parametric analysis of material removal rate and surface...
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Prepared by:
Bhavin D. Patel (090780119014)Vivek S. Patel (090780119056)
Guided by:
Prof. Nikunj.M.Patel
Parametric Analysis of material
removal rate and surface roughness
on Electric Discharge Machine
125-May-13
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2
CONTENT:-
Introduction of EDM
Working principle of EDM
Objective of EDM
Types of EDM
Application of EDM
Advantages of EDM
Limitation of EDM
Method Of Formulation
Detail description
25-May-13
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Experimental Set Up
Property table
Experimental table
Conclusion
Graph
Analysis of Variance(ANOVA)
325-May-13
Photos
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Electro Discharge Machining (EDM) is an electro-thermal non-
traditional machining Process, where electrical energy is used
to generate electrical spark and material removal mainly occurs
due to thermal energy of the spark.
EDM is mainly used to machine difficult-to-machine materials
and high strength temperature resistant alloys. EDM can be used
to machine difficult geometries in small batches or even on job-
shop basis. Work material to be machined by EDM has to be
electrically conductive.
INTRODUCTION OF EDM
25-May-13
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Fig : Schematic of EDM process
25-May-13
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WORKING PRINCIPLE OF EDM
In this process the metal is removing from the work piece due to
erosion case by rapidly recurring spark discharge taking place
between the tool and work piece. mechanical set up and electrical
set up and electrical circuit for electro discharge machining.
A thin gap about 0.025mm is maintained between the tool and
work piece by a servo system
Both tool and work piece are submerged in a dielectric fluid.
Kerosene/EDM oil is very common type of liquid dielectric
although gaseous dielectrics are also used in certain cases.
25-May-13
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Figure : Set up of Electric discharge machining
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OBJECTIVE OF EDM
To understand of basic principle of EDM process.
To understand application of EDM die sinking machine.
To familiar with typical specification and structure of EDM die
sinking machine.
To familiar with the operation procedure.
To be able to prepare parameter setting for different application.
To be able to set the alignment of the electrode and work piece.
To be able to appreciate the quality of result product.
25-May-13
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TYPES OF EDM
Die-sinking
wire-cut
DIE-SINKING EDM
In the Sinker EDM Machining process, two metal parts submerged in an insulating
liquid are connected to a source of current which is switched on and off
automatically depending on the parameters set on the controller.
When the current is switched on, an electric tension is created between the two
metal parts. If the two parts are brought together to within a fraction of an inch the
electrical tension is discharged and a spark jumps across. Where it strikes, the
metal is heated up so much that it melts. Sinker EDM, also called cavity type EDM
or volume EDM consists of an electrode and work piece submerged in an
insulating liquid such as, more typically, oil or, less frequently, other dielectric
fluids. The electrode and work piece are connected to a suitable power supply.
The power supply generates an electrical potential between the two parts. As
the electrode approaches the work piece, dielectric breakdown occurs in the fluid,
forming a plasma channel, and a small spark jumps.
25-May-13
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APPLICATION OF EDM
It is used to machine extremely hard materials that are difficult
to machine like alloys, tool steels, tungsten carbides etc.
It is used for forging, extrusion, wire drawing, thread cutting.
It is used for drilling of curved holes.
It is used for internal thread cutting and helical gear cutting.
It is used for machining sharp edges and corners that cannot be
machined effectively by other machining processes
Higher Tolerance limits can be obtained in EDM machining.
Hence areas that require higher surface accuracy use the EDM
machining process.25-May-13
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ADVANTAGES OF EDM
By this process, materials of any hardness can be machined.
No burrs are left in machined surface.
One of the main advantages of this process is that thin and
fragile/brittle components can be machined without distortion.
Complex internal shapes can be machined.
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LIMITATIONS OF EDM
Material removal rate is low and the process overall is
slow compared to conventional machining processes.
Unwanted erosion and over cutting of material can occur.
Rough surface finish when at high rates of material
removal.
This process can only be employed in electrically
conductive materials.
25-May-13
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METHOD OF FORMULATION
We do ANOVA analysis basis of data obtain
DETAIL DESCRIPTION
Pulse On-time : The duration of time the current is allowed
to flow per cycle. Material removal is directly proportional to
the amount of energy applied during this on-time. This
energy is really controlled by the peak current and the length
of the on-time.
Discharge current : Current is measured in amp Allowed to
per cycle. Discharge current is directly proportional to the
Material removal rate.
