Question

The mechanism of material removal in electric discharge machining process is

• A. Micro-Chipping and Erosion
• B. Erosion and Cavitation
• C. Melting and Evaporation
• D. Ionic Dissolution

Hint:

In EDM, material removal occurs through melting and evaporation caused by high-temperature sparks, with the dielectric fluid flushing away the debris.

Answer 1

The Correct Option is C

Step 1: Understand Electric Discharge Machining (EDM).
Electric Discharge Machining (EDM) is a non-traditional machining process where material is removed from a workpiece by a series of electrical discharges (sparks) between an electrode (tool) and the workpiece, separated by a dielectric fluid. The process is used for hard materials that are difficult to machine with conventional methods. Step 2: Identify the mechanism of material removal in EDM.
In EDM, a high voltage is applied between the electrode and the workpiece, causing a spark to jump across the small gap through the dielectric fluid.
The spark generates intense heat (temperatures can reach 6000°C), which melts and vaporizes a small amount of material from the workpiece at the point of discharge.
The dielectric fluid helps to flush away the molten and vaporized material, preventing it from re-solidifying on the workpiece.
The primary mechanism of material removal is therefore melting and evaporation due to the high-temperature spark. Step 3: Evaluate the options.
(1) Micro-Chipping and Erosion: Incorrect, as micro-chipping is a mechanical process (e.g., in grinding), and erosion in this context is not the primary mechanism for EDM. Incorrect.
(2) Erosion and Cavitation: Incorrect, as cavitation (bubble collapse) is relevant in processes like ultrasonic machining, not EDM. Erosion alone does not describe the process. Incorrect.
(3) Melting and Evaporation: Correct, as the spark in EDM causes localized melting and evaporation of the workpiece material. Correct.
(4) Ionic Dissolution: Incorrect, as ionic dissolution is the mechanism in electrochemical machining (ECM), not EDM. Incorrect. Step 4: Select the correct answer.
The mechanism of material removal in electric discharge machining is melting and evaporation, matching option (3).