1

1. Module-3: ADVANCED MATERIAL REMOVAL PROCESSES
Lecture No-11
Wire Cut Electric Discharge Machining (WEDM)
The Wire Electric Discharge Machining (WEDM) is a variation of EDM and is
commonly known as wire-cut EDM or wire cutting. In this process, a thin metallic wire is
fed on-to the workpiece, which is submerged in a tank of dielectric fluid such as de-
ionized water. This process can also cut plates as thick as 300mm and is used for making
punches, tools and dies from hard metals that are difficult to machine with other methods.
The wire, which is constantly fed from a spool, is held between upper and lower diamond
guides. The guides are usually CNC-controlled and move in the x–y plane. On most
machines, the upper guide can move independently in the z–u–v axis, giving it a
flexibility to cut tapered and transitioning shapes (example: square at the bottom and
circle on the top). The upper guide can control axis movements in x–y–u–v–i–j–k–l–.
This helps in programming the wire-cut EDM, for cutting very intricate and delicate
shapes.
In the wire-cut EDM process, water is commonly used as the dielectric fluid. Filters and
de-ionizing units are used for controlling the resistivity and other electrical properties.
Wires made of brass are generally preferred. The water helps in flushing away the debris
from the cutting zone. The flushing also helps to determine the feed rates to be given for
different thickness of the materials. The schematic of wire cut EDM is shown in Figure
3.11.1

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ire-Cut EDM
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achining pro
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3. between the tool-electrode gap thereby creating a path for each discharge. The area
wherein discharge takes place gets heated to very high temperatures such that the surface
gets melted and removed. The cut particles (debris) get flushed away by the continuously
flowing dielectric fluid.
WEDM is a non-conventional process and is very widely used in tool steels for pattern
and die making industries. The process is also used for cutting intricate shapes in
components used for the electric and aerospace industries.
Applications of Wire-Cut EDM
Wire EDM is used for cutting aluminium, brass, copper, carbides, graphite, steels and
titanium. A schematic of the cutting through wire EDM is shown in Fig. 3.11.2. The wire
material varies with the application requirements. Example: for quicker cutting action,
zinc-coated brass wires are used while for more accurate applications, molybdenum wires
are used.
The process is used in the following areas:
 Aerospace, Medical, Electronics and Semiconductor applications
 Tool & Die making industries.
 For cutting the hard Extrusion Dies
 In making Fixtures, Gauges & Cams
 Cutting of Gears, Strippers, Punches and Dies
 Manufacturing hard Electrodes.
 Manufacturing micro-tooling for Micro-EDM, Micro-USM and such other micro-
machining applications.

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in WEDM i
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of a large s
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5. sy
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Process Para
The process p
WEDM proc
ig.3.11.3. Th
 Electr
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 Non-e
rate of
 Electr
 Dielec
ead the wire
out or break
ameters in W
parameters t
cess are sho
he major para
rical paramet
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electrical par
f flushing.
rode based p
ctric System
e from the u
ks.
WEDM
that can affe
own through
ameters are
ters: Peak cu
ity.
rameters: W
arameters: M
m: Type, visc
upper to the l
ect the quali
h an Ishika
as follows:
urrent, pulse
ire speed; w
Material and
osity, and ot
lower guide
ity of machi
awa cause-e
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work feed rate
d size of the w
ther flow cha
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effect diagra
ulse off time
e, machining
wire.
aracteristics
or to detect w
ting or drilli
am as show
and supply
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when
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and