subject: Neodymium And Other Magnet Choices [print this page] Neodymium magnets are made of a combination of iron, boron, a few other trace metals and, of course, neodymium. They are small but very strong, look metallic, and can be shaped as rings, discs or blocks. Most commonly used for computers, neodymium magnets are also found in servomotors, microphones, linear actuators, vehicle starters, printers and speakers.
There are several reasons why neodymium could be a good choice for magnet properties. The metal combination is extremely resistant to any demagnetization, has a very high energy level, and performs well in ambient temperatures. Neodymium is also a less expensive material than several other metals used for magnets.
There are disadvantages to neodymium magnets, however. The metal can be quite corrosive, and coating is suggested to assure a long-lasting output of energy. It is not currently resistant to high heat, though scientists are working on resolving this problem. There are other things to watch out for when using neodymium for magnets as well. For instance, the metal is prone to chip and crack, so it is not the ideal choice in magnet material for conventional machining processes. On the other hand, it can be ground abrasively with a large amount of coolant. This cooling process reduces the chance of fracture caused by heat. The coolant also cuts back on the risk that the oxidized dust from the grinding process could cause a fire.
For those who must have a less costly magnet there is one other option, even less expensive than neodymium. It is ceramic. Used typically for speakers, ceramic magnets are also include in the manufacture of lawnmower and outboard motor magnetos, medical Magnetic Resonance Imaging (MRI)machines, vehicle motors, and assembly systems designed to lift, hold, separate and retrieve manufactured items. The finishing process for ceramic magnets requires either a grinding wheel or a diamond cutter. These magnets do not allow for much variation in shape, and they give off less energy than the neodymium magnets.
In contrast, cobalt magnets are far more costly than either the ceramic or the neodymium magnets. The price is driven by the fact that cobalt is highly resistant to any demagnetization, maintains its temperature for an extended period and gives off a comparatively high amount of energy. Cobalt magnets are used for sensors, computer disc drives, satellites, linear actuators, and wave tubes. Any motor that requires temporary stability is generally made with cobalt magnets as well.
Alnico magnets lend themselves to a very wide variety of uses. These include radar, coin slots, clutches, bearings, electron tubes, sensors, motors, separators, magnetos, telephones, microphones, generators, loudspeakers, security systems and ringers for bells. Alnico is far better for high heat uses than neodymium magnets, working well at more than 1000 degrees Fahrenheit.
