Electrical discharge machining and wire cut EDM

Group canditates Name Roll no 1. Muhammad Shaban 13-MT-03 2. Ali Gohar 13-MT-503. Tahir Hanif 13-MT-35

Muhammad Shaban 13-MT-03

Thermal Removing Techniques HISTORY OF EDM Introduction EDM Working principle Important characteristic Working

Ali Gohar 13-MT-50

Advantages Disadvantages Application Wc-edm Working principle Important characteristic

Tahir Hanif 13-MT-35

Major components W-c edm Process Advantages Disadvantages Application

Thermal Removing Techniques In thermal removing processes, thermal

energy, provided by a heat source, melts and/or vaporizes the volume of the material to be removed.

Among thermal removal methods, electrical discharge machining or EDM is the oldest and most widely used.

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.

Introduction

Wire cut EDM

Electrical discharge machining wire cutting (EDM-WC) is a thermal mass-reducing process that uses a continuously moving wire to remove material .

A thin wire of brass, tungsten or copper is used as an electrode.

Deionized water is used as the dielectric. With wire edm you can basically cut out

any design.

working principle The working principle is based on

thermoelectric energy. This energy is created between work piece and tool.

Important characteristic Tool material : brass, tungsten or copper Work piece material :conducting material and

alloys. Process parameters : voltage, spark gap and

melting temperature of work. Material removal : Melting and vaporization Wire diameter : 0.25mm Kerf width : 0.41mm Die electric flushing pressure :

( 10 -15 kgf/ ) Spark gap : (kerf width –wire dia/2)mm

Major Components 1. CNC .

Process is controlled by CNC.2. Power supply .

Provide energy to the spark.3. Mechanical section .

worktable,workstand,wire drive mechanism.4. Dielectric system.

The water reservoir where filtration , condition of water(resistivity/conductivity)and temperature of water is provided and maintained.

Wire EDM Machining Process

In this process, a thin metallic wire is fed on-to the work piece, which is submerged in a tank of dielectric fluid such as deionized water.

The wire, which is constantly fed from a spool, is held between upper and lower diamond guides. The guides are usually CNC-controlled.

In the wire-cut EDM process, water is commonly used as the dielectric fluid. Filters and de-ionizing units are used for controlling the resistivity and other electrical properties.

Wires made of brass are generally preferred.

The area where in discharge takes place gets heated to very high temperatures such that the surface gets melted and removed. The cut particles (debris) get flushed away by the continuously flowing dielectric fluid and keep the wire and workpiece cool.

The wire and workpiece must be electrically conductive.

Schematic illustration of the wire EDM process. As much as 50 hours of machining can be performed with one reel of wire, which is then discarded.

Pieces over 16 in thick can be machined.

Typical EDM-WC products

Advantages

Machining accuracy is higher. As the cutting path is very small, there is

very less removal ratio of material. During machining, electrode wire doesn’t

touch work piece, there is no physical cutting force.

There is very little heat impact on the surface of work piece

It can machine small shape holes, small gap or job with complicated shape.

Disadvantages

Consumes high levels of energy Only able to machine conductive

materials. More expensive process than

conventional milling or turning.

Applications Aerospace, Medical, Electronics and

Semiconductor applications Tool & Die making industries. In making Gauges & Cams Cutting of Gears Manufacturing hard Electrodes.