XGS33 Expands Bunting’s Samarium Cobalt Magnets Range

By Paul Fears | 02 February 2021

Bunting’s range of Samarium Cobalt (SmCo) Rare Earth Magnets now includes the XGS33, XGS33M and XGS33H grades, which provide higher stability and magnetic performance at raised temperatures.  Such performance characteristics are critical in applications for the automotive, aerospace and electronics sectors.

Advantages of Samarium Cobalt Magnets

Rare Earth magnets made from Samarium Cobalt (SmCo) were originally developed in the early 1960s, much earlier than the more widely known and used Neodymium Iron Boron (NeFeB).  The energy density of SmCo 2:17 is similar to the very high coercivity grades of NdFeB (e.g. AH grades) magnets, with the advantage of significantly enhanced coercivity, meaning the magnets can run faster, hotter and harder without demagnetising.

Samarium Cobalt Discs
Samarium Cobalt Discs

This increased coercivity comes through carefully controlled processing and thermal treatment and does not need any addition elements, unlike NdFeB, which requires a very high percentage of the scarce rare earth element Dysprosium (Dy) to maintain magnetic performance in difficult environments.

Samarium Cobalt’s higher coercivity (i.e. being able to withstand an external magnetic field without becoming demagnetised) leads to use in extremely demanding applications where temperatures exceed 300°C.  As there is barely any free iron in the magnet material composition, SmCo is suitable for use in corrosive environments .  When a suitable coating is applied, SmCo magnets are almost impervious to corrosion.

High-speed magnet rotors, with rotational speeds exceeding 100,000RPM also feature SmCo magnets.  Such challenging environments are found in the automotive (especially motorsport), aerospace and electronics industries with electric motors, sensors, and high efficiency magnet rotors.  Being slightly more dense means that SmCo magnets can run hotter.  In operation, the eddy currents generated by such rapid rotation warm the SmCo magnets, but do not demagnetise them.

Enhanced Samarium Cobalt Magnets

Performance comparison at high temperatures
Performance comparison at high temperatures

The newly introduced XGS33 grade of SmCo starts outperforming N42 grades of NeFeB at around 170°C and continues to maintain strong magnetic properties up to 350°C.  The XGS33 grade also produces the highest magnetic performance in the SmCo range with a maximum energy product (BHmax) of 32 MGOe.

The three different grades (i.e. XGS33 XGS33M and XGS33H) have different coercivities, with the lower coercivity grades being easier to post assembly magnetise although are less resistance to demagnetisation at higher temperatures.

“Technological advances, especially with green technology, continue to drive development of magnet materials,” explained Matthew Swallow, Bunting’s Technical Product Manager.  “The new XGS33 grade of Samarium Cobalt further enhances the performance of the rare earth magnet, enabling users to considering harsher environments previously unthinkable.”

Related Technical Article

Magnet and Magnet Assembly Design

Bunting designs and manufactures a wide range of magnets and magnetic assemblies.  Many are bespoke for specific applications.  For further information on any of the products mentioned in this article, or for bespoke magnet assemblies and magnet designs, please contact us via:

Phone:  +44 (0) 1442 875081

Email:  sales.berkhamsted@buntingmagnetics.com

Via the Bunting-Berkhamsted website for specialist magnets, magnetic assemblies and magnetising equipment

Via Bunting-eMagnets for online purchase of Magnets and Magnetic Technology

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