EXPERIMENTAL STUDIES OF EFFECT OF COMPOSITE ELECTRODE ON DIE

STEEL USING EDMA Synopsis report submitted in partial fulfilment of the

requirement for the award of degree ofMASTER OF ENGINEERING

InMECHANICAL ENGINEERING

By

SHEKH SHAHJADA(1465307)

Under the guidance

of

Prof. Pankaj ChhabraHOD, Department of Mechanical Engineering

Surya School of Engineering & Technology, PTU

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ABSTRACT• Electrical discharge machining (EDM) is a non-conventional

machining method used to machine materials with high degree of dimensional accuracy.

• In this research work the effect of composite material electrode fabricated by powder metallurgy technique to machine die steels will be studied.

• Properties like material removal rate, micro hardness and electrode wear will be studied.

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INTRODUCTION

• EDM: Electric Discharge Machining (EDM) is a non-conventional machining process in which metal is removed using thermoelectric energy.

• PM: Powder metallurgy is a process in which the powder of metals is heated below their melting point so they can attain bonding.

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EDM

• Basic components of EDM.

• In EDM process, discrete electric discharges (sparks) are generated between the workpiece-electrode and the tool-electrode immersed in a dielectric medium.

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Process parameters

• Some of the parameters which depend on the tool performance in EDM machining

i. material removal rate (MRR)ii. surface roughness of the workpieceiii. tool wear • Tool performance is highly influenced by the

composition of the metals.

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• Different results can be obtained by simply varying the composition of the tool material and powder metallurgy (PM) is a very efficient method for making these tool-electrodes.

• Through this method we can easily control the properties of the electrode by varying the composition and input parameters of compacting and sintering processes in PM.

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PM Processes

Step by step process

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Advantages of PM processed electrodes

• No additional machining.• No waste products, hence very economical.• Reasonably complex shapes can be produced.• Possible to produce parts with a combination of

materials. For example metals and ceramics• Metals like tungsten that cannot be manufactured

by other methods can be done by PM.

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About the workpiece

• EN24 steel is a popular grade of through-hardening alloy steel used in components such as gears, shafts, studs and bolts.

• EN24 can be further surface-hardened to create components with enhanced wear resistance by process like nitriding.

• EN8 is a medium strength steel, good tensile strength. Suitable for shafts, stressed pins, studs, keys.

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Literature review

• George and Philip [1] examined the performance of the EDM process and tool wear using copper tool and die steel as workpiece. They discussed the interaction of the main electrical parameters such as discharge current, polarity, pulse width and pulse energy.

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• Scott et al. [2] showed their study on the optimization of cutting parameters which were efficient in MRR and surface finish. They investigated that if the discharge current and the pulse duration is increased then the surface finish also increases.

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• N. Tosun et al [3] studied the variation of workpiece surface roughness with varying pulse duration, open circuit voltage, wire speed and dielectric fluid pressure was experimentally investigated in Wire Electrical Discharge Machining (WEDM).

• Brass wire with 0.25 mm diameter and SAE 4140 steel with 10 mm thickness were used as tool and workpiece materials in the experiments, respectively. It was found experimentally that the increasing pulse

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Cont.

duration, open circuit voltage and wire speed, increase the surface roughness whereas the increasing dielectric fluid pressure decreases the surface roughness.The variation of workpiece surface roughness with machining parameters was modeled by using a power function. The level of importance of the machining parameters on the workpiece surface roughness was determined by using analysis of variance (ANOVA).

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• Yu et al. [4] compared machining characteristics between dry EDM milling, oil EDM milling and oil die sinking EDM and found that dry EDM milling is most advantageous to three-dimensional milling of cemented carbide considering the total machining time and cost.

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• H.K. Kansal and coworkers [5] carried out there research in powder mixed EDM (PMEDM). In this research they used an electrically conductive powder along with the dielectric which reduced its insulating strength.

• Pellicer et al. [6] presented the influence of the main EDM process parameters and different tool geometries on basic process performance measures.

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• In addition, material removal rate, surface roughness and different dimensional and geometrical micro-accuracies were analyzed through statistical methods. Results help to select appropriate EDM process parameters to machine parts depending on product requirements.

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• Parveen Goyal [7] investigated that less EWR is observed in copper-manganese composite electrode when copper to manganese weight ratio is 80-20 rather than using Cu-Mn weight ratio as 70-30.

