GUIDED BY:Prof. S.S Singh

PRESENTED BY :ASHIS KUMAR JENAREGD NO-1101304073

ANSHUL NISHANT KANDULNAREDG NO-1101304072

MECHANICAL ENGINEERING7th sem

ELECTRO DISCHARGE MAHINE

GITAM

CONTENT OBJECTIVES INTRODUCTION EVOLUTION IN EDM MACHINES TYPES OF EDM CONSTRUCTION WORKING PRINCIPLE TOOL MATERIAL MEDIUM MACHINING RATIO PROCESS PARAMETERS ADVANTAGES DISADVANTAGES APPLICATIONS REFERENCE

OBJECTIVES

TO study about Electro discharge machine.

To give small introduction about the types of electro discharge machining.

To study the process parameter of EDM machine.

INTRODUCTION The history of EDM itself begins in 1943, with the invention of its

principle by Russian scientists Boris and Natalya Lazarenko in

Moscow.

Electro Discharge Machining (EDM) is an electro-thermal non-

traditional machining process, where electrical energy is used to

generate electrical spark and material removal mainly occurs due to

thermal energy of the spark.

Electro discharge machining is also called

as spark machining/spark erosion machining.

EVOLUTION IN EDM MACHINES:

50 year

evolution

Eleroda D1 (1955) Robofil 2050 TW (2005)

TYPES

There are two type‘s of EDM machining process

Die-Sinking EDM ( The Ram Type ):

• In the die - sinker EDM Machining process, two metal parts are

submerged in an insulating liquid and are connected to a source of

current . When the current is switched on, an electric tension is

created between the two metal parts and if the two parts are brought

together to within a fraction of an inch, the electrical tension is

discharged and a spark jumps across. Where it strikes, the metal is

heated up so much that it melts.

• It is also called as cavity type EDM or volume EDM .

Die-Sinking EDM

Wire-cut EDM: In this process a moving metalic wire made off up copper ,brass and

zinc coated brass wire is acting as electrode is used to cut complex outlines and find the detail in the required work piece.

CONSTRUCTION The setup consist for an EDM are a power supply source ,a dielectric

medium , workpiece ,tool, servo control, speed reduction gear box, a rack and pinion arrangement or other suitable mechanism for tool feed.

In EDM the tool is connected to the negative terminal of DC power

supply act as cathode and the workpiece is connected to positive

terminal of DC power supply, act as anode.

A gap is maintained between the tool and the work piece which is

called as spark gap , the spark gap is usually varies from 0.005mm to

0.05mm.The spark gap is feed by dielectric which brake down when a

proper dc voltage is applied between the tool and the work piece.

when a circuit voltage of 50 to 450v is applied then the electron starts flowing from cathode due to which the gap ionised.

.

WORKING PRINCIPLE

So there is drop in resistance and discharge of electric energy results in electrical brake down . so large amount of spark is generated.

The spark discharges heat to the work piece material with considerable force and velocity and results in development of high temperature around 10000`c.

These forces the work piece to melt and a portion of it is vaporized , these portion is taken away from the spark gap by the flow of dielectric through it.

(ELECTRO DISCHARGE MACHINING)

TOOL MATERIAL

The commonly used tool materials are brass, copper and some other

materials like cast iron , tungsten ,graphite , and alloys of silver etc.

Thus the basic characteristics of electrode materials are:

High electrical conductivity.

• High thermal conductivity .

High density.

High melting point.

Cheap cost.

The tool should be made of

Same material as the work piece.

In EDM material removal generally takes place due to thermal

evaporation and melting .The main aim of providing dielectric is to

maintain a oxygen free environment and it should have strong

dielectric resistance so that it does not breakdown so easily.

Dielectric is used as medium in EDM. The commonly used dielectrics

are paraffin or some light oil like transformer oil or kerosene.

MEDIUM

MACHINING RATIO We know

machining ratio=material removal rate / tool wear• The material removal rate of the work piece is the volume of the material

removed per minute.

So machining ratio depends upon the melting temp. of tool and work piece If melting temp. of tool = melting temp. of work piece then machining ratio will

be 1 to 2. If melting temp. of tool > melting temp. of work piece then machining ratio will

be 8 to 10. If melting temperature of tool < melting temperature of work piece then

machining ratio will be 0.1 to 0.3.

PROCESS PARAMETERS There are two types of process parameters for EDM. Electrical parameters: Pulse Duration.

Pulse Interval.

Electrode gap (spark gap). Polarity.

Non electrical parameters: Rotation of Tool Electrode Tool material (Electrode) Tool Geometry

ADVANTAGES

The deep hole can be produced.

Material removal cost is very low.

The operation is noiseless.

The machined surface are free of stress.

Any material that is electrically conductive can be cut using the EDM process .

Complex dies sections and moulds can be produced accurately, faster, and at

lower costs.

Hardened work pieces can be machined easily.

DISADVANTAGES

The work piece material must be electric conductive.

Perfect square corners cannot be produced by EDM.

It is only used for machining of small work pieces.

Dielectric vapour can be dangerous.

The energy required for the operation is more than that of the

conventional process and hence will be more expensive.

APPLICATION

in the aerospace, automobile and electronics industries in which

production quantities are relatively low.

It is used to machine extremely hard materials that are difficult to

machine like alloys, tool steels, tungsten carbides etc .

It is used for forging, extrusion, wire drawing, thread cutting .

It is used for internal thread cutting and helical gear cutting .

It is used for machining sharp edges .

Ceramic materials that are difficult to machine can be machined by the

EDM machining process.

REFERENCE

International Journal of Engineering Science and Technology Vol. 2(6),

2010, 2172-2191.

International Journal of Modern Engineering Research (IJMER) .

REPUBLIC OF IRAQ. MINISTRY OF HIGHER EDUCATION &SCIENTIFIC

RESEARCH. UNIVERSITY OF TECHNOLOGY PRODUCTION & METALLURGY

ENG. DEP. CONSIDEORATION OF GRADUATIN.

Version 2 ME, IIT Kharagpur .

Mohan, B., Rajadurai, A., Satyanarayana, K. G Journal of Materials Processing

Technology

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