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STUDY THE EFFECT OF MACHINING

PARAMETERS ON THE

PERFORMANCE OF WIRE EDM

PROJECT REPORT

SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD

OF THE DEGREE OF

BACHELOR OF TECHNOLOGY

(Mechanical)

SUBMITTED BY: UNDER GUIDANCE:

GURPRATAP SINGH (80101114018) Dr. PARAMJIT SINGH BILGA

HARDEEP SINGH (80101114021) Er. JATINDER KAPOOR

RAJVIR SINGH (80101114068)

RAMIT SINGH (80101114072)SAHIL ARORA (80101114079)

DEPARTMENT OF MECHANICAL ENGINEERINGGURU NANAK DEV ENGINEERING COLLEGE, LUDHIANA

MAY 2010


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CANDIDATES DECLARATION

I hereby certify that the work which is being presented in the project report entitled STUDY

THE EFFECT OF MACHINING PARAMETERS ON THE PERFORMANCE OF

WIRE EDMbySAHIL ARORA in partial fulfillment of requirements for the award of

degree of B. Tech (Mechanical Engineering) submitted in the Department of Mechanical

Engineering at GURU NANAK DEV ENGINEERING COLLEGE, LUDHIANA under

PUNJAB TECHNICAL UNIVERSITY, JALANDHAR is an authentic record of my own

work carried outduring a period from DEC 2011 to APRIL, 2012 under the supervision of

Er. JATINDER KAPOOR, Associate Professor, Department of Mechanical Engineering.

The matter presented in this project report has not been submitted by me in any other

University/Institute for the award ofB. Tech. Degree.

SAHIL ARORA

80101114079

81002

This is to certify that the above statement made by the candidate is correct to the best of my

knowledge.

Signature of Project Guide


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ABSTRACT

Wire electrical discharge machining process is a highly complex, time varying & stochastic

process. The process output is affected by large no of input variables. Therefore a suitable

selection of input variables for the wire electrical discharge machining (WEDM) process relies

heavily on the operators technology & experience because of their numerous & diverse range.

WEDM is extensively used in machining of conductive materials when precision is of prime

importance. Rough cutting operation in wire EDM is treated as challenging one because

improvement of more than one performance measures viz. Metal removal rate (MRR), surface

finish & cutting width are sought to obtain precision work. In this report an approach to

determine parameters setting is proposed.

Using parametric design, significant machining parameters affecting the performance measures

are identified as pulse peak current, pulse on time, and duty factor .The effect of each control

factor on the performance measure is studied individually. The study demonstrates that the

WEDM process parameters can be adjusted so as to achieve better metal removal rate, surface

finish, electrode wear rate.

The performance of WEDM depends much on the wire electrode used. Graphite wire is used

extensively as a wire electrode in WEDM. Various high performance electrodes like zinc

coated, diffusion annealed, coated steel core wires etc. have been developed to satisfy the

machining needs. In the present study, three wires (brass wire, zinc coated wire and High

Cutting Speed (HCS) wire) were selected and the performance parameters cutting rate, wire

wear and surface roughness were studied on the machining of HCHCr plate. The full factorial


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design was used to analyze the relationship of input parameters (pulse on time, peak current

and type of wire) with performance characteristics (cutting rate, wire wear and surface

roughness).Results obtained shows the improvement in surface roughness using wire edm

technique. Results show some deposition of work piece material on the wire. Scanning Electron

Microscopy revealed the wire wear and surface roughness of work piece (after machining).


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ACKNOWLEDGEMENT

The authors are highly grateful to the Director, Guru Nanak Dev Engineering College

(GNDEC), Ludhiana, for providing this opportunity to carry out the present project work. The

constant guidance and encouragement received from Dr. SEHJPAL SINGH, Professor and

Head, Department of Mechanical Engineering, GNDEC Ludhiana has been of great help in

carrying out the present work and is acknowledged with reverential thanks. The authors would

like to express a deep sense of gratitude and thanks profusely to Dr. PARAMJIT SINGH

BILGA, Associate Professor, and Er. DAVINDER SINGH BHOGAL, Asstt. Professor

Department of Mechanical, GNDEC, who was our project guides. Without the wise counsel

and able guidance, it would have been impossible to complete in this manner. I take this

opportunity to thank the project supervisor of Mechanical Engineering department for awarding

me such an interesting & informative topic to work on. I am highly indebted to my project

guide Er. JATINDER KAPOOR, Associate Professor, Mechanical Engineering Department,

GURU NANAK DEV ENGINEERING COLLEGE, LUDHIANA, for his guidance &

words of wisdom. He always showed me the right direction during the course of this project

work.

GURPRATAP SINGH (80101114018)

HARDEEP SINGH (80101114021)

RAJVIR SINGH MUNDAY (80101114068)

RAMIT SINGH SAHAYE (80101114072)

SAHIL ARORA (80101114079)


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CONTENTS

Front Cover 1

Candidates Declaration 2

Abstract 3

Acknowledgement 5

Contents 6

CHAPTER 1: INTRODUCTION 9-24

1.1 Wire electrical discharge machining 10

1.2 History 13

1.3 Importance of Wire EDM process in present day

manufacturing 14

1.4 Basic principle of Wire EDM process 15

1.5 Features of Wire EDM process 17

1.6 Various phases 17

1.7 The process parameters which affect the

performance of WEDM on machined part 20

1.7.1 Pulse on Time 20

1.7.2 Pulse off Time 20

1.7.3 Peak Current 20

1.7.4 Spark Gap Set Voltage 20

1.7.5 Wire Feed 21

1.7.6 Wire Tension 21


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1.7.7 Pulse Peak Voltage 21

1.7.8 Flushing Pressure 21

1.8 Process parameters in Wire EDM 22

1.8.1 Parameters range

1.9 Types of wire used in wire EDM machine 22

1.9.1 Copper wire 22

1.9.2 Brass wire 23

1.9.3 Coated wire 23

1.9.4 Molybdenum Wire 23

1.9.5 Water Dielectric 24

2.0 Advantages of WIRE EDM 25

CHAPTER 2: LITERATURE REVIEW 25-36

2.1 A study on the machining parameters 26

Optimization of WEDM

2.2 Monitoring & control of the WIRE EDM PROCESS 27

CHAPTER 3: PROBLEM FORMULATION& OBJECTIVE 37-38

3.1 Problem formulation 28

3.2 Objectives 29

CHAPTER 4: PRESENT WORK 39-57

4.1 Introduction 30

4 2 Experimental set -up 30


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4.2.1 Machine Tool 31

4.2.2 Work piece Material 32

4.3 Measurements of experimental parameters 32

4.3.1 Cutting Rate Measurement 32

4.3.2 Surface Roughness Measurement 32

4.4 Pilot experimentation 33

4.4.1 Experimental Set Up 33

4.4.2 Selection of Control Parameters 35

4.4.3 Selection of input parameter for each experiment. 36

Table showing Cutting Speed & Surface Roughness 37

4.5 Trouble shooting on machines 38

4.6 Design of experimentation (DOE) 42

4.7 Analysis using MINITAB SOFTWARE 43

4.7.1 for current speed 43

4.7.2 For surface roughness 46

HAPTER 5: RESULTS AND DISCUSSION 50-53

5.1 Introduction 50

5.2 Effect of input parameters on response parameters 50

5.2.1. Effect of Pulse on Time 50

5.2.2. Effect of Peak Current 51

5.2.3 Effect of Peak off Time 53


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CHAPTER 6: CONCLUSION AND FUTURE SCOPE 62-63

6.1 Conclusion 54

6.2 Future scope 55

REFERENCES 56

ANNEXURE 58


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CHAPTER- 1

INTRODUCTION

1.1 Introduction

Electrical discharge machining (EDM) is a nontraditional, thermoelectric process which erodes

material from the work piece by a series of discrete sparks between a work and tool electrode

immersed in a liquid dielectric medium. These electrical discharges melt and vaporize minute

amounts of the work material, which are then ejected and flushed away by the dielectric.

The sparks occurring at high frequency continuously & effectively remove the work piece

material by melting & evaporation. The dielectric acts as a demonizing medium between 2

electrodes and its flow evacuates the resolidified material debris from the gap assuring optimal

conditions for spark generation.

In wire EDM metal is cut with a special metal wire electrode that is programmed to travel

along a preprogrammed path. A wire EDM generates spark discharges between a small wire

electrode (usually less than 0.5 mm diameter) and a work piece with deionizer water as the

dielectric medium and erodes the work piece to produce complex two- and three dimensional

shapes according to a numerically controlled (NC) path.

The wire cut EDM uses a very thin wire 0.02 to 0.3 mm in diameter as an electrode and

machines a work piece with electrical discharge like a band saw by moving either the work

piece or wire erosion of the metal utilizing the phenomenon of spark discharge that is the very

same as in conventional EDM . The prominent feature of a moving wire is that a complicated


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cutout can be easily machined without using a forming electrode .Wire cut EDM machine

basically consists of a machine proper composed of a work piece contour movement control

unit ( NC unit or copying unit), work piece mounting table and wire driven section for

accurately moving the wire at constant tension ; a machining power supply which applies

electrical energy to the wire electrode and a unit which supplies a dielectric fluid ( distilled

water) with constant specific resistance.

Wire EDM Process (S.S. Mahapatra and Amar Patniak, 2007)

Wire electrical discharge machining (WEDM, wire-EDM) has grown tremendously in

conductive material machining recently because of its advantages of being unaffected by

material hardness, no cutting force, high accuracy and the ability to achieve complex work

piece shape as well as unmanned machining. WEDM is a special form of the traditional EDM

process in which the electrode is a continuously moving conductive wire.


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Material is eroded from the work piece by a series of discrete sparks between the work piece

and the wire electrode (tool) separated by a thin film of dielectric fluid (deionizer water) which

is continuously force fed to the machining zone to flush away the eroded particles. The

movement of the wire is controlled numerically to achieve the desired three-dimensional shape

and accuracy for the work piece. Although the average cutting speed, relative machining costs,

accuracy and surface finish have been improved many times since the commercial inception of

the machine, much more improvement is still required to meet the increasing demand of

precision and accuracy by different industries. It is a well-known fact that a high material

removal rate and a very good surface finish can never be achieved simultaneously in WEDM

process. This is an age-long problem and continuous efforts are being made by different

researchers all over the world to fulfill such an objective.

The main goals of WEDM manufacturers and users are to achieve a better stability and higher

productivity of the WEDM process, i.e., higher machining rate with desired accuracy and

minimum surface damage. However, due to a large number of variables and the stochastic

nature of the process, even a highly skilled operator working with a state-of-the-art WEDM is

unable to achieve the optimal performance and avoid wire rupture and surface damage as the

machining progresses. Although most of the WEDM machines available today have some kind

of process control, still selecting and maintaining optimal settings is an extremely difficult job

The lack of machinability data on conventional as well as advanced materials, precise gap

monitoring devices, and an adaptive control strategy that accounts for the time-variant and

stochastic nature of the process are the main obstacles toward achieving the ultimate goal of

unmanned WEDM operation.


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Fig 1.1 EDM Experimental Set up

1.2 HISTORY

In 1943 The Soviet government assigned Russian scientists Boris and Natalya

Lazarenko to investigate the wear caused by sparking between tungsten electrical

contacts. This problem was particularly critical for maintenance of automotive engines

during the Second World War. They found that when the electrodes were put in oil, the

sparks were more uniform and predictable than in air. They had then the idea to

reverse the phenomenon, and to use controlled sparking as an erosion method


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Although they failed to solve the original problem but they were able to develop the

first EDM. The Lazarenko circuit remained the standard EDM generator for years. In

the 1950s, Swiss industries successfully produced the first EDM machines. Agie was

founded in 1954, and les Ateliers des Charmilles produced their first machine in 1955.

Due to the poor quality of electronic components, the performances of the machines

were limited at that time.

In the 1960s, the development of the semi-conductor industry permitted considerable

improvements in EDM machines. Die-sinking machines became reliable and produced

surfaces with controlled quality, whereas wire-cutting machines were still at their very

beginning. In late 1960s and in the beginning of 1970s with the introduction of

numerical position control, the movement of electrodes becomes more accurate. Due

to this the performance of wire cutting machines improved a lot. During the 1980s,

efforts were principally made in generator design, process automatization, servo-

control and robotics. Applications in micro-machining became also of interest during

the 1980s. It is also from this period that the world market of EDM began to increase

strongly, and that specific applied EDM research took over basic EDM research.

Finally, new methods for EDM process control arose in the 1990s: fuzzy control and

neural networks.

1.3 IMPORTANCE OF WEDM PROCESS IN PRESENT DAY MANUFACTURING

WEDM technology has grown tremendously since it was first applied more than 30

years ago. In 1974, D.H. Dulebohn applied the optical line follower system to

automatically control the shape of the components to be machined by the WEDM

process. By 1975, its popularity rapidly increased,


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As the process and its capabilities were better understood by the industry. It was only

towards the end of the 1970s, when computer numerical control (CNC) system was

initiated into WEDM, which brought about a major evolution of the machining process.

Its broad capabilities have allowed it to encompass the production, aerospace and

automotive industries and virtually all areas of conductive material machining. This is

because WEDM provides the best alternative or sometimes the only alternative for

machining conductive, exotic, high strength and temperature resistive materials,

conductive engineering ceramics with the scope of generating intricate shapes and

profiles.

WEDM has tremendous potential in its applicability in the present day metal cutting

industry for achieving a considerable dimensional accuracy, surface finish and contour

generation features of products or parts. Moreover, the cost of wire contributes only

10% of operating cost of WEDM process. The difficulties encountered in the die

sinking EDM are avoided by WEDM, because complex design tool is replaced by

moving conductive wire and relative movement ofwire guides.

1.4 BASIC PRINCIPLE OF WEDM PROCESS

The WEDM machine tool comprises of a main worktable (X-Y) on which the work

piece is clamped; an auxiliary table (U-V) and wire drive mechanism. The main table

moves along X and Y-axis and it is driven by the D.C servo motors. The traveling wire

is continuously fed from wire feed spool and collected on take up spool which moves

though the work piece and is supported under tension between a pair of wire guides

located at the opposite sides of the work piece. The lower wire guide is stationary

where as the upper wire guide, supported by the U-V table, can be displaced

transversely along U and V-axis with respect to lower wire guide The upper wire guide


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can also be positioned vertically along Z axis by moving the quill. A series of electrica

pulses generated by the pulse generator unit is applied between the work piece and

the traveling wire electrode, to cause the electro erosion of the work piece material. As

the process proceeds, the X-Y controller displaces the worktable carrying the work

piece transversely along a predetermined path programmed in the controller. While the

machining operation is continuous, the machining zone is continuously flushed with

water passing through the nozzle on both sides of work piece. Since water is used as

a dielectric medium, it is very important that water does not ionize. Therefore, in order

to prevent the ionization of water, an ion exchange resin is used in the dielectric

distribution system to maintain the conductivity of water. In order to produce taper

machining, the wire electrode has to be tilted. This is achieved by displacing the upper

wire guide (along U-V axis) with respect to the lower wire guide. The desired taper

angle is achieved by simultaneous control of the movement of X-Y table and U-V table

along their respective predetermined paths stored in the controller. The path

information of X-Y table and U-V table is given to the controller in terms of linear and

circular elements via NC program.

Fig 1.2. Schematic Diagram of WEDM Process (Aoyama, 2001)


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1.5 Features of Wire EDM process

1. Forming electrode adapted to product shape is not required.

2. Electrode wear is negligible.

3. Machined surfaces are smooth.

4. Geometrical & dimensional tolerances are tight.

5. Relative tolerance between punch & die is extremely high & die life is extended.

6. Straight holes can be produced to close tolerances.

7. EDM machine can be operated unattended for long time at high operating rate.

8. Machining is done without requiring any skills.

9. Any electrically conductive material can be machined irrespective of its hardness

& strength.

10. EDM allows the shaping of complex structures with high machining accuracy in

the order of several micrometers and achievable surface roughness Rz=0.m.

11. It proves to be a competitive method for ceramic processing because of the

abilities to provide accurate, cost-effective and flexible products.

1.6 VARIOUS PHASES-

Preparation phase

On switching on the power supply, electric field is set-up in the gap between the electrodes.

The electric field reaches maximum value at the point where the gap between the electrodes is

smallest. Spark location is determined by the gap distance and the gap conditions. In the

presence of electrically conductive particles in the gap, thin particle bridges are formed. When

the strength of the electric field exceeds the dielectric strength of the medium, electric

breakdown of the medium takes place. Ionization of the particle bridges takes place and a


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plasma channel is formed in the gap between the electrodes. The steps in the phase are shown

in Figure 1.2(a).

Discharge phase

During the discharge phase high current flows through the plasma channel and produces high

temperature on the electrode surfaces is shown in Figure 1.2 (b). This creates very high

pressure inside the plasma channel creating a shock wave distribution within the dielectric

medium. The plasma channel keeps continuously expanding and with it the temperature and

current density within the channel decreases. Plasma channel diameter stabilizes when a

thermal equilibrium is established between the heat generated and the heat lost to evaporation,

electrodes and the dielectric. This enlarged channel is still under high pressure due to

evaporation of the liquid dielectric and material from the electrodes.

The evaporated material forms a gas bubble surrounding the plasma channel. During this phase,

high-energy electrons strike the work piece and the positively charged ions strike the tool (for

negative tool polarity). Due to low response time of electrons, smaller pulses show higher

material removal from the anode where as longer pulses show higher material removal from the

cathode.

Interval phase

The plasma channel de-ionizes when power to the electrodes is switched off is shown in figure

1.2 (c). The gas bubble collapses and material is ejected out from the surface of the electrodes

in the form of vapors and liquid globules. The evaporated electrode material solidifies quickly

when it comes in contact with the cold dielectric medium and forms solid debris particles,

which are flushed away from the discharge gap. Some of the particles stay in the gap and help

in forming the particle bridges for the next discharge cycle. Power is switched on again for the


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next cycle after sufficient de-ionization of dielectric has occurred. The ability of the wire

material to enhance spark formation and the flushing process has become increasingly

important with the growing need for both higher productivity and accuracy. It is highly

desirable for the wire to erode or wear because the vaporized wire material aids in the

formation of subsequent spark ionization channels. In addition, a higher degree of vaporization

into microscopic particles, rather than melting, greatly improves the efficiency of the flushing

process and by suppressing arcing stability of the cut.

Figure 1.3 (a). Preparation phase

Figure 1.3 (b) Discharge phase

Figure 1.3 (c) Interval phase


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1.7 The process parameters which affect the performance of

WEDM on machined parts:-

1.7.1 Pulse on Time:

The pulse on time is referred as TON and represents the duration of time in micro

seconds,s, forwhich the current is flowing in each cycle. During this time the voltage, VP, is

applied across the electrodes. The single pulse discharge energy increases with increasing TON

period, resulting in higher cutting rate.

1.7.2 Pulse off Time:

The pulse off time is referred as TOFF and it represents the duration of time in micro

seconds, s,between the two simultaneous sparks. The voltage is absent during this part of the

cycle.

1.7.3 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. Increase in the IP value will increase the pulse

discharge energy which in turn can improve the cutting rate further.

1.7.4 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.


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1.7.5 Wire Feed

Wire feed is the rate at which the wire-electrode travels along the wire guide path and is

fed continuously for sparking. It is always desirable to set the wire feed to maximum. This will

result in less wire breakage, better machining stability and slightly more cutting speed.

1.7.6 Wire Tension

Wire tension determines how much the wire is to be stretched between upper and lower

wire guides. This is a gram-equivalent load with which the continuously fed wire is kept under

tension so that it remains straight between the wire guides. More the thickness of job more is

the tension required. Improper setting of tension may result in the job inaccuracies as well as

wire breakage.

1.7.7 Pulse Peak Voltage

Pulse peak voltage setting is for selection of open gap voltage. Increase in the VP value

will increase the pulse discharge energy which in turn can improve the cutting rate.

1.7.8 Flushing Pressure

Flushing Pressure is for selection of flushing input pressure of the dielectric. High input

pressure of water dielectric is necessary for cutting with higher values of pulse power and also

while cutting the work piece of more thickness. Low input pressure is used for thin work piece

and in trim cuts.


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1.8 Process parameters of Wire EDM process

PARAMETERS RANGE

Machine parameters

1. Table Feed

2. Pulse On Time

3. Pulse Off Time

4.Flushing

Wire parameters1. Material of wire

2. Diameter of wire

3. Wire speed

4. Wire tension

1.9 Types of wire used in wire EDM machine

As both wire EDM machines and the science of wire manufacturing has matured a variety of

new wire materials and types have become available. Each type has its own distinct

characteristics and recent developments give the user a variety of choices.

Copper Wire

Copper was the original material first used in wire EDM. Although its conductivity rating is

excellent, low tensile strength, high melting point and low vapor pressure rating severely

limited its potential. Today its practical use is confined to earlier machines with power supplies

designed for copper wire.


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Brass wire

Brass was the first logical alternative to copper when early EDMers was looking for better

performance. Brass EDM wire is a combination of copper and zinc, typically alloyed in the

range of 6365% Cu and 3537% Zn. The addition of zinc provides significantly higher tensile

strength, lower melting point and higher vapor pressure rating, which more than offset the

relative losses in conductivity. Brass quickly became the most widely used electrode material

for general-purpose wire EDM. It is now commercially available in a wide range of tensile

strengths and hardness.

Coated Wire

Since brass wires cannot be efficiently fabricated with any higher concentration of zinc, the

logical next step was the development of coated wires, sometimes called plated or stratified

wire. They typically have a core of brass or copper, for conductivity and tensile strength and

are electroplated with a coating of pure or diffused zinc for enhanced spark formation and flush

characteristics. Originally called speed wire due to their ability to cut at significantly higher

metal removal rates, coated wires are now available in a wide variety of core materials, coating

materials, coating depths and tensile strengths, to suit various applications and machine

requirements. Although more expensive than brass, coated wires currently represent the

optimum choice for top all-around performance and their relative economics are covered in a

later section.

Molybdenum and Tungsten Wires

High precision work on wire EDM machines, requiring small inside radii calls for wire

diameters in the range of .001 .004". Since brass and coated wires are not practical, due to


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their low load carrying capacity in these sizes, molybdenum and tungsten wires are used.

However, due to limited conductivity, high melting points and low vapor pressure ratings are

not suitable for very thick work and tend to cut slowly. A composite wire called MolyCarb

does offer significant advantages for small diameter work, since it coats moly wire with a

mixture of graphite and molybdenum oxide to improve its flushing characteristics.

Water dielectric

Characterization & suitability of wire cut medium

The use of water as dielectric permits widening of spark gap to minimize short circuit, resulting

in high cutting speed. Water has good wire electrode cooing effect (than kerosene as example).

It is non flammable and its vapours are non-toxic.

Dielectric strength

Since the insulation characterization of dielectric fluid decides the overcut so it is important to

keep the conductivity of dielectric water constant. Conductivity of water changes due to

generation of metallic ions and dissolution of ambient gases. The conductivity can be decreased

by passing the water through de-ionize resin. This is done automatically by the machine.

Flushing

Flushing is important to achieve stable condition. It plays very important role as far as cutting

speed concerned. Both the nozzles upper and lower should be just about 0.22 mm away from

the workpiece, otherwise cutting performance drops considerably. Also both the nozzles should

also be checked periodically for damages, scratches or slight damage on the contact edge affect

cutting speed. Purity of the water should be machined by firm displacements of filters.


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Advantages of WEDM

The popularity of WEDM process is due to the following advantages (Pandey, 1980):

Complicated die contours in hard materials can be produced to a high degree of

accuracy and surface finish.

The process can be applied to all electrical conductive materials irrespective of their

strength, toughness, microstructure etc.

As there is no physical contact between tool electrode and work piece, there will not be

any mechanical deformation of work piece, as a result fragile jobs can be machined

conveniently.

There is no heating of bulk of the material during the process.

The process can be automated easily requiring very little attention from the machine

operator.

The overall production rate compares well with conventional process because it can

dispense with operations like grinding etc.


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Chapter 2LITERATURE REVIEW

2.1. A study on the machining parameters optimization of WEDM.

Y.S Liao et al.[1,5] devised an approach to determine machining parameter settings for WEDM

process .Based on the quality design and the analysis of variance (ANOVA), the significant

factors affecting the machining performance such as MRR, gap width ,surface roughness

,sparking frequency ,average gap voltage, normal ratio(ratio of normal sparks to total sparks)

are determined. By means of regression analysis, mathematical models relating the machining

performance and various machining parameters are established. Based on the mathematical

models developed, an objective function under the multi-constraint conditions is formulated.

The optimization problem is solved by the feasible direction method, and the optimal

machining parameters are obtained. Experimental results demonstrate that the machining

models are appropriate and the derived machining parameters satisfy the real requirements in

practice.

.


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2.2. Monitoring & control of the WIRE EDM PROCESS

In this paper an attempt was made by Tian et al. towards process monitoring and control of

wire EDM process by developing g a new pulse discrimination & control system. This system

functions by identifying 4 major gap states classified as open circuit, normal spark, arc

discharge, and short circuit by observing the characteristics of gap voltage waveforms. The

influence of pulse interval , machining feed rate, and work piece thickness on the normal ratio ,

arc ratio & short ratio. It could be concluded from the experiment that a longer pulse interval

would result in increase of short ratio at constant machining feed rate. A high machining

federate as well as increase of work piece height results in increase of short ratio.

To achieve stability in machining a control strategy is proposed by regulating the pulse interval

of each spark in real time basis by analyzing the normal ratio , arc ratio & short ratio.

Experimental results show that the developed pulse discrimination system & control strategy is

very useful in reducing both arc discharge & short sparking frequency which are undesirable

during the process. Also with this process monitoring a stable machining under the condition

where the instability of machining operation is prone to occur can be achievable.

Experimental results not only verify the effectiveness of the proposed control method they also

indicate that the developed pulse discriminating & control system is capable of achieving stable

machining under the condition where there exists an unexpected disturbance during machining.


