International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 649...
International Journal of Advanced Research i0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), ...
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 649...
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 649...
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 649...
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 649...
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 649...
International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 649...
Upcoming SlideShare
Loading in...5
×

Comparative study on variation of process characteristics on al and die steel process

90

Published on

Published in: Business, Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
90
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
2
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Comparative study on variation of process characteristics on al and die steel process

  1. 1. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME170COMPARATIVE STUDY ON VARIATION OF PROCESSCHARACTERISTICS ON AL AND DIE STEEL COMPONENTS INSINK EDM PROCESS1K.L.Uday Kiran, 2R.Rajendra, 3G.Chandramohan Reddy, 4A.M.K Prasad1, 2, 4University College of Engineering, Osmania University, Hyderabad, A.P, India3Mahatma Gandhi Institute of Technology, Hyderabad, A.P, IndiaABSTRACT:Electrical Discharge Machining (EDM) process is a well established non-traditionalmachining option for manufacturing geometrically complex and hard material parts that are extremelydifficult to machine by conventional machining process. In this process the material removal isoccurred electro thermally by a series of successive discrete discharges between electrode and thework piece.This paper presents the results of experimental studies carried out to conduct a comprehensiveinvestigation on the influence of EDM parameter (current) on process characteristics in sink EDMprocess. The studied process characteristics included material removal rate, tool wear ratio, andsurface roughness parameters of two work pieces (Al & Die steel) by using a common tool (Cu). Thevariation of process characteristics at different currents was studied. The observation revealed that theMRR, TWR, Surface roughness parameters and machining time of work pieces were influenced bycurrent and thereby improves the quality of surface finishing and rate of production. The results ofthis study could be utilized in the selection of optimum process parameter (current) to achieve thedesired EDM efficiency and surface roughness when machining Al and Die steel.Keywords: EDM, Machining time, Material removal rate, Surface roughness, Tool wear ratio.1. INTRODUCTIONElectrical Discharge Machining (EDM) is one of the important non-traditional machiningprocesses and it is widely accepted as a standard machining process in manufacturing industries. Thetheory of the process was established by soviet scientists in the middle of 1940’s. They invented therelaxation circuit and a simple servo controller tool that helped to maintain the gap width between thetool and the work piece. This reduced arcing and made EDM machining more profitable andproduced first EDM machining in 1950’s. Major development of EDM was observed when computernumerical control systems were applied for the machine tool industry. Thus, the EDM Processbecame automatic and unattended machining method. The process uses thermal energy to generateheat that melts and vaporizes the workpeice by ionization within the dielectric medium. The electricalINTERNATIONAL JOURNAL OF ADVANCED RESEARCH INENGINEERING AND TECHNOLOGY (IJARET)ISSN 0976 - 6480 (Print)ISSN 0976 - 6499 (Online)Volume 4, Issue 3, April 2013, pp. 170-177© IAEME: www.iaeme.com/ijaret.aspJournal Impact Factor (2013): 5.8376 (Calculated by GISI)www.jifactor.comIJARET© I A E M E
