignacio Puertas Carmelo J. Luis [9] WC-CO, B4C,SiC Multiple SR, linear MRR,EWR regression 2008 Aminollah Mohmmadi [21] Taguchi L18 MRR Taguchi MRR, EWR,ROC 2008 R. Ramakrishnan, Inconel L.Karunamoorthy 781 [22] Taguchi L9 MRR Cutting speed, cutting load 2008 Aminollah Mohammadi, et. al. [23] Taguchi L18 SR, TWEDM 2008 Gauri, S. K. Chakraborty [24] Process MultiApplied Response Weighted Optimizati Principal on Component 2011 D.V Ghewade, Inconel S.R Niparka [10] Chao-LiehYang [11] Glass fiber Taguchi and grey relation analysis 2010 N.G.Patil Reinforced Taguchi Brahmankar [12] aluminium matrix composite 2010 M. N. Islam, et. al. [13] Cutting speed,sr, kerf width Mild steel Taguchi Study three 1040 and pareto different ANOVA accuracy characterist ics 2010 Kapoor, S. Singh ---and J. S. Khamba [14] S.Sarkar, et. al. [25] MRR, SR 2009 M.G. Xua., et. al., [15] Cemented ---carbide material Analyzing microstruct ure of machined surface 2009 Jin Yuan, Kesheng Wang [16] High speed Regression MRR, SR steel model Gamma RMS titanium aluminide SR SR, dimensiona l shift, cutting speed Dc Kanlayasiri K. and S.Boonmung [26] ANOVA technique 2006 Aminollah Mohammadi, et.al. [27] Taguchi L18 SR 2006 S.S. Mahapatra, Amar Patnaik [28] Taguchi L27 MRR,surfa ce finish and cutting width for a rough cut SR 2009 Susanta Kumar High speed Gauri, steel Shankar Chakrabort [17] Taguchi Compariso and n of weighted methods principle component processes (WPC) 2006 A.Manna Pt-Al-SiC Taguchi L18 ComparisoB.Bhattacharyya MMC n Gauss [29] elimination mathod 2009 H. Siddhi Jailani, Al-Si et. al. [18] (12%)alloy /fly ash composite Taguchi L9, Sintering parameters grey relational analysis 2006 R. Ramakrishnan, L. Karunamoorthy [30] 40 Taguchi L16 MRR,SR, Wire wear ratio

5 2006 A.Manna, Al/SiC B. Bhattacharya MMC [31] Taguchi 18 MRR, SR Gauss elimination method 2006 Hari Singh, Pradeep Kumar[32] En24 Taguchi 2005 Sarkar, S. et al [33] γ-titanium Mthematic Parametric aluminide al model analysis alloy 2005 Hewidey, et.al. [34] Inconel 601 [5] C. Sommer & S. Sommer, The Wire EDM Hand book, [6] Benedict, G. F. (1987), Electrical discharge machining (EDM), nontraditional manufacturing process, Marcel Dekker, Inc, New York & Basel, [7] S. Y. Martowibowo, A. Wahyudi(2012) Taguchi Method Implementation in Taper Motion Wire EDM Process Optimization,Journal of The Institution of Engineers (India): Series C Volume 93, Issue 4, pp [8] S Sivakiran, C. Bhaskar Reddy, C. Eswara reddy (2012) Effect Of Process Parameters on MRR In Wire Electrical Discharge Machining of En31 Steel International Journal of Engineering Research and Applications (IJERA) ISSN: , Vol. 2, Issue 6, November- December 2012, pp [9] Ignacio Puertas & Carmelo J. Luis (2011), Optimization of EDM conditions in the manufacturing process of B4C and WC-Co conductive ceramics International Journal of Advanced Manufacturing Technology (2012) Vol. 59, pp [10] D. V Ghewade, S.R Niparkar (2011), Experimental Study of Electro Discharge Machining For Inconel Material Journal of Engineering Research and Studies Vol.2, Issue 2, April-June,2011 pp [11] Chao-Lieh Yang(2011), Optimizing the Glass Fiber Cutting Process Using the Taguchi Methods and Grey Relational Analysis, New Journal of Glass and Ceramics, 2011, 1, MRR, SR Mathemati Modeling cal model the Machining Parameters 2005 Kuriakose, S. Shunmugam [35] Genetic Multi algorithm, objective optimizatio n 2004 K.H.Ho, et. al. [36] Taguchi L27 Cutting speed, SR, geometrical Inaccuracy due to wire lag 7. CONCLUSION Based on the study carried, it has been observed that process parameters viz, voltage, current and pulse related parameters (viz. pulse on time, pulse off time) are the most important [12] parameters in WEDM. They are affecting the output parameters viz., MRR, surface