Electro-Discharge Machining

16 Pages·2017·0.96 MB·English

by  Anbesh Jamwal

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 05 Issue: 02 | Feb-2018 www.irjet.net p-ISSN: 2395-0072

Electro-Discharge Machining: Recent Developments and Trends

Anbesh Jamwal1, Ankur Aggarwal2, Nishant Gautam3, Akhil Devarapalli4
1,2,3PG Student, Dept. of Mechanical Engineering, Amity University, Noida, U.P., India
4UG Student, Dept. of Mechanical Engineering, Amity University, Noida, U.P., India
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Abstract - In the present manufacturing scenario, the requirement of the EDM. Generally used tool materials in
industrial product not only requires the high precision and the EDM are tungsten and copper. The EDM technique is
quality but should be produced in the minimum time in developed in the 1940 by two Russian Scientist B.R
order to sustain their position in the global market Lazarenko and N.I Lazarenko. Later in 1967 the
competition. Thus, it is required to regulate the input scientists of Soviet Union developed first EDM in which
process parameters for achieving the desired output or the they used wire as the electrode [5-6]. EDM utilizes the
performance. EDM is the most popular machining process electrical energy to generate the electrical spark and the
in the present time among all the machining processes. material removal is done by the thermal energy that is
EDM is the widely used non-conventional machining generated by the electrical spark [7]. The tool material
process that is capable to machine the hard materials such and work-piece are maintained by a small gap known as
as alloys, composite and even the ceramics also. EDM has spark gap which is 0.005mm-0.05mm [8]. There are the
wide range of application in automobile, aerospace, continuously electrical charges occurred between the
defense and precision engineering industries. In the past tool and work-piece in the presence of the dielectric fluid
years, the many studies have been done to improve the [9]. The dielectric fluid may be the EDM oil and kerosene
EDM process. This paper reviews the current research oil [10]. The main purpose of dielectric fluid is to provide
trends and recent developments in EDM process and the dielectric medium and flushing out the machining
modeling techniques. debris from the work table [11]. The major disadvantage
of the EDM is the overcutting and the formation of the
Key Words: Electro-discharge machining, WEDM, recast layer [12]. When the DC supply given then the
Powder additives, Process parameters, Dielectric, electric spark is generated and the ions starts flowing
optimization techniques. from the work-piece and electrons from the tool material
[13]. The electric field is generated between the work-
1. INTRODUCTION piece and the tool and it is maximum where the gap
between the work-piece and tool is minimum [14]. The
EDM is widely using non-traditional machining process recent research is EDM on the composites because
in the present manufacturing scenario. The electro- composites are widely used in the industries due to their
discharge machining has widely used in the production special properties and these are hard in nature [15]. Due
of dies and molds [1]. Basically, EDM is used to machine to hard in nature they are difficult to machine by
those materials which are difficult to machine by the conventional machining processes. Current trends in the
conventional machining process. Finishing parts of EDM is carried by researchers on the machining
aerospace and automobile industries are machined by techniques like Dry EDM [16], EDM with additives [17],
the EDM process. There is no direct contact between the EDM in water [18] and the different modelling
tool material and work-piece. The material is removed techniques [19] for the better results. These days micro-
by the thermal erosion in the EDM process [2]. EDM gains more popularity because it can achieve the
Previously studied on EDM reported that the material surface finish up to micro level [20]. The power
removal rates are less in the EDM than the other consumption is very less in the case of micro-EDM. The
conventional machining processes. The major advantage material removal rates are very low but the surface
of using EDM rather than conventional machining finish rates are very high [21]. The tool wear rates are
processes is very high surface finish rates. The depending upon the polarity [22]. Previous studies show
advantage of using EDM there are no mechanical that when the polarity is reverse the tool wear are high
vibrations and mechanical stresses occurs during and it is less when the polarity is positive [23-24]. These
machining because of no direct contact between the days EDM is using in the industries where the better
work-piece and tool material [3]. Another advantage of surface finish is the major requirements [25]. This paper
using EDM over other machining processes that it can provides the review of various researches carried out in
machine any profile or geometry. It can easily machine the past on the electro-discharge machining. This paper
the complicated geometry which can be difficult to also aims to the review of various modelling techniques
machine by some other machining processes [4]. But the used in the electro-discharge machining and future
limitation is only the tool material and work-piece must research directions. Figure 1 shows the all research
be electrically conducted. This is one of the major areas in EDM.
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Sometimes it is nearly about 20,000°C which is too high
Fuzzy Logic
and can machine any material. The location of electric

spark which is generated by heat energy is determined
Mocnointitororiln tgh ea nd Pulse/Time by the narrowest gap between the tool and work-piece
process Domian [33]. Duration for each spark is very short. The
frequency for each spark is high as thousands sparks per
second. However, spark radius is very small and the
Radio Frequency

temperature in the spark zone is very high [34]. This
temperature of spark is capable for partially vaporize
Electrical and
and melting the material from both the work-piece and
Non-Electrical
Parameters tool material. The volume of material removal per
Optimization of
process variables discharge from the work-piece depends upon the
Electrode Design
and specific applications and it is ranging from 10-6-10-4
manufacturing mm3. The material removed from the surface of work-
Research areas piece is in the form of craters which is all overspread on
in EDM
Surface Quality the work-piece. Craters sizes is highly influenced by the
value of current. Previous studies show that the size of

Improving the crater is increase with increase in discharge current.
performance Tool wear Figure 2 shows studies conducted in EDM field.
measures

Material removal Research Studies

Conducted in EDM
EDM application
areas
EDM
Developments EDM- Other EDM
Hybrid
Machining Milling Methods
Processes 10% 7%

EDM
Fig -1: Research Areas in EDM 35%
WEDM
23%
2. ELECTRO-DISCHARGE MACHINING UEDM
25%
EDM is one of the most popular non-traditional or
unconventional machining process in the present
EDM UEDM
manufacturing scenario [26]. With the high surface finish
rates and ability to machine those material which are WEDM EDM-Milling
difficult to machine by conventional machining
Other EDM Methods
processes [27]. This section provides the basics of EDM