  2. 2. International Journal of Advanced Research i0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEMEdischarges generate impulsive pressure by dielectric explosion to remove the melted material. Thus,the amount of removed material can be effectively controlled to produce complex and precisemachine components. However, the melted material is flushed away incompletely and the remainingmaterial re-solidifies to form discharge craters. As a result, machined surface has micro cracks andpores caused by high temperature gradient which reduces surface finish quality.There have been published studies continuing surface finish of machined materials by EDM. It wasnoticed that various machining parameters influenced thesurface roughness and by setting possible combination ofmaterial removal rate and tool wear ratiosurface roughness parameters are pulsed current, pulse time, pulse pause time, voltage, dielectricliquid pressure and electrode material. The present studyremoval rate, tool wear ratio andmaximum height of the profile -Rz & Maximum roughness depthComponents using copper tool in EDM2 .MECHANISM OF EDMThe working principle of EDM process is based on the thermoelectric energy.Discharge Machining (EDM) is a controlled metalmeans of electric spark erosion. In thiselectrode submerged in a dielectric fluid with the passage ofelectrode are separated by a specific small gapgap filled with an insulating medium, preferably a(de-mineralized) water as in fig.1.a [2]work piece to produce the finished part to the desired shape. The metalby applying a pulsating (ON/OFF) electrical charge of highthe work piece. This removes (erodes) vercontrolled rate.Fig. 1(a). Working principle of EDMThe polarity normally used is straight (or normal polarity) in which tool iswhile in reverse polarity the tool istool is towards the work piece is controlled by a servomechanism. The sparking takes place over theentire surface of the work piece hence the replica of the tool is produced on the work piece. Usually, acomponent made by EDM process is machined in two stages, vizpoor surface finish and finish machining at low MRR with high surface finish.International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN6499(Online) Volume 4, Issue 3, April (2013), © IAEME171discharges generate impulsive pressure by dielectric explosion to remove the melted material. Thus,the amount of removed material can be effectively controlled to produce complex and preciseowever, the melted material is flushed away incompletely and the remainingsolidifies to form discharge craters. As a result, machined surface has micro cracks andpores caused by high temperature gradient which reduces surface finish quality.There have been published studies continuing surface finish of machined materials by EDM. It wasnoticed that various machining parameters influenced the material removal rate, tool wear ratiosurface roughness and by setting possible combination of these parameters optimum surface qualityool wear ratio was obtained. The machining parameters which influencesurface roughness parameters are pulsed current, pulse time, pulse pause time, voltage, dielectricd electrode material. The present study deals with the effect of current onsurface roughness parameters (Average roughnessRz & Maximum roughness depth –Rzmax) of Al aEDM process.The working principle of EDM process is based on the thermoelectric energy.Discharge Machining (EDM) is a controlled metal-removal process that is used to remove metmeans of electric spark erosion. In this process the energy is created between a work piece and anctric fluid with the passage of electric current. The work piece and theby a specific small gap called spark gap. Pulsed arc discharges occur in thisinsulating medium, preferably a dielectric liquid like hydrocarbon oil or deas in fig.1.a [2]. The electric spark is used as the cutting tool to cut (ework piece to produce the finished part to the desired shape. The metal-removal process is performedby applying a pulsating (ON/OFF) electrical charge of high-frequency current through the electrode to(erodes) very tiny pieces of metal from the workWorking principle of EDM Fig. 1(b) Normal and reverse polarity inEDMThe polarity normally used is straight (or normal polarity) in which tool is –ve and work piece is +ve,while in reverse polarity the tool is +ve and work piece is negative shown in fig 1.b. Movement of thehe work piece is controlled by a servomechanism. The sparking takes place over theentire surface of the work piece hence the replica of the tool is produced on the work piece. Usually, acomponent made by EDM process is machined in two stages, viz. rough machining at high MRR withpoor surface finish and finish machining at low MRR with high surface finish.n Engineering and Technology (IJARET), ISSN6499(Online) Volume 4, Issue 3, April (2013), © IAEMEdischarges