Question

The mechanism of material removal in Electric Discharge Machining (EDM) process is:

• A. melting and evaporation
• B. melting and corrosion
• C. corrosion and cavitation
• D. cavitation and evaporation

Hint:

EDM is often called "Spark Erosion." Sparks are incredibly hot—much hotter than the melting point of any metal. Therefore, the only way they can remove metal is by Melting it and turning it into gas (Evaporating it).

Answer 1

The Correct Option is A

Electric Discharge Machining (EDM) is a non-traditional machining process used for hard metals that are difficult to machine using conventional methods. It relies on thermoelectric energy rather than mechanical force. 1. The EDM Principle: The process involves a series of rapid, discrete electrical sparks between an electrode (tool) and a conductive workpiece, both submerged in a dielectric fluid (like kerosene or deionized water).

2. Material Removal Mechanism: When the voltage between the tool and work reaches a certain level, the dielectric fluid breaks down, and a spark jumps across the gap.

• Melting: The spark creates an extremely high-temperature plasma channel (ranging from 8,000$^\circ$C to 12,000$^\circ$C). This localized heat instantly

melts a tiny volume of the metal on both the tool and the workpiece.

• Evaporation: A portion of this molten metal is so hot that it instantly turns into vapor (

evaporation).

3. The Role of the Dielectric Fluid: As the spark ends, the plasma channel collapses. The surrounding dielectric fluid rushes into the area, cooling the molten metal and "flushing" away the debris (now in the form of tiny solidified spheres) from the gap. This process repeats thousands of times per second, slowly eroding the shape of the tool into the workpiece.

4. Why Other Options are Wrong:

• Corrosion: This involves chemical or electrochemical reactions (as in Electrochemical Machining/ECM), which is not the primary mechanism of EDM.

• Cavitation: This refers to the formation and collapse of vapor bubbles in a liquid due to pressure changes (as in Ultrasonic Machining), which is not how sparks remove metal.