Electron-Beam Machining (EBM)

 

               Electron beam machining

Electron-beam machining (EBM) is a process where high-velocity electrons concentrated into a narrow beam are directed toward the work piece, creating heat and vaporizing the material. EBM can be used for very accurate cutting or boring of a wide variety of metals. Surface finish is better and kerf width is narrower than those for other thermal cutting processes.

Process

To achieve the fast evaporation of the material, the power planar density in the beam cross-section must be as high as possible: - values up to 10^7 W/mm^2 can be achieved at the spot of impact. As the electrons transfer their kinetic energy into heat in a very small volume, the material impacted by the beam is evaporated in very short time.

Equipment

EBM equipment in construction is similar to electron beam welding machines (see electron beam welding). EBM machines usually utilize voltages in the range of 150 to 200 kV to accelerate electrons to about 200,000 km/s. Magnetic lenses are used to focus the electron beam to the surface of the work-piece. By means of electromagnetic deflection system the beam is positioned as needed, usually by means of a computer.

Electron-beam machining (EBM)

The EBM technique is used for cutting fine holes and slots in any material. In a vacuum chamber, a beam of high-velocity electrons is focused on a workpiece. The kinetic energy of the electrons, upon striking the workpiece, changes to heat, which vaporizes minute amounts of the material. The vacuum prevents the electrons from scattering, due to collisions with gas molecules. EBM is used for cutting holes as small as 0.001 inch (0.025 millimetre) in diameter or slots as narrow as 0.001 inch in materials up to 0.250 inch (6.25 millimetres) in thickness. EBM is also used as an alternative to light optics manufacturing methods in the semiconductor industry. Because electrons have a shorter wavelength than light and can be easily focused, electron-beam methods are particularly useful for high-resolution lithography and for the manufacture of complex integrated circuits. Welding can also be done with an electron beam, notably in the manufacture of aircraft engine parts.