The NORMA Company, born in 1949 on initiative
of a group of friends, is gone from the very beginning towards
the industrial application of the electricity.
The production of ceramic permanent magnets started in 1963
in order to obtain components with high uniformity and stability,
characteristics almost too difficult to find in the market at
As a matter of fact the first NORMA magnets were used initially
on a new device designed and produced by the company: the magnetic
switch. Soon after, due to the increase of the productive capacity
it was decided to put on the market cylindrical and square magnets
where the overall dimensions correspond to a geometric series.
The possibility to find out, quickly and at lower price, ceramic
permanet magnets has helped the performance of these components.
For that reason their industrial applications have been greatly
Today permanet magnets are used in many fields such as electric
motors, generators, telephone appliances, automatic machinery,
level transducers, antitheft devices, arcing contacts, filters,
conveyors, watermeters, couplings, magnet closures, etc.
SOME HISTORY OVER MAGNETISM
The presence of magnetism is well known to the man, in his
most simple appearance, since about 2000 years. The word “magnet”
probably comes down from the thessalic town of Magnesia where
at first was found and digged out a material, the magnetite,
with peculiar characteristics.
The Chinese, around the second century A.D., utilized an instrument,
based on magnetism, which could be compared to a very primitive
In Europe the first experiments over magnetism were taken around
the thirteenth century A.D. Well known in Italy is Flavio Gioia,
who probably discovered the terrestrial magnetism and to follow
invented to the compass.
In the year 1600 Gilbert published the first systematic work
which can be regarded as a proper and genuine treatise of experimental
Finally in the year 1820, thanks to the Danish scientist Oersted,
the teoric foundations of magnetism were laid down giving incontrovertible
proof of its links with the electricity.
MATERIALS AND THEIR MAGNETIC PROPERTIES
Materials can be classified also according to their behaviour
in a magnetic field, and divided consequently between non-magnetic
To the non-magnetic materials (diamagnetic and paramagnetic)
belong the gases, liquids, organic matter and some metals. They
don’t have any tendency to be magnetized and the magnetic
flux goes through them without any resistance thus not modifiyng
their physical condition. These non-magnetic materials cannot
be used as magnetic shields or insulators. They are normally
used as supports or containers for the magnets.
Ferromagnetic materials come under two categories: SOFT and
Between the SOFT ferromagnetic materials we may recall:
These materials are easily saturated even by magnetic fields
very weak. But disappearing these external actions they lose
almost completely the magnetic characteristics. Soft ferromagnetic
materials are used normally as preferential circuits for the
magnetic flux lines (cores, armatures, polar expansions).
HARD ferromagnetic materials are the most suitable for the production
of permanent magnets. Among these compounds we may recall: