FEM Modeling Final PPT (final ).pptx for mechanical

FEM MODELING OF ELETRICAL DISCHARGE
MACHINING OF SS304-CU IN GAS
GUIDED BY
Mr. AJEESH AS
ASSISTANT PROFESSOR
MECHANICAL ENGINEERING.
GROUP MEMBERS
AHMAD SUBAIR JAFAR (MUS20ME005)
ALHAM SHAREEF PK (MUS20ME006)
ASWIN GS (MUS20ME009)
SUHAIL MOHAMMED S(MUS20ME019)

CONTENTS
 ABSTRACT
 INTRODUCTION
 LITERATURE REVIEW
 AIM
 STUDY OF EDM
 METHODOLOGY
 MODELLING
 RESULT
 CONCLUSIONS
 FUTURE WORK
 REFERENCES
2

ABSTRACT
 Electro discharge machining (EDM) process is a non-conventional and
noncontact machining operation which is used in industries for high precision
operation
 EDM in gas uses gaseous dielectric medium instead of a conventional liquid
dielectric such as water, kerosene etc.
 This is an environment friendly technology and has many advantages.
 In the present work we have developing a FEM based model for the simulation
of gas dielectric EDM of SS304- Cu in Oxygen and Helium.
3

INTRODUCTION
 Due to the continuous developments in the field of engineering and
technology, the scientists and the researchers are facing more and more
challenging jobs in these fields of designing and manufacturing.
 Since 1940, a revolution has been taking place that once again allows
manufacturers to meet the demands imposed by increasingly sophisticated
designs, but unmachinable.
 As a result, a new form of manufacturing processes used for material
removal, forming, and joining, known as non-conventional manufacturing
processes has introduced.
4

• Electric Discharge Machining (EDM)
• Electro Chemical Machining (ECM)
• Abrasive Jet Machining (AJM)
• Abrasive Water Jet Machining (AWJM)
• Water Jet Machining (WJM)
• Ultrasonic Machining (USM)
• Laser Beam Machining (LBM)
NON-CONVENTIONAL METHODS OF MACHINING
5

 In this present study we have developed a numerical based
finite element model to simulate the process of gas di-electric
electro discharge machining in Oxygen and Helium. The
model is validated by comparing the simulated results with the
existing experimental results. A comparative analysis of EDM
performance with respect to the material removal rate of
Oxygen and Helium based dielectric process was also carried
out
6

LITERATURE REVIEW
 Jia Tao, Albert J. Shih, Jun Ni, ”Experimental Study of the Dry
and Near-Dry Electrical Discharge Milling Processes”, Journal of
Manufacturing Science and Engineering, FEBRUARY 2008, Vol.
130 / 011002-1
 investigated the dry and near-dry electrical discharge machining
(EDM) milling to achieve a high material removal rate (MRR) and
fine surface finish for roughing and finishing operations.
 They found that Oxygen demonstrated the capability to promote
MRR and exothermal oxidation in both the dry and the near-dry
EDM.
 Nitrogen and helium gases could prevent the electrolysis and yield
better surface finish in near-dry EDM.
7

 Avinash Choudhary, Mohan Kumar Pradhan, ”Finite Element
Analysis of Electro Discharge Machining using Ansys”, Proceedings
of 1st International Conference on Mechanical Engineering:
Emerging Trends for Sustainability
 modelled the EDM process with the help of Finite Element Method
(FEM) using ANSYS 12.0 software and the effects of most
significant machining parameters on the workpiece such as current,
voltage and pulse duration was analyzed.
 The analysis showed the temperature distribution at the end of pulse
duration, development of residual stresses after the completion of
cooling and the changing nature of compressive stresses to the
tensile stresses in various stages of machining process
8

 P. Govindan, Suhas S. Joshi, ”Experimental characterization of
material removal in dry electrical discharge drilling “,International Journal
of Machine Tools & Manufacture 50 (2010) 431–443
 conducted experimental characterization of material removal in dry
electrical discharge drilling.
 The experiments were performed by controlling pulse off-time so as to
maximize the material removal rate (MRR).
 The main response variables analyzed in this work were MRR, tool wear
rate(TWR), oversize and compositional variation across the machined
cross-sections.
 Statistical analysis of the results show that discharge current(I),gap
voltage(V) and rotational speed(N) significantly influence MRR. TWR
was found close to zero in most of the experiments.
9

 S Jithin, Ajinkya Raut, Upendra V Bhandarkar,” FE Modeling
for Single Spark in EDM Considering Plasma Flushing
Efficiency,International Journalof Machine Tools 2018, Pages 617-
628.
 presented a finite element simulation of a single spark during
electrical discharge machining taking into consideration significant
aspects such as temperature dependency of material properties,
Gaussian distribution of heat flux, plasma flushing efficiency etc.
 Finite element simulations showed that the crater radius and crater
depth increase with increasing values of operating parameters such
as discharge current and pulse on time.
 The validation of the Finite element model is made against
experiments. Due to consideration of these important aspects, this
model could give a more accurate prediction of crater profile.
10

