How are alnico magnets manufactured?

2nd March 2020

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	How are alnico magnets manufactured?


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			Alnico magnets are made from a combination of aluminium, nickel, cobalt, iron and copper. To create these magnets, manufacturers usually follow these steps:

			Step 1 – Strip casting First, a combination of aluminium, nickel, cobalt, iron and copper are ground up and melted in a large oven at 14426.7°C (26000°F).



			Step 2 – Milling The metal compound is ground down to a fine powder and mixed together thoroughly in a ball mill.

			Step 3 – Die pressing The powder is then weighed and put in a die pressure machine which places a total of 21000psi of pressure onto it. The die is usually the shape of the final magnet, so should not need any further shaping. PSI is the amount of pressure there is Per Square Inch, inside the machine.

			Step 4 – Sintering The shaped metal is placed into an electric oven. The oven heats the metal compound gradually from 250°C (482°F) to 900°C (1652°F).

			The magnets can take from 20 to 36 hours to be heated depending on the quality of the end magnet. A top quality magnet will take a lot longer in the oven than a low quality one, as a slower temperature rise will produce a greater magnetic force. For information on sintering, see the Magnets glossary

			Step 5 – Cooling After heating, the magnets are removed from the oven and left to cool.

			Step 6 – Coating The magnets are then coated. For more information on the types of coatings, see our page: What are magnets coated with?

			Step 7 – Magnetising Finally, the mixture is magnetised. A magnetising machine envelops the magnet in a high strength magnetic field by sending 2400 volts electrical current through the magnet to create a permanent alnico magnet. For information on permanent magnets, see the Magnets glossary