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Electron-beam
Machining - EBM
In electron-beam machining
(EBM), electrons are accelerated to a velocity
nearly three-fourths that of light (~200,000
km/sec). The process is performed in a vacuum
chamber to reduce the scattering of electrons
by gas molecules in the atmosphere. The
electron beam is aimed using magnets to
deflect the stream of electrons and is focused
using an electromagnetic lens. The stream
of electrons is directed against a precisely
limited area of the workpiece; on impact,
the kinetic energy of the electrons is converted
into thermal energy that melts and vaporizes
the material to be removed, forming holes
or cuts.
Typical applications are
annealing, welding, and metal removal. A
hole in a sheet 1.25 mm thick up to 125
micro m diameter can be cut almost instantly
with a taper of 2 to 4 degrees. EBM equipment
is commonly used by the electronics industry
to aid in the etching of circuits in microprocessors.
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