Experimental investigation of machining parameters of electric
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This document summarizes an experimental investigation of machining parameters for electrical discharge machining (EDM) of tungsten carbide (K-10). Experiments were conducted using different levels of pulse on time, pulse off time, current, and voltage. Material removal rate (MRR) was measured for each experiment. Analysis of variance (ANOVA) found that voltage had the highest contribution to MRR, followed by current. The optimal parameters for maximum MRR were found to be: current of 20 amps, pulse on time of 100 microseconds, pulse off time of 6 microseconds, and voltage of 50 volts.
![International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383
(Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME
40
surgical instruments. The principle of EDM is to use the eroding effect of controlled electric
spark discharges on the electrodes. It is thus a thermal erosion process. The sparks are created
in a dielectric liquid, generally water or oil, between the workpiece and an electrode, which
can be considered as the cutting tool. There is no mechanical contact between the electrodes
during the whole process. Since erosion is produced by electrical discharges, both electrode
and workpiece have to be electrically conductive. Thus, the machining process consists in
successively removing small volumes of workpiece material, molten or vaporized during a
discharge. The volume removed by a single spark is small, in the range of 10-6
-10-4
mm3
, but
this basic process is repeated typically 10’000 times per second. Electrical discharge
machining (EDM) is a process that is used to remove metal through the action of an electrical
discharge 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/EDM
oil/deionized water is very common type of liquid dielectric although gaseous dielectrics are
also 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 of
temperatures. It has a high specific strength and cannot be easily processed by conventional
machining techniques. Tungsten carbide is a type of cemented carbide; the particles of
carbide are bound by the process of powder metallurgy [3-5] to produce tungsten carbide
(WC).
2. EXPERIMENTATION PROCESS
A number of experiments were conducted to study the effects of various machining
parameters on EDM process. These studies have been undertaken to investigate the effects of
current (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 Carbide
Properties
Melting
point
Density
Thermal
expansion
Hardness
Elastic
modulus
Tungsten
carbide
(Wc)
2,800 Oc
14.5 g/cm3 5×10-6
Oc
93.7 (HRA) 648 Gpa
In the experiment we calculate the MRR and for the calculation of MRR we have to measure
the weight of workpiece after every run of experiment. Every time the material is removed
from the workpiece due to heat generated by the arc, the remove debris from the workpiece
as a result of that the weight of the workpiece decreases. to measure the initial and final
weight of workpiece.](https://image.slidesharecdn.com/experimentalinvestigationofmachiningparametersofelectric-130529032755-phpapp01/85/Experimental-investigation-of-machining-parameters-of-electric-2-320.jpg)
![International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383
(Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME
45
y2
opt =
ଵ
ଵ
ష
భబ
y2
opt =
ଵ
ଵ
యవ.లభభర
భబ
yopt =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 is
10%.
4. CONCLUSION
In the present study, for EDM process the effect of current, pulse-on time, pulse off
time and voltage has been investigated. The effect of input parameter on output response
Material removal rate was analyzed for work material tungsten carbide (K-10). L16
orthogonal array based on Taguchi design and ANOVA was performed for analyzing the
result.
For the MRR, voltage is most influencing factor and then discharge current and after
that pulse-on time and last is pulse off time.MRR increases with the increase in the value of
voltage. After that current also affect the MRR with increases. Other factors for higher value
of 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 Materials
Processing Technology 162-163, pp. 637-643.
[2] Soo Hiong Lee, Xiaoping Li. 2003. Study of the Surface Integrity of the Machined Workpiece
in 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 Discharge
Machining of Hardened Tool Steel Using Different Electrode Materials. Journal of Materials
Processing Technology 149 (1-3), pp. 272-277.
[4] George P.M., Raghunath B.K., Manocha L.M., M.W. Ashish., 2004. EDM Machining of
Carbon-Carbon Composite-a Taguchi Approach. Journal of Materials Processing Technology
145, pp. 66-71.
[5] Lee S.H., Li X.P., 2001. Study of the Effect of Machining Parameters on the Machining
Characteristics in Electrical Discharge Machining of Tungsten Carbide. Journal of Materials
Processing Technology.115, (3), pp. 344-358.
