What is a Neodymium Magnet?
A neodymium magnet aka NdFeB, is the most common sort of rare earth magnet. It is also the strongest magnet in the world. Neodymium magnet is made out of an alloy of neodymium, iron and boron. It was first developed in 1982 by General Motors and Sumitomo Special Metals. The two companies employed different methods to create the magnet. General Motors used a powder-bonded method and Sumitomo used a sintered method two different methods of production caused different properties for the magnets. Usually sintered method magnets are slightly stronger.
The reason they needed to create neo magnet was that the previous industry standard of the Samarium Cobalt (SmCo) magnet was becoming too expensive to produce and there was a need for a cheap magnet. Neodymium magnets replaced other types of magnets in the many applications in modern products that require strong permanent magnets, such as wind turbines, electric motors, hard disk drives, cell phones,printers and microphones.
What is a rare earth element?
Neodymium magnets are from the Rare Earth magnet family and are the most powerful permanent magnets in the world. Rare earths are a series of chemical elements found in the Earth that are crucial to many current age technologies. There are 17 elements that are considered to be rare earth elements—15 elements in the lanthanide series and two additional elements that share similar chemical properties.
Neodymium magnets are all graded by the number next to N. As a very rule of thumb, the higher the grade, the stronger the magnet. The highest grade of neodymium magnet currently available is N52. The letter after the grade number signifies the temperature rating of the magnet. If there is no letter after the grade, then the magnet is considered standard temperature. Current grades of NdFeB magnets are N35, N38, N40, N42, N45, N48, N50 and N52. For Neodymium magnet specs please click here.
Neodymium magnets are a made out of Neodymium, Iron and Boron. Hence they are almost always coated to prevent the Iron content from rusting. Another aspect of coating is to protect the magnet from chipping for Neodymium magnets are known to be very brittle and break easily. There are a multiple options for coatings, but nickel is the most common and mostly preferred. Other common coatings are zinc, tin, copper, silver and gold.
Machine use and Automation
Neodymium magnets are brittle due to the technics used to make them, hence automation and mahcining them makes them even more prone to cracking. The dust of the magnet is toxic if burned and could be dangerous. Also if exposed to heat magnets will easily lose their strength. Machining should be done carefully by experts to minimize risk.
Rare Earth magnets, unlike most other types of magnets have a high resistance to demagnetization . They do not lose strength if dropped or being around other magnets. However they will lose magnetization over maximum operating temperature. For N35 that temperature is 176°F or 80°C. For a complete chart of magnets and heat resistance see this picture.
Neodymium magnets are the strongest magnets in the market for their volume. Compared to a ceramic magnet they are about 10 times stronger. The strength can be measured by a Gauss reader or commonly called as Gaussmeters. Strength can also be measured with a Magnetometers. Gaussmeters measure the strength in Gauss, Magnetometers measure in Gauss or arbitrary units (so its easy to compare one magnet to another), and Pull-Testers can measure pull in pounds, kilograms.
Due to their strength NdFeB magnets could easily pinch fingers hence they need to be handled carefully. Also they should never be used by little children, these magnets are never intended to be a toy and little children can swallow them easily. Since they are extremely powerful they could cause wipe memory of electronic devices, erase hard drives, distort credit card magnetization, and can even be lethal in case they are used near pacemakers. NdFeB is corrosive toxic and flammable, the gases it releases if it is set to fire can be very harmful.
See our Neodymium Magnet Gallery for more images of Neodymium Magnets