Neodymium Magnets are made from an alloy containing, amongst others, the elements Neodymium, Iron and Boron (NdFeB). The NdFeB magnets are the strongest type of rare earth magnet commercially available and are manufactured in a wide range of shapes, sizes and grades.
The NdFeB magnets are anisotropic sintered neodymium iron boron magnets – the alloy is jet milled to a fine powder.The magnetization diraction depends on the element of raw material.The Neodymium magnet are then sintered to fuse the powder together before final machining and magnetising produces the completed super strength Neodymium magnet.
Sintered NdFeB magnets are the most powerful magnets known. Maximum allowed temperature varies, but is up to 240°C for some grades. This maximum temperature is important, because usually the price of the magnet increase with temperature. The magnets consists of powder compacted in a magnetic field therefore they have process-fixed and limited magnetizing directions. Usually the magnetic field-lines have to be parallel in the material.
• Highest magnet strength available
• High resistance to demagnetization
• Operating temperature up to 240ºC
• Good at withstanding low temperatures (down to – 100ºC)
Corrosion protection is however always recommended for sintered neodymium magnets, because of the materials low corrosion resistance. The corrosion resistance of sintered NdFeB magnets can be compared to pure untreated iron.
A range of different coatings are available but sometimes complete encapsulation in i.e. stainless steel is preferable.
For special applications, e.g. in the event of direct contact with water, it may be necessary to apply a surface treatment to certain types of magnets.
We provide different options for surface treatment such as nickel, zinc and epoxy, or alternatively complete enclosure in stainless steel.
The potential applications for magnets are endless, but the most common include:Motors, Couplings, Sensors, Holding systems, Loudspeakers and microphones.
We ourselves use permanent magnets for our magnetic systems, couplings, rotors and other magnetic subcomponents.
How Neodymium Magnets are made
Neodymium Iron Boron is an alloy made mainly from a combination of Neodymium, Iron, Boron, Cobalt and varying levels of Dysprosium and Praseodymium. The exact chemical composition within NdFeB depends on the grade of NdFeB. Dysprosium and Praseodymium are added as a replacement for some of the Neodymium to improve the corrosion resistance and to improve the Hci (Intrinsic coercivity) of the “Neo”. An example of the composition is given below.
Typical composition of NdFeB alloy
|Main Elements within NdFeB||Percentage by weight|
|Neodymium (Nd)||29% – 32%|
|Iron (Fe)||64.2% – 68.5%|
|Boron (B)||1.0% – 1.2%|
|Aluminium (Al)||0.2% – 0.4%|
|Niobium (Nb)||0.5% -1%|
|Dysprosium (Dy)||0.8% -1.2%|
Positive and Negative of Neodymium Magnet
Neodymium Iron Boron (NdFeB) is another type of rare earth magnetic material. This material has similar properties as the Samarium Cobalt except that it is more easily oxidized and generally doesn’t have the same temperature resistance. NdFeB magnets also have the highest energy products approaching 50MGOe. These materials are costly and are generally used in very selective applications due to the cost. Cost is also driven by existing intellectual property rights of the developers of this type of magnet. Their high energy products lend themselves to compact designs that result in innovative applications and lower manufacturing costs. Neodymium magnets are highly corrosive. Surface treatments have been developed that allow them to be used in most applications. These treatments include gold, nickel, zinc and tin plating and epoxy resin coating.
|Very High Energy Product||Higher Cost (Except from us!)|
|High Coercive Force||Low Mechanical Strength – Brittle|
|Moderate Temperature Stability|
|Low Corrosion Resistance (When uncoated)|