generate impulsive pressure by dielectric explosion to remove the melted material. Thus,the amount of removed material can be effectively controlled to produce complex and preciseowever, the melted material is flushed away incompletely and the remainingsolidifies to form discharge craters. As a result, machined surface has micro cracks andThere have been published studies continuing surface finish of machined materials by EDM. It wasool wear ratio andthese parameters optimum surface quality,machining parameters which influencesurface roughness parameters are pulsed current, pulse time, pulse pause time, voltage, dielectricthe effect of current on material(Average roughness -Ra, Averageof Al and Die-SteelThe working principle of EDM process is based on the thermoelectric energy. Electricalremoval process that is used to remove metal bycreated between a work piece and anThe work piece and thePulsed arc discharges occur in thisdielectric liquid like hydrocarbon oil or de-ionizedspark is used as the cutting tool to cut (erode) theremoval process is performedfrequency current through the electrode towork piece at aNormal and reverse polarity inve and work piece is +ve,ovement of thehe work piece is controlled by a servomechanism. The sparking takes place over theentire surface of the work piece hence the replica of the tool is produced on the work piece. Usually, amachining at high MRR with
  3. 3. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME1723. DESCRIPTION OF EXPERIMENTAL SET-UP3.1 Machine toolThe experimental setup consists of CR-6C Creator (SYCNC PC-60) Sink type Electro DischargeMachine, Taiwan (shown in fig. 2) available at Department of Mechanical Engineering, UniversityCollege of Engineering, Osmania University, Hyderabad-500007. It is energized by a 50 A pulsegenerator. Ruslic oil dielectric fluid was used during the experiments. The surface roughness wasmeasured by Handy surf Surface testing analyzer3.2 Work piece materialThe work piece materials in this work were Al and Die steel, having the properties shown inTable.13.3 Electrode materialElectrode material considered for analysis was copper and its properties being shown in Table.2Table.1: Work piece material propertiesMaterial Al Die-SteelDensity(g/cm3) 2.70 7.7-8.0Thermal conductivity (W/m K) 237 19.9-48.3Electrical resistivity (µΏ/cm) 26.50 72Coefficient of thermal expansion (x 10-6 0C-1) 23.1 9.5-15.1Melting point (oC) 660 1435Table.2: Electrode material properties (copper)(g/cm3)Thermalconductivity(W/m K)Electrical resistivity(µΏ/cm)Coefficient of thermalexpansion (x 10-6 0C-1)Meltingpoint(oC)8.9 268-389 1.96 6.6 10833.4 Experimental ProcedureThe Experimental study was carried out on CR-6C Creator (SYCNC PC-60) Sink typeElectro Discharge Machine using ruslic oil as a die electric fluid. The experiments on Die steel and Alsamples which were in the form of cylindrical shapes of diameter 50mm each were carried out usingdifferent machining setting’s with Copper electrode. Cylindrical copper tool’s with a diameter of12mm each ware used as electrode’s for machining both Al and die steel work pieces. The copperelectrodes ware finished ground before experimental study. Three work pieces of each Aluminum andDie Steel were used and machined on EDM using separate copper electrodes giving 1mm depth atthree different currents (i.e. 10 A, 15 A & 20 A).Fig. 2 Sink type Electro Discharge Machine Fig 3 shows the Tool (Cu) and Workpiece (Al)
  4. 4. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME173The material removal rate of Al and die steel work pieces were determined by the following equationMRR = (Wb-Wa ) /Tm , where Wb =Weight of the work piece before machiningWa =Weight of the work piece after machiningTm = Machining time in minThe tool wear rate of copper tool for machining Al and Die steel work pieces ware determined by thefollowing equation [3].TWR = (Wtb-Wta ) /Tm, where Wtb =Weight of the tool before machiningWta =Weight of the tool after machiningTm = Machining time in minThe surface roughness parameters (Ra, Rz & Rz max) of machined surfaces of each material atcorresponding currents (10A, 15A & 20 A) were measured by Handy surf Surface testing analyzer(made in Japan). The sampling length of machined surface was taken as 1.25mm.Electronic weighing machine was used to find the weights of work samples before and aftermachining.The machining time were also recorded for carrying out analysis.4. RESULTS AND DISCUSSION4.1 Effect of current on material removal rate: When the current is increased from 10A to 20A, thecorresponding MRR shown in fig. 4 for Al increases from 6.22 to 10.87(x 10-3gm/min) and from 9.20to 17.99 (x 10-3gm/min) for Die steel respectively. The MRR values for Al and Die steel are shown inthe Table. 