COMSATS INSTITUTE OF INFORMATION TECHNOLOGY

EDM Working Principle & Application

Submitted To:

Sir JahanTab

Submitted By:

Hafiz khalid

SP14-BME-057

Grade: __________

Checked By: __________

Date: __________

Department of Mechanical Engineering

Definition:

Electrical discharge machining (EDM), sometimes colloquially also referred to as spark machining, spark eroding, burning, die sinking, wire burning or wire erosion, is a manufacturing process whereby a desired shape is obtained by using electrical discharges (sparks).

Working Principle of EDM:

CNC wire cut EDM machine puts impulse voltage between electrode wire and work piece through impulse source, controlled by servo system, to get a certain gap, and realize impulse discharging in the working liquid between electrode wire and work piece. Numerous tiny holes appears due to erosion of impulse discharging, and therefore get the needed shape of work piece

Electrode wire is connecting to cathode of impulse power source, and work piece is connecting to anode of impulse power source. When work piece is approaching electrode wire in the insulating liquid and gap between them getting small to a certain value, insulating liquid was broken through; very shortly, discharging channel forms, and electrical discharging happens. And release huge high temperature instantaneously, up to more than 10000 degree centigrade, the eroded work piece is cooling down swiftly in working liquid and flushed away

Application:

Prototype production: The EDM process is most widely used by the mold-making tool

and die industries, but is becoming a common method of making prototype and production parts, especially in the aerospace, automobile and electronics industries in which production quantities are relatively low. In sinker EDM, a graphite, copper tungsten or pure copper electrode is machined into the desired (negative) shape and fed into the work piece on the end of a vertical ram.

Coinage die making: For the creation of dies for producing jewelry and badges, or blanking and

piercing (through use of a pancake die) by the coinage (stamping) process, the positive master may be made from sterling silver, since (with appropriate machine settings) the master is significantly eroded and is used only once. The resultant negative die is then hardened and used in a drop hammer to produce stamped flats from cutout sheet blanks of bronze, silver, or low proof gold alloy. For badges these flats may be further shaped to a curved surface by another die. This type of EDM is usually performed submerged in an oil-based dielectric. The finished object may be further refined by hard (glass) or soft (paint) enameling and/or electroplated with pure gold or nickel. Softer materials such as silver may be hand engraved as a refinement.