The document discusses electro discharge machining (EDM), a machining method used for hard, electrically conductive metals. EDM works by using electrical sparks to erode unwanted material away from a workpiece. This allows machining of metals that other techniques cannot cut. The document covers the history of EDM's development, how the process works using sparks and a dielectric fluid, and different EDM techniques like wire EDM and spark EDM as well as their applications and advantages/disadvantages.
3. 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.
4. WHAT IS EDM ?
Electro Discharge Machining
Used on hard metals
Works with electrically
Conductive materials
5. HISTORY OF EDM
In1770s, discovered by Joseph Priestly.
Developed in the mid 1970s
In the mid 1980s, the EDM techniques
were Transferred to a machine tool
Today it is a viable technique that helped
shape
The metal working industry.
6.
7. ACCESSORIES
Surface plate
Sine plate
Slip gauge
Dial indicator
Magnetic ‘V’ block
Precision vise
Pin gauge set
Tooling ball set
Special holders
8. BASIC OF E D M
Workpiece
Electrodes
Sparks
Dielectric fluid
Deionized water
Dielectric oil
Cutting speed
9.
10. HOW EDM WORKS?
Uses very powerful sparks (~3x106 V/m)
Series of rapidly recurring
Charges
Electroerosion
Remove excess by fluid
Flow
11. SPARKS
The phenomena “Breakdown”
occurs
A path for the current through
dielectric
Locally 10-15.000 ºC Ionize the
fluid
Metal melts or vaporizes
12. WIRE EDM
Needs wire feed
o Pre hole is required
for machining for passing
the wire
o Wire dia + spark gap is the
kerf
13. Applications for wire edm
Gears, splines
Machining of carbide
Cone shape angle profiles
Prototype production
14. Advantages Disadvantages
handles delicate tasks
highly accurate
very small kerf for wire
EDM
produces complex
shape
deep, or 3-D shapes
o wire wear out
oslow cutting rates
o heat affected local
stress formation.
oBlind holes can not be
produce
16. Applications for spark
edm
Slots, keyways, square & hex drives ,Gears
Small or deep holes, especially in hardened
material
Removal of broken taps and drills
Hardened jobs can be tapped (cnc edm)
Machining of carbide
17. Advantages Disadvantages
handles delicate tasks
may cut or drill very
hard materials
highly accurate
produces complex
shape
deep, or 3-D shapes
o electrode wear
oslow cutting rates
o heat affected local
stress formation.