An Introduction to Neodymium Magnets

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 magnet commercially available and are manufactured in a wide range of shapes, sizes and grades. We offer 47 grades of licensed Neodymium Iron Boron with 25 types of surface /coating finish for each grade.

The NdFeB magnets are anisotropic sintered magnets – the alloy is jet milled to a fine powder and is then compacted in the presence of a magnetic field to give it a preferred direction of magnetisation (making it anisotropic in performance). The NdFeB magnets are then sintered to fuse the powder together before final machining and magnetising produces the completed super strength Neodymium magnet.

The Neodymium magnets are also known as Neo magnets, Neodymium Iron Boron magnets, Neodymium-Iron-Boron magnets, NdBFe magnets, NdFeB magnets, NIB magnets, Super Strength magnets and Rare Earth magnets (please note that SmCo is also called a Rare Earth magnet). NdFeB is called a Rare Earth magnet because the Neodymium is a Rare Earth element, having a value of 60 on the Periodic Table. For note, there is nothing rare about Rare Earth magnets – the required elements are readily available and the NdFeB magnets are produced in several hundreds of tonnes each year.

The Neodymium Iron Boron (NdFeB) magnets were developed just over 25 years ago and were first commercially available in 1984. Neodymium magnets were initially developed for voice coil motors in computer hard disk drives and this market still accounts for over 50 percent of all Neodymium magnets produced. Other applications include high performance motors, brushless DC motors, generators, magnetic separation, magnetic resonance imaging, sensors and loudspeakers. They are becoming increasingly popular across a wide range of novelty products such as fridge magnets and all kinds of magnetically attachable gadgets for retail markets.

For note, our standard NdFeB is rated to +80 deg C. We offer the whole range of Neodymium Iron Boron magnets, with Maximum Energy Product (BHmax) ratings from 27 MGOe to 52 MGOe (N27 to N52) and with a maximum operating temperature rating ranging from +60/+80 deg C to +220/+230 deg C (Nxx up to NxxVH / NxxAH, where xx is the Maximum Energy Product in MGOe). The complete range of grades is as follows:-

N35, N38, N40, N42, N45, N48, N50, N52, N30M, N33M, N35M, N38M, N40M, N42M, N45M, N48M, N50M, N30H, N33H, N35H, N38H, N40H, N42H, N45H, N48H, N30SH, N33SH, N35SH, N38SH, N40SH, N42SH, N45SH, N28UH, N30UH, N33UH, N35UH, N38UH, N40UH, N28EH, N30EH, N33EH, N35EH, N38EH, N33VH/AH.

Neodymium-Iron-Boron magnets contain 60-75% iron (amount is dependent on grade) and are therefore prone to corrosion. Protective coatings are applied to Neo magnets and the most common one is electroless nickel plating (Ni-Cu-Ni; effectively a triple coating). The current range of coatings available are as follows:-

Nickel-Copper-Nickel (Ni-Cu-Ni) [standard], Nickel (Ni), Epoxy, Zinc (Zn), Gold (Au), Silver (Ag), Tin (Sn), Titanium (Ti), Titanium Nitride (TiN), Parylene C, Everlube, Chrome, PTFE ("Teflon"; white, black, grey, silvery) , Ni-Cu-Ni plus Epoxy, Ni-Cu-Ni plus Rubber, Zn plus Rubber, Ni-Cu-Ni plus Parylene C, Ni-Cu-Ni plus PTFE, Tin (Sn) plus Parylene C, Zinc Chromate, Phosphate Passivation and Uncoated (i.e. bare – not recommended but is sometimes required by the customer). Other coatings may be possible - please let us know your requirements.

Apart from offering over 1100 combinations of NdFeB grade and finish, we also manufacture bespoke NdFeB sizes upon request. The NdFeB magnets vary from D1mm x 1mmA discs up to e.g. 200mm x 130mm x 25mmA blocks. Standard NdFeB tolerances are +/-0.1mm. +/-0.05mm tolerances are also available for these Neodymium Iron Boron magnets. We can produce smaller Neodymium magnets down to +/-0.005mm tolerances as part of our bespoke Precision NdFeB range (we would specify the tolerance that could be achieved for each shape but please note that the production runs would be subject to 100k minimum order quantity).

The NdFeB (NIB) magnets, in disc, ring and rod forms, are usually axially magnetised (the round ends are the magnet poles). Diametrically magnetised discs and rings can be produced upon request (looking at the circular end face, the magnetism runs from the 12 o'clock position to the 6 o'clock position in diametrically magnetised magnets). Likewise, the rectangular blocks can be specially produced to be magnetised in any of the three axes (the magnets cannot be re-magnetised in another axis due to the method of production – the sintered NdFeB is anisotropic). Arcs, trapezoids and other shapes and assemblies (e.g. Pot Magnets, Separator Grids, etc) can generally also be produced. Bespoke Directions of Magnetisation within the magnet shape may also be possible (subject to confirmation) e.g. for Halbach Array assemblies.

We supply globally to all industries, including Automotive, Aerospace, Military, Advertising, Design House, Electronic and Academic/R&D. Our factory and our subcontractors have between them ISO9001:2000, ISO9001:2008, ISO14001:2004 and ISO/TS16949:2002 quality control accreditation. To aid protection of information, we can also provide our services under Confidentiality Agreements / Non Disclosure Agreements / NDA. PPAP (Production Part Approval Process) is available under our NDA.

If you require a bespoke Neodymium Iron Boron (NdFeB, NIB, Neodymium, Neo) magnet or magnetic assembly, Technical Support or our NdFeB Technical Data Sheet, please contact us.