1. OPTIMIZATION OF WIRE ELECTRICAL DISCHARGE MACHINING
PROCESS PARAMETERS USING TAGUCHI METHOD
Overview
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Wire Electric Discharge Machining
Process Parameters
Taguchi Design of Experiments
Grey Based Taguchi Method of
Optimization
Raju Kumar
(Roll no 1002061)
Dharam Deo Prasad
(Roll no 1002062) 1

2. ELECTRIC DISCHARGE MACHINING
Introduction
 Sometimes it is referred to as spark machining, spark eroding, burning, die
sinking or wire erosion
 Its a manufacturing process whereby a desired shape is obtained using
electrical discharges (sparks).
 Material is removed from the workpiece by a series of rapidly recurring
current discharges between two electrodes, separated by a dielectric liquid and
subject to an electric voltage.
 One of the electrodes – ‘tool-electrode’ or ‘tool’ or ‘electrode’.
 Other electrode - workpiece-electrode or ‘workpiece’.
 As distance between the two electrodes is reduced, the current intensity
becomes greater than the strength of the dielectric (at least in some points)
causing it to break.
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3. ELECTRIC DISCHARGE MACHINING
• EDM - System
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4. WIRE ELECTRIC DISCHARGE MACHINING
Introduction
 Also known as wire-cut EDM and wire cutting.
 A thin single-strand metal wire (usually brass) is fed through the workpiece
submerged in a tank of dielectric fluid (typically deionized water).
 Used to cut plates as thick as 300 mm and to make punches, tools, and dies
from hard metals that are difficult to machine with other methods.
 Uses water as its dielectric fluid; its resistivity and other electrical properties
are controlled with filters and de-ionizer units.
 The water flushes the cut debris away from the cutting zone.
 Flushing is an important factor in determining the maximum feed rate for a
given material thickness.
 Commonly used when low residual stresses are desired, because it does not
require high cutting forces for material removal.
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5. WIRE ELECTRIC DISCHARGE MACHINING
WEDM - System
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6. WIRE ELECTRIC DISCHARGE MACHINING
WEDM Components
-four major components
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Computerized Numerical Control (CNC) - The Brains.
Power Supply -The Muscle
Mechanical Section - The Body
Dielectric System -The Nourishment
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7. WIRE ELECTRIC DISCHARGE MACHINING
ADVANTAGES
• Better stability and higher productivity .
• Higher machining rate with desired accuracy and minimum
surface damage.
• Uses in the production of forming tools.
• To produce plastics moldings, die castings, forging dies etc.
• Can be applied to all electrically conducting metals and alloys
irrespective of their melting points, hardness, toughness, or
brittleness.
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8. WIRE ELECTRIC DISCHARGE MACHINING
Applications – Wire EDM
•Special form of EDM - uses a continuously moving conductive wire
electrode.
Material removal occurs as a result of spark erosion as the wire electrode is
fed, from a fresh wire spool, through the workpiece.
Horizontal movement of the worktable (CNC) determines the path of the cut.
Application - Machining of super hard materials like polycrystalline diamond
(PCD) and cubic boron nitride (CBN) blanks, and other composites.
Carbon fiber composites are widely used in aerospace, nuclear, automobile,
and chemical industries, but their conventional machining is difficult
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9. MACHINING PROCESS PARAMETRS
• Main Machining Parameters
Pulse-on time(μs)
Pulse-off time(μs)
Wire feed(mm/min)
Gap voltage(volt)
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10. The Taguchi Approach to DOE
Orthogonal array
From every trial series we can obtain an average result level and a measure of
the variation, si, i=1,2, … ,9. These values can then be used as a basis for
choosing the combination of factor levels that provides the most robust design.
Control
Factors
EXP.NO
A
B
C
D
1
1
1
1
1
2
1
2
1
2
3
1
3
3
3
4
2
1
2
3
5
2
2
3
1
6
2
3
1
2
7
3
1
3
2
8
3
2
1
3
9
3
3
2
1
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11. The Taguchi Approach to DOE
Process parameters & their levels
symbol
Control
factor
Unit
Level 1
Level 2
Level 3
A
Pulseon time
μs
4
6
8
B
Pulseμs
off time
4
6
8
C
Wire
feed
mm/min
2
4
6
D
Gap
voltage
volts
40
50
60
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12. Optimizing Techniques using Taguchi method
Two types of optimizing techniques
1. Grey based Taguchi method
2. Fuzzy based Taguchi method
We have used grey based Taguchi method for optimizing
machining parameters in wire EDM using LM6B4C
composite material produced by stir casting .
Two types of LM6B4C Composite material was
manufactured as workpiece for cutting by WEDM.
•LM6 +5%B4C
•LM6 +10%B4C
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13. Grey based Taguchi method
Introduction
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widely used in different fields of engineering to optimize the process
parameters.
To solve the multiple performance characteristics problems , the Taguchi
method is coupled with grey relational analysis.
An OA provides a set of well-balanced experiments, and Taguchi’s
signal-to-noise. (S/N) ratios, which are logarithmic functions of the
desired output, serve as objective functions for optimization.
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14. Grey based Taguchi method
Procedure of the grey-based Taguchi method.
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15. Grey based Taguchi method
To find S/N ratios values
For MRR
And, For surface roughness and kerf
width(k)
Where
n = number of replications and
yij = observed response value
Where
i=1, 2... ....n; j = 1, 2...k.
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16. Grey based Taguchi method
Further analysis & calculations
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find normalized S/N ratio values .
find grey relational coefficient .
find grey relational grade.
Draw graphs for Grey relational grades for maximum
MRR, Minimum Ra and minimum kerf width .
• find optimum levels of the factors from the graphs & the
tables of experiments separately.
• Compare both the optimal values obtained from the tables
& graphs.
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17. Grey based Taguchi method
RESULTS AND DISCUSSION
• Confirmation test for the optimal parameter setting was
conducted.
• LM6 +10%B4C has the optimal value within the orthogonal
array .
• LM6 +5%B4C the optimal value from the L9 orthogonal array
is different from the optimal value obtained from the Grey
theory design .
• Hence a conformation experiment is conducted to find the
improvements in the process.
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18. Grey based Taguchi method
RESULTS AND DISCUSSION
Conformation experiment for LM6 +5%B4C
Optimal process parameters
Orthogonal Array
Level
MRR (g/min)
Time(sec)
Ra (μm)
Kerf(mm)
A2B2C3D1
Grey theory Design
A2B1C3D1
0.0612
0.0841
2.13
1.55
3.26
3.79
0.336
0410
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19. Grey based Taguchi method
RESULTS AND DISCUSSION
The optimal process parameters based on Grey Relational
Analysis
For Aluminium boron
carbide (5%)
for Aluminium boron carbide
(10%)
40 V Gap Voltage
40 V Gap Voltage
4 μs pulse on-time
4 μs pulse on-time
6 μs pulse off-time
4 μs pulse off-time
6 mm/minute Wire Feed rate
2 mm/minute Wire Feed
rate
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20. Grey based Taguchi method
CONCLUSION
• The Material Removal Rate shows an increased value of
0.0612g/min to 0.0841g/min.
• The time shows a reduced value of 2.13 sec to 1.55 sec .
• Positive indicators of efficiency in the machining
process.
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21. Grey based Taguchi method
THE END
THANK YOU
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