roughness, etc. The depth of crater, temperature generated and the resultant surfaces obtained are result of pulse energy applied. Study also reveals that which parameter is actually affecting the cutting speed. This paper also [13] show the various advancement made in the field of WEDM research. REFERENCES [1] P. K. Mishra, Non-Conventional Machining Narosa [14] publication House, Edition [2] Anand Pandey et. al. (2010) Current research trends in variants of Electrical Discharge Machining: A review International Journal of Engineering Science and [15] Technology Vol. 2(6), [3] Boothroyd, G.; Winston, A. K. (1989), Nonconventional machining processes, Fundamentals of Machining, Marcel Dekker, Inc, 491. [4] McGeough, J. A. (1988), Electro discharge machining, Advanced Methods of Machining, Chapman & Hall, London, 1988, pp [16] N. G. Patil and P. K. Brahmankar (2010), Some Studies into Wire Electro-Discharge Machining of Alumina Particulate-Reinforced Aluminum Matrix Composites,International Journal of Advanced Manufacturing Technology, vol. 48, M. N. Islam, N. H. Rafai and S. S. Subramanian (2010), An Investigation into Dimensional Accuracy Achievable in Wire-cut Electrical Discharge Machining, Proceedings of the World Congress on Engineering, Vol. 3 Kapoor, S. Singh and J. S. Khamba (2010) Recent Developments in Wire Electrodes for High Performance WEDM, Proceedings of the World Congress on Engineering, Vol.2. M. G. Xua., J. H. Zhangb, Y. Lia, Q. H. Zhangb, S. F. Rene.(2009), Study Material removal mechanisms of cemented carbides machined by ultrasonic vibration assisted EDM in gas medium, Journal of materials processing technology Vol.209, pp Jin Yuan, Kesheng Wang (2009) Reliable multiobjective optimization of high-speed WEDM process based on Gaussian process regression, International Journal of Machine Tools & Manufacture, vol.48, pp

6 [17] Susanta Kumar Gauri & Shankar Chakraborty (2009), Optimisation of multiple responses for WEDM processes using weighted principal components International Journal of Advanced Manufacturing Technology, Vol. 40 pp [18] H. Siddhi Jailani, A. Rajadurai, B. Mohan, A. Senthil Kumar, T. Sornakumar(2009), Multi-response optimisation of sintering parameters of Al Si alloy/fly ash composite using Taguchi method and grey relational analysis, The International Journal of Advanced Manufacturing Technology, Volume 45, Issue 3-4, pp [19] A. Noorul Haq, S. Guharaja, K. M. Karuppannan (2009), Parameter optimization of CO2 casting process by using Taguchi method, International Journal on Interactive Design and Manufacturing (IJIDeM),February 2009, Volume 3, Issue 1, pp [20]. Esme. U, Sagbas. A, and Kahraman. F,(2009), Prediction of Surface Roughness in Wire Electrical Discharge Machining using Design of Experiments and Neural Networks, Iranian Journal of Science and Technology, Transaction-B, Engineering, Vol. 33, No. B3, pp [21] Aminollah Mohammadi, Alireza Fadaei Tehrani [2008], Statistical analysis of wire electrical discharge turning on material removal rate, Journal of materials processing technology 205, pp [22] R. Ramakrishnan, L. Karunamoorthy [2008], Modeling and multi-response optimization of Inconel 718 on machining of CNC WEDM process, Journal of Materials Processing Technology, Volume 207, Issues 13, pp [23] Alireza Fadaei Tehrani, Ehsan Emanian, Davoud Karimi (2008), A new approach to surface roughness and roundness improvement in wire electrical discharge turning based on statistical analyses, The International Journal of Advanced Manufacturing Technology, October 2008, Volume 39, Issue 1-2, pp [24]. Gauri, S. K. and Chakraborty, S.,(2008) MultiResponse Optimization for WEDM Process Applying Weighted Principal Component, Proc. of the 2nd International & 23rd AIMTDR Conference. [25] S. Sarkar, M. Sekh, S. Mitra, B. Bhattacharyya (2007), Modelling and optimization of wire electrical discharge machining of TiAl in trim cutting operation, Journal of Material Processing Technology. [26] Kanlayasiri K. and S. Boonmung (2007), Effects of Wire-EDM Machining Variables on surface Roughness of newly developed DC 53 die steel: Design of Experiments and Regression Model J. Mater. Process Technology, : [27] Aminollah Mohammadi, Alireza Fadaei Tehrani, Ehsan Emanian and Davoud Karimi (2007), A new approach to surface roughness and roundness improvement in wire electrical discharge turning based on statistical analyses, The International Journal of Advanced Manufacturing technology, Volume 39, Numbers 1-2,pp [28] S. S. Mahapatra, Amar Patnaik (2006), Optimization of wire electrical discharge machining (WEDM) process parameters using Taguchi method, International Journal of Advance Technology. [29] A. Manna, B. Bhattacharya (2006), Taguchi and Gauss elimination method: A dual response approach for parametric optimization of CNC wire cut EDM of Pt-AlSiC MMC, International Journal of Advanced Manufacturing Technology vol. 28,pp [30] R. Ramakrishnan, L. Karunamoorthy(2006), Multi response optimization of wire EDM operations using robust design of experiments, the International Journal of Advanced Manufacturing Technology, Volume 29, Issue 1-2, pp [31] A. Manna, B. Bhattacharya (2006), Taguchi and Gauss elimination method: A dual response approach for parametric optimization of CNC wire cut EDM of PRAlSiCMMC, the International Journal of Advanced Manufacturing Technology February 2006, Volume 28, Issue 1-2, pp [32] Hari Singh, Pradeep Kumar (2005), Optimizing multi machining characteristics through Taguchi's approach and Utility concept, Journal of Manufacturing Technology management, Volume 17, No-2, pp [33]. Sarkar, S. et al., (2005), Parametric analysis and optimization of wire electrical discharge machining of γtitanium aluminide alloy, Journal of Materials Processing Technology, 159, pp [34]. Hewidey, M. S., El-Taweel, T. A. and El-Safty, M.F., (2005), Modelling the Machining Parameters of Wire Electrical Discharge Machining of Inconel 601 using RSM, Journal of Materials Processing Tech, V. 169, pp [35] Kuriakose, S. and Shunmugam, M.S.,(2005) Multi objective optimization of wire EDM process by nondominating sorting genetic algorithm, J. of Materials Processing Technology,170, pp [36] K. H. Ho, S. T. Newman, S. Rahimfard, R. D. Allen [2004], State of the art in wire electrical discharge machining (WEDM), International Journal of Machine Tools and Manufacture, Volume 44, pp

7 Biographical of Author(s) CHANCHALA received B.E. from Jabulpur Engineering College,Jabalpur, M.P India in 2010 and P..G (Manufacturing Technology and automation) from YMCAUST, Faridabad, Haryana India in Navdeep Malhotra has obtained his B.E (Production Engineering) Degree from NMU, Jalgaon in 1996, PGdMM from NMU in 1998, M.P.M. from NMU in 1999, PGdPE (Plastics Engineering) from CIPET Mysore, India in 2000, M.E (Industrial Engineering) from Thapar University (TIET) 2002, Patiala, India and Ph.D, from NIT, Kurukshetra, Haryana, India The major field of interest is Plastics Engineering, Advanced Manufacturing Processes, Optimization, Composites, Fibre Reinforced Plastics and Engineering Graphics. He worked as faculty incharge Central workshop, Shri Mata Vaishno Devi University, katra (J&K) He has more than 15 years of Teaching Experience. Presently he is working as Professor in Mech. Engg. Department of YMCA university of Science & Technology. Dr. Malhotra is life member of various technical societies like SME, ISTE, IE, FRPI, ISAMPE, MRIS. He also organized various International and National Conferences. He has published more than 30 papers in Journals and conferences. 43