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Research gaps• As observed from the above literature review we can say

that satisfactory work has been done in this field.• Research done till date is quite impressive but still, more

research can be done using different parameters so that we can refine EDM up to the best possible state.

• Some parameters used in this research work are copper and composite electrodes on Die steel (EN 24, EN 8) as workpiece.

• EN24 steel is a popular grade of through-hardening alloy steel used in components such as gears, shafts, studs and bolts, its hardness is in the range 248/302 HB

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RESEARCH OBJECTIVES

• To fabricate the composite material electrode• To Compare copper electrode and composite

material electrode• To Study the parametersi. Material removal rate.ii. Electrode wear rate.iii. Surface micro hardness of die steel.

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METHODOLOGY TO BE ADOPTED

• The Electric discharge machining of Die steel (EN 24 and EN 8) will be conducted using copper and composite electrodes. The experiments will be conducted considering the properties of the electrode materials which are shown below in the table 1.1

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Table 1.1S.no. METALS

1 Copper (cu)

2 Tin (Sn)

3 Manganese (Mn) 1519 K (1246 °C) 2334 K (2061 °C) 196 Mpa

PHYSICAL PROPERTIESMELTING POINT

1357.77 K (1084.62 ⁰C)BOILING POINT BRINELL HARDNESS2835 K (2562 ⁰C) 235-878 Mpa

505.08 K (231.93 °C) 2875 K (2602 °C) 50–440 MPa

ELECTRIC PROPERTIESELECTRIC RESISTIVITY

16.78nΩ.m

115 nΩ·m

1.44 µΩ·m120 Gpa21.7 µm/(m·K) at 25 °C 7.81 W/(m·K)

BULK MODULUS140 GPa

MECHANICAL PROPERTIESTHERMAL EXPANSION16.5 µm/(m.K) at 25⁰C

THERMAL CONDUCTIVITY401 N/(m.K)

66.8 W/(m·K) 58 GPa22.0 µm/(m·K) at 25 °C

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WORK JUSTIFICATION

• EDM using powder metallurgy composite electrodes is to be done because it can reduce the surface roughness and can also increase the micro hardness at the surface of the workpiece.

• This can improve the overall efficiency of the EDM process. The combination of copper and tin or copper and manganese can be really effective as a composite electrode for EDM.

• This is because copper, tin and manganese are good electric conductors and have high melting and boiling points.

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WORK DONE TILL DATE

• Two sintered electrodes, one of copper and another composite of tin and copper are prepared

• Then studied the surface properties by • Scanning electron microscopy (SEM) • Energy-dispersive X-ray spectroscopy (EDS).

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• The figures of EDS spectrum of electorde surface and SEM micrograph of electrode surface are shown below.

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• SEM micrograph of copper-tin electrode

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• EDS spectrum of copper electrode

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• EDS spectrum of copper-tin electrode

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REFFRENCES

• [1] V. George and P. K. Philip, “Analysis of EDM performance and tool wear in copper-die steel system—a review,” in Proceedings of the 8th AIMTDR Conference, IIT, Bombay, 1978, pp. 521–525.

• [2] D. Scott, S. Boyina, and K. P. Rajurkar, “Analysis and optimization of parameter combinations in wire electrical discharge machining,” Int. J. Prod. Res., vol. 29, no. 11, pp. 2189–2207, 1991.

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• [3] N. Tosun, C. Cogun, and A. Inan, “The effect of cutting parameters on workpiece surface roughness in wire EDM,” Mach. Sci. Technol., vol. 7, no. 2, pp. 209–219, 2003.

• [4] Z. Yu, T. Jun, and K. Masanori, “Dry electrical discharge machining of cemented carbide,” vol. 149, pp. 353–357, 2004.

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• [5] H. K. Kansal, S. Singh, and P. Kumar, “Technology and research developments in powder mixed electric discharge machining (PMEDM),” J. Mater. Process. Technol., vol. 184, no. 1–3, pp. 32–41, 2007

• [6] N. Pellicer, J. Ciurana, and J. Delgado, “Tool electrode geometry and process parameters influence on different feature geometry and surface quality in electrical discharge machining of AISI H13 steel,” pp. 575–584, 2011.

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• [7] P. Goyal, “Effect of EDM Process Parameters on Composite Material Electrode Wear,” no. 11, pp. 11–13, 2014

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Thank you