process and EDM variations which combines other
material removal methods. Fig -2: Studies conducted in EDM
2.1 EDM Process 2.2 EDM Variations
Lot of research has been done in the EDM field There are number of EDM variations have
[28-29]. EDM is one of the earliest un-conventional emerged in the industries to machine the super hard
machining processes. Electro-discharge machining is a alloys, composites, aerospace parts and ceramics [35-
thermoelectric process which utilizes the heat energy 36].
generated by spark to remove the material from the
surface of work-piece [30]. The only limitation in the 2.2.1 Wire EDM: WEDM is most widely used in
EDM is that the work-piece and the tool material both industries these days because of capability to generate
should be electrically conductive. The electrical energy complicated shapes and profiles without use of pre-
converted into the thermal energy by series of the shaped electrode which were required in the basic EDM
electric discharge that occurred between the work-piece [37]. The only limitation in the WEDM is same as EDM
and tool which are immersed into the dielectric fluid that the tool material and work-piece both should be
[31]. The plasma channel is generated by thermal energy electrically conductive. WEDM uses the thin
between anode and cathode. The plasma channel is continuously traveling wire that is feeding by the
generated at a temperature range of 8000-1200°C [32]. microprocessor through the work-piece. To overcome
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the common problems in the conventional and non- grinding process [55]. EDG capable to achieve high
conventional machining processes there is development accuracy and high surface finish rates (0.2-0.3µm) than
of Hybrid machining processes which involves the EDM the conventional grinding [56].
with Ultrasonic vibration (USM) [38], Laser beam
machining (LBM) [39], High-speed machining (HSM) 2.2.6 Electro-Chemical Discharge Machining:
[40], grinding [41], electrical discharge grinding (EDG) Hybridization of EDM and ECM is studied since 1970
[42] and electrochemical discharge machining (ECDM) [57-58]. ECDM is also known as Electro-erosion
[43]. dissolution machining process (EEDM). ECDM has wide
variety of applications especially in non-conductive
2.2.2 Ultrasonic Vibration: Ultrasonic vibration to the materials such as various types of ceramics and
electrode is one of method introduced to improve the composites [59-60].
machining performance of EDM [44]. It expands the
machining area of EDM and helps to improve the 3. RECENT DEVELOPMENT IN EDM
machining performance of EDM over the hard materials
which are difficult to machine by conventional In the past five years there are lot of studies and
machining processes [45]. The main advantage of developments have been done in the field of EDM still
ultrasonic vibration in EDM it improves the dielectric there are research gaps [61-62]. In the past year’s lot of
circulation which helps to generate the large amount of developments have been done in the materials and
pressure between the work-piece and tool material [46]. modeling techniques. Lot of research has been done in
Another advantage of ultrasonic vibration is it facilitates the composites and ceramics which creates a new
the debris removal from the work table. The spark research scopes in the EDM [63-64].
erosion which was usually produced by pulse power
3.1 Recent developments in EDM electrode and
supply is replaced by the DC supply and the pulse charge
is produced by the relative motion between the work- work-piece materials
piece material and tool material [47]. It simplifies the
In the past few year studies in the material,
equipment and reduce overall cost of equipment. It is
science has scored the new successes. In the past few
found that a new combined technology can be developed
decades’ strength of ceramic materials has been
with the benefits of both the EDM and ultrasonic
improved by 100% [65]. Although the outstanding
machining [48].
properties of ceramic materials, it is difficult to attain the
2.2.3 Laser Beam Machining: The hybridization of laser good surface finish on these materials. In recent years
beam machining and EDM using in the micro-machining the development of electrically conductive ceramics has
processes to reduce the production time and eliminating made the scope of research in the EDM to achieve the
the recast layer produced by EDM [49]. Laser beam good surface finish rates on ceramic materials [66]. Lot
machining is used to fabricating the desired shape from of work have been done on improving the performance
the material and EDM is used for the final finishing. The of EDM by electrodes. Different tool materials like
machining rate is faster in the hybridization of LAEDM copper, tungsten carbide, copper tungsten, aluminum
[50]. Nd-YAG laser are commonly used in the LAEDM. and composite based electrodes used for improving the
Main purpose of EDM is only to provide the finish performance of EDM [67]. Copper and graphite are most
operations [51]. Production rate, surface finish and commonly used tool materials in EDM process. Recent
efficiency are higher and tool wear rate is very less in the development in the tool materials and selection of
hybridization of LAEDM as compared to conventional optimum machining condition led to very low tool wear
EDM and Laser beam machining [52]. rates with high machining efficiency [68]. Electrode
material should undergo less tool wear rate when it is
2.2.4 High-Speed Machining: Comparatively less affected by the positive ions. Density and melting point
research has been done in the hybridization of EDM with of tool material should be high to avoid the tool wear
High-speed machining as compared to other EDM and inaccuracy of tool. Copper electrode material having
variations. The hybridization of HSM and EDM would good EDM wear, good conductivity and good surface
give number if benefits [53]. In present time high-speed finish rates(Ra=0.5µm) with less manufacturability cost.
machining has replaced use of EDM. But for deep Manufacturing cost of EDM tool material is 50% of total
cavities, and complicated shapes components having the EDM process. Manufacturing cost of EDM tool material
internal corners and some work-piece materials which can be reduced by powder metallurgy [69-70].
are difficult to cut, EDM is still required [54].
2.2.5 Electric Discharge Grinding: Electric discharge
grinding is the hybrid grinding process works on the
same principle as basic EDM. The hybrid grinding
capable to machine extremely hard materials which such
as carbides 2-3 times faster than the conventional
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The major process parameters of the EDM process are
EDM-electrode wear
shown below:
800
Process parameters
700
% 600
o Electrical Non electrical Powder based Electrode based
ita 500 parameters parameters parameters parameters
r
ra 400
e
w
300
ren 200 Polarity Electtriomdee Lift conPcoewntdreart ion Electrode size
r
o
C
100
Electrode
0 Gap Voltage Working time Powder size material
Powder
Average current Nozzle Flushing Electrode shape
conductivity
Tool Material Pulse on time Grain Size Powder density

Fig –3. Electrode Wear Ratio with respective tool Pulse frequency
material
3.2 Responses and its influence parameters
Pulse off time
The process parameters help to analyze the
effect of the machining performance of any machining
process. The performance of EDM depends upon its Duty factor
responses and influence parameters [71-72]. The
performance of EDM is depends upon the electrical pulse
Discharge
parameters and rest on the machining conditions. Voltage
Discharge current and pulse duration are the main
electrical pulse parameters which affect the machining
performance of EDM [73]. It was found that tool wear Peak Current
rate increase with increase in electrical pulse
parameters and tool wear rate is highly influenced by
discharge current. Surface finish depends upon the Electrode Gap
discharge current and pulse duration [74].

Fig -4. Major EDM Process Parameters

3.3 Effect of Electrical parameters

In EDM it is difficult to explain the effect of all
electrical parameters on the individual performance
measure. This section describes about the various

electrical parameters which affect the performance of
EDM.
3.3.1 Effect of peak current: To investigate the effect of
peak current in EDM on MRR and surface roughness

pulse on time varied and other parameters like pulse off
time, voltage and wire feed rate kept constant. The

material removal rate is slow at low values of current
and it is nearly constant as the values of current are low
[75-76]. The material removal rate of material starts

increasing the value of current increasing [77-78].
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3.3.2 Effect of pulse-on-time: To observe the effect of 3.4.2 Effect of rotational movement of tool material:
pulse-on-time on the EDM performance peak current is Besides the dielectric flushing effect on the performance
varied while the other parameters like pulse-off-time, of EDM, the rotational movement of tool material also
voltage and wire feed rate kept constant. It is observed affects the performance measures of EDM. Better surface
that the MRR is increasing with the pulse-on-time at all quality and material removal rate be achieved by the
the values of current and surface quality of material applying the rotational movement of tool material over
starts decreasing when there is an increase in the value the work-piece by improving the circulation of dielectric
of pulse-on-time [79-80]. Optimum values of surface fluid in the spark gap [100-101].
roughness can be found at the lower value of pulse-on-
time and current [81]. 3.4.3 Effect of rotational movement of work-piece
material: Rotational movement of work-piece material
3.3.3 Effect of pulse-off-time: It is found that MRR in EDM improves the performance measures of EDM in
starts decreasing when there is an increase in the values terms of surface quality and material removal rate [102-
of pulse-off-time. Long pulse-off-time makes a cooling 103]. The rotation of work-piece improves the dielectric
effect on both the electrode and the work-piece material flushing over the work-piece which results in the better
hence results in decreasing the cutting speed and EDM surface quality and low electrode wear rate and High
performance degradation [82-83]. Surface roughness material removal rates [104]. Still, these non-electrical
improves with the higher values of pulse-off-time. It was parameters need further study.
also found in some studies that first the surface
roughness decreasing with the pulse-off-time then starts 3.5 Powder additives
increasing when there is an increase in the values of
pulse-off-time [84-85]. The performance of EDM can be improved by
addition of powder additives. Fine abrasive powder
3.3.4 Effect of servo voltage: The effect of servo voltage particles are mixed in dielectric fluid which utilize the
on the performance of EDM is observed by varying the low pulse energy and increase the spark gap between
pulse duration and kept constant all other parameters. the electrode and the work-piece. This hybrid process is
MRR starts increasing with increase in the servo voltage called powder mixed-EDM. The surface quality and MRR
initially. But then starts decreasing with increase in the can be increased by the powder mixed-EDM. Too high
servo-voltage [86-87]. On other hand surface quality of and too low concentration of powder in EDM oil reduces
material also starts decreasing with increase in the the machining performance of EDM [105-106].
voltage [88-89].
3.6 Material Removal Rate
3.4 Effect of Non-electrical parameters
In the EDM process material removal takes
In addition, the non-electrical parameters such as place from both tool material and work-piece. The
rotation of work-piece, rotation of tool material and material removal rate depends upon the work-piece
flushing of dielectric fluid also plays an important role material, tool material and machining variables.
for achieving the optimal performance measures of EDM. Materials having low melting point having high material
removal rate and hence lower surface finish [107-108]. It
3.4.1 Effect of dielectric flushing: Dielectric flushing is found that with increase in pulse current and constant
affects the performance measures of EDM. During the pulse-on-time material removal rates increases but it
roughing operations, flushing of dielectric fluid affects affects the surface finish of material [109]. EDM
the tool wear rate and electrode wear rate while during efficiency can be increased by supplying the oxygen gas
the finishing operations it affects the surface roughness between the spark gap and stack removal rate can be
[90-91]. In addition, different properties of dielectric increased by increasing the volume of discharge crater
fluids also play a vital role in the performance of EDM. It and regular occurrence of discharges [110]. Optimum
was found in the studies the kerosene oil with additives values for material removal rate can be achieved at low
provides the excellent EDM performance and high MRR values of current [111].
and low electrode wear rate can be achieved without
formation of any metal carbide on the surface of work- 3.7 Surface roughness
piece [92-93]. The flushing methods can classify into
Normal flow flushing [94], Jet flow flushing [95], Surface finish is primary aim of machining in
Immersion flow flushing [96] and reverse flow flushing EDM. In CMC’s pulse on time is most dominant factor
[97-98]. Some researchers applied the magnetic field to which affects the surface roughness. It is also found that
move the debris from the gap and some applied the surface roughness increases with increase in discharge
forced vibrations to move the machining debris from the current and pulse on time [112]. Better surface finish
gap between tool material and work-piece [99]. with no surface cracks can be achieved at low values of
current [113]. An experiment to obtain the good surface
finish in view of Die-sinking EDM and concluded that
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surface finish of work-piece is highly influenced by ceramics which having the good wear resistance and
discharge energy [114]. It is observed that at lower chemical stability properties which make them suitable
discharge energy good surface quality can be achieved for use as the modern cutting tools [130]. It is difficult to
[115]. machine these materials by conventional machining
processes. Machining and achieving high surface finish
3.8 EDM process development rates on these materials is possible with EDM [131-132].
Since EDM process is non-linear nature, still it 4. OPTIMIZATION TECHNIQUES USED IN EDM
requires lot of improvements. Lot of research has been PROCESS
done on the process development of EDM [116-117].
Many authors have discussed about the recent trends 4.1 Grey relational analysis
and development in the EDM process. Optimization of
process variables, modeling techniques, control of The grey theory is firstly introduced by Deng in
sparking process, monitoring and performance 1982. This theory is useful for dealing with the poor and
measures in EDM process still needs further study [118]. incomplete information [133-134]. The Grey theory is
There is need of controlling the process parameters of very effective technique and requires very limited
EDM to enhance the machining process. The information for the estimation of the behavior of the
development of new technologies for achieving the high discrete data problem and uncertainty system. In the
surface quality is the major research trend in the EDM Grey theory, there are three types of systems which are
[119]. It is observed that most of the research work in Black (No information), white (all information) and grey
EDM is concentrated on improving the surface quality system (imperfect information) which requires very
with mixing the powder in the dielectric medium. In limited information to estimate the behavior of the
many applications, traditional machining operations like problem [135-136]. The data processing range is 0 to 1
milling is replaced by EDM process [120]. Mechanical in this system and in the data, is distorted to comparable
stresses don’t induce in EDM during machining sequence in the normalization. There are three
operations this helps in manufacturing of complex conditions of normalization which are:
shapes [121]. There are several experiments done with
electrode of diameter 50µm and multi-electrode for the a) Higher is better
production of micro-parts by the batch production which b) Lower is better
reduces the fabricating cost and production time for c) Normal is best
both the parts and electrodes [122].

