With just a few exceptions, when magnets are manufactured they finish the process in the unmagnetised condition. That means the magnetic domains are randomly oriented within the body of the magnet so that there is no net external field.
In order to make the magnet exhibit an external field, we apply a strong field to the magnet, rotating the domains within the magnet so they all point in the same direction. The source of the external field can be another magnet (sometimes used for Alnico), a solenoid magnetising coil, a fixture shaped to provide the specific pattern of magnetisation specified by the customer or it may be the field generated between two poles of a powerful electromagnet. The duration of the applied field can be as long as several seconds or as short as 5 milliseconds. Shorter durations are typical when the applied field has to be extremely powerful.
Arnold has all of these techniques available. Solenoids and matching power supplies are available for magnets up to 9 inches (15.25 cm) in diameter and up to 8 inches (20.30 cm) long and for rectangular magnets up to 5 inches (12.7 cm) wide by 10 inches (25.4 cm) in length by 10 inches (25.4 cm) in height (direction of magnetic field). Multiple-pole magnets require specially built fixtures.
Contact Arnold to discuss your magnetising needs with our skilled staff.