Wire Electric Discharge Machining Process, MSBTE, Diploma Mechanical Engineering, Final Year, Fifth Semester, Advanced manufacturing Processes, Unit-I,

1. UNIT I
NON CONVENTIONAL MACHINING PROCESSES-
WEDM
S.G.R. Education Foundation
G H RAISONI COLLEGE OF ENGINEERING AND MANAGEMENT
AHMEDNAGAR
NAAC ACCREDITED
(APPROVED BY AICTE, NEW DELHI, RECOGNIZED BY GOVT. OF MAHARASHTRA & AFFILIATED TO SAVITRIBAI PHULE PUNE UNIVERSITY)
- Prof. Aniket V. Joshi
Asst. Professor
Mechanical Engineering Department
GHRCEM, A’Nagar.

2. WIRE CUT ELECTRIC DICSCHARGE
MACHINING (WEDM)
 Basic principle is same as EDM
 Employs electrical energy to
remove metal from workpiece
without touching it
 Process can be used only when
through cut has to be taken or cut
is to be taken from outer side of
workpiece
 Uses copper or tungsten wire of
0.3 mm dia. as tool
 Deionized water is used as
dielectric fluid
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3. Working principle of wedm
• Heat energy generated by a spark is used to remove
unwanted material from the workpiece
• Wire of dia. 0.3 mm used as electrode or tool
• Gap between wire and workpiece is 0.5 mm
• Wire is continuously moving at constant speed
• Dielectric fluid is constantly flushed in the area of machining
• When switch ON the supply, spark get generated and
dielectric fluid gets ionized allowing current to flow
between tool and workpiece.
• Due to heat, melting of metal takes place and melted
particles driven away by the dielectric fluid.
• Desired shape is achieved by table motions through control
system AVJ GHRCEM AHMEDNAGAR 3

4. Set-up for wedm
 Basic elements of WEDM are:
1) Power supply system
2) Dielectric system
3) CNC control system
4) Wire drive system
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5. Set-up for wedm
1) Power supply system:
- Workpiece is mounted on a
table
- Tool (-ve, cathode), workpiece
(+ve, anode)
- Anode and cathode
connected to DC power
supply
- Supply is in the form of pulse
- Voltage supplied is 50 V
- Because of small size of wire,
it cannot carry current more
than 30A
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6. Set-up for wedm
2) Dielectric fluid system:
- Deionized water is used as
dielectric fluid
- It gives high metal removal
rate and better surface
finish
- Nozzle is employed in
machining area
- Both workpiece and wire
are constantly flushed
- As serves as coolant.
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3) CNC control System:
- Used for the movement of
work table
- Table has movement in two
axis (direction)
- For taking contouring cuts,
table can be moved in both
directions simultaneously

7. Set-up for wedm
4) Wire drive system:
- this system performs three functions
a) To feed fresh wire for machining
b) To take-up the used wire
c) To maintain the tension in the wire
- Wire is used only once, because due to spark, wire surface
does not remain round
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8. Controlling parameters
for wedm
1) Discharge current:
- Material removal rate increases with current
- Increasing current increases crater depth to a certain
value, beyond that yield a smoother surface
- Current limit is 30A
2) Pulse duration:
- Directly proportional to MRR
- Inversely proportional to surface roughness
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9. Controlling parameters for
wedm
3) Pulse frequency:
- Directly proportional to MRR
- Pulse frequency is about 1 MHz
- Results in reduced crater size or better surface finish
4) Cutting Rate:
- Wire speed is between 205 to 150 mm/sec.
- Depends upon thickness of workpiece
- Maximum possible depth of cut is 90 mm
- Average machining rate is 10-15 mm2/min
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10. Controlling parameters for
wedm
5) Wire tension:
- Required to keep the wire straight
- A series of tension rollers is provided to keep the required
tension
- 50-60% of wire tensile strength
6) Dielectric flow:
- Nozzle is employed
- Continue and enough supply required to allow sparking
- Fluid can be reused only after filtration
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11. Advantages of wedm
 Straight holes can be produces to close tolerances
 Can be operated unattended for longer period of time
 High accuracy
 Good surface finish
 Very sharp angles can be cut
 Eliminates the need of post-machining
heat treating and possible part distortion
 Parts produced are burr-free
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12. disadvantages of wedm
o Wire can not be reused
o Proper tension needs to be
maintained
o Only electrically conductive material
can be machined
o Residual stresses are induced in the
workpiece
o limit for maximum depth of
workpiece is 90 mm
o A hole is necessary in the workpiece
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13. Applications of wedm
WE
DM
Punches &
dies used in
press tools
Production
of moulds
and dies
Complex
contours
Simple flat
shapes with
superior
quality edge
Cylindrical
pins up to
5 mm dia.
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14. 14
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