3.9 Micro-EDM
Production of smaller size and 3D shape
products given a new research scope in micro-EDM field. Multi- Grey Single
Micro-EDM is not only capable to machine micro-holes objective relational objective
Optimization analysis optimization
up to 5µm but also machine complex 3D shapes [123].
Micro-EDM process is unlike conventional mechanical
drilling which can produces the holes up to 70µm or the
other unconventional machining like laser beam which
can produce up to 40µm [124]. Elimination of
Fig -5. Grey Relational Analysis
conventional boring or drilling operation is eliminated
while performing the EDM operation by the trajectory 4.2 Neural Network
EDM technique in which tool material is move along with
a smooth trajectory [125-126]. There are some other Neural network is a system which is capable to
attempts made on EDM trajectory but there is need of receive, store and apply the knowledge that is gained by
complex mechanism or special apparatus to develop the experience [137]. Artificial neural network is a flexible
trajectory motion of EDM tool material [127]. modeling tool which is capable to learn the mapping
between the input and output parameters of a process
3.10 Composites and ceramics materials which helps in solving the non-linear problems using the
software computing methods [138]. An artificial neural
The development in composites and ceramics
network is a model which runs like human brain [139]. It
materials in last decades has expand the application area
is used to solve the complex problems whose analytical
of EDM [128]. Due to better material properties like
and numerical solutions are very tough [140]. Generally,
Hardness, tensile strength and wear resistance it is
the neural network design having the three steps which
difficult to machine these materials with conventional
are: configuration how layers be connected and
machining processes. Composites are widely used in
organized, learning how information is stored and
cutting tools these days [129]. Al O based composite
2 3 generalization how neural network produces the
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reasonable outputs for the inputs which are not found in c) Crossover is one of the most important
the training. ANN model is based upon some operation which is helps in generating the
assumptions: new offspring by exchanging of some parts
of two genes. It is very helpful when
a) Information in the ANN is processed at searching the whole space rapidly.
many simple elements called neurons.
d) Mutation is also a process which is applied
b) Signal is passed between the over to provide a small randomness to a new
connection links and neurons. chromosome.

c) Each connection link having the associated e) The encoding process is done to evaluate
weight. each of chromosome.

d) Each neuron applies an activation function
which is non-linear to its net input which
helps to determine its output signal.
The multilayer neural networks are formed with
numerous neurons having the parallel connection
between them and they are jointed in several layers. The
structure of the NN contains the input data, number of
hidden layers which contains the numerous neurons in
each layer and the external layer which is connected the
neurons to output.

