There are a number of mechanisms by which different magnet
material can be magnetised – the following is a simplified version of
one that is a useful model.
Materials capable of holding magnetisation (if looked at on a
very small scale), can be considered to be many separate domains each
acting as a tiny magnet. When a material is magnetised these
magnets” are all aligned in the same direction.
To demagnetise an item the objective is to totally randomise
these “tiny magnets” so they all point in different directions.
The randomisation is achieved by applying a magnetic field, of
a sufficient strength, that switches these domains between north and
south. The magnitude of the applied field is reduced to zero
in a demagnetised item.
The “tiny magnets” will at first try to align themselves with
the applied magnetic field and as it changes polarity they will also
try to rotate. As the magnitude of the field decreases a point
occur when an individual “tiny magnet” will get “stuck” and will no
longer follow the applied field. Each individual “tiny magnet”
stuck at a different magnetic field strength. The overall effect
therefore, be to produce a lower overall magnetic field from the
To generate a demagnetising field a large current is passed
through a coil. The unit capable of generating the required
current is referred to as the demagnetiser. The current
the demagnetiser is fed into a demagnetising fixture or demagnetising
coil. A demagnetising fixture is a special coil of wire that has
optimally designed to achieve the desired demagnetisation field when
coupled with the appropriate demagnetiser.
While the above description is not technically correct in
detail, for all magnetic materials, it is a useful model that is able
to explain demagnetising behaviour.
Our approach objective is simple, total customer
satisfaction. From initial consultation, through the design phase
to manufacture and supply, Hirst will effectively manage the whole
process making your "turnkey solution" a reality.
Are used to achieve very accurate demagnetisation.
CHOOSING THE RIGHT SOLUTION
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for your demagnetising application, we have prepared a short on-line
questionnaire. Please view this questionnaire to enable us to
provide a quick response to your requirements.