EDM works by using electrical discharges (sparks) to erode away unwanted material from a workpiece to create a desired shape. A CNC wire cut EDM machine controls the gap between an electrode wire and workpiece to cause precise electrical discharges in insulating liquid. These discharges vaporize small amounts of material from the workpiece surface, gradually forming the final shape. EDM is commonly used for mold making, prototype production in industries like aerospace and electronics, and for creating coinage dies due to its ability to accurately machine hard metals and intricate details.

1. COMSATS INSTITUTEOF INFORMATION TECHNOLOGY
EDM Working Principle & Application
Submitted To:
Sir JahanTab
Submitted By:
Hafiz khalid
SP14-BME-057
Grade: __________
Checked By: __________
Date: __________
Department of Mechanical Engineering

2. Definition:
Electrical discharge machining (EDM), sometimes colloquially also referred to as
spark machining, spark eroding, burning, die sinking, wire burning or wire erosion,
is a manufacturing process whereby a desired shape is obtained by using electrical
discharges (sparks).
Working Principle of EDM:
CNC wire cut EDM machine puts impulse voltage between electrode wire
and work piece through impulse source, controlled by servo system, to
get a certain gap, and realize impulse discharging in the working liquid
between electrode wire and work piece. Numerous tiny holes appears due
to erosion of impulse discharging, and therefore get the needed shape of
work piece
Electrode wire is connecting to cathode of impulse power source, and work piece
is connecting to anode of impulse power source. When work piece is approaching
electrode wire in the insulating liquid and gap between them getting small to a
certain value, insulating liquid was broken through; very shortly, discharging
channel forms, and electrical discharging happens. And release huge high
temperature instantaneously, up to more than 10000 degree centigrade, the eroded
work piece is cooling down swiftly in working liquid and flushed away

3. Application:
Prototypeproduction:
 The EDM process is most widely used by the mold-making tool
and die industries, but is becoming a common method of making prototype
and production parts, especially in the aerospace, automobile and electronics
industries in which production quantities are relatively low. In sinker EDM,
a graphite, copper tungsten or pure copper electrode is machined into the
desired (negative) shape and fed into the work piece on the end of a vertical
ram.
Coinage die making:
 For the creation of dies for producing jewelry and badges, or blanking and
piercing (through use of a pancake die) by the coinage (stamping) process,
the positive master may be made from sterling silver, since (with appropriate
machine settings) the master is significantly eroded and is used only once.
The resultant negative die is then hardened and used in a drop hammer to
produce stamped flats from cutout sheet blanks of bronze, silver, or low
proof gold alloy. For badges these flats may be further shaped to a curved
surface by another die. This type of EDM is usually performed submerged in
an oil-based dielectric. The finished object may be further refined by hard
(glass) or soft (paint) enameling and/or electroplated with pure gold or
nickel. Softer materials such as silver may be hand engraved as a refinement.