Introduction Electric Discharge Machine

1. GOVERNMENT COLLEGE OF ENGINEERING KARAD
(An Autonomous Institute of Govt. Of Maharashtra)
A
Seminar On
Study on Electric Discharge Machining and
Scope for New Era
Guided by: Prof. V. S. Jadhav
Presented by : Mr. Bhushan J. Sarise
Registration No:18241208
DEPARTMENT OF PRODUCTION ENGINEERING
2018-19

2. CONTENTS
• INTRODUCTION
• PRINCIPLE OF EDM
• CONSTRUCTION
• TOOL MATERIAL
• FLUID PROPERTIES
• ADVANTAGES
• DISADVANTAGES
• APPLICATIONS
• FUTURE SCOPE
• CONCLUSION
• REFERENCES

3. History
The EDM process we know today started with the observations of
Joseph Preistly in 1770. He noticed that electrical discharges had
removed material from the electrodes in his experiments. This is also
known as electro-discharge erosion.
 In the 1940's Soviet researchers developed a machining process
that formed the foundation for modern EDM.
Fig. Electric Discharge Machine(EDM)

4. INTRODUCTION
• EDM is a machining method typically used for hard metals
which are electrically conductive.
• It makes possible to work with metals for which traditional
machining techniques are ineffective.
• The use of a thermoelectric source of energy in developing the
nontraditional techniques has greatly helped in achieving an
economic machining of the extremely low machinability
materials and difficult jobs.
• The process of material removal by a controlled erosion through
a series of electric sparks, commonly known as EDM.
• Electro Discharge Machining (EDM) is an electro-thermal nontraditional
machining Process, where electrical energy is used to generate electrical
spark and material removal mainly occurs due to thermal energy of the
spark.
•The EDM process is based on the thermoelectric energy created between a
work- pieces and an electrode submerged in an insulated dielectric fluid.

5. PRINCIPLE OF EDM
• The principle of EDM is also called electro discharge or spark erosion
or electro erosion, is based on erosion of metals by spark discharges.
• Since, when two current carrying conductors/wires are allowed to
touch each other, an arc is produced . If we look closely at the point of
contact b/w the two wires, we note that a small portion of metal has been
eroded away, leaving a small crater.
•. In EDM , when a discharge takes place b/w two points of the anode
and the cathode, the intense heat generated near the zone melts &
evaporates the materials in the sparking zone.
• For improving effectiveness, the w/p & tool both are submerged in a
dielectric fluid (hydrocarbon or mineral oils).

6. CONSTRUCTION
Fig(a). Principle Of EDM

7. The main components of EDM :
Power Supply
Tool (Electrode)
 Spark Generator
Di-electric fluid
 Power Supply: Power supply converts AC into pulsed DC, used to
produce spark b/w tool and w/p. This high power pulsed output responsible
for generating spark between the electrodes.
 TOOL (ELECTRODE) : The shape of the tool should be replica of the
desired product, except that an allowance is made for side clearance, over
cuts for broaching small holes.
Solid tool(rod) may be used but for larger ones hollow tools are used.

8.  SPARK GENERATOR : The spark generator performs the important
function of supplying sufficient voltage to initiate & maintain the discharge.
It also absorbs the supply of varying current intensity and the discharge
duration and controll the recurring rhythm of the discharge.
 DI-ELECTRIC FLUID : In EDM, the dielectric fluid is flushed through
the spark gap.
• It is supplied either to a hole in the tool or from external jet.
• This fluid works as the spark conductor.
• The widely used dielectric fluid is kerosene; others used are deionized
water, Si oils, ethylene glycol etc.
• The fluid must be hydrocarbon becoz deionization occurs due to the
involvement of hydrogen in hydrocarbon.

9. TOOL MATERIALS
• The selection for tool material is depends upon various factors.
The main factor is, the tool should have electrical conductive.
• Other factors are, volume of material to be removed, required
surface finish, desired tolerance, wear ratio & many more.
• The various materials which can be used for making tool may be
of brass, copper, graphite
Fig(b).Tool Material

10. FLUID PROPERTIES
The dielectric fluid used in EDM should have following properties
1) It should have sufficient dielectric strength.
2) It should have low viscosity & good wetting capacity.
3) It should be chemically neutral.
4) It should not evolve toxic vapors during entire operation range.
5) The flash point should be high.
6) It should provide sufficient cooling medium.
7) It should be less costly & easily available.
8) It should flush the debris produced during operation.

11. ADVANTAGES
1) Hard & tough metals can be machined with better surface
finish.
2) Complex & internal shapes can be machined.
3) No cutting force due to no contact b/w metal and w/p.
4) The surface finish is non-directional.
5) No effects of material hardness and tool wear.
6) Tolerance upto 0.4 micro meter is achieved.
7) Secondary finishing operation can be neglect.
8) No need of Heat treatment before machining.

12. DISADVANTAGES
1) Low MRR.
2) The w/p must be electric conductor.
3) The surface after machining is highly
stressed.
4) Machining time is too long.
5) Specific power consumption is too high.
6) Excessive tool wear.

13. APPLICATIONS
1) It is used in the production of die for fabrication of all components .
2) EDM can be used in manufacturing of hydraulic valve spools, gear wheels,
fine holes or slots in hard blade materials used in gas turbines, compressors
, diesel engines etc.
3) It is used in fabrication, extrusion, blanking, stamping and embossing dies.
4) It is also used for removal of drill and tapes from components

14. FUTURE SCOPE
1. The mathematical model can be developed different work
piece and electrode materials for EDM and WEDM
processes,
2. Responses like roundness, circularity, cylindricity, machining
cost etc .are to be considered in further research.
3. The standard optimization procedure can be developed and
the optimal results are to be validated.

15. CONCLUSION
The EDM is an untraditional material removal process and flexible enough to
meet the miscellaneous machining needs raised by the demand in the global and
local metal cutting industries.
With addition of computers, the EDM process has been extensively brought
under various methods. Among them, the wire EDM has become more popular. In
future trends there is also scope for rotating type EDM disc cutter which gives
more material removal rate in compare wire EDM.
 It gives machining option of producing highly complex parts, independent of
the mechanical properties of workpieces material. It has economical advantages in
compare if same shape of material was machined through any conventional
process.
In this process the stochastic sparking phenomenon depends on both electrical
and non electrical parameters and the quality of machined surface and metal
removal rate also depends on types of die electric fluid were used.

16. REFERENCES
1] Lazarenko, B. R., and N. Lazarenko. "About the inversion of metal erosion
and methods to fight ravage of electric contacts." WEI-Institute, Moscow in
Russian (1943). [2] Jegan, TM Chenthil, M. Dev Anand, and D. Ravindran.
"Determination of electro discharge machining parameters in AISI202 stainless
steel using grey relational analysis." Procedia Engineering 38 (2012): 4005-
4012.
[3] Srivastava, Vineet, and Pulak M. Pandey. "Effect of process parameters on
the performance of EDM process with ultrasonic assisted cryogenically cooled
electrode." Journal of Manufacturing Processes 14.3 (2012): 393-402.
[4] Zhang, Yanzhen, et al. "Investigation on the influence of the dielectrics on
the material removal characteristics of EDM." Journal of Materials Processing
Technology 214.5 (2014): 1052-1061.
[5] Ho, K. H., and S. T. Newman. "State of the art electrical discharge
machining (EDM)." International Journal of Machine Tools and
Manufacture43.13 (2003): 12871300. [

17. THANK YOU….