This article is the second of a two-part series exploring rare Earth magnets and the part they play in the most industry, specifically Permanent Magnet Motors. Click here to review the first article.

Chinese Rare Earth Metal Near-Monopoly

Other than environmental issues associated with Mountain Pass, and resulting regulation that hampered its use, there are other reasons why China currently produces 90% of the world’s supply of rare earth metals.

• Less robust environmental regulation
• Lower labor costs
• The number and size of Chinese rare earth element deposits

The United States has largely lost its former status as a global leader in rare earth element technology. This comes at a time when rare earth metals are increasing in importance for new technologies. However, as of July 2011, mining did eventually resume at Mountain Pass, and mining began at Mount Weld.

One ongoing problem is the lack of active rare earth element deposits outside of China. Some deposits could be economical to mine, but it could take over a decade to process the regulatory, environmental, technological, and financial issues that need to be dealt with before new mines are established.

It’s possible that by 2020, there could be shortages of many widely used rare earth metals — including neodymium, which is used in rare earth magnets.

Using Rare Earth Metals to Create Permanent Magnet Motors

Rare earth metals are ferromagnetic, but by themselves, their Curie temperatures are below room temperature. This means that their magnetism is only present at low temperatures. However, they form compounds with nickel, cobalt, and other transition metals, which have Curie temperatures well above room temperature. These compounds are the basis of rare earth magnets used in permanent magnet motors.

Rare earth magnets, like neodymium magnets and samarium-cobalt magnets, are incredibly strong. Their magnetic fields often exceed 1.4 teslas, compared to 0.5 to 1.0 teslas for ferrite or ceramic magnets. Neodymium magnets are also used in those little magnetic ball toys, which have incurred injury lawsuits because they’re so powerful that if a child swallows them, their intestines can be injured or perforated. These magnets are widely used in hard disk drives, motors in cordless power tools, and other applications where very strong magnets are needed.

Along with hand tool motors, rare earth magnets are also used in heavy machinery in manufacturing plants and other facilities. Permanent magnet motors are commonly used for large or high-end motor applications that need a precise measurement of speed, torque, and positioning.

The magnets are mounted or embedded on the rotor couple with magnetic fields generated internally by electrical input to the stator. Permanent magnets have magnetic fields that are stable and consistent, although extreme overheating could demagnetize them if their Curie temperatures are exceeded.

Permanent magnet motors have been widely used on machine tools and production machinery for years, due to their superior durability, good performance, low cost, and electrical stability. In many applications, they outperform induction motors. For example, the manufacture of plastic molding, paper and packaging, textiles, glass, ceramics, and many other materials requires precise motion control, for which permanent magnet motors are well suited.

Challenges of the Growing Demand for Rare Earth Metals

As permanent magnet motors have gained such widespread use in industrial applications — along with consumer electronics and other uses — the looming threat of potential rare earth metal shortages is an issue of worldwide concern. The ongoing exploration of new rare earth element deposits and ongoing efforts to begin mining activities could help ensure a stable and adequate supply in the future. Today, the vast majority of rare earth elements are mined in China, but viable deposits in the US, Australia, India, and other locations could potentially expand the number of nations producing these vital resources.

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