How Are Neodymium Magnets Produced?

Neodymium magnets are a rare earth magnet that is made from neodymium, iron, and boron. This type of magnet was first developed by General Motors in 1982. There are two different processes that are used to produce neodymium magnets; the classical process and rapid solidification.

The classical process for neodymium magnet production is done through powder metallurgy or sintered magnet process. This process requires that the Rare Earth Magnet, iron, and boron are melted down and cast into ingots. Once these ingots are cooled they are turned into a fine power of particles. The particles undergo liquid-phase sintering which causes the particles to magnetically align. Once the particles are aligned they are simultaneously heated and compressed to produce a magnet.

Rapid solidification is accomplished by taking an Nd-Fe-B alloy and melt spinning a thin ribbon of it. The ribbon that is produced through the melt spinning process has randomly oriented grains. The ribbon is then pulverized into small particles. A polymer is then added to the particles and that mixture is either injected molded or compressed into bonded magnets.

Approximately 50,000 to 55,500 tons of neodymium magnets are produced every year. These magnets are used in MRI machines, hard drives, loudspeakers, electric motors, and other applications. For example, the Toyota Prius uses 1 kilogram of neodymium to produce the motor that is in the car. Special care needs to be taken when handling neodymium magnets because of their magnetic power. Even a magnet as small as a couple centimeters have the ability to cause bodily harm if skin or other body parts get trapped between magnets. If magnets are near each other they may collide with enough force to cause them to chip. The magnetic fields are also hazardous to watches, credit card strips, magnetic media and other devices.

Of the total world production, sintered neodymium magnets make up 45,000 to 50,000 tons. China accounts for 75-80% of the world production. China is also the country where the majority of the products that are produced using these magnets are manufactured. Japan accounts for 17-25% of the production. Europe produces 3-5% of the world production annually.

The other 5,500 tons of neodymium magnets produced are the bonded type. The bonded magnets have several advantageous over the sintered magnets. They offer less flux which makes them better suited for scientific application. It is possible for them to be formed into parts that are not able to be done through the classical process. There is not eddy current loss with this type of magnet.

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