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CHAPTER 3

PROBLEM FORMULATION AND OBJ ECTIVE

3.1 PROBLEM FORMULATION

The increased use of wire-cut electrical discharge machining (WEDM) in

manufacturing has thus kept growing at a highly accelerated rate since its first

industrial application more than 40 years ago. Its broad capabilities have allowed it to

encompass production in aerospace and automotive industries and virtually all areas

of conductive material machining. The cutting speed, relative machining costs,

accuracy and surface finish have been improved since the commercial inception of the

machines; much more improvement is still required to meet the increasing demand of

precise products. Furthermore, it also reveals from the literature study that Brass wire

is used extensively as a tool in WEDM. Various high performance electrodes like zinc

coated, diffused wires, composite wires etc. have been developed to satisfy the

machining needs. The three requirements for high-speed cutting and high precision

machining are: (i) mechanical strength at high temperatures for good heat resistance,

(ii) high electrical conductivity for good calorification resistance, and (iii) high heat

conductivity for efficient heat release. In addition, the wire electrodes have to be very

straight to allow automatic threading and they need improved draw ability and stability

during commercial production to achieve good cost performance. High carbon high

chromium material is mostly used in blanking dies, plastic moulds, shear blades,

swaging dies and thread rolling dies.


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An investigation of different wire electrodes on the AISI D3 material is necessary for

understanding the performance characteristics. The purposed work has been aimed to

conduct the detailed experimentation to investigate the effects of variables, peak

current (IP ) , pulse on time(TON ) and type of wire to output parameters : cutting rate,

surface roughness and wire wear.

3.2 OBJECTIVES

The objectives of the present study are as follows:

To study the effect of input parameters on the performance of WEDM

To compare different parameters with respect to speed and surface roughness

with the help of analysis from their performance.


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CHAPTER 4

PRESENT WORK

4.1 INTRODUCTION

In the WEDM process, electrical energy is used in the form of intermittent impulses for the

machining. The heat generated due to the plasma is responsible for removal of material at the

interface. HCHCr is widely used in the manufacturing of dies. Different wire electrodes can be

used for machining purposes. In the present study effect of brass wire electrode on HCHCr

was carried out to analyze the effect of machining parameters on the cutting rate, wire wear and

surface roughness. The studies were conducted using different machining parameters settings.

Pilot experiment was conducted to know the responses of the wire electrodes on the

performance of WEDM. Input parameters of final experiment were designed according to pilot

experiment. Final experiments were performed according to factorial design. Surface roughness

was checked with the surface roughness tester. Cutting rate was analyzed directly from the

display unit of WEDM machine.It was observed that structural features varied with variation in

electrode under similar experimental conditions.

4.2 EXPERIMENTAL SET-UP

4.2.1 Machine Tool

The experiments were carried out on a wire-cut EDM machine (ELEKTRA

SPRINTCUT 734) of Electronica Machine Tools Ltd. installed at Central Tool Room


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(CTR), Ludhiana, Punjab, India. The WEDM machine tool has the following

specifications:

Table 4.1 Specifications of WEDM Machine Tool Parameter

Parameter Specification

Design Fixed column, moving table

Table size 440 x 650 mm

Max. workpiece height 200 mm

Max. workpiece weight 500 kg

Main table traverse (X, Y) 300, 400 mm

Auxiliary table traverse (u, v) 80, 80 mm

Wire electrode diameter 0.25 mm (Standard) ,0.15, 0.20 mm (Optional)

Controlled axes XY,U,V simultaneous / independent

Interpolation Linear & Circular

Least command input (X, Y, u, v) 0.0005mm

Input Power supply 3 phase, AC 415 V, 50 Hz


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4.2.2 Work piece Material

The HIGH CARBON HIGH CHROMIUM plate of 100 mm x 50 mm x 0 mm size has be

used as a work piece material for the present experiments. HCHCr material is mostly used

blanking dies, plastic moulds, shear blades, swaging dies and thread rolling dies.

4.3 MEASUREMENTS OF EXPERIMENTAL PARAMETERS

The discussions related to the measurement of WEDM experimental parameters cutt

rate, surface roughness, wire wear are presented in the following subsections.

4.3.1 Cutting Rate Measurement

For WEDM, cutting rate is a desirable characteristic and it should be as high as possible

give least machine cycle time leading to increased productivity. In the present study, cutt

rate is a measure of job cutting which is digitally displayed on the screen of the machine a

is given quantitatively in mm/min.

4.3.2 Surface Roughness Measurement

Roughness is often a good predictor of the performance of a mechanical component, sin

irregularities in the surface may form nucleation sites for cracks or corrosion. Roughness i

measure of the texture of a surface. It is quantified by the vertical deviations of a real surfa

from its ideal form. If these deviations are large, the surface is rough; if small, the surface

smooth. Roughness is typically considered to be the high frequency, short wavelen


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component of a measured surface. Surface roughness was measured with surfa

roughness tester

4.4 EXPERIMENTATION

4.4.1 Experimental Set Up

The purpose of the pilot experiment was to study the variations of the WEDM proce

parameters on performance measures such as cutting rate, surface roughness and w

wear. Also, it was intended to ascertain the range of different parameters required

experimental design methodology used in this work. The work piece used was a strip

HCHCr of dimensions 100mmX50mm X10mm. Three Square cuts of 10mmX10mmX10m

were cut using brass wire.

The work piece used for pilot study was shown in figure 4.1.

FIG 4.1 Shape of the small machined pieces (10*10*10) from original

pieces (100*50*10)


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SPECIFICATIONS OF WORKPIECE

FIG 4.2: Specifications of workpiece


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4.4.2 Selection of control

Parameters

Table 4.2 Input Parameters and their ranges

S. No. Name of Parameter Symbol Ranges

1 Pulse on Time TON 115 - 120

2 Pulse off Time TOFF 4852

3 Peak Current IP 200220

4 Wire Tension Wt 610

5 Water Pressure WP 8 11

6 Wire Feed WF 7 - 10


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4.4.3 Selection of input parameter for each experiment.

EXPERIMENTS PATTERN

Table 4.3 selection of input parameters for each experiment

S.No A B C D E F

1 1 1 1 1 1 1

2 1 1 1 1 2 2

3 1 1 1 1 3 3

4 1 2 2 2 1 1

5 1 2 2 2 2 2

6 1 2 2 2 3 3

7 1 3 3 3 1 1

8 1 3 3 3 2 2

9 1 3 3 3 3 3

10 2 1 2 3 2 2

11 2 1 2 3 3 3

12 2 1 2 3 1 1

13 2 2 3 1 2 2

14 2 2 3 1 3 3

15 2 2 3 1 1 1

16 2 3 1 2 2 2

17 2 3 1 2 3 3

18 2 3 1 2 1 1


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19 3 1 3 2 1 3

20 3 1 3 2 2 1

21 3 1 3 2 3 2

22 3 2 1 3 1 3

23 3 2 1 3 2 1

24 3 2 1 3 3 2

25 3 3 2 1 1 3

26 3 3 2 1 2 1

27 3 3 2 1 3 2

WHERE

A PULSE ON TIME

B PULSE OFF TIME

C PEAK CURRENT

D WIRE TENSION

E WIRE FEED

F WATER PRESSURE


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Table 4.4 Cutting Speed, and Surface Roughness for Brass Wireobtainted from each experiment.

