Electric discharge Machine: Introduction,working principle,parts,types of EDM,components,application,advantage,disadvantage,EDM

Introduction:-

Electric discharge Machine is the process of metal removal from the work surface due to an erosion of metal caused by electric Spark discharge between the two electrode tool and the work piece.

Electrical Discharge Machining is also called or known as Spark machining, spark eroding, burning, die sinking, wire burning or wire erosion.

This spark near to 8000 to 12000º C.

Parts of Electrical Discharge Machine :-

•DC Power supply 

•Voltmeter

•Ammeter

•Tool

•Die-electric fluid

•Pump

•Filter

•Servo- controlled feed

•Fixture

•Table

Working of Electrical Discharge Machine :-

It consists of an electric power supply, the dielectric medium, the tool, workpiece, and servo control.

The workpiece is connected to the positive terminal and the tool is connected to a negative terminal of the DC power supply.

An air gap of 0.005 to 0.05 mm is maintained between the tool and the work.

The die electric fluid which is non-conductor of electricity is forced under pressure through the gap.

When a DC power is supplied, the fluid in the gap gets ionized and produces a spark between the tool and workpiece, causing a local rise in temperature at about 1000 degrees Celsius, when melts the metal in a small area of the workpiece and vaporizes.

The DC supply generates a pulse between 40 to 3000 V and the frequency of spark at the rate of 10000 sparks per second can be achieved.

The electric and magnetic fields on heated metal cause a compressive force which removes the metal from the work surface.

The die electric fluid acts as a coolant carry the cooled metal from the work surface.

The die electric fluid acts as a coolant carries the eroded metal particles which are filtered regularly and supplied back to the tank.

A servomechanism is used to feed the tool continues to maintain a constant gap between two electrodes.

The accuracy of about 0.005 mm can be achieved in this process.

Application of Electrical Discharge Machine:-

•Drilling for microholes in nozzle

•Thread cutting

•Wire cutting

•Helical profile Milling

•Curved hole Drilling

•Cutting off operation

•Rotary from cutting

Advantage of Electrical Discharge Machine:-

•Hard material and even in the heat treated condition used 

•Any complicated shapes made

•High accuracy

•Good surface finish

•Machining time is less

•No mechanical stress are developed.

Disadvantage of Electrical Discharge Machine:-

•Excessive tool wear

•High power consumption

•Sharp corners can not be reproduced

•High heat developing caused-change in metallurgical properties of material

•Over cut formed