Difference between rare-earth magnets and ordinary magnets
Magnets are the unsung heroes of modern technology and daily life, from sticking notes on the refrigerator to driving high-speed trains. Magnets are mainly divided into two categories: rare earth magnets and ordinary magnets. The two are very different in materials, performance, cost, and application. This article will deeply analyze the difference between the two, take you into the world of magnets, and help you find the best balance between performance and budget.
Material composition
Rare earth magnets:
Rare earth magnets are “magnetic nobles” made of rare earth elements in the periodic table and alloys such as iron, boron, or cobalt. Rare earth elements are scarce in the Earth’s crust, difficult to mine, and the processing process involves complex high-temperature smelting and precision molding. The production of rare earth magnets requires high-purity raw materials and strict environmental control.
Ordinary magnets:
Ordinary magnets or ceramic magnets are basically made of iron oxide (Fe2O3) and elements of a similar nature, such as barium, strontium, nickel, or zinc. These materials are plentiful in the Earth’s crust, have low mining costs, and the production processes are simple. Ferrite magnets are shaped and coiled through the powder metallurgy process, which has high production efficiency, and the cost is only 1/10 to 1/20 of that of the rare earth magnets.
Remanence
Remanence is an indicator of how much magnetic force a magnet can still “stick” to after the external magnetic field is removed. Remanence directly affects the actual magnetic field strength of the magnet, measured in Tesla (T).
Rare earth magnets:
Rare earth magnets have a remanence of up to 1.0-1.4 T. This ultra-high remanence stems from the unique crystal structure of rare earth elements, which can efficiently arrange magnetic domains. Historically, NdFeB magnets have completely changed the trend of miniaturization of electronic devices since their introduction in the 1980s.
Ordinary magnets:
With a remanence of only 0.2-0.4 T, the low remanence of ferrite magnets stems from their loose crystal structure and low efficiency in magnetic domain arrangement. Despite this, their stability gives them a place in cost-sensitive applications.
Coercive force
Coercive force measures the “psychological quality” of a magnet to resist external interference, and the unit is kilo-oersted (kOe).
Rare earth magnets:
With a coercivity of up to 10-20 kOe, this hard-core compressive resistance stems from the high magnetic anisotropy of rare earth elements, which can firmly lock the magnetic domains. NdFeB magnets can resist complex electromagnetic interference in industrial motors, while samarium cobalt magnets can cope with high temperatures and corrosion in aerospace equipment.
Ordinary magnets:
With a coercivity of only 1-3 kOe, their crystal structure is fragile, and the magnetic domains are easily disrupted by external interference. Even so, the low coercivity of ferrite magnets is an advantage in some scenarios, such as applications in magnetic separators that require rapid response to external magnetic field changes.
Magnetic energy product
The magnetic energy product (BHmax) is the “energy slot” where the magnet stores magnetic energy. The unit is mega-gauss-oersted (MGOe), which directly determines the magnetic field strength and volume efficiency of the magnet.
Rare earth magnets:
The magnetic energy product is as high as 15-50 MGOe. This high energy density makes them a great choice for compact devices. The advent of NdFeB magnets helped drive the electronics revolution at the end of the 20th century, making devices smaller and more powerful. They are also widely used in wind turbines, where a single magnet can support the energy conversion of megawatt-class generators.
Ordinary magnets:
The magnetic energy product is only 1-4 MGOe. Although the magnetic force is not strong, they are stable and cheap. The low magnetic energy product of ferrite magnets limits their application in high-tech fields, but their low cost allows them to occupy a huge share of the global market.
Curie temperature
The Curie temperature is the “crash point” at which a magnet loses its magnetism and determines its ability to survive in high-temperature environments.
Rare earth magnets:
Neodymium-based rare earth magnets have a low Curie temperature (310-370°C) and are prone to “giving up” at high temperatures. They need to be enhanced by adding dysprosium or cooling systems to enhance heat resistance. Samarium cobalt-based rare earth magnets have a Curie temperature of up to 700-800°C and can work calmly in aircraft engines or high-temperature sensors.
Ordinary magnets:
The Curie temperature of ferrite magnets is about 450-460°C. In high-temperature environments, steel smelting, their crystal structure gives them good thermal stability, making them suitable for industrial scenarios.
Conclusion:
Rare earth magnets and regular magnets are different and each has its strengths which make them suitable for different situations. Magnet choice involves a compromise among the performance, cost, and the place where the magnet will be used. Rare earth magnets dominate with high remanence, high coercivity, and high magnetic energy product, suitable for high-performance, compact, or high-temperature corrosion-resistant applications. Ordinary magnets, on the other hand, have low remanence, coercivity, and magnetic energy product, but are affordable and high-temperature resistant, making them perfect for cost-sensitive scenarios such as home appliances, automotive sensors, and industrial magnetic separators.
Looking for a high-quality NdFeB supplier or in-depth knowledge of magnets? Visit www.topmag.in for professional resources to help you choose the most suitable magnet solution!
