Slide 2:
Electron beam machining ( line diagram)
Cutting and hole making on thin materials; very small holes and slots (0.1-0.3mm depending on thickness); heat affected zone; require vacuum, expensive equipment; 1-2 mm3/min.
Slide 3:
Electron Beam Machining EBM is a metal removal process by a high velocity focused stream of electrons. As the electrons strike the work piece with high velocity , their kinetic energy is transformed into thermal energy which melts and vaporizes the material.
The production of free electrons ( negatively charged particles) are obtained by electron gun.
Due to pattern of electrostatic field produced by grid cup, electrons are focused and made to flow in the form of a converging beam through anode. The electrons are accelerated while passing through the anode by applying high voltage at anode
A magnetic deflection coil is used to make electron beam circular and to focus electron beam at a point ( localized heating)
The process is carried out in a vacuum chamber to prevent electrons from colliding with molecules of the atmospheric air and to prevent tungsten filament from getting oxidizing with air
Slide 4:
Disadvantages of EBM Very small holes can be machined in every type of material with high accuracy
There is no mechanical contact between tool and work piece, hence no tool wear. Advantages of EBM 1. Cost of equipment is high
2. Rate of material removal is low
3 . It can used for small cuts only
4 . Vacuum requirements limits the size of work piece Application of EBM Drilling of holes in pressure differential devices used in nuclear reactors, air craft engine
Machining of wire drawing dies having small cross sectional area.