Input parameter
1325-May-13
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Pulse Off-time: The duration of time between the sparks This
time allows the molten material to solidify and to be wash out of
the arc gap. This parameter is to affect the speed and the stability
of the cut. Thus, if the off-time is too short, it will cause sparks to
be unstable.
Output parameter
We can do measure material removal rate (MRR)
M.R.R =Initial weight - Final weight
Density of material Machining time
In this experiment, take machining time = 5 minutes
Density of work piece material 7.84 gm/cm3
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Dielectric fluid
It acts as a coolant in quenching the sparks.It carries away the eroded metal along with it.
Kerosene & paraffin oil are generally used as
dielectric fluid
Roughness is a measure of the texture of a surface. It is
quantified by the vertical deviations of a real surface from its
ideal form. If these deviations are large, the surface is rough, if
they are small the surface is smooth. Rough surfaces usually
wear more quickly and have higher friction coefficients than
smooth surfaces.
Surface Roughness
25-May-13
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PHOTOS
Copper electrode
(15mm =Diameter)
(25mm =Length)
Brass electrode
(15mm =Diameter)
(25mm=Length)
Mild steel work piece
(30 30 mm)
(a)Before machining (b)After machining
1625-May-13
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EDM Die sink machine
EXPERIMENTAL SET UP
Working current 15 to 25 amps
Power consumption 3 KW
Pulse ON/OFF Time 2 - 2000µs
Input power 415V,50HZ,3Phase,
AC
Table size 350×220mm
Table travel:(Longitudinal X axis)
(Cross Y axis)
220mm
130mm
Workpice maximum height 150mm
Workpice maximum weight 130mm
Maximum electrode weight 20Kg
Tank size (inside) 600×370×90mm
Dielectric receivers capacity 50 Ltrs
Specification :-
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Surface roughness tester
1825-May-13
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PROPERTY TABLE
Sr.no Material properties
Ultimate
tensile
stress
(MPa)
Yield
tensile
stress
(MPa)
Poisson’s
ratio
Density
(Kg/m^3)
Thermal
conductivity
(W/m-K)
Modulus
of
elasticity
(MPa)
1 Copper 172-220 62-69 0.34 8800-
8940
391 0.117
2 Brass 338-469 124-
310
0.31 8490 115 0.097
3 Mild
steel
280-410 280 0.3 7840 47 2.0
1925-May-13
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Sr. No Current Pulse ON Pulse OFF M.R.R S.R1 7.8125 3 3 0.008418 3.15
2 7.8125 3 5 0.007653 3.74
3 7.8125 3 7 0.003827 3.36
4 7.8125 5 3 0.010714 4.24
5 7.8125 5 5 0.008929 3.79
6 7.8125 5 7 0.005612 3.12
7 7.8125 7 3 0.010459 4.88
8 7.8125 7 5 0.010969 4.32
9 7.8125 7 7 0.008673 4.85
10 14.0625 3 3 0.022194 2.26
11 14.0625 3 5 0.014031 3.21
12 14.0625 3 7 0.005612 3.28
13 14.0625 5 3 0.021173 3.81
14 14.0625 5 5 0.015816 2.34
15 14.0625 5 7 0.009184 3.63
16 14.0625 7 3 0.019898 4.99
17 14.0625 7 5 0.020663 4.81
18 14.0625 7 7 0.017092 5.4
19 23.4375 3 3 0.030102 2.76
20 23.4375 3 5 0.034184 3.26
21 23.4375 3 7 0.030357 3.34
22 23.4375 5 3 0.038776 3.61
23 23.4375 5 5 0.037755 3.93
24 23.4375 5 7 0.033673 4.63
25 23.4375 7 3 0.040306 4.21
26 23.4375 7 5 0.041327 6.51
27 23.4375 7 7 0.039286 4.3
EX
PE
RIM
EN
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L T
AB
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FO
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PP
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2025-May-13
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EX
PE
RIM
EN
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L T
AB
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AS
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Sr. No Current Pulse ON Pulse OFF M.R.R S.R1 7.8125 3 3 0.002296 1.99
2 7.8125 3 5 0.001786 2.37
3 7.8125 3 7 0.001531 1.86
4 7.8125 5 3 0.003827 1.85
5 7.8125 5 5 0.003316 2.07
6 7.8125 5 7 0.002296 1.75
7 7.8125 7 3 0.004082 2.17
8 7.8125 7 5 0.003316 1.91
9 7.8125 7 7 0.002806 2.34
10 14.0625 3 3 0.008418 2.21
