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Injection moulding opens up opportunities for high performance NdFeB magnets
Feature article: PIM International, Vol.3 No. 1 March 2009, pages 41-43, 1605 words
The market for NdFeB permanent magnets has grown rapidly over the last fifteen years thanks to the continuing expansion of the 3C market. As Bernard Williams* reports, powder injection moulding technology has played a vital role in the development of this sector.
Powder technology is the preferred method for manufacturing more than 80% of hard (permanent) magnets using NdFeB, samarium-cobalt, hard ferrites, and Alnico materials. Additionally, some 25-30% of soft magnets are made from powder-based soft ferrites (Ni-Zn, Mn-Zn), NiFe, and iron-based powders. Applications for all powder-based magnetic materials have been achieving annual growth averaging 10-15% in recent years. In particular, there has been spectacular growth in demand for NdFeB magnets which were first introduced in 1983 as sintered magnets, and as bonded (injection moulded) magnets in 1989.
According to Professor Luo Yang  global production of sintered and bonded NdFeB magnets increased from 19,000mt in 1996 to around 70,000 mt in 2008 (Fig. 1). The surge in production over the past five years is largely due to the lapsing of patents for NdFeB magnetic materials - excepting those NdFeB materials which contain cobalt. Sintered NdFeB magnets make up around 88% of output with the bonded (injection moulded) variety making up the remainder.......
Further sections of this article include:
- Injection moulding opens up new opportunities
- NdFeB powders for injection moulded magnets
- Applications and future trends
Figures and Tables:
Fig. 1 Production of bonded NdFeB magnets from 1996 to 2008 in different regions (Source ‘The Marvellous Development of the Rare Earth Magnet Industry’, by Prof Luo Yang. Magnews Winter 2008, pp 32-35)
Fig. 2 Development of magnetic properties of various permanent magnet materials (Source ‘Hard Magnetic Materials’ CD Rom – ‘Powder Metallurgy: Materials, Processes, and Applications’, EPMA, 2001)
Fig. 3 Examples of complex shape NdFeB magnets produced by injection moulding. (Courtesy Magnet Applications Ltd)
Fig. 4 Breakdown of applications for Magnequench’s MQTJ NdFeB powders (Courtesy Magnequench – Division of Neo Materials Technology)
Table 1 Typical magnetic properties of injection moulded (bonded) NdFeB magnets. (Courtesy Magnet Applications Ltd)