International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) ...
International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) ...
International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) ...
International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) ...
International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) ...
International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) ...
International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) ...
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Experimental investigation of machining parameters of electric

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Experimental investigation of machining parameters of electric

  1. 1. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME39EXPERIMENTAL INVESTIGATION OF MACHINING PARAMETERSOF ELECTRIC DISCHARGE MACHINE ON TUNGSTEN CARBIDE(K-10)Er. RAVINDER KHANNA1, Er. SUMIT GARG21(Mechanical Engineering, PCET, Lalru/Punjab Technical University, Jalandhar)2(Mechanical Engineering, PCET, Lalru/Punjab Technical University, Jalandhar)ABSTRACTMachining of hard metal is very difficult process by conventional method. So we usea non conventional method for hard material the method is known as electrical dischargemachining (EDM) process. And the material for machining is tungsten carbide (k-10). Wherethe composition of that material is (94% of W & 6% of C)? Electrical discharge machining(EDM) is one of the most widely used non-traditional machining processes. ElectricalDischarge Machining (EDM) is the process of machining electrically conductive materials byusing precisely controlled sparks that occur between an electrode and a workpiece in thepresence of a dielectric fluid. The electrode may be considered the cutting tool. This paperinvestigate about the effect of EDM parameters using pulse on time, pulse of time, currentand voltage on material removal rate (MRR) . In the present Work we take copper aselectrode. Using Taguchi method, an L16 orthogonal array is used in the experiment and fourlevels corresponding to each of the variables are taken.Keywords: EDM, metal removal rate (MRR), Taguchi method, Tungsten Carbide (WC)1. INTRODUCTIONElectrical Discharge Machining (EDM) is a well-known machining technique sincemore than fifty years. Nowadays it is the most widely-used non-traditional machiningprocess, mainly to produce injection molds and dies, for mass production of very commonobjects. It can also produce finished parts, such as cutting tools and items with complexshapes. EDM is used in a large number of industrial areas: automotive industry, electronics,domestic appliances, machines, packaging, telecommunications, watches, aeronautic, toys,INTERNATIONAL JOURNAL OF PRODUCTION TECHNOLOGY ANDMANAGEMENT (IJPTM)ISSN 0976- 6383 (Print)ISSN 0976 - 6391 (Online)Volume 4, Issue 1, January - April (2013), pp. 39-45© IAEME: www.iaeme.com/ijptm.aspJournal Impact Factor (2013): 4.3285 (Calculated by GISI)www.jifactor.comIJPTM© I A E M E
  2. 2. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME40surgical instruments. The principle of EDM is to use the eroding effect of controlled electricspark discharges on the electrodes. It is thus a thermal erosion process. The sparks are createdin a dielectric liquid, generally water or oil, between the workpiece and an electrode, whichcan be considered as the cutting tool. There is no mechanical contact between the electrodesduring the whole process. Since erosion is produced by electrical discharges, both electrodeand workpiece have to be electrically conductive. Thus, the machining process consists insuccessively removing small volumes of workpiece material, molten or vaporized during adischarge. The volume removed by a single spark is small, in the range of 10-6-10-4mm3, butthis basic process is repeated typically 10’000 times per second. Electrical dischargemachining (EDM) is a process that is used to remove metal through the action of an electricaldischarge of short duration and high current density between the tool and the workpiece [1-2].Both tool and work piece are submerged in a dielectric fluid .Kerosene/EDMoil/deionized water is very common type of liquid dielectric although gaseous dielectrics arealso used in certain cases. Tungsten carbide (WC) is an important tool and dies material,mainly because of its high hardness, strength and wears resistance over a wide range oftemperatures. It has a high specific strength and cannot be easily processed by conventionalmachining techniques. Tungsten carbide is a type of cemented carbide; the particles ofcarbide are bound by the process of powder metallurgy [3-5] to produce tungsten carbide(WC).2. EXPERIMENTATION PROCESSA number of experiments were conducted to study the effects of various machiningparameters on EDM process. These studies have been undertaken to investigate the effects ofcurrent (Ip), pulse on time (Ton), pulse off Time (Toff) and voltage (v).The selected work piece material for the work is tungsten carbide. The tungsten carbide has(94% of W & 6% of C).The material for the electrode is copper. Have a diameter of 6mm.Experiments are conducted on brand Elektra model number es 5535 Die Sinking Machine.Physical Properties of Tungsten CarbidePropertiesMeltingpointDensityThermalexpansionHardnessElasticmodulusTungstencarbide(Wc)2,800 Oc14.5 g/cm3 5×10-6Oc93.7 (HRA) 648 GpaIn the experiment we calculate the MRR and for the calculation of MRR we have to measurethe weight of workpiece after every run of experiment. Every time the material is removedfrom the workpiece due to heat generated by the arc, the remove debris from the workpieceas a result of that the weight of the workpiece decreases. to measure the initial and finalweight of workpiece.