11 14.0625 3 5 0.007398 2.22
12 14.0625 3 7 0.004082 2.12
13 14.0625 5 3 0.008929 1.91
14 14.0625 5 5 0.007908 2.04
15 14.0625 5 7 0.005612 2.64
16 14.0625 7 3 0.008416 2.32
17 14.0625 7 5 0.008673 2.76
18 14.0625 7 7 0.007653 2.65
19 23.4375 3 3 0.014031 2.02
20 23.4375 3 5 0.013265 2.11
21 23.4375 3 7 0.014031 2.05
22 23.4375 5 3 0.016837 2.07
23 23.4375 5 5 0.015816 2.12
24 23.4375 5 7 0.017857 2.36
25 23.4375 7 3 0.0125 2.07
26 23.4375 7 5 0.014031 2.39
27 23.4375 7 7 0.011224 2.19
2125-May-13
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Analysis of variance (ANOVA) for Brass (MRR)
parameter DOF Sum of squares
SS
Variance
(Mean square)
Variance ratio
(F)
Percentage
contribution
P (%)
Current 2 0.000612694 0.00030635 153.945 90.784
Pulse ON 2 0.00001373 0.00000687 3.407 2.034
Pulse OFF 2 0.00000873 0.00000437 2.196 1.294
Residual
Error20 0.00003974 0.00000199 1 5.88
Total 27 0.000674894 100
2225-May-13
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Analysis of variance (ANOVA) for Brass (SR)
parameter DOF Sum of squares
SS
Variance
(Mean square)
Variance ratio
(F)
Percentage
contribution
P (%)
Current 2 0.36736 0.18368 4.39636 22.751
Pulse ON 2 0.27416 0.137086 3.28100 16.979
Pulse OFF 2 0.13746 0.06873 1.64505 8.513
Residual
Error20 0.83569 0.04178 1 51.756
Total 27 1.61467 100
2325-May-13
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parameter DOF Sum of squares
SS
Variance
(Mean square)
Variance ratio
(F)
Percentage
contribution
P (%)
Current 2 0.00370929 0.00185465 242.755 89.170
Pulse ON 2 0.000152 0.000076 9.948 3.654
Pulse OFF 2 0.0001457 0.00007285 9.535 3.503
Residual
Error20 0.00015281 0.00000764 1 3.673
Total 27 0.0041598 100
Analysis of variance (ANOVA) for Copper (MRR)
2425-May-13
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Analysis of variance (ANOVA) for Copper (SR)
parameter DOF Sum of squares
SS
Variance
(Mean square)
Variance
ratio
(F)
Percentage
contribution
P (%)
Current2 0.44891 0.22446 0.55323 1.895
Pulse ON2 14.82831 7.41416 18.27363 62.598
Pulse OFF2 0.29629 0.14815 0.36514 1.251
Residual
Error20 8.11454 0.40573 1 34.256
Total27 23.68805 100
2525-May-13
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2625-May-13
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2725-May-13
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2825-May-13
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2925-May-13
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In this work, analysis of variance (ANOVA) with Taguchi method is used to
investigate the significant effects on the performance characteristic and the
optimal machining parameter of EDM process.
Finding the result of MRR discharge current is most influencing factor and
then pulse OFF time. From percentage contribution we can clearly say that
MRR and contribution of input parameters are depends on” THERMAL
CONDUCTIVITY” of material.
For high discharge current, copper electrodes show highest MRR, whereas
brass gives good surface finish and normal MRR
Surface roughness was mainly affected by the current and pulse on time. At
higher value of current causes the more surface roughness. Higher surface
finish can be achieved at lower current.
3025-May-13
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The optimum levels of various process parameters obtained in this
experimental work are: Copper electrodes gives highest MRR than
Brass electrodes when Discharge current = 23.2475 A, 7 μs pulse on
time, 5 μs pulse off time.
Similarly Brass electrodes gives lowest MRR than copper electrode when
Discharge current = 7.8125 A, 5 μs pulse on time, 7 μs pulse on time.
Brass electrodes gives better surface finishing when Discharge current =
7.8125A, 5 μs pulse on time, 7 μs pulse on time.
Similarly copper electrodes gives poor surface finishing when Discharge
current = 23.4375 A, 7 μs pulse on time, 5 μs pulse on time.
3125-May-13
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THANK YOU…..
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