3.Table.3: MRR values of Al and Die steel work samplesThe peak current increases the input power by which the increase of MRR is expected due to morespark energy flowing from tool into work piece. This causes craters and pits on the sample andmachining becomes faster.4.2 Effect of current on tool wear rate: When the current increases from 10A to 20A, thecorresponding TWR shown in fig.5 for machining Al increases from 1.70 to 7.80 (x 10-3gm/min) and from 2.20 to 9.60 (x 10-3gm/min) for Die steel. The TWR values are shown in thetable.4. Higher current causes a strong spark which results in more eroded material from the tool.Current(Amps)Aluminum Work Sample Die Steel Work SampleWeight(gms) Time(min)MRR×10-3(gm/min)Weight(gms) Time(min)MRR×10-3(gm/min)Before After Difference Before After Difference10 213.40 212.08 1.32 212 6.22 589.24 586.462.78 302 9.2015 212.40 210.90 1.50 162 9.25 587.04 583.643.40 231 14.7120 218.30 216.50 1.74 160 10.87 575.48 571.364.12 229 17.99
  5. 5. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME174Table.4: TWR values of copper tool for machining Al and Die steel work samplesFig .4 Material Removal Rate vs Current for Al & Die steel samplesFig .5 Tool Wear Rate vs Current of Copper Tool for Machining Al & Die steel samples4.3 Effect of current on surface roughness parameters: Average roughness (Ra), averagemaximum height (Rz) and maximum roughness depth (Rzmax) of the profile parameters variation onsurface of Die steel and Al work samples for variation of current parameter at 10, 15, 20 Amps for 1mm depth erosion. When the current is increased from 10A to 20A, the corresponding averageroughness, average maximum height and maximum roughness depth values shown in fig. 6(a) for Alincrease from 1.62 to 1.97 µm, 9.03 to 10.86 µm and 10.96 to 14.54 µm respectively. Similarly forDie steel as shown in fig. 6(b), the corresponding average roughness, average maximum height andmaximum roughness depth values increases from 1.99 to 2.55µm, 10.02 to 13.43µm and 10.90 to15.40 µm respectively. The surface roughness parameter values for Al and Die steel are shown.At a low current, a small quantity of heat is generated and a substantial portion of itis absorbed by the surroundings. As a result, the amount of utilized energy in melting and vaporizingCurrent(Amps)For Machining Aluminum Work Sample For Machining Die Steel Work SampleWeight(gms) Time(min)TWR×10-3(gm/min)Weight(gms) Time(min)TWR×10-3(gm/min)Before After Difference Before After Difference10 96.68 96.32 0.36 212 1.70 96.32 95.64 0.68 302 2.2015 95.16 94.74 0.42 162 2.60 93.04 91.66 1.58 231 5.9720 98.02 96.76 1.20 160 7.80 94.60 92.40 2.20 229 9.60
  6. 6. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME175the electrodes is not so intense. However, with an increase in pulse current and with a constantamount of pulse on-time, a stronger spark with higher thermal energy is produced, and a substantialquantity of heat will be transferred into the electrodes. Furthermore, as the pulse current increases,discharge strikes the surface of the sample more intensely, and creates an impact force on the moltenmaterial in the crater and causes more molten material to be ejected out of the crater, so the surfaceroughness of the machined surface increases [4].Fig .6 (a) Surface Roughness Parameters (Ra, Rz & Rzmax) vs Current for Al samples4.4 Effect of current on machining time: When the current is increased from 10A to 20A, thecorresponding machining time was decreased from 212 to 160 min for Al and 302 to 229 min for Diesteel samples as shown in fig.7. The machining time for both samples at corresponding currents asdepicted in Table.6.Table.6: Machining Time for Al & Die steel work pieces:.Fig .7 Machining Time vs Current for Al & Die steel samplesCurrent(Amps)Machining Time in minAl Die steel10 212 30215 162 23120 160 229
