Application of Sintered NdFeb Magnet - Professor Yang Luo, IEEE TC-15 Voting Member, China

Sintered NdFeB magnets were first developed in 1983, as the age of computing, office automation and consumer electronics dawned. High energy magnets are extremely important for motors to reduce size and weight and to increase torque. Such motors are widely used in computers, office automation and various consumer electronics. In developed countries such as Japan, VCM, MRI, Motor/generator are three major applications of sintered NdFeB magnets. NdFeB magnets are widely used in HDD of computers and consumer electronics. VCM is the largest application of NdFeB magnets, although its weight percentage is reducing continuously. The proportion of magnets used for MRI is relatively stable, ranging between 13~17%. The proportion of magnets used for motor/generator is the fastest growing application type.  Moreover, NdFeB magnets are used in communication and acoustic devices as well.

In Japan before 1995, the largest application was VCM, MRI was second and motor/actuator third. By 1999, the proportion of magnets used for motor/actuator became the second largest application, exceeding MRI. By 2005, the proportion of magnets used for motor/actuator exceeded that of VCM and became the largest application. The proportion of magnets used for MRI dropped to 6%, ie the same level as acoustics. The proportion of magnets used for communication became the third largest application.

The NdFeB magnet industry in China is export oriented: 89% of total magnet production was exported in 1998.  But things have changed, and the use of magnets in the domestic market has increased significantly since the turn of the century. Since 2002, more than half of NdFeB magnets produced have been used in the domestic market, namely 55% of the total. The applications for NdFeB magnets in China are different from those in developed countries. There are three traditional applications: speaker, separator, magnetizer including dewaxers used in oil fields. Low grade uses include magnetic buttons for clothing, boxes and furniture. As for high-tech applications, they were developed after 2003. The applications for NdFeB magnets in China are summarized in present paper.