A Neodymium magnet, also known as NdFeB or Neo magnet, is the strongest known type of permanent magnet. Because of their lightweight, strength and the consistency of their magnetization, Neo magnets have become a popular choice for a wide variety of applications, from loudspeakers to magnetic therapy jewelry. A rare earth magnet is made from an alloy of neodymium, iron, and boron.
Neodymium magnets entered the marketplace in the 1980s and were always strong – more than 10x stronger than ceramic magnets - but the first neodymium magnets for sale were very expensive. However, improvements in manufacturing processes and other factors have now also made them affordable for everyday use.
Unlike other types of magnets, Neodymium magnets have a high resistance to demagnetization. They cannot be formed with conventional drilling, turning or milling processes, and must be ground before they are magnetized. Additionally, large or complex assemblies are usually magnetized prior to assembly. Standard tolerances for Neo magnets are +/-.005 for ground dimensions. They require extremely high magnetizing fields and particular consideration must be given to this when designing complex assemblies. A Neodymium magnet can be magnetized in any direction as long as it is aligned properly. In some instances multiple pole magnetization is not possible; when it is possible, special fixtures are required.
A low coercivity grade Neodymium magnet may begin to lose strength if heated above 176°F (80°C). High coercivity grade Neo magnets have been developed to function at temperatures up to 428°F (220°C) with little irreversible loss. The need for low temperature coefficient in neodymium magnet applications has triggered several grades to be developed to meet specific operating requirements. Please refer to our chart of magnetic properties to compare the characteristics of each grade.
While today's Neo magnets are more temperature and corrosion-resistant, a protective coating is still necessary for certain applications.
Neodymium magnets have replaced Alnico and ferrite magnets in many applications where strong permanent magnets are required, because their greater strength allows the use of smaller, lighter magnets. These applications include: