projects mech 35-36-5
DESCRIPTION
proyectoTRANSCRIPT
College of Engineering
Mechanical Engineering Department
Machiningof Complex Shape Design
by Electrical Discharge Machining
Process
A Senior Project report submitted in partial fulfillment of the Requirement for the degree of Bachelor of Science (B.Sc.),
InMechanicalEngineering.
By
Team Members: 1-Fahad Ali Sharahily(200910648)
2-Fahad Ali dahgriry (200911527)
3-Bandar SalehAlamri(200801150)
4-Moath Hassan Gadi(200801274)
5- Abdullah MohmmedGissy (200922254)
PROJECT ADVISOR:
Associate Prof.Helmi Mahmoud Osman Abolila
(Completion Date7/1435)
College of Engineering
Mechanical Engineering Department
Machining of complex shape design by electrical discharge machining process
APPROVAL RECOMMENDED:
_______________________________
PROJECT ADVISOR
_______________________________
DATE
_______________________________
DEPARTMENT HEAD
________________________________
DATE
______________________________
COURSE INSTRUCTOR
______________________________
DATE
Examination Committee
___________________________
___________________________
___________________________
APPROVED: DEAN, COLLEGE OF ENGINEERING _____________________________________
DATE ____________________________________
ABSTRACT
Machining of Complex Shape Design by Electrical Discharge Machining Process
The newly developed machining processes are often called modern
machining processes or non-traditional machining processes (NTMP). In EDM,
the removal of material is based upon the electro discharge erosion (EDE) effect
of electric sparks occurring between two electrodes that are separated by a
dielectric liquid. Metal removal takes place as a result of the generation of
extremely high temperatures generated by the high intensity discharges that melt
and evaporate the two electrodes.
Recently, the machining speed has gone up by 20 times, which has
decreased machining costs by at least 30 percent and improved the surface
finish by a factor.
The correct selection of manufacturing conditions is one of the most important
aspects totake into consideration in the majority of manufacturing processes and,
particularly, in processesrelated to Electrical Discharge Machining (EDM). It is a
capable of machining geometricallycomplex or hard material components, that
are precise and difficult-to-machine such as heattreated tool steels, composites,
super alloys, ceramics, carbides, heat resistant steels etc. beingwidely used in
die and mold making industries, aerospace, aeronautics and nuclear industries.
i
DEDICATION
I would like to dedicate this Bachelor dissertation to my family and all members of
a community. There is no doubt in my mind that without his continued support
and counsel I could not have completed this process.
ii
ACKNOWLEDGEMENT
First we would like to acknowledge the continuous help and guidanceofAllah
through our life.We express our deep sense of gratitude and indebtedness to our
project supervisorAssoc. Prof. Helmi Mahmoud Osman Abulila, Associate
Professor, Department of Mechanical Engineering for providing
preciousguidance, inspiring discussions and constant supervision throughout this
work. Histimely help, constructive criticism, and conscientious efforts made it
possible to present the work contained in this project.
We are grateful to Head of the Department of Mechanical Engineering for
providing me the necessary facilities in the department. Weare also thankful to all
the staff membersof the department of Mechanical Engineering and to all our well
wishers for their inspiration andhelp. Grateful acknowledgement is made to out
mechanical engineeringprofessors and all members the college of engineering,
JazanUniversity.
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TABLE OF CONTENTS
PAGE
ABSTRACT…………………………………………………….…………………………i
DEDICATION…………………………………………………………………….………ii
ACKNOWLEDGEMENT………………………………………………..…….…….....iii
ABLE OF CONTENTS…………………………………………….....……...………...iv
LIST OF FIGURES ……………………………………………..….………………....vi
LISTOFTABLES………….………………………..…..…………..…..…..………..vii
NOMENCLATURE ……………...……………………….…………..…….……...…viii
CHAPTER1.Literature Review
1.1Introduction……………….………………….…………………………………....…1
1.2 Problem Statement Objective ………………….……………..……………..…..3
1.3 Problem justification and Outcomes……………………………………...….....3
1.4 Problem Constraints……………….………………………………………...……..3 CHAPTER 2.DESIGN APPROACH AND METHODOLOGY
2.1 Design approach…………………………….………..………………………..…..4
2. 2 Design Methodology …………………………….…..…………………….......…9
2.2.1 EDM Electrodes…………………...…………………………………….…......10
2.2.2 Dielectric Fluids……………………….…………………………………...……13
2.2.3 Material Removal Rates……………………………….…………………….…14
2.2.4 Surface Integrity…………………………...………………….……………..…17
2.2.5 EDM Heat-Affected Zone…………………………………………..…….….…19
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PAGE
CHAPTER 3. THEORETICAL BACKGROUND
3.1 Design specifications and assumptions…….………………….….….....……21
3.1.1 Transistorized Pulse Generator Circuits………………..………………...…21
3.1.2 EDM-Tool Electrodes…...……...……………....………...….........……..…22
3.1.3 Design of tool electrodes for workpiece…...……...………………………..24
3.2 Mathematical Models and Formulations…...……...…………...….....…..…...25
3.2.1: EDM-Spark Circuits…...……...……......……...……………………...……...25
3.2.2: Resistance-Capacitance Circuit …...………........................…...……...….25
CHAPTER 4. RESULTS AND DISSCUSION
4.1Design of work program for machining Procedures …………………...…..…27
4.2Design Implementation………………………………………….…………….….32
4.2.1 The project………………….…………………..…………..........................…32
4.2.3 Other formshave been designed………………....….…….……….….….….32
CHAPTER 5. FEASIBIILITY STUDIES AND MARKET NEEDS…………....…..33
CHAPTER 6. CONCLUSION AND RECOMMENDATIONS
6.1 Conclusion …………………………………………………………….…………..34
6.2 Recommendations…..………………………………….………………….……..34
6.3Reference………………….…………………………………………..…………35
6.4 Capstone Design Project……………………….………………………………..36
v
LIST OF FIGURES
FIGURE No DESCRIPTION PAGE FIGURE 1.1: Nontraditional Machining Processes.
FIGURE 1.2:contour cutting process
FIGURE 2.1:Electrical Discharge Machine
FIGURE 2.2:Schematic of EDM Process
FIGURE 2.3:Typical EDM Pulse Current Train for Controlled Pulse Generator
FIGURE 2.4:Variation of Voltage with Time Using an RC Generator
FIGURE 2.5:Voltage and Current Waveforms during EDM
FIGURE 2.6: EDM Spark
FIGURE 2.7:EDM Spark Description
FIGURE 2.8:Periodic Discharges Generator
FIGURE 2.9: EDM Schematic
FIGURE 2.10:EDM System Components
FIGURE 2.11: Types of Electrode Wear in EDM
FIGURE 2.12: Corner Wear Ratios for Different Electrode Materials
FIGURE 2.13: Common Dielectric Flushing Modes
FIGURE 2.14: Parameters Affecting EDM Performance
FIGURE 2.15: EDM Removal Rates and Roughness for Different Materials
FIGURE 2.16: Effect of Pulse Current on Removal Rate.
FIGURE 2.17: Effect of Pulse ON-Time on Removal Rate.
FIGURE 2.18: EDM Heat Affected Zones.
FIGURE 3.1:Pulse generators of Charmilles Technologies
FIGURE 3.2:Shape of Workpiece.
FIGURE 3.3:Shape of Workpiece.
FIGURE 3.4:(a) RC circuit and (b) capacitor voltage-charging
time exponential relationship.
FIGURE 4.1:EDM used in the process
FIGURE 4.2:Select material
FIGURE 4.3: Select contact area
FIGURE 4.4: Select operation type
FIGURE 4.5: Select of difficulty
FIGURE 4.6: Input Z value
FIGURE 4.7:Specify the number of layers
FIGURE 4.8:The project
FIGURE 4.9: Other project
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LIST OF TABLES TABLE No DESCRIPTION PAGE TABLE 2.1: Electrode Polarities for Different Workpiece Materials.11
TABLE 3.1: Polarity for Most Common Electrode/WP Material Combinations23
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NOMENCLATURE
Symbols DESCRIPTION UNITS 𝜶Tool feed rate mm/min
D EDM depth mm
D/LcCorner wear ratio mm
D/LeEnd wear ratio
D/LsSide wear ratio
dtTool diameter mm
evNumber of pulses
F Frequency of oscillation Hz
I EDM current A
KhConstantμm/μJ
PrPulse power W
Qv Volumetric removal rate mm3/min
Ra Surface roughnessμm
TrRatio of workpiece to tool electrode melting points
TtMelting point of tool electrode°C
TwMelting point of workpiece material °C
V Gap voltage V
VeVolume of electrode consumed mm3
VgGrinding wheel penetration speedmm3/min
VRRMaterial removal ratemm3/min
VsMachining ratemm2/min
VwVolume of workpiece removed mm3
Vw / VeVolume wear ratio
W Pulse energyμJ
Wt Wear rate of toolmm3/min
X, Y, ZWorkpiece coordinates mm
viii
CHAPTER1
Literature Review
CHAPTER 1
1. Literature Review 1.1- introduction The nontraditional machining methods (NTMP) Figure1.1 are classified according
to the number of machining actions causing the removal of material from the
workpiece.NTMP are generally classified according to the type of energy utilized
in material removal as shown in Figure 1.2. They are classified into the following
three main groups:
1- Mechanical processes. In these, the material removal depends on mechanical
abrasion or shearing.
2- Chemical and EC processes. In chemical processes, the material is removed
In layers due to ablative reaction where acids or alkalis are used as etchants.
3-The ECM is characterized by a high removal rate. The machining action is due
To anodic dissolution caused by the passage of high-density dc current in the
machining cell.
4- Thermoelectric processes. In these, the metal removal rate depends upon the
thermal energy acting in the form of controlled and localized power pulses
leading to melting and evaporation of the work material.
FIGURE1.1: Nontraditional Machining Processes.
1
The history of electrodischarge machining (EDM) dates back to the days of World
Wars I and II when invented the relaxation circuit (RC). Using a simple servo
controller they maintained the gap width between the tool and the workpiece,
reduced arcing, and made EDM more profitable.
Since 1940, die sinking by EDM has been refined using pulse generators,
planetary and orbital motion techniques, computer numerical control (CNC), and
the adaptive control systems During the 1960s the extensive research led the
progress of EDM when numerous problems related to mathematical modeling
were tackled.
The evolution of wire EDM in the 1970s was due to the powerful generators, new
wire tool electrodes, improved machine intelligence, and better flushing.
Recently, the machining speed has gone up by 20 times, which has decreased
machining costs by at least 30 percent and improved the surface finish by a
factor of EDM has the following advantages:
1. Cavities with thin walls and fine features can be produced.
2. Difficult geometry is possible.
3. The use of EDM is not affected by the hardness of the work material.
4. The process is burr-free.
FIGURE. 1.2:Contour Cutting Process
2
1.2: Problem Statement Objective In modern machining practice, harder, stronger, and tougher materials that are
more difficult to cut are frequently used. More attention is, therefore, directed
toward machining processes where the mechanical properties of the workpiece
material are not imposing any limits on the material removal process. In this
regard, the Electrical Discharge Machining techniques came into practice as a
possible alternative concerning machinability, shape complexity, surface integrity,
and miniaturization requirements. Innovative machining techniques or
modifications to the existing method by combining different machining processes
were needed.
1.3: Problem justification and Outcomes
EDM has become an indispensable process in the modern manufacturing
industry. It produces complex shapes to a high degree of accuracyin difficult-to-
machine materials such as heat-resistant alloys, super-alloys, and carbides. The
incorporation of EDM within a computer-integrated manufacturing (CIM) system
reduced the length of time thatthe unit operation, without stops for maintenance,
is required.Micro-machining of holes, slots, and dies; procedures for surface
deposition; modification; texturing; milling; and mechanical pulsing are typical
applications.For a while, there were trends toward reducing the workpiece size
and dimensions after it became possible to drill ultra-small-diameter holes (10–
100 µm) in hard materials using the available machining processes.
1.4: Problem Constraints The process solves the problem of manufacturing accurate andcomplex-shaped
electrodes for die sinking of three-dimensional cavities. EDM milling enhances
dielectric flushing due to thehigh-speed electrode rotation. The electrode wear
can be optimizedbecause of the rotational and contouring motions of the
electrode. Themain limitation in the EDM milling is that complex shapes with
sharpcorners cannot be machined because of the rotating tool electrode.These
numerous andtime-consuming steps are greatly reduced using EDM milling.
EDM milling also replaces the conventional die making thatrequires the use of a
variety of machines such as milling, wire cutting,and EDM die sinking machines.
3
CHAPTER 2
DESIGN APPROACH AND METHODOLOGY
CHAPTER 2
2. DESIGN APPROACH AND METHODOLOGY 2.1: Design approach In EDM, the removal of material is based upon the electro discharge erosion
(EDE) effect of electric sparks occurring between two electrodes that are
separated by a dielectric liquid as shown in Figure 2.1 and Figure 2.2. Metal
removal takes place as a result of the generation of extremely high temperatures
generated by the high intensity discharges that melt and evaporate the two
electrodes.
FIGURE 2.1: Electrical Discharge Machine
4
FIGURE 2.2: Schematic of EDM Process
A series of voltage pulses (Figure 2.3) of magnitude about 20 to 120 V and
frequency on the order of 5 kHz is applied between the two electrodes, which are
separated by a small gap, typically 0.01 to 0.5 mm.
FIGURE 2.3: Typical EDM Pulse Current Train for Controlled Pulse Generator.
When using RC generators, the voltage pulses, shown in Figure 2.4, are
responsible for material removal. The application of voltage pulses, as shown in
Figure 2.5, causes electrical breakdown to the dielectric in a channel of radius 10
μm. The breakdown arises from the acceleration toward the anode of both
electrons emitted from the cathode by the applied field and the stray electrons
present in the gap. These electrons collide with neutral atoms of the dielectric,
5
thereby creating positive ions and further electrons, which in turn are accelerated
respectively toward the cathode and anode.
When the electrons and the positive ions reach the anode and cathode, they give
up their kinetic energy in the form of heat. Temperatures of about 8000 to
12,000°C and heat fluxes up to 1017 W/m2 are attained. With a very short
duration spark of typically between 0.1 to 2000 μs the temperature of the
electrodes can be raised locally to more than their normal boiling points.
FIGURE 2.4: Variation of Voltage with Time Using an RC Generator.
FIGURE 2.5: Voltage and Current Waveforms during EDM. 6
Owing to the evaporation of the dielectric, the pressure on the plasma channel
rises rapidly to values as high as 200 atmospheres. Such great pressures
prevent the evaporation of the superheated metal. At the end of the pulse, the
pressure drops suddenly and the superheated metal evaporates explosively.
Metal is thus removed from the electrodes as shown in Figure 2.6 and Figure 2.7.
Fresh dielectric fluid rushes in, flushing the debris away and quenching the
surface of the workpiece. Unexpelled molten metal solidifies to form what is
known as the recast layer. The expelled metal solidifies into tiny spheres
dispersed in the dielectric liquid along with bits from the electrode. The remaining
vapor rises to the surface. Without a sufficient off time, debris would collect
making the spark unstable. This situation creates an arc, which damages the
electrode and the workpiece.
FIGURE 2.6: EDM Spark
FIGURE 2.7: EDM Spark Description.
7
The relation between the amount of material removed from the anode and
cathode depends on the respective contribution of the electrons and positive ions
to the total current flow. The electron current predominates in the early stages of
the discharge. Since the positive ions are roughly 104 times more massive than
electrons, they are less easily mobilized than the electrons. Consequently the
erosion of the anode workpiece should be greater than that of the cathode. At the
end of the EDM action, the plasma channel increases in width, and the current
density across the inter-electrode gap decreases. With the fraction of the current
due to the electrons diminishing, the contributions from the positive ions rise, and
proportionally more metal is then eroded from the cathode.The high frequency of
voltage pulses supplied, together with theforward servo-controlled tool motion,
toward the workpiece, enables sparking to be achieved along the entire length of
the electrodes. Figure 2.6 shows the voltage and current waveforms during EDM.
Figure 2.8 shows the periodic discharges occurring when using an RC generator
in EDM. The frequency of discharges or sparks usually varies between 500 and
500,000 sparks per second. With such high sparking frequencies, the combined
effects of individual sparks provide a substantial material removal rate.
FIGURE 2.8: Periodic Discharges Generator.
The position of the tool electrode is controlled by the servomechanism, which
maintains a constant gap width (200–500 μm) between the electrodes in order to
increase the machining efficiency through active discharges. EDM performance
measures such as material removal rate, electrode tool wear, and surface finish,
for the same energy, depends on the shape of the current pulses. Based upon
8
the situation in the inter-electrode gap, four different electrical pulses are
distinguished, namely, open circuit pulses, sparks, arcs, and short circuits. They
are usually defined on the basis of time evolution of discharge voltage and/or
discharge current. Their effect upon material removal and tool wear differs quite
significantly. Open gap voltages that occur when the distance between both
electrodes is too large obviously do not contribute to any material removal or
electrode tool wear. When sudden contact occurs between the tool and
workpiece, micro short circuits occur, which do not contribute to the material
removal process. The range of the electrode distance between these two
extreme cases forms the practical working gap for actual discharges, i.e., sparks
and arcs.
2.2: Design Methodology Figures 2.9and 2.10 show the main components of the EDM system. These components
include the tool feed servo-controlled unit, which maintains a constant machining gap
that ensures the occurrence of active discharges between the two electrodes. The power
supply is responsible for supplying pulses at a certain voltage, current, on time, and off
time. The dielectric circulation unit flushes the dielectric fluid to the interelectrode gap
after being filtered from the machining debris.
FIGURE 2.9: EDM Schematic.
9
FIGURE 2.10: EDM System Components.
2.2.1: EDM Electrodes Material. Metals with a high melting point and good electrical conductivity are
usually chosen as tool materials for EDM. Graphite is the most common
electrode material since it has fair wear characteristics and is easily machinable
and small flush holes can be drilled into graphite electrodes. Copper has good
EDM wear and better conductivity. It is generally used for better finishes in the
range of 0.5 μmRa. Copper tungsten and silver tungsten are used for making
deep slots under poor flushing conditions especially in tungsten carbides. It offers
high machining rates as well as low electrode wear. Copper graphite is good for
cross-sectional electrodes. It has better electrical conductivity than graphite while
the corner wear is higher. Brass ensures stable sparking conditions and is
normally used for specialized applications such as drilling of small holes where
the high electrode wear is acceptable.
Movements. In addition to the servo-controlled feed, the tool electrode may have
an additional rotary or orbiting motion. Electrode rotation helps to solve the
flushing difficulty encountered when machining small holes with EDM. In addition
to the increase in cutting speed, the quality of the hole produced is superior to
that obtained using a stationary electrode. Electrode orbiting produces cavities
10
having the shape of the electrode. The size of the electrode and the radius of the
orbit (2.54-mm max.) determines the size of the cavities. Electrode orbiting
improves flushing by creating a pumping effect of the dielectric liquid through the
gap.Polarity. Electrode polarity depends on both the workpiece and electrode
materials. Table 2.1 shows the possible electrode polarity for different workpiece
and tool combinations.Electrode wear. The melting point is the most important
factor in determining the tool wear. Electrode wear ratios are expressed as end
wear, side wear, corner wear, and volume wear as shown in Figure 2.11. The
term no wear EDMoccurs when the electrode-to-workpiece wear ratio is 1
percent or less. Electrode wear depends on a number of factors associated with
the EDM, like voltage, current, electrode material, and polarity. The change in
shape of the tool electrode due to the electrode wear causes defects in the
workpiece shape.
TABLE2.1: Electrode Polarities for Different Workpiece Materials.
Electrode wear has even more pronounced effects when it comes to
micromachining applications. As can be seen from Figure 2.12 the corner ratio
depends on the type of electrode. The low melting point of aluminum is
associated with the highest wear ratio. Graphite has shown a low tendency to
wear and has the possibility of being molded or machined into complicated
electrode shapes. The wear rate of the electrode tool material Wtand the wear
ratio Rw, are described by:
Wt= (11 × 103)iTt–2.38
Rw= 2.25 Tr–2.3
where Wt= wear rate of the tool, mm3/min
I= EDM current, A
Tt= melting point of the tool electrode, °C
Tr= ratio of the workpiece to tool electrode melting points
11
FIGURE 2.11: Types of Electrode Wear in EDM.
FIGURE 2.12: Corner Wear Ratios for Different Electrode Materials.
12
2.2.2: Dielectric Fluids The main functions of the dielectric fluid are to
1. Flush the eroded particles from the machining gap
2. Provide insulation between the electrode and the workpiece
3. Cool the section that was heated by the discharging effect
The main requirements of the EDM dielectric fluids are
1- adequate viscosity,
2- high flash point,
3- good oxidation stability,
4- minimum odor,
5- low cost,
6- good electrical discharge efficiency.
For most EDM operations kerosene is used with certain additives that
prevent gas bubbles and doddering. Silicon fluids and a mixture of these fluids
with petroleum oils have given excellent results. Other dielectric fluids with a
varying degree of success include aqueous solutions of ethylene glycol, water in
emulsions, and distilled water. Flushing of the dielectric plays a major role in the
maintenance of stable machining and the achievement of close tolerance and
high surface quality. Inadequate flushing can result in arcing, decreased
electrode life, and increased production time. Four methods of introducing
dielectric fluid to the machining gap are considered at.