S.No TON TOFF IP WT WF WP CUTTINGSPEED

WIREBREAK

S.F

1 115 48 200 6 8 7 2.5 4 4.51

2 115 48 200 6 9 8 2.25 0 6.1

3 115 48 200 6 11 10 2.3 0 3.61

4 115 50 210 8 8 7 2.38 3 5.68

5 115 50 210 8 9 8 2.28 0 2.83

6 115 50 210 8 11 10 2.2 0 4.41

7 115 52 220 10 8 7 2 1 5.97

8 115 52 220 10 9 8 1.86 0 3.33

9 115 52 220 10 11 10 1.81 0 1.93

10 118 48 210 10 8 8 2.35 33.11

11 118 48 210 10 9 10 2.65 0 3.65

12 118 48 210 10 11 7 2.54 0 6.68

13 118 50 220 6 8 8 2.39 0 3.5

14 118 50 220 6 9 10 2.33 0 6.5

15 118 50 220 6 11 7 2.31 0 2.58

16 118 52 200 8 8 8 2.19 0 2.3

17 118 52 200 8 9 10 2.14 0 8.49

18 118 52 200 8 11 7 2.08 0 6.27

19 120 48 220 8 8 10 2.42 0 2.57

20 120 48 220 8 9 7 2.18 0 5.7

21 120 48 220 8 11 8 2.45 02.88

22 120 50 200 10 8 10 2.41 2 3.82

23 120 50 200 10 9 7 2.32 0 3.37

24 120 50 200 10 11 8 2.37 1 3.54

25 120 52 210 6 8 10 2.37 0 4.12

26 120 52 210 6 9 7 2.26 0 3.57

27 120 52 210 6 11 8 2.23 0 2.91

WHERE

TON PULSE ON TIMETOFF PULSE OFF TIMEIP PEAK CURRENTWT WIRE TENSIONWF WIRE FEEDWP WATER PRESSURES.F SURFACE ROUGHNESS


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4.5 TROUBLE SHOOTING ON MACHINES

Wire breakage:

There are lots of causes for wire breakage. The location of wire breakage provides important clues.

Table 4.5 Causes of wire breakage and their remedies

WIRE BREAKAGE

POSITION

CHECK CAUSES AND REMEDIES

1.Wire inlet side Wire tension Reduce the wire tension slightly.

The movement of the tension roller should

smooth.

Check for any groove for the tension roller.

Change if the wire gets trapped completely

into the groove.

2.Wire outlet side Wire feed

Wire feed

mechanism

The wire after sparking has become weak due

to wear. Increase the feed.

Distributed wire feed causes wire breakage or

produces vertical streaks over the machined

surface. This may be due to copper deposited

or foreign particles got stuck in the wire guide.

Clean the guide.

Unsmooth movement of lower roller. Change

the bearing of the roller.


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Machining

condition

Feed spool break which prevents over travel of

spool is not properly set. Set it right.

Setting of Ip, no load voltage etc. are too high,

increased electrode wear. Set as per the

technology chart.

WF is too low, WT is too high. Set as per the

technology chart and trim if required.

3.Inside of machining gap Flushing

Dielectric

water

Conductivity

Wire

Clean the lower flushing nozzle.

Excessive injection pressure causes water

dielectric to escape or mix with air thus

developing aerial discharge. Air will not be

trapped if upper and lower flushing gets

balanced in the spark gap. Adjust flushing.

Low conductivity will cause wire breakage.

Set at 20 and control it within 2 units.

Twisted or bent wire will develop discharge


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Work piece:

1.Stocked work

piece

2. Material

quality

3. Workpiece

thickness

concentration that causes wire breakage. Wire

position towards the end of winding is liable to

snap.

Machining of the stocked workpiece is to be

out at lower speed.

Clearance between stocked pieces will cause

air to be trapped in between and result aerial

discharge.

Crack holes or any flow in the internal

structure of the workpiece can cause wire

breakage.

Machining thicker jobs 50 mm and above,

parameters like wire feed, tension, flushing

conductivity become critical. Follow the

technology chart closely and trim the

parameters slightly if required.

Wire electrode inlet position

machining gap

Upper flushing Upper flushing set inadequately.

Twist or bent on wire set adequately.


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4.6 DESIGN OF EXPERIMENT (DOE)

4.6.1 DOE Principle

Design of Experiments (DOE) is the branch of applied statistics deals with planni

conducting, analyzing and interpreting controlled tests to evaluate the factors that control

value of a parameter or group of parameters. When the problem involves data that a

subjected to experimental error, statistical methodology is the only objective approach

analysis. There are two aspects of an experimental problem: the design of the experime

and the statistical analysis of the data. In performing a designed experiment, changes a

made to the input variables and the corresponding changes in the output variables a

observed. The input variables are called factors and the output variables are cal

response. Factors may be qualitative or quantitative. Qualitative factors are discrete

nature. Each factor can take several values during the experiment. Each such value of t

factor is called a level. DOE approach enables to separate the important factors from t

unimportant factors from the unimportant ones by comparing the factor effects. A

interactions effect among different factors can be studied through designed experimen

The various advantages

a) Numbers of trials is significantly reduced.

b) Important decision variables which control and improve the performance of the product

process can be identified.

c) Optimal setting of the parameters can be found out.

d) Qualitative estimation of parameters can be made.Experimental error can be estimated

f) Inference regarding the effect of parameters on the characteristics of the process can

made.


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4.7 ANALYSIS USING MINITAB SOFTWARE

Analysis of each side is done independently using the software MINITAB under

Tagchuci technique where we check the variation of various input parameters on spe

and surface roughness. The effect of particular input pattern can be verified through vario

graphics and analysis. Here we undergo the various readings.