  3. 3. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME413. DESIGN OF EXPERIMENTS AND ANALYSIS3.1 Design of ExperimentsThe experimental layout for the machining parameters using the L16 orthogonal array wasused in this study.Table no. 3.3.1 Input Machining ParametersS.NO.INPUTPARMETERSLEVEL OBSERVED VALUE1 2 3 4 Material removal rate(MRR)Ing/min.1. Current (Ip) 10 13 17 202. Pulse on time (Ton) 50 100 150 2003. Pulse off time (Toff) 3 6 9 124. Voltage(V) 20 30 40 50This array consists of four control parameters and four levels, as shown in table no. 3.3.1. Inthe taguchi method, most all of the observed values are calculated based on ‘higher is thebetter’. Each experimental trial was performed with three simple replications at each setvalue. Next, the optimization of the observed values was determined by comparing thestandard analysis and analysis of variance (ANOVA) which was based on the taguchimethod.3.2 Results and analysis of MRR for machined surfaceThe effect of parameters i.e. Current, Pulse on time, Pulse off time and Voltage someof their interactions were evaluated using ANOVA. A confidence interval of 95% has beenused for the analysis. To measure Signal to Noise ratio (S/N ratio) calculated by the formula(S/N) HB = -10 log (MSDHB)For material removal rate (MRR) the S/N ratio is larger is better.Where MSDHB = Mean Square deviation for higher the better response.3.3 Observation tableDuring the conduction of all the 16 experiments with different set of input parametersobservation were made for the weight lost in the gram from the workpiece in each experimentand time taken in the minute for the machining of each experiment was also observed. For allthe readings time taken was 1 hour. After the completion of all the experiments theobservation reading of the weight loss and time taken were filled in orthogonal array asshown in table 3.3.1
  4. 4. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME42Table no. 3.3.1 Average Table for MRR for MaterialSRNO.Ip(A)Ton(µs)Toff(µs)Voltage(V)MRR(gm/min)S/NRatioMEANRatioM1 M2 M31 10 50 3 200.0015 0.0013 0.0013 -57.2867 0.00136672 10 100 6 300.0047 0.0028 0.0016 -50.3616 0.00303333 10 150 9 400.0023 0.0016 0.0038 -51.8126 0.00256674 10 200 12 500.0035 0.0025 0.0033 -50.1728 0.00315 13 50 6 400.0047 0.0031 0.0045 -47.7443 0.00416 13 100 3 500.0095 0.0075 0.0066 -42.0842 0.00786677 13 150 12 200.0023 0.0016 0.002 -54.1254 0.00196678 13 200 9 300.002 0.003 0.0028 -51.7005 0.00269 17 50 9 500.0078 0.0063 0.0083 -42.5375 0.007466710 17 100 12 400.0025 0.0043 0.0045 -48.4809 0.003766711 17 150 3 300.003 0.0046 0.0035 -48.636 0.003712 17 200 6 200.0025 0.0016 0.0021 -53.6946 0.002066713 20 