[6] N.Vijayponraj, Dr.G.Kalivarathan and Vettivel.S.C, “Investigation Of Mechanical Behaviour
In Forming Of Sintered Copper-15%Tungsten Nano Powder Composite”, International Journal of
Production Technology And Management (IJPTM), Volume 3, Issue 1, 2012, pp. 54 - 60, ISSN
Print: 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 Abrasive
Jet 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.](https://image.slidesharecdn.com/experimentalinvestigationofmachiningparametersofelectric-130529032755-phpapp01/85/Experimental-investigation-of-machining-parameters-of-electric-7-320.jpg)
Experimental investigation of machining parameters of electric
- 1. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383 (Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME 39 EXPERIMENTAL INVESTIGATION OF MACHINING PARAMETERS OF ELECTRIC DISCHARGE MACHINE ON TUNGSTEN CARBIDE (K-10) Er. RAVINDER KHANNA1 , Er. SUMIT GARG2 1 (Mechanical Engineering, PCET, Lalru/Punjab Technical University, Jalandhar) 2 (Mechanical Engineering, PCET, Lalru/Punjab Technical University, Jalandhar) ABSTRACT Machining of hard metal is very difficult process by conventional method. So we use a non conventional method for hard material the method is known as electrical discharge machining (EDM) process. And the material for machining is tungsten carbide (k-10). Where the 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. Electrical Discharge Machining (EDM) is the process of machining electrically conductive materials by using precisely controlled sparks that occur between an electrode and a workpiece in the presence of a dielectric fluid. The electrode may be considered the cutting tool. This paper investigate about the effect of EDM parameters using pulse on time, pulse of time, current and voltage on material removal rate (MRR) . In the present Work we take copper as electrode. Using Taguchi method, an L16 orthogonal array is used in the experiment and four levels corresponding to each of the variables are taken. Keywords: EDM, metal removal rate (MRR), Taguchi method, Tungsten Carbide (WC) 1. INTRODUCTION Electrical Discharge Machining (EDM) is a well-known machining technique since more than fifty years. Nowadays it is the most widely-used non-traditional machining process, mainly to produce injection molds and dies, for mass production of very common objects. It can also produce finished parts, such as cutting tools and items with complex shapes. 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 AND MANAGEMENT (IJPTM) ISSN 0976- 6383 (Print) ISSN 0976 - 6391 (Online) Volume 4, Issue 1, January - April (2013), pp. 39-45 © IAEME: www.iaeme.com/ijptm.asp Journal Impact Factor (2013): 4.3285 (Calculated by GISI) www.jifactor.com IJPTM © I A E M E
- 2. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383 (Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME 40 surgical instruments. The principle of EDM is to use the eroding effect of controlled electric spark discharges on the electrodes. It is thus a thermal erosion process. The sparks are created in a dielectric liquid, generally water or oil, between the workpiece and an electrode, which can be considered as the cutting tool. There is no mechanical contact between the electrodes during the whole process. Since erosion is produced by electrical discharges, both electrode and workpiece have to be electrically conductive. Thus, the machining process consists in successively removing small volumes of workpiece material, molten or vaporized during a discharge. The volume removed by a single spark is small, in the range of 10-6 -10-4 mm3 , but this basic process is repeated typically 10’000 times per second. Electrical discharge machining (EDM) is a process that is used to remove metal through the action of an electrical discharge 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/EDM oil/deionized water is very common type of liquid dielectric although gaseous dielectrics are also 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 of temperatures. It has a high specific strength and cannot be easily processed by conventional machining techniques. Tungsten carbide is a type of cemented carbide; the particles of carbide are bound by the process of powder metallurgy [3-5] to produce tungsten carbide (WC). 2. EXPERIMENTATION PROCESS A number of experiments were conducted to study the effects of various machining parameters on EDM process. These studies have been undertaken to investigate the effects of current (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 Carbide Properties Melting point Density Thermal expansion Hardness Elastic modulus Tungsten carbide (Wc) 2,800 Oc 14.5 g/cm3 5×10-6 Oc 93.7 (HRA) 648 Gpa In the experiment we calculate the MRR and for the calculation of MRR we have to measure the weight of workpiece after every run of experiment. Every time the material is removed from the workpiece due to heat generated by the arc, the remove debris from the workpiece as a result of that the weight of the workpiece decreases. to measure the initial and final weight of workpiece.
