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How are Samarium Cobalt (SmCo) magnets manufactured?

How are samarium cobalt (SmCo)
magnets manufactured?

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Samarium cobalt SmCo internal threaded female pot magnet Samarium cobalt magnets are made from an alloy of samarium and cobalt. To create SmCo magnets, manufacturers usually follow these steps:
Strip casting samarium cobalt magnet

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.

Wonkee Donkee says "Strip casting is the name given to heating up a group of different metals until they are molten and then cooling them down together into a solid"
Ball milling making magnet powder

Step 2 – Milling

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

Moulds for different shaped magnets

Step 3 – Moulding

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

Pressing machine

Step 4 – Pressing

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

Wonkee Donkee says "Psi stands for the amount of pressure there is per square inch inside the machine"

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).

Extremely hot thermometer 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

Electrical discharge machine

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.

Flowing water They need to be machined with a constant flow of water due to the heat created in the machining process.
Samarium cobalt SmCo internal threaded female pot magnet

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.

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