50 12 300.0028 0.0053 0.0045 -47.535 0.004214 20 100 9 200.0031 0.0033 0.0037 -49.456 0.003366715 20 150 6 500.0068 0.008 0.009 -42.0109 0.007933316 20 200 3 400.0037 0.0048 0.0055 -46.6199 0.00466673.4 Analysis of variance – MRR:The results were analyzed using ANOVA for identifying the significant factorsaffecting the performance measures. The Analysis of Variance (ANOVA) for the mean MRRat 95% confidence interval is given in Tables. The variation data for each factor and theirinteractions were F-tested to find significance of each calculated by the formula. Theprinciple of the F-test is that the larger the F value for a particular parameter, the greater theeffect on the performance characteristic due to the change in that process parameter. ANOVAtable shows that current, pulse on time, pulses off time, voltage are the factors thatsignificantly affect the MRR. Voltage has highest contribution to MRR. Main effect plot forthe mean MRR is shown in the graph which shows the variation of MRR with the inputparameters. As can be seen MRR increases with increase in voltage from 20v to 50v.3.5 Conformation testFrom mean of each level of every factor we will construct response table for MRR isgiven below:
  5. 5. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME43Table no. 3.5.1 Response Table for Signal to Noise Ratios (Larger is Better)LEVELCURRENT(A)Pulse on time(B)Pulse off time(C)Voltage(D)1 -52.41 -48.78 -48.66 -53.642 -48.91 -47.60 -48.45 -49.563 -48.34 -49.15 -48.88 -48.664 -46.41 -50.55 -50.08 -44.20Delta 6.00 2.95 1.63 9.44Rank 2 3 4 1Table no. 3.5.2Response Table for MeansLevel Current Pulse on time Pulse off time Voltage1 0.002517 0.004283 0.004400 0.0021922 0.004133 0.0045080 0.004283 0.0033833 0.004250 0.004042 0.004000 0.0037754 0.005042 0.003108 0.003258 0.006592Delta 0.002525 0.001400 0.001142 0.004400Rank 2 3 4 1From above main effect plot of MRR we can conclude the optimum condition for MRR isA4, B2, C2, D4 i.e. Current (20amp.), Pulse-on (100µs) and Pulse-off (6 µs), Voltage (50V).4321-45.0-47.5-50.0-52.5-55.043214321-45.0-47.5-50.0-52.5-55.04321AMeanofSNratiosBC DMain Effects Plot for SN ratiosData MeansSignal-to-noise: Larger is better43210.0060.0050.0040.0030.002432143210.0060.0050.0040.0030.0024321AMeanofMeansBC DMain Effects Plot for MeansData MeansMain Effect Plot for S/N Ratio of MRR Main Effect Plot for Means of MRRThe table showing the s/n ratio of MRR where we check the value of p which is less than of0.05 and in the table 0.023 for current and 0.007 of voltage .which have been showingvoltage factor have more contribution for removing the material after that current have beengiving there contribution for that.
