SmCo Magnet

Samarium Cobalt magnets offer the best value when comparing performance and size in high temperature or adverse environments. They are higher in cost, but magnetically very strong and typically allow for dimensional reductions. They offer excellent corrosion resistance and typically do not require a surface treatment. No magnet material should be employed as a structural element in a design, but Samarium Cobalt is especially prone to fracturing and is very weak under tensile or compressive loads. Samarium Cobalt has good resistance to external demagnetizing fields because of its high Intrinsic Coercive Force (Hci) . This resistance makes Samarium Cobalt magnets an excellent choice for electromechanical applications.
Samarium Cobalt Manufacturing Process
Fully dense Samarium Cobalt magnets are usually manufactured by a powdered metallurgical process. Micron size SmCo 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 alloy’s 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 magnets are sintered and heat treated until they reach their fully dense condition. The alloy is then machined to the final dimensional requirements and cleaned.
Samarium Cobalt Temperature Characteristics
Sintered Samarium Cobalt magnets are extremely resistant to demagnetization and they can operate at temperatures up to 500°F (260°C). There are many grades which can withstand higher temperatures, but several factors will dictate the overall performance of the Samarium Cobalt magnet. One of the most pertinent variables is the geometry of the magnet or magnetic circuit. Magnets which are thin relative to their pole cross-section (Magnetic Length / Pole Area) will demagnetize easier than 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 design assistance when elevated temperatures are involved in your application.
Samarium Cobalt Corrosion Characteristics (Surface Treatment)
Samarium Cobalt magnets are very resistant to corrosion and do not normally require any surface treatment.
Samarium Cobalt Machining
Samarium Cobalt magnet material is very brittle and conventional machine tools and cutters are not appropriate. The brittle nature combined with the powder metal grain/crystal structure inhibits the use of carbide tools. Diamond tooling, electrostatic discharge machines (EDM), and some abrasives are the conventional means of fabrication for this magnet alloy. Most magnet materials are machined in the un-magnetized state. Once the fabrication and cleaning operation are complete the 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 production or prototype 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 Magnetizing
Samarium Cobalt magnets are extremely strong and they require a large magnetizing field. Large magnetizing fields require special equipment and they are not 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 simple paint dot or a laser engraved mark.
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.