Normal flow. In the majority of EDM applications, the dielectric fluid is introduced,
under pressure, through one or more passages in the tool and is forced to flow
through the gap between the tool and the workpiece. Flushing holes are
generally placed in areas where the cuts are deepest. Normal flow is sometimes
undesirable because it produces a tapered opening in the workpiece as shown in
Figure 2.13.
Reverse flow. This method is particularly useful in machining deepcavity dies,
where the taper produced using the normal flow mode can be reduced. The gap
is submerged in filtered dielectric, and instead of pressure being applied at the
source a vacuum is used. With clean fluid flowing between the workpiece and the
tool, there is no side sparking and, therefore, no taper is produced as shown in
Figure 2.13.
Jet flushing. In many instances, the desired machining can be achieved by using
a spray or jet of fluid directed against the machining gap. Machining time is
always longer with jet flushing than with the normal and reverse flow modes.
Immersion flushing. For many shallow cuts or perforations of thin sections,
simple immersion of the discharge gap is sufficient. Cooling and machining
debris removal can be enhanced during immersion cutting by providing relative
motion between the tool and workpiece. Vibration or cycle interruption comprises
13
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periodic reciprocation of the tool relative to the workpiece to effect a pumping
action of the dielectric fluid. Synchronized, pulsed flushing is also available on
some machines. With this method, flushing occurs only during the non-machining
time as the electrode is retracted slightly to enlarge the gap. Increased electrode
life has been reported with this system. For proper flushing conditions, the
following was recommended:
1. Flushing through the tool is more preferred than side flushing.
2. Many small flushing holes are better than a few large ones.
3. Steady dielectric flow on the entire workpiece-electrode interface is desirable.
4. Dead spots created by pressure flushing, from opposite sides of the
workpiece, should beavoided.
5. A vent hole should be provided for any upwardly concave part of the tool-
electrodeto prevent accumulation of explosive gases.
6. A flush box is useful if there is a hole in the cavity.
FIGURE 2.13: Common Dielectric Flushing Modes.
2.2.3: Material Removal Rates In EDM the metal is removed from both the workpiece and the tool electrode. As
can be seen from Figure 2.14, the material removal rate depends not only on the
workpiece material but on the material of the tool electrode and the
14
machining variables such as pulse conditions, electrode polarity, and the
machining medium. In this regard a material of low melting point has a high metal
removal rate and hence a rougher surface. Typical removal rates range from 0.1
to 400 mm3 /min. The results of Figure 2.15 quote machining rates and surface
roughness for different materials. Figures 2.8and 2.9 explain the effect of pulse
energy (current) and duration on the crater size and hence the removal rate. The
material removal rate, or volumetric removal rate (VRR), in mm3/min, was
described by:
VRR = (4 × 104)iTw–1.23
Where Iis the EDM current (A) and Twis the melting point of the work.
FIGURE 2.14: Parameters Affecting EDM Performance.
15
Explain:
FIGURE 2.15: EDM Removal Rates
16
2.2.4: Surface Integrity The spark-machined surface consists of a multitude of overlapping crates that
are formed by the action of microsecond-duration spark discharges. These
craters depend on the physical and the mechanical properties of the material and
the composition of the machining medium as well as on the discharge energy
and duration as shown in Figures 2.16 and 2.17. The integral effect of many
thousands of discharges per second leads to the formation of the corresponding
workpiece profile with a specified accuracy and surface finish. The depth of the
resulting craters usually represents the peak to valley (maximum) surface
roughness Rt. The maximum depth of the damaged layer can be taken as 2.5
times the average surface roughness Ra. The maximum peak to valley height, Rt,
was considered to be 10 times Ra. The average roughness can be expressed in
terms of pulse current ip (A) and pulse duration tp(μs) by
Ra= 0.0225 ip0.29 tp
0.38
Figure 2.16: EDM Roughness for Materials.
17
The machined surface roughness, which is formed by mutual overlap of
craters, is a third of the crater depth. Hence,
Ra = (K2W0.33)/12
where Kh= 0.4 to 0.75 μm/μJ0.33 and W is the pulse energy (μJ).
Surface roughness increases linearly with an increase in the material
removal rate. The graphite electrodes produce rougher surfaces than metal ones.
The crater volume/metal removal per discharge to surface roughness Hrms while
other expressed the roughness in terms of the frequency of pulses fpand power
Prby
Hrms = 267 (Pr/fp)0.258
Also that as the pulse energy is decreased, the surface finish improves and
consequently, the depth at which all formed craters disappear from the machined
surface (free polishing depth) is reduced. This depth was found to lie between 3
to 6 times Hrms and is important when polishing dies and molds and when the
residual stresses are to be removed from the machined surfaces. Accordingly, a
reduction of surface roughness from 22 μmRmax to 8 μm has been reported
together with the removal of the heat-affected layer. In contrast, the matte
appearance of the machined surfaces has been found satisfactory in some
applications of electrodischarge texturing (EDT). The introduction of oxygen gas
into the discharge gap provides extra power by the reaction of oxygen, which in
turn increased the melting of the workpiece and created greater expulsive forces
that increased the metal removal rate and surface roughness. When EDM is
used for cusp removal, the silicon powder has been suspended in the working
fluid, during the stage of finish EDM. Consequently, a change of surface
roughness from 45 μm to 10 μmRmax. The choice of the correct dielectric flow, in
the gap, has a significant effect in reducing the surface roughness by 50 percent,
increasing the machining rate, and lowering the thermal effects in the workpiece
surface. The recommended dielectrics having low viscosity for EDM of smooth
surfaces. For Al-Li alloys, the tensile strength of the machined parts are reduced
by increased surface roughness. This reduction was enhanced by increased
pulse current. The heat-affected layer reached 200 μm compared to 80 μm for
steel due to deference in their thermal conductivity. Normal tolerances are about
±25 μm with ±5 μm obtained by proper choice of process variables.
18
FIGURE2.17: Effect of Pulse Current on Removal Rate and Surface Roughness.
2.2.5: EDM Heat-Affected Zone With the temperature of the discharges reaching 8000 to 12,000°C, metallurgical
changes occur in the surface layer of the workpiece. Additionally a thin recast
layer of 1 μm at 5- μJ powers to 25 μm at high powers is formed. The heat-
affected zone adjacent to the re-solidified layer reaches 25 μm. Some annealing
of the workpiece can be expected in a zone just below the machined surface. In
addition, not all the workpiece material melted by the discharge is expelled into
the dielectric. The remaining melted material is quickly chilled, primarily by heat
conduction into the bulk of the workpiece, resulting in an exceedingly hard
surface. The depth of the annealed layer is proportional to the amount of power
used in the machining operation. It ranges from 50 μm for finish cutting to
approximately 200 μm for high metal removal rates. The amount of annealing is
usually about two points of hardness below the parent metal for finish cutting. In
the roughing cuts, the annealing effect is approximately five points of hardness
below the parent metal (Figure 2.18).
Choosing electrodes that produce more stable machining can reduce the
annealing effect. A finish cut removes the annealed material left by the previous
19
high-speed roughing. The altered surface layer, which is produced during EDM,
significantly lowers the fatigue strength of alloys. The altered layer consists of a
recast layer with or without micro-cracks, some of which may extend into the
base metal, plus metallurgical alterations such as re-hardened and tempered
layers, heat-affected zones, and inter-granular precipitates. Generally, during
EDM roughing, the layer showing micro structural changes, including a melted
and re-solidified layer, is less than 0.127 mm deep, while during EDM finishing, it
is less than 0.075 mm. Posttreatment to restore the fatigue strength is
recommended to follow EDM of critical or highly stressed surfaces. There are
several effective processes that accomplish restoration or even enhancement of
the fatigue properties.
FIGURE 2.18: EDM Heat Affected Zones.
20
CHAPTER 3
THEORETICAL BACKGROUND
CHAPTER 3
3.THEORETICAL BACKGROUND
3.1 Design specifications and assumptions
3.1.1 Transistorized Pulse Generator Circuits Among the disadvantages of the RC relaxation circuits are interdependence
(lack of control of parameters), the restricted choice of electrode material, and
their high wear rate. The adoption of the transistorized pulse generators in the
1960s allowed the process parameters (frequency and energy of discharges) to
vary with a greater degree of control, in which charging takes only a small portion
of the cycle. Furthermore, the voltage of these machines is reduced to 60–80 V
range, permitting low discharge current pulses of a square profile. This results in
shallower and wider craters, which means better surface texture. Alternatively,
when required, they provide high MRRs at the expense of surface quality by
permitting high discharge currents. Moreover, this type of generators provide
considerably lower electrode wear as compared to simpler RC circuits.
In the simple form of the transistorized pulse generators, the parameters are
selected and pre-adjusted according to the machining duty. The selected
parameters remain constant; that is, not influenced by the variation of working
conditions in the gap during machining.
An improved circuit incorporating feedback is illustrated in Figure 3.1. In
such a circuit, the conditions into the spark gap are monitored by a detector unit,
which determines the exact moment of current flow after the ignition lag. The
time base for the on-time then becomes effective, providing a constant discharge
period. The time base for the off-time ensures a constant interval for deionization
and flushing away the debris by the dielectric. The following are the
specifications of a typical pulse generator, 25 A.
______________________________________________________________
Power. 2 kW
Open gap voltage. 80 V
Discharge energy. 0.18–1 J
Maximum discharge current. 25 A
Discharge duration. Off-time 2–1600 µs; on-time 2–1600 µs
Achieved roughness. Ra = 0.4 µm
21
FIGURE 3.1: Pulse generators of Charmilles Technologies.
3.1.2: EDM-Tool Electrodes In ED sinking, electrodes are often the most expensive part of an EDM
operation. Most electrodes for EDM are usually made of graphite, although
brass, Cu, or Cu/W-alloys may be used. These electrodes are shaped by
forming, casting, and powder metallurgy, or, frequently, by machining. EDM tool
wear is an important factor, as it affects the dimensional and form accuracy. It is
related to melting point of the tool material involved-the higher the melting point,
the lower the wear rate. Consequently, graphite electrodes have the highest wear
resistance, as graphite has the highest melting point of any known material
(3600°C); moreover, it is low in cost and readily fabricated. Tungsten (3400°C),
and W alloys are next in melting temperature, followed by molybdenum (2600°C);
however, these metals are expensive and difficult to fabricate. The tool wear can
be minimized by reversing the polarity, which depends on the tool/WP
combination. Table 3.1 illustrates the recommended polarity for various
electrode/WP material combinations.
22
TABLE 3.1: Polarity for Most Common Electrode/WP Material Combinations
WP Material Electrode Material
Graphite Cu Cu–W
Steel SR S S
Cu R R R
Cemented carbide R SR SR
Al S S S
Ni-base alloys SR S S
Note: S-straight polarity (WP positive electrode)
and R-reverse polarity (WP Negative electrode).
The wear may reach a zero value during the so-called no-wear EDM process.
Work material machinable by no-wear EDM can be steels, satellites, Ni-base
alloys, and aluminum. However, no-wear EDM is not recommended for
machining carbides. No wear EDM requires pulse generators and equipment
capable of attaining the following conditions:
1- Reverse polarity of the tool electrode.
2- Low-pulse frequency ranging from 0.4 to 20 kHz. (2 kHz is recommended).
3- Graphite, Cu, Cu/W, or Ag/W electrodes.
4- High duty cycle of more than 90%.
5- High-intensity discharge current.
6- Smooth control of servomechanism.
7- Supply voltage of not more than 80 V.
8- Temperature of dielectric of not above 40°C, and dielectric recycled at low
pressure
23
3.1.3: Design of tool electrodes for different shape of workpiece
Design of tool electrode from cupper is made to produce the following workpiece
as shown in Figure 3.2 and Figure 3.3.
FIGURE 3.2: Shape of Workpiece.
FIGURE 3.3: Shape of tool.
24
3.2 Mathematical Models and Formulations 3.2.1: EDM-SparkCircuits (Power Supply Circuits) The ED machine is equipped with a spark-generating circuit that can be
controlled to provide optimum conditions for a particular application. This
generator should supply voltage adequate to initiate and maintain the discharge
process, and provides necessary control over the process parameters such as
current intensity, frequency, and cycle times of discharge. The cycle time ranges
from 2 to 1600 µs. Two main types of generators are applicable for this purpose.
These are the resistance-capacitance generator (RC circuit) and the
transistorized pulse generator.
3.2.2: Resistance-Capacitance Circuit It is also called the Lazerenko circuit, which is basically a relaxation oscillator. It
is simple, reliable, rigid, low-cost power source that is ordinarily used with copper
or brass electrodes. It provides a fine surface texture of 0.25 µm Ra, but the
machining rate is slow, because the time required to charge the capacitors
prevents the use of high frequencies. The relaxation circuit operates at
selectively high input voltages and is difficult to operate. The reversed polarity
encountered in a relaxation circuit leads to an additional tool wear.
The basic form of the RC circuit is shown in Figure 3.4a. On commencing
operation, the capacitor is in the uncharged condition. Then it is charged with a
dc voltage source Vo usually 200–400 V, via the resistor R, which determines the
charging rate. The capacitor voltage Vcincreases exponentially as charging
proceeds (Figure3.4b).
Vc = Vo(1 − e−t /RC )
where,
t = time (s)
RC = time constants = resistance ( Ω) × capacitance (Farad)
When Vcattains the level of breakdown voltage Vsexisting in the working gap, the
capacitor charges across the gap eroding both WP (causing material removal)
and the tool electrode (causing wear). The spark is not sustained, because the
capacitance is discharged more quickly than it can recharge via the resistor,
td = 0.1 tc
where,
tc = charging time
td = discharging time
25
The cycle charging and discharging is repeated until the cut is performed.
For maximum production rate:
Vs = 0.73 Vo
The energy of each individual spark discharge in joule is given by
Ed= ½ CV s2
Therefore, the increase in Vo, Vs, and C leads to an increase in machining rate;
however, it leads to
poor surface texture.
A reduction of Vs enables a smaller gap to be used, improving finish and
accuracy, but reducing machining rate. High rates of machining are obtained by
reducing the time constant RC to give rapid charging. However, as R is
reduced, the frequency increases and may reach a point at which deionization is
prevented from taking place and arcing occurs. Arcing causes effective
machining to cease and creates thermal damage to the machined surface. It
follows that in an RC circuit, the machine setting for optimum performance in a
given set of machining conditions involves a compromise in selecting the process
parameters.
FIGURE 3.4: (a) RC circuit and (b) capacitor voltage-charging time exponential relationship.
26
CHAPTER 4
RESULTS AND DISSCUSION
CHAPTER 4
4. RESULTS AND DISSCUSION
4.1 Design of work program for machining Procedures
How to implement a program on the EDM as shown in Figure 4.1?
1- the operating of the machine is through opening the behind button and
releasing the emergency button ,then the following message will appear on the
screen (press any key to start ) then press (Enter) the screen will appear .
FIGURE 4.1: EDM used in the process
2- the axes X &Y are to be reset after the adjustment of the electrode and
moving it on the plate used in drilling and keeping it away from the fixing place ,
adjust the lock to make sure that it is fixed well with regard to axes X & Y and
then we press on ( F9) button , then the axe X will be red colored , after that we
press the button ( F4 ) until X=0 and its color change into blue .
27
3- to reset the axe Y we move the pointer to the bottom using the triangled
buttons on the control panel (+) then Y will appear in red color and then we
press ( F4 ) until Y =0 be blue .
4- to adjust the axe Z we press ( F9 ) the head will automatically move toward the
(w.p), when we hear ringing sound in the machine we press ( F2 ) to come in
contact with (w.p) then we press ( F4 ) until Z=0 . if Z is still red colored then we
press ( ESC ) button to get X , Y and Z in blue color and each of them equal
zero.
5- We raise the head ( axe Z ) up to a distance of 1.5-2 mm using Z+ button on
the head ,Then we press ( ESC )
7- We start implementing the program by ( F6)(easy logic) , a table contains the
electrodes types will appear with the metal we want to use , for example (cu)
electrode with steel, and so on according to the electrode type and the metal
used in drilling , as shown FIGURE 4.2and we select the first choice .
FIGURE 4.2:Select material
8- Then we press ( NEXT ) on the table by using the small triangles on the
control panel to open the dialogue column in front of number 1 in the previous
table , then another table will appear which contains the diameter of the used
electrode then we select from 60-80 mm as shown FIGURE 4.3. select of contact
area.
28
FIGURE 4.3: Select contact area
9- And then we press on 20-80 mm , then a third table will appear writing on it
machining , then we select ( medium wear) which written in the beginning of
the table . as shown FIGURE 4.4select of operation type.
FIGURE 4.4: Select operation type
10 - Then we press in front of ( medium wear ) column in the third table , a fourth table
will appear written on it ( difficulty ) then we select (low ) . as shown figure4.5select of
difficulty.
29
FIGURE 4.5: Select of difficulty
11- Then we press ( enter ) , a table will appear on which we move to the bottom
until we reach the bottom of ( Z ) column which refers to the depth up to which
we will reach in the (w.p) for example ( - 2 ) or any number we want which will be
written in negative because we moving down then we press ( enter ) as shown
FIGURE 4.6 .
FIGURE 4.6: Input Z value
12- Then we press ( F4 ) , we will be asked for the number of layers we want to
select , at the end of the previous table . in front of this sentence (copy this line
to block 1-50) we write ( 1 ) and then press ( enter ) .
13- Another request will appear by (yes ) or (no) we select (yes) by writing ( 1 )
then we press ( enter ) as shown FIGURE 4.7.
30
FIGURE 4.7: Specify the number of layers
14 - Another table will appear include ( Z ) and (start and end ) we change ( z )
value by( -2 ) according to the selected depth and we move the pointer until we
reach ( T! ) then we write in its bottom( 1.5 – 2 ). moving is done by using(pg up)
to change(T!) value then we exit from the program by pressing ( ESC ) .
15- We press ( F10 ) and then ( F9 ) written (pump) in its bottom then the vehicle
tank will be filled with kerosene . we raise the filling handle and press the
drainage handle to close the drainage hole .During filling , a red alarm will
appear on the screen , and when the the tank is completely filled the red color
will disappear and we leave the filling handle as it is until the filling finish.
16- We press (start spark) by (F1)for operating and we observe the operating
steps on the screen. a Billy will appear on the top of screen beside X,Y and Z
column in which the level will decrease gradually, also we observe the movement
of Ampere& volts counters during implementation as if one of them increased
the other will decrease to carry out the spark.
17- To stop we press HALT , ( F2 ) then we close the pump by pressing F 9 then
we pull the handle of drainage to remove the kerosene from the tank , we raise(
z+ ) up to raise the electrode .
18 - When final stop, we press the emergency button and then the main
operating button behind the machine.
Note : we can restart the program with changing the cutting depth when
need whereas the program is already saved on the machine.
31
4.2Design Implementation
4.2.1The project:
Designisageometricshapecontainsanglesandshapesare difficult
tofortraditionaloperating.
FIGURE 4.8 Different shape of tool and workpiece.
4.2.3 Other formshave been designed
FIGURE 4.9 Different shape of workpiece
32
CHAPTER 5
FEASIBIILITY STUDIES AND MARKET NEEDS
CHAPTER 5 5: FEASIBIILITY STUDIES AND MARKET NEEDS There are several reasonsled to thewidespread use ofmachinesoperatingina non-
traditionalindustry.
We havecreatedtheappearanceofnon-traditionalmachiningway toreduce the cost
ofproductionforindustriescharacterizedbythe size oftheproductionis low, such as
makingthepiecestohelpin the aircraft
industryandindustrymachineryequipmentitselfinalltheseindustriesthat we have
mentionedandotherindustrieswithrequirementssimilartofindthat it is
necessarythatthe product ishighqualityand content ofwhen used.
We also findthat the volume ofproduction in
thesecasesisoftendozens,hundredsand in somecasesthousands, but
rarelyreachthe volume of productionon top of that.
The use ofnon-conventionalmachining in suchareasmentionedcanbringthe
following benefits:
1.Reduce the timewastedwithoutproducinganactualmachine
2.The use ofequipmentinstallationsimplerthanusedwithconventional
machines.
3.Achievea more flexibleproductionsystemto changes inproductionschedules.
4.Increase the accuracy ofmanufacturingand the reduction ofmistakes in which
workers.
It is clear from the above-mentioned non-traditional machines that are suitable for
certain situations but not in all cases and can conclude that the operations that
can be investigated by the machinery of non-conventional economic benefits has
the following characteristics:
1. Designs required for the manufacture of narrow pieces.
2. The processing requires several operations.
3. Quantities of metal you want to remove the large manufacturing.
4.The needto examine thequality of the productby 10%.
But thisshouldnotmake us forgetthatifwe have introducednon-
traditionalmachinesfor production inanyfactorywillfacethe following problems:
1.Maintenance andincreasediversitywithin the plant.
2.High initial costnon-traditionalmachines.
3.Highcost of runningmachinery.
4.Anew trainingforworkersat all levelstoaccommodatenon-traditionalsystem
Ofmachinesandrequirementsoftheprogramming, operation and maintenance.
33
CHAPTER 6
CONCLUSION AND RECOMMENDATIONS
CHAPTER 6
6: CONCLUSION AND RECOMMENDATIONS
6.1:Conclusion
1- The aim of
thestudyElectrodischargemachiningillustratethedifferenceinsavingtimeand
effortas well asprecisioninexecution.
