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Specialists
in Permanent Magnets
More
than a magnet supplier!
Cermag Ltd are suppliers of
all items magnetic. Operating since 1978, Cermag have
built up a vast knowledge of magnetics. We are
manufacturers and suppliers of all types of permanent magnets
including: -
Our expertise has always been in the
machining of permanent magnetic materials achieving very tight
tolerances and with a very fast turnaround. Of course we have a large stock range of
sizes but we have the capability to offer you the size you
require in a short space of time. Offering you the right material for your
application is vital, if you require assistance please contact
our sales team.
A Brief History of Magnets
The
ancient Greeks knew that lodestone attracted Iron. More
importantly, they noticed that if a long thin piece of the
mineral was suspended freely, it would point in a North/South
direction. For centuries, the historical development of
magnetism largely consisted of the increasing use of lodestone
as a navigation aid for ships.
During the 16th
Century a William Gilbert concluded that the Earth itself had
two magnetic poles: - North & South. He suggested
that a piece of lodestone had a pole at each end and that one
of these was attracted to the North pole of the Earth while
the other end was attracted to the South pole. This is consistent
with modern thinking. A magnet is described as having a
North seeking pole at one end and a South seeking at the
other. Two poles of the same kind repel each other while
opposite poles attract. Gilbert also knew that a piece of iron
would become magnetised if it was stroked with a piece of
lodestone.
In the 19th
Century, Oersted discovered that a magnetic compass needle
could be deflected by an electric current in a wire.
Faraday's electric motor was based on this effect. His
generator was essentially an electric motor in reverse. (i.e.
relative movement of a magnet and a conductor gave rise to
electrical current)
It is common to
think of two distinct kinds of magnetism: - Electromagnetism
& Permanent magnetism. The second of these is
displayed be materials such as Iron, Nickel & Cobalt.
Modern theory,
however attributes all magnetic phenomenon to
electricity. To see how this applies to a compass needle
or a fridge magnet it is necessary to examine magnetic
material at a atomic level. Each atom consists of a
central nucleus with a positive electrical charge, surrounded
by negative electrons. Each electron orbits the nucleus
and spins on its own axis, thus giving rise to magnetic
effects.
For details of
specific magnet materials please see: -
Ceramic
Neodymium
Samarium Cobalt
Alnico
Polymer Bonded
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