  7. 7. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME1765. CONCLUSIONSAnalysis from an experimental investigation on the effect of current on material removal rate,tool wear ratio and surface roughness parameters in EDM process have been presented. The leadingconclusions are drawn as follows:1. The increase in pulse current leads to a sharp increase in the MRR and surface roughness ofboth Al and Die steel samples, low currents produce good surface finish quality.2. At higher currents the surface finishing quality will be low, but the MRR will be high whichleads to improve the rate of production.3. It was evident that the tool wear ratio increases by the increase in the pulse current, but wasless compared to MRR values for same currents.4. It was experimental that for same currents the material removal rate, tool wear ratio andsurface roughness parameters of Die steel work samples were more than that of Al samples.5. There was a high increase in material removal rate for Die steel compared to Al work piecesfor same machining time.6. It was observed that the machining time decreases as the current increases and the machiningtime of Die steel work samples were more than that of Al samples.ACKNOWLEDGEMENTSThe authors are thankful to the managements of their respective institutions for theirencouragement during the course of this work.REFERENCES1. Benedict G.F. (1987) Non-traditional manufacturing Process, Marcel Dekker Inc., New York.2. Kuldeep ojha, Garg R. K., Singh K. K.(2010), MRR Improvement in Sinking ElectricalDischarge Machining: A Review, Journal of Minerals & Materials Characterization &Engineering., Vol. 9, No.8, pp.709-739.3. Nikhil kumar et al. (2012), Comparative study for MRR on Die-Sinking EDM using Electrodeof Copper & Graphite, Int. Journal of Advanced Tech. & Engg. Research., vol.2,issue 2,170-174.4. Shabgard M.R et al. (2010), Influence of input parameters on characteristics of EDM process,Journal of Mechanical Engineering.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 materialprocessing Technology., 115 344-358.6. Ho K.H, Newman S.T.(2003), State art of electrical discharge machining (EDM), Int, Journalof Machine Tools & Manufacture , 43 (2003) 1287-1300.7. Mc Geough J.A. (1988), Advanced Methods of Machining, Chapman and Hall, London.8. Snoeys R., Stalens F., and Dekeyser W. (1986). Current Trends in Non-conventional materialRemoval Processes. Annals of the CIRP, Vol.35 (2).P.467.9. CIRP Scientific Technical Committee E (1979), Summary specification of Pulse analyzers forspark erosion machining.vol.2.No.2.10. Vitlin V.B (1977), Electro-contact abrasion as a Finishing metal cutting process, Machines andTooling. Vol.48.No.4.pp.32-34.11. Pandey P.C. and Shan H.S. (1980). Modern Machining processes, Tata McGraw-Hill, NewDelhi, India.12. Dauw D.F., Snoeys R. and Dekyser W. (1983),Advanced Pulse Discrimating system for EDMProcess Analysis and Control. Annals CIRP, vol., 32, pp. 541-549.
  8. 8. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME17713. Hewuvelman C.J.(1980),CIRP Technical Reports, Annals CIRP,vol 29, No.2,pp.541-544.14. Jilani S.T. and Pandey P.C (1984), Experimental Investigations into the performance of wateras Dielectric in EDM,Int. Mach. Tool Design & Res., vol.24,No.1.pp.31-43.15. Masuzawa T.and Heuvelman C.J. (1983), A self Flushing method with spark erosionmachining, Annals of CIRP, vol.32, pp, 109-111.16. Quinlan J.C (1983), Harnessing the spark –the evolution in EDM, Tooling & Prod.,37-42.17. Suzuki K., Umematsu T. and Nakagawa T.(1987), on Machine Trueing Dressing of MetalsBond of Metal Bond grinding wheels by Electric discharge Machining .Annals CIRP,Vol.36,No.1,pp. 115-118.18. K.H.Ho, S.T.Newman (2003), State of the art of electrical discharge machining, Int. Mach.Tool & Mfg, 43, pp.1287-1300.19. Mane S.G., Hargude N.V., PVPIT Budhgaon, Sangli “An Overview Of ExperimentalInvestigation Of Near Dry Electrical Discharge Machining Process” International Journal OfAdvanced Research In Engineering & Technology (IJARET)Volume 3,Issue 2, 2012,pp. 22 -36, ISSN PRINT : 0976-6480, ISSN ONLINE : 0976-649920. Prof. P. R. Cheke, Prof. D. S. Khedekar, Prof. R. S. Pawar, Dr. M. S. Kadam, “ComparativePerformance Of Wet And Near-Dry Edm Process For Machining Of Oil Hardned Non SinkingSteel Material” International Journal Of Mechanical Engineering & Technology (IJMET)Volume 3, Issue 2, 2012, pp 13 - 22, ISSN PRINT: 0976 – 6340, ISSN ONLINE: 0976 – 6359

×