Electron beam weld ( EBM & EBW )

Electron beam weld is one of the electron beam machining process. EBM is a process where the metal removal is achieved by means of a very high powered electrons striking on a target surface. These electrons are produced by an electron emitting source and then allowed to get deflected and focused by means of magnetic field.

The welding using electron beam takes place when the high energy electrons strike the metal surface and cause the electrons on surface to get excited. This excitation provides space for high temperature to be created which result in welding.

When the electrons strike the target the kinetic energy of the electrons is converted into heat energy. This causes vaporization of the work piece material. This process takes place in a total vacuum conditions to prevent any air present inside the work medium.

The major components of an EBW process is

1. A cathode or negatively charged end which is the tungsten filament emitting electrons.
2. Grid cup which is used to provide passage for electron movement.
3. Anode which provides attractive force to electrons.

The amount of negative potential applied determines the acceleration of the electrons. Before the collision of the electrons a magnetic field is used to focus it. The beam has very small diameter of the order of micrometer.

High magnification can be achieved by adjusting the process parameters. It is possible to direct the beam at the specified spot using a computer controlled system. Suitable protection chamber must be available to prevent high velocity energized particles from contacting operator.

It is usually carried out with latest CNC machining technology.

Advantages of EBM or EBW process

1. It removes less material and provides higher surface finish.
2. Small holes can be drilled and small portions can be welded.
3. No residual stresses due to no contact between machined surface and tool.
4. Closer finish can be achieved.
5. Brittle materials can be machined.

Limitations of EBM or EBW process

1. Low material removal rate.
2. Very high capital cost.
3. Skilled operator is required.
4. Size of component is restricted.