Rare Earth Magnets

How Magnets Work

Earth's Magnetic Fields

History of Magnets

Industrial Magnet Uses

Electromagnetism

Types of Magnets

Rare Earth Magnets

 

 

 

 

 

 

 Rare Earth Magnets are Neodymium Magnets. They are also called also known as NdFeB, NIB, or Neo magnets.

Manufacturing

General Motors and Sumitomo Special Metals developed the permanent Neodymium Magnets from an alloy of Boron, iron, and neodymium (NdFeB or NIB). They are the strongest type of manufactured permanent magnets and have replaced other types of strong, required, permanent magnets in such devices as cordless tool motors, fasteners, and computer hard disk drives.

There are two manufacturing processes primarily used to develop neodymium magnets:

  • Bonded magnet (rapid solidification) process
  • Sintered magnet (classical powder metallurgy) process

Bonded Magnet Process

A thin ribbon of NdFeB is melt-spun and pulverized into particles, blended with a polymer, and then either compression or injection molded into bonded magnets.  This process offers less flux than the Sintered Magnet Process, but can be shaped into intricate parts and forms, and do not suffer a loss in foucault currents.

Approximately 5,500 tons of NdFeB bonded magnets are produced each year.

Sintered Magnet Process

In the Sintered Magnet Process, raw materials are melted down, cast into molds, and cooled to form ingots.  These ingots are then crushed into small particles.  Liquid-phase sintering magnetically aligns the resulting powder into dense blocks which are then, again, heat-treated, custom shaped, surface treated, and magnetized.

China and Japan are the primary producers of sintered neodymium magnets, producing between 45,000 and 50,000 tons each year. 

Hazards

Rare earth magnets exert a greater force that can create hazards not associated with other magnetic material.  Those that are larger than a few centimeters are strong enough to injury body parts pinched between two magnets or a magnet and metal surface.  They can even break bones.

When a person becomes stuck between two magnetic areas, instinct urges him/her to pull away.  However, this movement decreases the space between the magnets and the pinching force increases to dangerous levels.  If possible, pain should be born and measures should be taken to prevent distance from closing.  When the distance is secured, the person may pull free.  Professionals working with these magnets sometimes use brass wedges as part of a standard tool set.

Common Applications

Neodymium magnets have replaced alnico and ferrite magnets in many modern technological devices.  Because they have a greater strength, smaller magnets may be used.  Some common devices are:

  • computer hard disks
  • MRI Technology (Magnetic Resonance Imaging)
  • Loudspeakers
  • Couplings and bearings
  • Cordless tool motors and other small electric motors
  • Drive motors for hybrid vehicles such as the Toyota Prius
  • Magnetic jewelry clasps
  • Children's building sets
  • Modern Sport Parachute closing mechanisms

This website was developed by Geno Jezek. When he is not doing research he operates The Advertising Store, Inc and Custom Magnets. 
Magnet material is a way of life.  It is used to make a printable magnet and magnetic inkjet paper.

© 2006-2012 Geno Jezek - All Rights Reserved. This site is copyrighted and cannot be reproduced in any form without written consent.