  6. 6. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME44Table no. 3.5.3 ANOVA for S/N Ratio of MRRSource DF Seq SS Adj SS Adj MS F PCurrent 3 75.179 75.179 25.060 16.34 0.023Pon 3 17.743 17.743 5.914 3.86 0.148Poff 3 6.378 6.378 2.126 1.39 0.397Voltage 3 179.945 179.945 59.982 39.12 0.007Residualerror3 4.600 4.600 1.533Total 15 283.845Table no. 3.5.4 ANOVA for Mean Ratio of MRRSource DF Seq SS Adj SS Adj MS F PCurrent 3 0.0000135 0.0000135 0.0000045 11.04 0.040Pon 3 0.0000045 0.0000045 0.0000015 3.72 0.154Poff 3 0.0000032 0.0000032 0.0000011 2.59 0.228Voltage 3 0.0000417 0.0000417 0.0000139 34.18 0.008Residualerror3 0.0000012 0.0000012 0.0000004Total 15 0.0000640** Significant at 95% confidence levelSeq SS= Sum of squares, DOF= degree of freedom, Adj MS= adjusted mean square orvariance.3.6 Optimal design for MRRIn the experimental analysis, main effect plot of S/N ratio is used for estimating theS/N ratio of MRR with optimal design condition. As shown in the graphs, there are highestvalues which effect the material removal rate which are the current (A4), pulse-on (B2), pulseoff (C2) and voltage (D4) respectively. After evaluating the optimal parameter settings, thenext step of the Taguchi approach is to predict and verify the enhancement of qualitycharacteristics using the optimal parametric combination. The estimated S/N ratio using theoptimal level of the design parameters can be calculated:nopt = -49.016 + ( -46.41+49.016) + (-47.60+49.016) + (-48.45+49.016) +(-44.20+49.016)= -39.6114
  7. 7. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383(Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME45y2opt =ଵଵ଴ష೙೚೛೟భబy2opt =ଵଵ଴యవ.లభభరభబyopt =0.010g/min.As per the optimal level again the experiment is performed as A4, B2, C2 and D4.The Experimental value that is obtained is 0.009g/min. So the value of percentage change is10%.4. CONCLUSIONIn the present study, for EDM process the effect of current, pulse-on time, pulse offtime and voltage has been investigated. The effect of input parameter on output responseMaterial removal rate was analyzed for work material tungsten carbide (K-10). L16orthogonal array based on Taguchi design and ANOVA was performed for analyzing theresult.For the MRR, voltage is most influencing factor and then discharge current and afterthat pulse-on time and last is pulse off time.MRR increases with the increase in the value ofvoltage. After that current also affect the MRR with increases. Other factors for higher valueof pulse on time and pulse off the MRR are highest.REFERENCES[1] Mahdavinejad, R.A., Mahdavinejad, A., 2005. ED Machining of WC-Co. Journal of MaterialsProcessing Technology 162-163, pp. 637-643.[2] Soo Hiong Lee, Xiaoping Li. 2003. Study of the Surface Integrity of the Machined Workpiecein the EDM of Tungsten Carbide” Journal of Materials Processing Technology 139, pp. 315-321.[3] Singh, S., Maheshwari, S., Pandey, P.C., 2004. Some Investigation into the Electric DischargeMachining of Hardened Tool Steel Using Different Electrode Materials. Journal of MaterialsProcessing Technology 149 (1-3), pp. 272-277.[4] George P.M., Raghunath B.K., Manocha L.M., M.W. Ashish., 2004. EDM Machining ofCarbon-Carbon Composite-a Taguchi Approach. Journal of Materials Processing Technology145, pp. 66-71.[5] Lee S.H., Li X.P., 2001. Study of the Effect of Machining Parameters on the MachiningCharacteristics in Electrical Discharge Machining of Tungsten Carbide. Journal of MaterialsProcessing Technology.115, (3), pp. 344-358.[6] N.Vijayponraj, Dr.G.Kalivarathan and Vettivel.S.C, “Investigation Of Mechanical BehaviourIn Forming Of Sintered Copper-15%Tungsten Nano Powder Composite”, International Journal ofProduction Technology And Management (IJPTM), Volume 3, Issue 1, 2012, pp. 54 - 60, ISSNPrint: 0976- 6383, ISSN Online: 0976 – 6391.[7] U. D. Gulhane, P. P. Patkar, P. P. Toraskar, S. P. Patil and A. A. Patil, “Analysis of AbrasiveJet Machining Parameters on MRR and Kerf Width of Hard and Brittle Materials Like Ceramic”,International Journal of Design and Manufacturing Technology (IJDMT), Volume 4, Issue 1,2013, pp. 51 - 58, ISSN Print: 0976 – 6995, ISSN Online: 0976 – 7002.

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