How are Samarium Cobalt (SmCo) magnets manufactured?

2nd March 2020

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	How are samarium cobalt (SmCo) magnets manufactured?


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			Samarium cobalt magnets are made from an alloy of samarium and cobalt. To create SmCo magnets, manufacturers usually follow these steps:

			Step 1 – Strip casting First, the two materials are ground up and melted in a large oven at 14426.7°C (26000°F). When they are cool, the metals are all mixed together to create small chips.



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

			Step 3 – Moulding The powder is then weighed and pressed into the moulds, which can be any shape of magnet.

			Step 4 – Pressing The moulds are placed into a pressing machine which places a total of 21000psi of pressure onto them.



			Step 5 – Sintering The shaped metal is then placed into an electric oven, which 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 more information on sintering, see the Magnets glossary

			Step 6 – Machining After the magnets have been removed from the oven and left to cool, they are ground down to the correct size. A diamond-coated machine takes off millimetres of metal until the required size is achieved.

			They need to be machined with a constant flow of water due to the heat created in the machining process.

			Step 7 – Coating The magnets are then coated to prevent them from oxidising. For more information on the types of plating and coatings, see the page: What are magnets coated with?

			Step 8 – Magnetising Finally, the alloy is magnetised. A magnetising machine envelops the magnet in a high strength magnetic field by sending 2400 volts of electrical current through it to create a permanent samarium cobalt magnet.