AIM
 Develop a FEM model for the simulation of gas dielectric EDM
process with SS304 workpiece and Cu as electrode
 Predict the workpiece material removal rate using the developed
model with oxygen as gas dielectric medium
 Validate the simulated results of oxygen by comparing with the
experimental values.
 Conduct a comparative analysis of material removal rate of
electrical discharge machining in Oxygen with respect to Helium.
11

STUDY OF EDM
 INTRODUCTION TO ELECTRIC DISCHARGE MEACHINING
 Electric discharge machining (EDM) process is a non-conventional and
non-contact machining operation which is used in industry for high
precision products especially in manufacturing industries, aerospace and
automotive industries.
 It is known for machining hard and brittle conductive materials since it can
melt any electrically conductive material regardless of its hardness.
 EDM is a type of thermal machining where the material from the
workpiece is removed by the thermal energy created by the electrical
spark.
12

 Controlled axis
 Electrical generator
 Control panel
 Work table
 Dielectric fluid container
BASIC COMPONENTS OF AN EDM SYSTEM
13

ELECTRICAL DISCHARGE MACHINING PROCESS
 EDM is the thermal erosion process in which metal is removed by a
series of electrical discharges between a cutting tool acting as an
electrode and a conductive workpiece.
 When electrode is brought closer to the work piece, sunk in the
dielectric fluid, current is passed to the electrode and the work piece,
which generates heat in the form of frequent series of sparks that
vaporizes the pieces at the closest point of work piece and electrode.
 After removing the piece at the closest distance between electrode
and work piece, the next spark occurs simultaneously at the next
closest point between them and so on. This process results on
forming a cavity on the work piece with the shape of the electrode.
14

 During this operation the
tool and work piece are
suppose to keep a distance
between them, known as
sparking gap.
 ▪ This point of
transformation of dielectric
fluid from non-conductor to
conductor is called
"ionization point"
 A flushing operation is
undergoing in order to
remove the chips from the
work piece
15

Advantages of gas dielectric EDM
 Environment friendly technology
 No need for special treatment for disposal of sludge,
dielectric waste, filter cartridges, etc.
 Higher Precision
 Near-zero tool electrode wear
 No electrolytic corrosion of work piece
 No toxic fumes generated
 Smaller Heat Affected Zone (HAZ)
 Narrower discharge gap length
16

METHODOLOGY
 Identified the limitations of EDM.
 Studied different possibilities of electric discharge machining and
ANSYS modeling.
 Created 2D model of EDM in ANSYS 19, transient thermal
module.
 Preprocessing and post-processing are done.
 Generated results by conducting various simulations and analyzed
the result.
 The obtained results were validated by pre-existing experimental
data.
17

ASSUMPTION
 The workpiece and tool are axi-symmetric.
 The workpiece and tool material are homogeneous and isotropic
 Heat flux is assumed to be Gaussian distributed. The zone of
influence of the spark is assumed to be axi-symmetric in nature.
 The analysis is done for only one spark.
 The material properties of the workpiece are temperature
independent
 The ambient temperature is room temperature.
 The shape of crater is assumed to be a cone
 Workpiece is selected as stainless steel 304 and Cu tool electrode is
selected with Dielectric as Oxygen
18

Axisymmetric model for EDM
simulation and boundary conditions
Proposed Simulation Model
19

INPUT DATA
Sl
no. V(Volts) I(A)
Toff
(μs) Toff(s)
Ton
(μs) Ton(s)
Spark
Radius(mm) Q(W/m2)
1 50 12 22 0.000022 66 0.000066 0.085956245 35439234270
2 50 12 33 0.000033 198 0.000198 0.139383314 13477757109
3 50 12 67 0.000067 603 0.000603 0.227519026 5058290392
4 50 15 22 0.000022 66 0.000066 0.094612548 36563834238
5 50 15 33 0.000033 198 0.000198 0.15342004 13905449342
6 50 15 67 0.000067 603 0.000603 0.250431541 5218806084
7 50 18 22 0.000022 66 0.000066 0.102328516 37509139912
8 50 18 33 0.000033 198 0.000198 0.165931954 14264954859
9 50 18 67 0.000067 603 0.000603 0.270855065 5353730856
10 65 12 22 0.000022 66 0.000066 0.085956245 38392503792
INPUT VALUES FOR OXYGEN DI-ELECTRIC
20