For current speed

Linear Model Analysis: Means versus A, B, C, D, E, F

Estimated Model Coefficients for Means

Term Coef SE Coef T P

Constant 2.28037 0.01934 117.910 0.000

A 1 -0.10481 0.02735 -3.832 0.002

A 2 0.05074 0.02735 1.855 0.085

B 1 0.12407 0.02735 4.536 0.000

B 2 0.05185 0.02735 1.896 0.079

C 1 0.00407 0.02735 0.149 0.884

C 2 0.08185 0.02735 2.993 0.010

D 1 0.04630 0.02735 1.693 0.113

D 2 -0.02259 0.02735 -0.826 0.423

E 1 0.05407 0.02735 1.977 0.068

E 2 -0.02815 0.02735 -1.029 0.321

F 1 0.00519 0.02735 0.190 0.852

F 2 -0.01704 0.02735 -0.623 0.543

S = 0.1005 R-Sq = 84.8% R-Sq(adj) = 71.8%

Analysis of Variance for Means

Source DF Seq SS Adj SS Adj MS F A 2 0.148363 0.148363 0.074181 7.35 0.00

B 2 0.441296 0.441296 0.220648 21.85 0.00

C 2 0.126896 0.126896 0.063448 6.28 0.01

D 2 0.028941 0.028941 0.014470 1.43 0.27

E 2 0.039496 0.039496 0.019748 1.96 0.17

F 2 0.004119 0.004119 0.002059 0.20 0.81

Residual Error 14 0.141385 0.141385 0.010099


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Total 26 0.930496

Unusual Observations for Means

Observation Means Fit SE Fit Residual St Resid10 2.350 2.550 0.070 -0.200 -2.77 R

11 2.650 2.497 0.070 0.153 2.11 R

20 2.180 2.327 0.070 -0.147 -2.03 R

Response Table for Signal to Noise Ratios

Larger is better

Level A B C D E F

1 6.704 7.605 7.162 7.330 7.347 7.156

2 7.328 7.352 7.452 7.061 7.019 7.071

3 7.357 6.432 6.776 6.999 7.023 7.163

Delta 0.653 1.174 0.676 0.331 0.327 0.093

Rank 3 1 2 4 5 6

Response Table for Means

Level A B C D E F

1 2.176 2.404 2.284 2.327 2.334 2.286

2 2.331 2.332 2.362 2.258 2.252 2.263

3 2.334 2.104 2.194 2.257 2.254 2.292Delta 0.159 0.300 0.168 0.070 0.082 0.029

Rank 3 1 2 5 4 6

Main Effects Plot for Means

Main Effects Plot for SN ratios

Residual Plots for SN ratios

Residual Plots for Means


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45

321

7.50

7.25

7.00

6.75

6.50

321 321

321

7.50

7.25

7.00

6.75

6.50

321 321

A

MeanofSNratios

B C

D E F


Data Means

Signal-to-noise: Larger is better

FIG 4.3: VARIATION USING MAIN EFFECTS PLOLT FOR MEANS

321

2.4

2.3

2.2

2.1

321 321

321

2.4

2.3

2.2

2.1

321 321

A

MeanofMeans

B C

D E F


Data Means

FIG 4.4: VARIATION USING MAIN EFFECTS PLOLT FOR SN RATIO


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For surface roughness

Taguchi Analysis: C7 versus A, B, C, D, E, F

Linear Model Analysis: SN ratios versus A, B, C, D, E, F

Estimated Model Coefficients for SN ratios


Constant -11.9123 0.6781 -17.566 0.000

A 1 -0.1579 0.9590 -0.165 0.872

A 2 -0.8351 0.9590 -0.871 0.399

B 1 -0.3107 0.9590 -0.324 0.751

B 2 0.1837 0.9590 0.192 0.851

C 1 -0.8513 0.9590 -0.888 0.390

C 2 -0.0030 0.9590 -0.003 0.998

D 1 -0.0812 0.9590 -0.085 0.934

D 2 -0.4477 0.9590 -0.467 0.648

E 1 0.3828 0.9590 0.399 0.696

E 2 -1.1985 0.9590 -1.250 0.232

F 1 -1.5418 0.9590 -1.608 0.130

F 2 1.6225 0.9590 1.692 0.113

S = 3.524 R-Sq = 36.4% R-Sq(adj) = 0.0%

Analysis of Variance for SN ratios

Source DF Seq SS Adj SS Adj MS F P

A 2 15.376 15.376 7.6881 0.62 0.552

B 2 1.318 1.318 0.6590 0.05 0.949

C 2 13.091 13.091 6.5456 0.53 0.602

D 2 4.381 4.381 2.1906 0.18 0.840

E 2 20.235 20.235 10.1174 0.81 0.463

F 2 45.145 45.145 22.5726 1.82 0.199

Residual Error 14 173.829 173.829 12.4164Total 26 273.376

Linear Model Analysis: Means versus A, B, C, D, E, F


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Estimated Model Coefficients for Means


Constant 4.21926 0.3331 12.668 0.000

A 1 0.04407 0.4710 0.094 0.927

A 2 0.56741 0.4710 1.205 0.248B 1 0.09185 0.4710 0.195 0.848

B 2 -0.19370 0.4710 -0.411 0.687

C 1 0.44852 0.4710 0.952 0.357

C 2 -0.11259 0.4710 -0.239 0.815

D 1 -0.06370 0.4710 -0.135 0.894

D 2 0.34963 0.4710 0.742 0.470

E 1 -0.26704 0.4710 -0.567 0.580

E 2 0.61852 0.4710 1.313 0.210

F 1 0.70630 0.4710 1.500 0.156

F 2 -0.83037 0.4710 -1.763 0.100

S = 1.731 R-Sq = 39.7% R-Sq(adj) = 0.0%

Analysis of Variance for Means

Source DF Seq SS Adj SS Adj MS F P

A 2 6.2802 6.2802 3.1401 1.05 0.376

B 2 0.5070 0.5070 0.2535 0.08 0.919

C 2 2.9402 2.9402 1.4701 0.49 0.622

D 2 1.8725 1.8725 0.9362 0.31 0.737E 2 5.1967 5.1967 2.5984 0.87 0.441

F 2 10.8339 10.8339 5.4169 1.81 0.200

Residual Error 14 41.9305 41.9305 2.9950

Total 26 69.5610

Response Table for Signal to Noise Ratios

Smaller is better

Level A B C D E F

1 -12.07 -12.22 -12.76 -11.99 -11.53 -13.45

2 -12.75 -11.73 -11.92 -12.36 -13.11 -10.29

3 -10.92 -11.79 -11.06 -11.38 -11.10 -11.99

Delta 1.83 0.49 1.71 0.98 2.01 3.16

Rank 3 6 4 5 2 1


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Response Table for Means

Level A B C D E F

1 4.263 4.311 4.668 4.156 3.952 4.9262 4.787 4.026 4.107 4.569 4.838 3.389

3 3.608 4.321 3.883 3.933 3.868 4.343

Delta 1.179 0.296 0.784 0.636 0.970 1.537

Rank 2 6 4 5 3 1



Residual Plots for SN ratios

Residual Plots for Means

321

5.0

4.5

4.0

3.5

321 321

321

5.0

4.5

4.0

3.5

321 321

A

MeanofMeans

B C

D E F

Main Effects Plot for MeansData Means

FIG 4.5: VARIATION USING MAIN EFFECTS PLOLT FOR MEANS


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49

321

-10

-11

-12

-13

321 321

321

-10

-11

-12

-13

321 321

A

MeanofSNratios

B C

D E F


Data Means

Signal-to-noise: Smaller is better

FIG 4.6: VARIATION USING MAIN EFFECTS PLOLT FOR SN RATIO


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CHAPTER 5

RESULTS AND DISCUSSION

5.1 INTRODUCTION

Results of the experimentation show the significant variations in response parameters w

HCHCr wire electrodes. Wire wear and cutting rate were noted with with brass w

Variation in surface roughness at different parameters was checked using profilometer .