2- The results showedthe huge
differencebetweenElectrodischargemachiningandtraditional machining
throughmanufacturedproductsinboth cases and the superiority
ofElectrodischarge machining infiniteprecision, as well as savetime by
usingfewertools.
3- Hence we seethatEDMhave becomepartand parcel of
themodernindustrialsystemand needs inallareasofengineeringand industry.
4- It is clear from the above-mentioned EDM that are suitable for certain
situations but not in all cases and can conclude that the operations that
can be investigated by the machinery of EDM economic benefits has the
following characteristics:
1. Designs required for the manufacture of narrow pieces.
2. The processing requires several operations.
3. Quantities of metal you want to remove the large manufacturing.
4.The needto examine thequality of the productby 10%.
5. Cavities with thin walls and fine features can be produced. 6. Difficult geometry is possible. 7. The use of EDM is not affected by the hardness of the work material. 8. The process is burr-free 6.2:Recommendations: 1- LaboratoryresultsshowedtheEDMis active inplaceswhichrequirespeedin
production andhighproduction rate.
2- Laboratory result showedthatthemachinesof EDM high-cost primary.Tests
provedtouson the machinethathave a high potentialtodealwithdifficult
formationsandcomplexcurves.
3- Througha feasibility studyappearedto us thatthemachinewithahighcostin
maintenance.
4- Throughtheinitialviewsof the machine, it is very sensitiveto external stimuli.
34
6.3: References
1- Wang, C.-. And Lin, Y.C., 2009. Feasibility study of electrical discharge
machining for W/Cu composite. International Journal of Refractory Metals
and Hard Materials, 27(5), 872-882.
2- Tsai, H.C., Yan, B.H. and Huang, F.Y., 2003. EDM performance of Cr/Cu-
based compositeelectrodes. International Journal of Machine Tools and
Manufacture, 43(3), 245-252.
3- Habib, S. S. (2009). Study of the parameters in electrical discharge
machining throughresponse surface methodology approach. Applied
Mathematical Modelling, 33(12), 4397-4407.
4- Saha, S.K. and Choudhury, S.K., 2009. Experimental investigation and
empirical modelingof the dry electric discharge machining process.
International Journal of Machine Tools andManuf., 49(3-4), 297-308.
5- Sohani, M.S., Gaitonde, V.N., Siddeswarappa, B. And Deshpande, A.S.,
2009.Investigations into the effect of tool shapes with size factor
consideration in sink electricaldischarge machining (EDM) process.
International Journal of Advanced ManufacturingTechnology, , 1-15.
6- Kung, K.-., Horng, J.-. and Chiang, K.-., 2009. Material removal rate and
electrode wearratio study on the powder mixed electrical discharge
machining of cobalt-bonded tungstencarbide. International Journal of
Advanced Manufacturing Technology, 40(1-2), 95-104.
7- Bleys, P., Kruth, J.-., Lauwers, B., Zryd, A., Delpretti, R. And Tricarico, C.,
2002. Realtime tool wear compensation in milling EDM. CIRP Annals -
Manufacturing Technology, 51(1), 157-160.
8- Chang, Y.-. and Chiu, Z. 2004. Electrode wear-compensation of electric
discharge scanningprocess using a robust gap-control. Mechatronics,
14(10), 1121-1139.
9- Ziada, Y. and Koshy, P., 2007. Rotating Curvilinear Tools for EDM of
Polygonal Shapeswith Sharp Corners. CIRP Annals - Manufacturing
Technology, 56(1), 221-224.
10- Yaw-shih shieh, and An-Chen lee, 1994. Cross-coupled biaxial step cobol
for cncedminternational J. Mach. Tools Manufact. 36 No. 12, pp. 1363-
1383.
11- Singh, S. and Maheshwari, S. AnfPandey, P. (2004). Some investigations
into the electricdischarge machining of hardened tool steel using different
electrode materials. Journal ofMaterials Processing Technology, 149(1-
3):272–277.
35
CAPSTONE DESIGN PROJECT
Project Submission
and ABET Criterion 3 a-k Assessment Report
Project Title:Machining of Complex Shape Design by Electrical Discharge Machining Process
DATE: 7/ 1435
PROJECT ADVISOR:Assoc. Prof. Helmi Mahmoud Osman Abulila
Team Leader:Fahad Ali Sharahily
Team Members:1-Fahad Ali Sharahily (200910648)
2-Fahad Ali dahgriry (200911527)
3-Bandar SalehAlamri (200801150)
4-Moath Hassan Gadi (200801274)
5- Abdullah MohmmedGissy (200922254)
Design Project Information
Percentage of project Content- Engineering Science % 20%
Percentage of project Content- Engineering Design % 80%
Other content % All fields must be added to 100% __________________
Please indicate if this is your initial project declaration Project Initial Start Version
or final project form Final Project Submission
Version
Do you plan to use this project as your capstone design project? ________________________
Mechanism for Design Credit Projects in Engineering Design
Independent studies in Engineering Engineering Special Topic
Fill in how you fulfill the ABET Engineering Criteria Program Educational
Outcomes listed below
Outcome (a), An ability to apply knowledge of
mathematics, science, and
engineering fundamentals.
Please list here all subjects (math, science, engineering) that
have been applied in your project. Example: let’s consider a study the engineering fundamental for
electrical discharge machining process(Mathematical Models and Formulations(EDM-Spark Circuits, Resistance-Capacitance Circuit)
36
Outcome (b). An ability to design and conduct
experiments, and to critically
analyze and interpret data.
In this part, if the project included experimental work for
validation and/or verification purposes, please indicate that. DESIGN APPROACH AND METHODOLOGY (Design approach Design
Methodology EDM Electrodes, Dielectric Fluids, Material Removal
Rates, Surface Integrity, EDM Heat-Affected Zone
Outcome (c). An ability to design a system,
component or process to meet
desired needs within realistic
constraints such as economic,
Environmental, Social, political,
ethical, health and safety,
manufacturability, and
sustainability
All projects should include a design component. By design we
mean both physical and non physical systems. Design specifications and assumptions (Transistorized Pulse Generator
Circuits, EDM Tool Electrodes, Design of tool electrodes for workpiece)
Design of work program for machining Procedures (Design
Implementation, the first project, the second project, and other
formshave been designed)
Outcome (d). An ability to function in multi-
disciplinary teams.
This outcome is achieved automatically by the fact that all
projects composed of at least 6 students. However, if the project
involved students from other departments, that would be a plus
that is worth to be highlighted.
Outcome (e). An ability to identify, formulate
and solve engineering problems.
In order to meet this specific outcome, it would help if you have
a Problem Statement section in your project report. If not, then
briefly highlight how the “students” were able identify,
formulate and solve the project’s problem.
Outcome (f). An understanding of professional
and ethical responsibility.
Here professional and ethical responsibility depends on the
project context. Example in the Tool Design For Electrical Discharge Machining Process
project it would be not ethical for example to ignore having a ventilation
and air conditioning for the rooms of the servants and janitors.
Outcome (g). An ability for effective oral and
written communication.
Good report and good presentation will fulfill this outcome
Outcome (h). The broad education necessary to
understand the impact of
engineering solutions in a global
economics, environmental and
societal context .
This outcome is usually fulfilled by highlighting the economic
feasibility of the project, and emphasizing that the project
would not harm the environment and does not negatively affect
human subjects. We havecreatedtheappearanceofnon-traditional machining way toreduce
the cost ofproductionforindustriescharacterizedbythe size
oftheproductionis low, such as makingthepiecestohelpin the aircraft
industryandindustrymachineryequipmentitselfinalltheseindustriesthat we
have mentionedandotherindustrieswithrequirementssimilartofindthat it is
necessarythatthe product ishighqualityand content ofwhen used.
37
Outcome (i). A recognition of the need for, and
an ability to engage in life-long
learning.
This outcome is fulfilled by suggesting a plan for future studies
and what else could be done based on the outcome of the
current project. 1- LaboratoryresultsshowedtheEDMis active
inplaceswhichrequirespeedin production andhighproduction rate.
2- Laboratoryresultsshowedthatthemachinesof EDM high-cost
primary.Testsprovedtouson the machinethathave a high
potentialtodealwithdifficultformationsandcomplexcurves.
3- Througha feasibility studyappearedto us
thatthemachinewithahighcostinmaintenance.
4- Throughtheinitialviewsof the machine, it is very sensitiveto external
stimuli.
Outcome (j). A knowledge of contemporary
issues.
Extensive literature review by the “students” for the current
state of the art will fulfill this outcome.
Outcome (k). An ability to use the techniques,
skills, and modern engineering
tools necessary for engineering
practice.
List all technologies included in the project (hardware and
software)
By signing below certify that this work is your own and fulfills the criteria
described above
Student Team Signatures _________________________ __________________________
_________________________ __________________________
_________________________ __________________________
Project Advisor Signature__________________ Date_________________
College Coordinator of Capstone Projects_________________________
Approved By _________________________
38
كلية الهىدسة
قسم الهىدسة الميكاويكية
تشغيم االشكال انمعقدة انتصميم
بعمهية انقطع بانشرارة
انكهربائية
ستقرير مشروع التخرج مقذم للحصىل على درجة البكالىريى
في الهنذسة الميكانيكية
:طالب فريق العمل
فهد علي شراحيلي- 1
فهد علي دغريري- 2
بىدر صالح العمري- 3
معاذ حسه قاضي - 4
عبدهللا محمد قيسي- 5
مشرف المشروع
حلمي محمىد عثمان أبىليله/ أستاذ مشارك د
(7/1435)تاريخ التقدم
ملخص عربي
تشغيم االشكال انمعقدة انتصميم بعمهية انقطع بانشرارة انكهربائية
. غالبا ما تسمي عمليات القطع المطورة حديثا عمليات القطع الحديثة أو عمليات القطع غير التقليدية
إزالة . وتتم إزالة المعدن بتأثير الشرارة الكهربائية التي تحدث بين قطبين يفصل بينهما سائل عازل
المعادن يحدث نتيجة لتوليد درجات حرارة عالية للغاية المتولدة عن شرارة كهربائية عالية الكثافة
. التي تصهر معدن الشغلة ويتبخر وينفصل عن الشغلة تاركا شكل أداة القطع المستخدمة
مرة عن سرعة القطع بطرق التشغيل 20 في اآلونة األخيرة ،قد ارتفعت سرعة قطع المعادن إلى
في المائة على األقل 30 أو القطع العادية وهذا يؤدى إلى تخفيض التكاليف بنسبة قد تصل إلى
. وتحسين في تشطيب األسطح ودرجة نعومتها
في عمليات القطع بالشرارة الكهربائية يمكن تشغيل وقطع المعادن ذات الصالدة العالية وكذلك
تشغيل األشكال المعقدة في التصميم وذلك بدقة عالية من حيث التشطيب وجودة األسطح مما يقلل
. من تكليف المنتج والمصنع من مواد يصعب تشغيلها بالطرق العادية
وقد تم تطبيق عملية التشغيل بالشرارة الكهربائية على أشكال غير نمطية المقاطع والتي يصعب
تشغيلها بالطرق العادية وذلك باستخدام أداة قطع مصنعة من النحاس األحمر لقطع معادن ذات ذو
. صالدة مثل الحديد الصلب
SUGGESTIONS FOR MAKING ORAL CAPSTONEDESIGN PROJECT PRESENTATIONS
1.SUGGESTIONS ON MAKING ORAL CAPSTONE PROJECT PRESENTATIONS
1) Opening: Use a title overhead to open the presentation 2) Organization: An early slide (probably the second one) should give an
outline (Agenda) of the presentation. Be sure to include any assumptions made.
Problem statements are an excellent way to begin the actual
presentation (after the outline). However, problem statements should describe the need not the solution. The solution is best presented in the objective of the design. Problem statements are an important part of this process.
3) Slides: Limit the amount of information on a slide and use large
print (presentation-sized fonts). Usually, typed material will be too difficult to read from a distance.
Do not read a list from an overhead word-for-word to the audience. Just summarize the points being presented.
4) General: Limit your discussions as much as possible. Be tolerant of questions. Most reviewers do not have
intimate knowledge of your project and may even be a different discipline than your own.
Do not try to cover too much detail, just enough to describe the design process.
Be prepared before standing up. Sorting through papers slides or setting up a demo while opening a presentation is too much of a distraction.
Practice enough so that you do not have to constantly refer to notes. This allows you to judge the time required for your presentation. Stay within the time guidelines provided (less than 20 minutes).
Include cost analysis information if your project involves construction or manufacturing. These cost estimates should include labor to build or assemble and not just be a summary of the cost of pa
2. PROBLEM STATEMENT
A good problem statement:
States the specifics of the problem - who, what, when, and where.
States the effect, but not the cause - what is wrong, not why it is wrong.
Focuses on the gap between what is and what should be. The gap may be a change or
deviation
from a norm, standard, or reasonable expectation.
Includes some measurements of the problem - how often, how much or
when.
Avoids broad categories like moral, productivity, communication and
training since these tend to have different meanings for different people.
Do not state problems as questions, since this implies that the answer to the
questions is the solution to the problem.
States why the problem is important.
3. FINAL ORAL PRESENTATION OUTLINE
TITLE
AGENDA and OUTLINES
GENERAL IMPORTANCE OF THE WORK
SPECIFIC MOTIVATION FOR THE WORK
OVERALL SCOPE OF THE WORK
SPECIFIC OBJECTIVES
DETAILS OF THE WORK
RESULTS
SUMMARY
CONCLUSIONS
FUTURE WORK
4: THE SUCCESSFUL ORAL PRESENTATION MUST PROVIDE THE
MEMBERS OF AN AUDIENCE WITH THE ANSWER TO THE FOLLOWING
QUESTIONS:
What is the title of the work?
What is the name of the presenter and his affiliation?
Why is the work important?
What is the presenter’s motivation for the work?
What related work exists?
What is unique about the presenter’s approach?
What is the overall scope of the work?
What are the specific objectives of the work?
How was the work performed?
What are the results?
Design ,Manufacturing Model Technical, results?
Economic results?
Environmental impact?
Safety and security requirements?
System managements results
Did the results meet the objectives?
What happens next?