A
commercially viable magnet such as Neodymium
magnets can hold their magnetic
field for more than thousands of
years, if no external demagnetize field will influences its force. There may be a chance of slight
degradation due to efflux of time or due to the aging process of the material.
But truly speaking it can hold an effective magnetic field for the years long. Often
it has been seen that magnets used in the real world application has a chance
to loss its magnetic field as always exposed to external demagnetizing
conditions. Magnet which is partially demagnetized cannot perform well in
specific area of application.
Different
Neodymium magnets are powered with
different level of external magnetic
field. They cannot perform beyond that level. If at
any time you want to change the magnetic field of the material you need to
expose them to an external energy
of higher magnetic field type of
material. However, the following are some real world factors which adversely
affect the strength and stability of Neodymium magnets.
TIME
Due to the aging process or wear and
tear during the life span of the Neodymium magnets, it has been seen that the material can decrease 3percent of their
value.
TEMPERATURE
Magnets highly affected by the temperature
factor, which can result in three kinds of losses such as:
REVERSIBLE LOSSES: These are the losses which may
occur during the heating process but the magnet can recover the strength back
which the process is over. It varies with different grades of material.
IRREVERSIBLE LOSSES:
These are the losses which are permanent
in nature. It is the damage due to fluctuation in the temperature of heating.
It generally takes place when the operating point cascade below the material demagnetization
curve. The mechanical process of external re-magnetization can help the
magnet to recover the magnetic field back.
METALLURGICAL CHANGES: It is the consequences when the permanent
magnets are
exposed to very high temperatures. Metallurgical changes make the
Neodymium magnets useless to be used in any application. That is the
reason why the manufacturers have set the Maximum Use Temperatures for all the grade
of Neodymium magnets.
RELUCTANCE
CHANGES
As per the material experts the
removal and replacement of magnetized Neodymium magnets may results in
operating slope to fall. When this operating slope drops down the magnetic
field also decline and the magnet cannot perform with the previous strength. Thus
any change or alteration in the magnet circuit during use may cause reluctance
changes.
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