Analysis of different parameters with respect to speed and surface roughness was not

down and analysis was done with the help of TAGUCHI TECHNIQUE. Results show

parametes which has an effect, also which may have part ial effect and which dont effect

all to the cutting on wire edm machine.

5.2 EFFECT OF INPUT PARAMETERS ON RESPONSE PARAMETERS

5.2.1 Effect of Pulse on Time

The effect of Pulse on time on cutting rate, and surface roughness is shown in figures

shows that with increase in value of pulse on time, the cutting rate and surface roughne

increases. Energy supply increases with pulse on time, therefore more number of partic

will strike to the work piece. Cutting rate is directly proportional to the energy supplied dur

this time .As particles penetrate more deeply due to increase in energy, the recast layer w

also be thick. This results in increasing the value of surface roughness with increase in pu

on time.Graphs showing the output


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Current Speed graph for Ton

Surface Roughness graph for Ton

FIG 5.1: Significance of pulse on time (Ton)

5.2.2 Effect of Peak CurrentThe effect of Peak current on cutting rate, wire wear and surface roughness, is shown in

figures .It shows that with increase in peak current, cutting rate and surface roughness

increases. Peak current is the maximum current supplied during one cycle. Increase in the


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value of peak current results in increase in the energy, therefore increase cutting rate, wire

wear and surface roughness.

Current Speed graph for I.P

Surface Roughness graph for I.P

FIG 5.2: Significance of peak current (I.P)

5.2.3 Effect of pulse OFF time

The effect of Pulse off time on cutting rate, and surface roughness is shown in figures

shows that with increase in value of pulse off time, the cutting rate and surface roughne

increases. Cutting rate is directly proportional to the voltage time for which it is remov


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This results in decreasing the value of surface roughness with increase in pulse off tim

Graphs showing the output

Current Speed graph for Toff

Surface Roughness graph for Toff

FIG 5.2: Significance of pulse off time (Toff)


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CHAPTER 6

CONCLUSION AND FUTURE SCOPE

6.1 CONCLUSION

The following conclusions were drawn from the study

1. All the three factors i.e. pulse on time (TON), pulse off time (Toff) and peak current

are statically found to be significant.

2. With increase in pulse on time, surface roughness and cutting rate increases.

Current Speed graph for Ton Surface Roughness graph for To

3. With increases in pulse off time, surface roughness and cutting rate decreases

Current Speed graph for Toff Surface Roughness graph for To

4. With increases in peak current, surface roughness and cutting rate decreases

Current Speed graph for I.P Surface Roughness graph for I.P


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6.2 FUTURE SCOPE

Similar study can be undertaken for improving machining capabilities of super allo

by wire EDM.

Effect of different micro-electrodes on the performance of wire EDM can be studied


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REFERENCES

Aoyama, S., Tamura, K., Sato, T., Kimura, T., Sawahata, K., Nagai, T. (1999) High-

Performance Coated Wire Electrodes for High-Speed Cutting and Accurate Machining,

Hitachi Cable Review, vol. 18, pp.75- 80.

Barthel, B., Neuser, B., Wire electrode, U.S. Pat. No.6,566,622, May20,2003.

Baumann, I. and Barthel B., Wire Electrode for the Spark-Erosive Cutting of Hard Met

U.S. Pat. No.6,348,667, Feb.19,2002.

Briffod, J.P., Electric Discharge Machining Electrode, U.S. Pat. No. 5,196,665, Mar.2

1993.

Briffod, J.P., Martin, R., Pfau, J., Bommeli, B., Schnellmann, D., "Wire Electrode for

Cutting an Electrode Workpiece by Electrical Discharges", U.S Pat. No. 4,341,93,

Jul.27,1982.

Convers, D., Balleys, F., Pfau, J., "Electrode for Electrical Discharge Machining", U.S P

No. 4,287,404, Jan. 09, 1981.

Datta, S. and Mahapatra, S. (2010), Modeling, Simulation and Parametric Optimization

Wire EDM Process using Response Surface Methodology Coupled with Grey-Tagu

Technique, International Journal of Engineering, Science and Technology ,vol. 2,5, pp. 1

183.

Delpritti, R., EDM Process and Apparatus for Machining a Workpiece by a Wire

Electrode, U.S.Pat.No.4,262,185, Apr.14,1981.

Hascalyk, A. &Caydas, U. (2004),Experimental Study of Wire Electrical Dischar

Machining of HCHCr Steel, Journal of Materials Processing Technology,Vol.148,3, pp.36

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Hewidy, M.S., EI-Taweel, T.A. and EI-Safty, M.F.(2005), Modeling the Machining

Parameters of Wire Electrical Discharge Machining of Inconel 601 using RSM Journal

Materials Processing Technology, vol. 169,2, pp.328-336.

Design, vol. 2,4, pp. 735-741.

Panday, P.C and Shan, H.S (1980), " Modern Machining Processes", Tata McGraw-

Publishing Company Limited, New Delhi.

Saha, S., Pachon, M., Ghoshal, A., Schulz, M.J. (2004), Finite Element Modeling and

Optimization to Prevent Wire Breakage in Electro-Discharge Machining, Mechanics

Research Communications, vol.31, pp.451463.

Sarkar, S., Mitra, S., Bhattacharya, B. (2005), Parametric Analysis and Optimization

Wire Electrical Discharge Machining of -titanium Aluminide Alloy, Journal of Materi

Processing Technology,159, 3, pp. 286-294.

Sawada, K., Takano, S., Ezaki, S., "Copper Based Wire Electrode for Wire Electro-

Discharge Machining", U.S Pat. No. 4,673,790, June 16, 1987.

Tosun, N., Cogun, C. and Tosun, G. (2004), A Study on Kerf and Material Removal Rate

Wire Electrical Discharge Machining based on Taguchi Method, Journal of Materi

Processing Technology, vol.152, pp. 316-322.


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ANNEXURE

Photographic view of WEDM, Electronica Sprintcut 734

(CTR,Ludhiana)


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Photographic View of Surface Roughness Tester


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advance cad cam

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