INPUT VALUES FOR HELIUM DI-ELECTRIC
Sl
no.
V(Volts) I(A)
Toff
(μs)
Toff(s)
Ton
(μs)
Ton(s)
Spark
Radius(mm)
Q(W/m2)
1 50 12 22 0.000022 66 0.000066 0.085956245 35439234270
2 50 12 67 0.000067 603 0.000603 0.227519026 5058290392
3 50 18 22 0.000022 66 0.000066 0.102328516 37509139912
4 50 18 67 0.000067 603 0.000603 0.270855065 5353730856
5 80 12 22 0.000022 66 0.000066 0.085956245 28351387416
6 80 12 67 0.000067 603 0.000603 0.227519026 4046632313
7 80 18 22 0.000022 66 0.000066 0.102328516 60014623859
8 80 18 67 0.000067 603 0.000603 0.270855065 8565969370
21

 Formulae used are:
 Spark radius: R(mm)=2.04 x I0.43 x Ton 0.44
 Heat flux Q (W/m2) = (4.57xFc x V x I)/ (π x R2)
 Crater volume Cv (mm3) = (π x r2 x h)/3
 Material removal rate MRR (mm3/min) = (60 x Cv)/(Ton +Toff )
Where,
I=Current (A)
V=Voltage(V)
Ton=Pulse on time (s)
Toff=Pulse off time (s)
Fc=Cathode energy fraction taken as 0.3(50V),0.25(65V),0.15(80V)
r =Radius of crater (mm) h=Depth of crater (mm)
22

MODELLING
 The modelling steps for all the four sections are similar only the input parameters
varies under different conditions.
 STEP 1:
 Under material properties, the workpiece material Stainless Steel 304 is
selected and its properties are fed
23

Material properties of SS304
24

STEP 2:
Before doing the 2D drawing the analysis type is changed from 3D to
2D
Changing analysis type
25

STEP 3:
The workpiece was designed using ANSYS DESIGN MODELLER
with dimensions of 14mm x 10mm [5].
Drawn 2D model
26

STEP 4:
Create the 2D geometry into a new surface for the ease of geometry
drawing
Create surface sketch
27

STEP 5:
Draw a circle in the edge of work piece of diameter 10mm.
Drawn a circle
28

STEP 6:
Extrude the circle by adding slice material and separate the two
sketches.
Create the two sketches
29

 The workpiece was designed using ANSYS DESIGN MODELLER
with dimensions of 14mm x 10mm
Two-Dimensional workpiece model
30

STEP 7:
The workpiece is split into two portions for ease of meshing. The
circular cross-section is split with respect to the spark radius using the
concept of split edges.
Splitting of edges
31

STEP 8:
The workpiece is meshed for FEM analysis using meshing tool in
ANSYS. The meshing is done in two parts where the non-circular
section is meshed as coarse mesh and circular section is meshed finely
with 3 times refinement for better analysis and results
Meshed model
32

Coarse meshing for non-circular section
33

Fine meshing for circular section
34

STEP 9:
Pulse on time is applied in analysis setting
Pulse-on-time application
35

STEP 10:
Heat flux Q(W/m2 ) which represent the energy of spark is applied on
the edge of the workpiece
Application of heat flux
36

STEP 11:
Heat flux of oxygen(dielectric) is applied on the edge.
Application of heat flux of oxygen (Di-electric)
37

STEP 12:
The three non-effected boundaries are insulated by selecting
heat flux as 0W.
Insulation of non-affected boundary
38

STEP 13:
The solution is found
Simulated solution
39

RESULTS
OXYGEN DIELECTRIC
Finite Element Analysis based numerical model for oxygen gas di-
electric electrical discharge machining of stainless steel 304 and Cu
electrode is developed and material removal rate is simulated under
different conditions.
40

SIMULATED RESULTS FOR OXYGEN DIELECTRIC
Sl
no.
Depth(mm) Radius(mm)
Crater Volume
(mm3)
MRR
(mm3/min)
MRRe
(mm3/min)
Error %
1 0.8 0.81 0.549653051 0.374763444 0.376 0.328871359
2 1.16 1.15 1.606505764 0.417274224 0.414 0.790875431
3 1.65 1.706 5.028872397 0.450346782 0.441 2.119451653
4 0.9 0.875 0.721584563 0.491989475 0.552 10.871472
5 1.2 1.3 2.123716634 0.55161471 0.62 11.02988546
6 1.8 1.75 5.772676502 0.516956105 0.515 0.379826142
7 0.87 0.9 0.737960114 0.503154623 0.794 36.63040007
8 1.35 1.36 2.614810398 0.679171532 0.679 0.025262429
9 1.85 2 7.74926188 0.69396375 0.691 0.428907444
10 0.8 0.86 0.619605847 0.422458532 0.426 0.831330478
41

The model is validated by comparing it with available experimental
values from the journal. From the table we can see that simulated
values of material removal rate in column 5 is comparable to the
experimentally found values of MRR. The average error in the
simulated values is 3.86%.
42

