Melting in Metallic Workpieces in Various Processes

Introduction:
Melting is a common phenomenon in various machining processes that involve the removal of material from metallic workpieces. This melting occurs due to the application of heat energy, which causes the workpiece material to reach its melting point and transition from a solid to a liquid state. This response will explain how melting is involved in three specific machining processes: Electric Discharge Machining (EDM), Laser Beam Machining (LBM), and Electron Beam Machining (EBM).

1. Electric Discharge Machining (EDM):
EDM is a non-traditional machining process that uses electrical discharges to remove material from the workpiece. In this process, a potential difference is created between the workpiece and an electrode, typically made of copper or graphite. When the voltage between the electrode and the workpiece exceeds a certain threshold, a high-intensity electric discharge occurs, creating a plasma channel through which the energy is transferred to the workpiece.

- Melting: The intense heat generated by the electric discharge causes the localized area of the workpiece to reach its melting point, resulting in melting of the material. The melted material is then removed from the workpiece by the flushing action of dielectric fluid, which also acts as a coolant.

2. Laser Beam Machining (LBM):
LBM is a thermal machining process that utilizes a focused laser beam to remove material from the workpiece. The laser beam is generated by a laser source and directed towards the workpiece using mirrors or lenses. The high-intensity laser beam heats up the workpiece material, causing it to melt and vaporize.

- Melting: The concentrated energy of the laser beam is absorbed by the workpiece material, leading to a rapid increase in temperature. When the temperature exceeds the melting point of the material, it melts and can be vaporized or removed by a gas jet or other mechanisms. The molten material can also solidify and form a heat-affected zone around the machined area.

3. Electron Beam Machining (EBM):
EBM is a thermal machining process that uses a high-velocity electron beam to remove material from the workpiece. The electron beam is generated by accelerating electrons to high speeds using an electron gun and then focusing them onto the workpiece using magnetic fields.

- Melting: When the high-velocity electrons strike the workpiece surface, their kinetic energy is converted into heat energy, causing the local temperature to rise rapidly. If the temperature exceeds the melting point of the material, it will melt. The molten material can be removed by vaporization, melting, or evaporation, depending on the process parameters.

Conclusion:
In summary, melting is involved in Electric Discharge Machining (EDM), Laser Beam Machining (LBM), and Electron Beam Machining (EBM) processes due to the application of intense heat energy. This heat causes the workpiece material to reach its melting point, leading to the melting and removal of material from the workpiece. These processes are widely used in various industries for precision machining applications.