Fig -6. Artificial Neural Network Fig -7. The Solution Procedure of GA
4.3 Genetic algorithm 4.4 Finite element method
The genetic algorithm is a higher-level FEM is a powerful tool that is used for obtaining
procedure that is developed for providing the the real engineering problems. FEM can handle a wide
sufficiently good solutions to an optimization problem. range of engineering problems. Powerful software is
In the last few years, GA has made some new research required to develop the FEM-based PMEDM model
scopes in the optimization field [141]. GA is inspired by which can be able to consider all aspects of the EDM
process of natural process of selection of large class of process [145-146]. ANSYS is one of the powerful tool
evolutionary algorithms. GA are commonly used to that can be used in the FEM analysis. Any complex
generate the high quality of solutions for the many geometry can be easily analyzed using ANSYS tool. Many
optimization problems in present time [142]. Some researchers have done work on modeling and simulation
researchers have investigated GA application in the of results for Powder mixed EDM [147-148]. Using the
electro-discharge machining and used the multi-goal boundaries condition the geometry of work is created
optimization approach [143-144]. There are few steps and different kind of load applied on the work domain.
which are required to apply GA in optimization of Mapped meshing technique is used for meshing of
machining process. workpiece [149].
a) The process parameters or the input 4.5 Artificial bee colony optimization
parameters are encoded as genes by the
binary encoding. In the last few years’ advancement in the EDM
process has given new research scopes. These new
b) A chromosome is formed by the
research scopes have given some new optimization
combination of the genes.
techniques also. Artificial bee colony optimization was
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proposed by Karaboga in 2005 [150]. ABC optimization of the fuzzy logic [156]. IF-THEN rules are used to make
is inspired by the foraging behavior of honey bees. In the fuzzy logic useful. The output of the fuzzy process needs
ABC optimization colony of artificial bees contains to be single scalar quantity. De- fuzzification is the
generally two groups that are unlooker bees or process of the conversion of fuzzy quantity into the
unemployed bees and employed bees. In which the scalar quantity [157].
employed bees have idea about the food source (nectar
position) and quality of food (nectar amount). Whereas 5. CONCLUSION
the unemployed bees are get the information of food
EDM is one of the widely used unconventional machining
source form the employed bees and they are attracted
method that is capable of producing the complex shapes.
towards the food source and becomes employed bees
The only limitation in the EDM is the work piece should
[151]. Once the food source is consumed then employed
be conductive in nature. With the time there is lot of
bees becomes scout bees and starts finding new food
improvements in the EDM and its assisted processes as
source. In the ABC analysis number of employed bees is
well as optimization techniques, which made some new
always equal to unemployed bees in the population.
research scopes in the EDM. Some studies found that
Presently the ABC analysis is used to solving the
non-electrical parameters also play an important role in
continual optimization problems [152]. The structure of
the performance of the EDM. Developments in modeling
artificial bee colony optimization is shown the figure
techniques have made new research scopes in the EDM
below:
and improves the performance of EDM process. Based on
the various research work presented the following
observations are made on the basis of this review work.
a) In this review paper, there is collection of
various research work in the field of assisted
EDM process developments which have been
developed to provide the better surface finish
and good quality products at the lower cost.

b) It is found that both the electrical and non-
electrical parameters play an important role in
the performance of EDM process but some
studies reported that non-electrical parameters
are main parameters which affects the surface
quality of the product.

c) It is also found that there are lots of
improvement in the optimization techniques but
the objective is same for all the optimization
techniques to improve the EDM performance, to
get the desired output from the input and to
develop some new hybrid techniques to
machine new materials under the better
working conditions.
Fig -8. Procedure of Bee Colony Optimization

d) Through the recent developments and
4.6 Fuzzy set theory
optimization techniques used in the EDM
processes minimize the tool wear rate,
Fuzzy logic is introduced by Lotfi Zadeh and
maximize the material removal rate and
Dieter Klaua in 1965, Fuzzy logic is a mathematical
improves the surface quality.
theory that allows a user to model the reasoning process
of human in the linguistic terms [153-154]. The values of
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International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 05 Issue: 02 | Feb-2018 www.irjet.net p-ISSN: 2395-0072

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