- 3. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383 (Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME 41 3. DESIGN OF EXPERIMENTS AND ANALYSIS 3.1 Design of Experiments The experimental layout for the machining parameters using the L16 orthogonal array was used in this study. Table no. 3.3.1 Input Machining Parameters S.NO . INPUT PARMETERS LEVEL OBSERVED VALUE 1 2 3 4 Material removal rate (MRR) In g/min. 1. Current (Ip) 10 13 17 20 2. Pulse on time (Ton) 50 100 150 200 3. Pulse off time (Toff) 3 6 9 12 4. Voltage(V) 20 30 40 50 This array consists of four control parameters and four levels, as shown in table no. 3.3.1. In the taguchi method, most all of the observed values are calculated based on ‘higher is the better’. Each experimental trial was performed with three simple replications at each set value. Next, the optimization of the observed values was determined by comparing the standard analysis and analysis of variance (ANOVA) which was based on the taguchi method. 3.2 Results and analysis of MRR for machined surface The effect of parameters i.e. Current, Pulse on time, Pulse off time and Voltage some of their interactions were evaluated using ANOVA. A confidence interval of 95% has been used 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 table During the conduction of all the 16 experiments with different set of input parameters observation were made for the weight lost in the gram from the workpiece in each experiment and time taken in the minute for the machining of each experiment was also observed. For all the readings time taken was 1 hour. After the completion of all the experiments the observation reading of the weight loss and time taken were filled in orthogonal array as shown in table 3.3.1
- 4. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383 (Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME 42 Table no. 3.3.1 Average Table for MRR for Material SR NO. Ip (A) Ton (µs) Toff (µs) Voltag e (V) MRR (gm/min) S/N Ratio MEAN Ratio M1 M2 M3 1 10 50 3 20 0.0015 0.0013 0.0013 -57.2867 0.0013667 2 10 100 6 30 0.0047 0.0028 0.0016 -50.3616 0.0030333 3 10 150 9 40 0.0023 0.0016 0.0038 -51.8126 0.0025667 4 10 200 12 50 0.0035 0.0025 0.0033 -50.1728 0.0031 5 13 50 6 40 0.0047 0.0031 0.0045 -47.7443 0.0041 6 13 100 3 50 0.0095 0.0075 0.0066 -42.0842 0.0078667 7 13 150 12 20 0.0023 0.0016 0.002 -54.1254 0.0019667 8 13 200 9 30 0.002 0.003 0.0028 -51.7005 0.0026 9 17 50 9 50 0.0078 0.0063 0.0083 -42.5375 0.0074667 10 17 100 12 40 0.0025 0.0043 0.0045 -48.4809 0.0037667 11 17 150 3 30 0.003 0.0046 0.0035 -48.636 0.0037 12 17 200 6 20 0.0025 0.0016 0.0021 -53.6946 0.0020667 13 20 50 12 30 0.0028 0.0053 0.0045 -47.535 0.0042 14 20 100 9 20 0.0031 0.0033 0.0037 -49.456 0.0033667 15 20 150 6 50 0.0068 0.008 0.009 -42.0109 0.0079333 16 20 200 3 40 0.0037 0.0048 0.0055 -46.6199 0.0046667 3.4 Analysis of variance – MRR: The results were analyzed using ANOVA for identifying the significant factors affecting the performance measures. The Analysis of Variance (ANOVA) for the mean MRR at 95% confidence interval is given in Tables. The variation data for each factor and their interactions were F-tested to find significance of each calculated by the formula. The principle of the F-test is that the larger the F value for a particular parameter, the greater the effect on the performance characteristic due to the change in that process parameter. ANOVA table shows that current, pulse on time, pulses off time, voltage are the factors that significantly affect the MRR. Voltage has highest contribution to MRR. Main effect plot for the mean MRR is shown in the graph which shows the variation of MRR with the input parameters. As can be seen MRR increases with increase in voltage from 20v to 50v. 3.5 Conformation test From mean of each level of every factor we will construct response table for MRR is given below:
- 5. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383 (Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME 43 Table no. 3.5.1 Response Table for Signal to Noise Ratios (Larger is Better) LEVEL CURRENT (A) Pulse on time (B) Pulse off time (C) Voltage (D) 1 -52.41 -48.78 -48.66 -53.64 2 -48.91 -47.60 -48.45 -49.56 3 -48.34 -49.15 -48.88 -48.66 4 -46.41 -50.55 -50.08 -44.20 Delta 6.00 2.95 1.63 9.44 Rank 2 3 4 1 Table no. 3.5.2Response Table for Means Level Current Pulse on time Pulse off time Voltage 1 0.002517 0.004283 0.004400 0.002192 2 0.004133 0.0045080 0.004283 0.003383 3 0.004250 0.004042 0.004000 0.003775 4 0.005042 0.003108 0.003258 0.006592 Delta 0.002525 0.001400 0.001142 0.004400 Rank 2 3 4 1 From above main effect plot of MRR we can conclude the optimum condition for MRR is A4, 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 -55.0 4321 4321 -45.0 -47.5 -50.0 -52.5 -55.0 4321 A MeanofSNratios B C D Main Effects Plot for SN ratios Data Means Signal-to-noise: Larger is better 4321 0.006 0.005 0.004 0.003 0.002 4321 4321 0.006 0.005 0.004 0.003 0.002 4321 A MeanofMeans B C D Main Effects Plot for Means Data Means Main Effect Plot for S/N Ratio of MRR Main Effect Plot for Means of MRR The table showing the s/n ratio of MRR where we check the value of p which is less than of 0.05 and in the table 0.023 for current and 0.007 of voltage .which have been showing voltage factor have more contribution for removing the material after that current have been giving there contribution for that.
