Electric discharge machining (EDM) is a process that removes small amounts of material from electrical contacts using electrical sparks. For efficient machining, short, high frequency sparks are needed. The sparks can be concentrated into a small area if the discharge is submerged in a dielectric fluid using a relaxation circuit. EDM is a thermoelectric process that uses the heat from sparks to remove material from the workpiece. EDM involves removing material from a conductive workpiece using electrical discharges between two electrodes submerged in a dielectric fluid.

2. Sparking takes place between two electrical contacts a
small amount of material is removed from each of the
contacts. This facts was realized and the attempts
were made to harness and control the spark energy to
employ it for useful purpose , say, for machining of
metals. It was found that the sparks of short duration
and high frequency are needed for efficient
machining.

3. It was also observed that if the discharged is
submerged in dielectric , the energy can be
concentrated into a small area . A relaxation circuit
(Known as RC circuit ) was proposed in which
electrodes (tool and work piece ) are immersed in the
dielectric like kerosene , and are connected to the
capacitor. EDM is a thermoelectric process in which
heat energy of a spark is used to remove material from
the work piece.

4. Electric Discharge Machining (EDM) is the removal of
materials conducting electricity by electrical discharge
between two electrodes (work piece electrode and tool
electrode ), a dielectric fluid being used in the process.

5. Classification
(1) Sinking by EDM
(2) Cutting by EDM
(3) Grinding by EDM

6. In this case, the metal removal is affected by non
stationary electrical discharges which are separated
from each other both spatially and temporarily. This
process includes those EDM operation in which the
average relative speed between the tool and work piece
is coincident with the penetration speed in the work
piece.

7. It includes these machining operations where the work
piece is cut off or notched.

8. Spark erosion grinding embraces the machining
processes made with an electrode rotating around an
axis in addition to the normal electrode feed.

9. THE END