2. BITS Pilani, Hyderabad Campus
1.CNC Wire cut EDM
OBJECTIVE:
Study and Prepare a program by ELCAM software and cut the profile by using
CNC Wire cut EDM.
3. BITS Pilani, Hyderabad Campus
Electrical energy is directly used to cut the material to get the final shape and size
– Electrical discharge machining (EDM)
– Wire cut Electrical Discharge Machining (WCEDM)
Introduction to EDM
4. BITS Pilani, Hyderabad Campus
Principle
Metal is removed by producing powerful electric
spark discharge between the tool (cathode) and the
work material (anode)
Also known as Spark erosion machining or electro
erosion machining
Machining action forms a gap between the part and
electrode (tool) which causes a spark which removes
the material from work piece
Electrode is (-) negative and part is (+) positive
Electrode can be made form brass, copper, graphite
Working Principle
6. BITS Pilani, Hyderabad Campus
EDM has the following advantages:
1. Cavities with thin walls and fine features
can be produced.
2. Difficult geometry is possible.
3. The use of EDM is not affected by the
hardness of the work material.
4. The process is burr-free.
Electrical Discharge Machining (EDM)
7. BITS Pilani, Hyderabad Campus
Wire Cut Electrical Discharge Machining
(WC-EDM)
Wire cut EDM machining (Electrical Discharge Machining) is an electro thermal production process.
In WEDM, A thin wire of brass, tungsten or copper is used as an electrode
Deionized water is used as the dielectric
Greater flexibility due to independent movement of upper guide helps in programming the wire-cut EDM, for
cutting very intricate and delicate shapes.
8. BITS Pilani, Hyderabad Campus
Working Principle
The working principle is based on thermoelectric energy. This energy is created between work piece and tool.
Major Components
1. 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.
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Important characteristics
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/𝑐𝑚2 )
Spark gap : (kerf width –wire dia/2)mm
11. BITS Pilani, Hyderabad Campus
Dielectric Fluid
Fluid medium which doesn’t conduct electricity
Dielectric fluids generally used are paraffin, white
spirit, kerosene, mineral oil
Must freely circulate between the work piece and
tool which are submerged in it
Eroded particles must be flushed out easily
Should be available @ reasonableprice
Dielectric fluid must be filtered before reuse so that chip
contamination of fluid will not affect machining
accuracy
Wire Cut Electrical Discharge Machining
(WC-EDM)
12. BITS Pilani, Hyderabad Campus
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 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.
(WC-EDM) Process
14. BITS Pilani, Hyderabad Campus
Wire Cut Electrical Discharge Machining
(WC-EDM)
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
o Consumes high levels of energy
o Only able to machine conductive materials.
o More expensive process than conventional milling or turning.
15. BITS Pilani, Hyderabad Campus
Aerospace, Medical, Electronics and Semiconductor applications
Tool & Die making industries.
In making Gauges & Cams
Cutting of Gears
Manufacturing hard Electrodes.
