Samarium Cobalt Magnets (SmCo)

information-iconSamarium Cobalt Technical Information

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Samarium Cobalt magnets are a rare earth magnet material that offers the best value when comparing performance and size in high temperature or adverse environments. Samarium Cobalt magnets are higher in cost, but magnetically very strong and typically allow for dimensional reductions. A Samarium Cobalt rare earth magnet will offer excellent corrosion resistance and typically will not require a surface treatment. No magnet material should be employed as a structural element in a design. Samarium Cobalt magnets are especially prone to fracturing and are very weak under tensile or compressive loads. Samarium Cobalt magnets have good resistance to external demagnetizing fields because of their high Intrinsic Coercive Force (Hci) . This resistance makes Samarium Cobalt rare earth magnets an excellent choice for electro-mechanical applications.samarium-cobalt-magnets

Samarium Cobalt Manufacturing Process

Fully dense rare earth magnets “Samarium Cobalt” are usually manufactured by a powdered metallurgical process. Micron size Samarium Cobalt powder is produced and then compacted in a rigid steel mold. The steel molds will produce shapes similar to the final product, but the mechanical properties of the alloy usually inhibit complex features at this stage of the manufacturing process.

The Samarium Cobalts magnetic performance is optimized by applying a magnetic field during the pressing operation. This applied field imparts a preferred direction of magnetization, or orientation to the Samarium Cobalt magnet alloy. The alignment of particles results in an anisotropic alloy and vastly improves the residual induction (Br) and other magnetic characteristics of the finished magnet.

After pressing, the Samarium Cobalt magnets are sintered and heat treated until they reach their fully dense condition. The rare earth magnet alloy is then machined to the final dimensional requirements and cleaned.

Samarium Cobalt Temperature Characteristics

Sintered Samarium Cobalt rare earth magnets are extremely resistant to demagnetization and they can operate at temperatures up to 500F (260C). There are many Samarium Cobalt grades which can withstand higher temperatures, but several factors will dictate the overall performance of the Samarium Cobalt rare earth magnet. One of the most pertinent variables is the geometry of the magnet or magnetic circuit. Samarium Cobalt magnets which are relatively thin compared to their pole cross-section (Magnetic Length / Pole Area) will demagnetize easier than Samarium Cobalt magnets which are thick. Magnetic geometries utilizing backing plates, yokes, or return path structures will respond better to increased temperatures. The maximum recommended operating temperatures listed on the Samarium Cobalt magnetic characteristics page do not take into account all geometry conditions. Please contact a Dura team member for Samarium Cobalt rare earth magnet design assistance when elevated temperatures are involved in your application.

Samarium Cobalt Corrosion Characteristics (Surface Treatment)

Samarium Cobalt rare earth magnets are very resistant to corrosion and do not normally require any surface treatment.

The various elements that compose a samarium cobalt magnet - samarium, cobalt, copper, zinc, and iron.

The various elements that compose a samarium cobalt magnet -
samarium (Sm), cobalt (Co), copper (Cu), zirconium (Zr), and iron (Fe).

Samarium Cobalt Machining

Samarium Cobalt magnet rare earth material is very brittle and conventional machine tools and cutters are not appropriate. The brittle nature combined with the powder metal grain/crystal structure hampers the use of carbide tools. Electrostatic discharge machines (EDM), diamond tooling and some abrasives are the usual means of fabrication for this rare earth magnet alloy. Most magnet materials are machined in the un-magnetized state. Once the fabrication and cleaning operation are complete the Samarium Cobalt magnet is then magnetized to saturation .

Dura Magnetics is capable of fabricating simple or complex shapes from Samarium Cobalt magnet alloy. We stock a variety of standard and exotic grades for prototype or production fabrication.

A Dura Magnetics team member can help determine if custom machining is required or if “pressed to size” option is possible. The determining factors are usually required lead-time, cost, and the alloy required.

samarium cobalt magnet shapes

Samarium Cobalt Magnetizing

Samarium Cobalt rare earth magnets are extremely strong and they require a huge magnetizing field. Huge magnetizing fields require special equipment and aren’t generally magnetized by customers. The anisotropic nature of sintered Samarium Cobalt magnets results in a single direction of magnetization. This direction must be observed when magnetizing and when integrating the magnet into the final assembly. Often times an indicator is used to identify a specific magnetic pole for the customer’s assembly process. This indicator can be a laser engraved mark or simple paint dot.

The high field required for magnetizing Samarium Cobalt will often times restrict the design of the magnet or magnetic assembly. Many variables must be taken into account and a Dura team member can assist with the design process.

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