Electron Beam Machining EBM Electron beam machining is
Electron Beam Machining
EBM Electron beam machining is the technology to use energy produced by forming argon gas stored in the vacuum chamber into plasma and to generate a "high power electron beam of a pulse shape in a large area" to melt the metal surface. The uneven surface is made flat by the repeated fusion and coagulation by heat and surface tension resulting in a mirrored finish.
EBM High-voltage electron beam directed toward workpiece Energy of electron beam melts/ vaporizes selected region of workpiece Workpiece placed in vacuum chamber The reason for using a vacuum chamber is that, if otherwise the beam of electrons will collide with gas molecules and will scatter.
Some Specifications Vacuum chamber carries vacuum of order 10 -5 mm of mercury. The filament wire is heated to temperature of about 2500 o. C in the vacuum. A potential difference of 50 to 150 KV is maintained between the cathode and anode. The electrons passing through the anode are accelerated to achieve as high velocity as around two-third of light.
COMPARE EDM finish EBM finish
Advantages of EBM Any material can be machined. Workpiece is not subjected to any physical or metallurgical damage. Problem of tool wear is non-existent. Heat can be concentrated on a particular spot. An excellent technique for micro machining. There is no contact between work and tool.
Disadvantages of EBM High initial investment needed. Highly skilled operator required to perform the operation. Not suitable for producing perfectly cylindrical deep holes. Suits for small and fine cuts. Workpiece size is limited due to requirement of vacuum in the chamber. Low rate of metal removal. High power consumption. Difficult to produce slots and holes of uniform shapes and dimensions.
Applications of EBM Very effective for machining of materials of low heat conductivity and high melting point. Micro-machining operations on workpieces of thin sections. Micro-drilling operations(upto 0. 002 mm) for thin orifices, dies for wire drawing, parts of electron microscopes, fibre spinners, injector nozzles for diesel engines.
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