Permanent magnet manufacture
Date: Around 1993
How are permanent magnets commercially made?
I do not know how they are made on a large scale, and I will bet
that each type of magnet is made differently. Maybe others will help outhere.
I can tell you how they are made for permanent magnet motors though. Once the
material is cast (Alnico, Sumarian Cobalt, "Neo-Iron", etc.) ground, and heat
treated (in some cases), it has no particular magnetic field. In the case of
a PM motor, they are all placed in the motor stator housing (or around the
rotor in the case of brushless systems) and placed around a cone with wire
windings and magnetic steel on them. It is a special machine that charges
large capacitors, and then very rapidly discharges them through the coil
surrounded by the magnetic material. Depending upon the air gap, and the rate
of discharge, and the amount of the charge, as well as the material used,
after each discharge it will yield magnetic fields around the material in the
motor. A good source for this data is a magazine called "Motion" published by
Dr. Jacob Tal in California.
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Update: June 2012