SIMULATED TEMPERATURE PROFILES FOR OXYGEN
Depth =0.8mm Radius=0.81mm
1. V=50V I=12A Ton=0.000066s
43

10. V=65V I=12A Ton=0.000066s
44

19. V=80V I=12A Ton=0.000066s
45

HELIUM DIELECTRIC
Sl no.
Depth(mm) Radius(mm)
Crater
Volume(mm3)
MRR
(mm3/min)
MRRe
(mm3/min) Error %
1 0.53 0.48 0.127875387 0.087187764 0.096 9.179412366
2 0.48 0.55 0.152053084 0.013616694 0.016 14.89566169
3 0.35 0.4 0.058643063 0.039983907 0.0385 3.854302612
4 0.5 0.55 0.15838863 0.014184056 0.0128 10.81294051
5 0.38 0.45 0.080581852 0.054942172 0.064 14.15285699
6 0.65 0.75 0.382881605 0.034287905 0.0385 10.94050676
7 0.3 0.25 0.019634954 0.013387469 0.016 16.32832065
8 0.53 0.45 0.112390477 0.010064819 0.0128 21.36860271
SIMULATED RESULTS FOR HELIUM DIELECTRIC
46

From the simulated values of MRR we can see that it is close to
the experimentally found values for MRR under similar
conditions and it further shows the capability of the developed
model in the simulation of gas dielectric EDM process.
47

SIMULATED TEMPERATURE PROFILES FOR HELIUM
V=50V I=12A Ton=0.000066S
48

V=80V I=12A Ton=0.000066s
49

COMPARITIVE ANALYSIS OF OXGEN AND HELIUM
MRR comparison for Helium and Oxygen
50

SAMPLE CALCULATION
V=50 V
I=12A
Ton=0.000066s=66µs
Toff=0.000022s=22us
Spark radius R=2.04 x 120.43 x 0.0000660.44 = 0.085956245 mm
Heat flux Q=(4.57 x 0.3 x 50 x 12)/(π x ((0.0859/1000))2) = 35439234270 W/m2
Depth = 0.80mm
Radius =0.81mm
Crater volume = (π x 0.812 x 0.80)/3= 0.549653051 mm3
Material removal rate MRR= (60 x 0.549)/ (22+66) = 0.374763444 mm3 /min
51

CONCLUSIONS
 Finite element model for the gas-dielectric electro discharge
machining is developed in ANSYS 19.1
 Experimental results of gas dielectric electro discharge machining in
Oxygen carried was used to validate the simulated results and it was
found that developed model was able to obtain results with
reasonable accuracy within an error of 3.86%.
 It was also found that the material removal rate increases with
increase in current and decreases with increase in voltage.
52

 Experimental results of gas dielectric electro discharge machining in
Helium was used to validate the simulated results and it was found
that developed model was able to obtain results with reasonable
accuracy within an error of 12.7%.
 When comparing the material removal rate for helium and oxygen
it was found the material removal rate in Helium is very low when
compared to oxygen. This may be attributed to lower dielectric
strength and thermal conductivity of helium when compared to
oxygen.
53

FUTURE WORK
 The model can be further extended to simulate the electrical
discharge machining under different gases such as Nitrogen.
 The impact of different parameters such as pressure, speed of
electrode may also be incorporated to the existing model with the
help of user defined functions (UDF) in ANSYS.
 Effect of different parameters on tool wear rate (TWR) may also be
investigated.
 The effect of mixture of two or more gases as dielectric on the
electro discharge machining process can also be simulated.
54

REFERENCES
1. Jia Tao, Albert J. Shih, Jun Ni, ”Experimental Study of the Dry and Near-
Dry Electrical Discharge Milling Processes”, Journal of Manufacturing Science
and Engineering, FEBRUARY 2008, Vol. 130 / 011002-1
2. Avinash Choudhary, Mohan Kumar Pradhan, ”Finite Element Analysis of Electro
Discharge Machining using Ansys”, Proceedings of 1st International Conference
on Mechanical Engineering: Emerging Trends for Sustainability
3. Mehrdad Hosseini Kalajahi,Samrand Rash Ahmadi,Samad Nadimi Bavil
Oliaei, ”Experimental and finite element analysis of EDM process and
investigation of material removal rate by response surface
methodology”,International Journal of Advanced Manufacturing Technology
(2013) 69:687–704
4. S Jithin, Ajinkya Raut, Upendra V Bhandarkar, Suhas S Joshi,” FE Modeling for
Single Spark in EDM Considering Plasma Flushing Efficiency,
Procedia Manufacturing, Volume 26, 2018, Pages 617-628
5. P. Govindan, Suhas S. Joshi ,”Experimental characterization of material
removal in dry electrical discharge drilling “,International Journal of Machine
Tools & Manufacture 50 (2010) 431–443
55

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