- 6. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383 (Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME 44 Table no. 3.5.3 ANOVA for S/N Ratio of MRR Source DF Seq SS Adj SS Adj MS F P Current 3 75.179 75.179 25.060 16.34 0.023 Pon 3 17.743 17.743 5.914 3.86 0.148 Poff 3 6.378 6.378 2.126 1.39 0.397 Voltage 3 179.945 179.945 59.982 39.12 0.007 Residual error 3 4.600 4.600 1.533 Total 15 283.845 Table no. 3.5.4 ANOVA for Mean Ratio of MRR Source DF Seq SS Adj SS Adj MS F P Current 3 0.0000135 0.0000135 0.0000045 11.04 0.040 Pon 3 0.0000045 0.0000045 0.0000015 3.72 0.154 Poff 3 0.0000032 0.0000032 0.0000011 2.59 0.228 Voltage 3 0.0000417 0.0000417 0.0000139 34.18 0.008 Residual error 3 0.0000012 0.0000012 0.0000004 Total 15 0.0000640 ** Significant at 95% confidence level Seq SS= Sum of squares, DOF= degree of freedom, Adj MS= adjusted mean square or variance. 3.6 Optimal design for MRR In the experimental analysis, main effect plot of S/N ratio is used for estimating the S/N ratio of MRR with optimal design condition. As shown in the graphs, there are highest values which effect the material removal rate which are the current (A4), pulse-on (B2), pulse off (C2) and voltage (D4) respectively. After evaluating the optimal parameter settings, the next step of the Taguchi approach is to predict and verify the enhancement of quality characteristics using the optimal parametric combination. The estimated S/N ratio using the optimal 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. International Journal of Production Technology and Management (IJPTM), ISSN 0976 – 6383 (Print), ISSN 0976 – 6391 (Online) Volume 4, Issue 1, January – April (2013), © IAEME 45 y2 opt = ଵ ଵ ష భబ y2 opt = ଵ ଵ యవ.లభభర భబ yopt =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 is 10%. 4. CONCLUSION In the present study, for EDM process the effect of current, pulse-on time, pulse off time and voltage has been investigated. The effect of input parameter on output response Material removal rate was analyzed for work material tungsten carbide (K-10). L16 orthogonal array based on Taguchi design and ANOVA was performed for analyzing the result. For the MRR, voltage is most influencing factor and then discharge current and after that pulse-on time and last is pulse off time.MRR increases with the increase in the value of voltage. After that current also affect the MRR with increases. Other factors for higher value of 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 Materials Processing Technology 162-163, pp. 637-643. [2] Soo Hiong Lee, Xiaoping Li. 2003. Study of the Surface Integrity of the Machined Workpiece in 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 Discharge Machining of Hardened Tool Steel Using Different Electrode Materials. Journal of Materials Processing Technology 149 (1-3), pp. 272-277. [4] George P.M., Raghunath B.K., Manocha L.M., M.W. Ashish., 2004. EDM Machining of Carbon-Carbon Composite-a Taguchi Approach. Journal of Materials Processing Technology 145, pp. 66-71. [5] Lee S.H., Li X.P., 2001. Study of the Effect of Machining Parameters on the Machining Characteristics in Electrical Discharge Machining of Tungsten Carbide. Journal of Materials Processing Technology.115, (3), pp. 344-358. [6] N.Vijayponraj, Dr.G.Kalivarathan and Vettivel.S.C, “Investigation Of Mechanical Behaviour In Forming Of Sintered Copper-15%Tungsten Nano Powder Composite”, International Journal of Production Technology And Management (IJPTM), Volume 3, Issue 1, 2012, pp. 54 - 60, ISSN Print: 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 Abrasive Jet 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.