What is Neodymium Magnets? Everything you need to know

Neodymium magnets (also known as rare earth, Neo, NIB, or NdFeB magnets) were invented in 1982 and are the most vital type of magnet.

There are two basic methods of manufacturing NIB magnets: sintering and bonding.

Sintered Neodymium Magnets
Sintered NIB magnets have the highest strength but are limited to simple geometries and can be very brittle. They are made by pressing the raw material into shape and undergoing a complex heating process. The blocks are then cut to shape and coated to prevent corrosion. Sintered magnets are usually anisotropic, which means they prefer the direction of the magnetic field. Magnetizing a magnet against a "pellet" can reduce the magnet's strength by as much as 50%. Commercially available magnets are permanently magnetized in the preferred direction of magnetization.

Bonded Neodymium Magnets
Bonded NIB magnets are typically about half the strength of sintered magnets but are less expensive and can be made in almost any size and shape. The raw material is mixed with an epoxy resin that acts as a binder, pressed into a mold cavity, and heat cured. Bonded magnets are isotropic, which means they have no "grain" or natural preference for their magnetic field orientation.

Demagnetization
Neodymium magnets are permanent magnets, losing their magnetism or natural demagnetization at about 1% per century. They typically operate over a temperature range of -215°F to 176°F (-138°C to 80°C). Samarium Cobalt (SmCo) magnets are used for applications requiring a more comprehensive temperature range.

Coatings
Because uncoated sintered NIBs corrode and chip with exposure to the atmosphere, they are sold with a protective coating. The most common coatings are nickel, although other commercially available coatings resist high temperatures, high humidity, salt spray, solvents, and gases.

Different grades of Neodymium magnets
Neodymium magnets are classified into different grades depending on their magnetic properties and magnetic field strength, ranging from N35 (the weakest and cheapest) to N52 (the strongest, most expensive, and more brittle). N52 magnets are about 50% stronger than N35 magnets (52/35 = 1.49). Consumer grade magnets in the N40 to N42 range can usually be found in the United States. If size and weight are not a major consideration in mass production, N35 is usually used because it is cheaper. If size and weight are key factors, higher grades are usually used. There is a price premium for the highest grade magnets, so N48 and N50 magnets are more commonly used in production than N52.

Neodymium grades are generally difficult to distinguish visually. The markings can only distinguish them on the product, so some Neodymium magnets may look different in shape but may be the same grade. You can find several common neodymium magnet shapes in our product category “Neodymium Ring Magnets”. If you need custom Neodymium magnets, tell us the magnetic grade and shape you need. Feel free to leave a message or contact us directly.

Reprinted from Haoxiang Magnets - “What is Neodymium Magnets? Everything you need to know”