Neodymium or samarium cobalt?

Two rare-earth magnet families. Different considerations for your design.

Start with the operating conditions.

Neodymium iron boron (NdFeB) and samarium cobalt (SmCo) are both rare-earth permanent-magnet materials. A choice between them needs to account for temperature, magnetic requirements, environment, dimensions and cost.

Neodymium: a family of grades.

NdFeB is used in many compact magnetic designs. Grade, geometry and operating conditions affect performance. Do not assume that a higher grade number automatically solves a temperature or assembly problem.

Samarium cobalt: consider thermal stability.

SmCo can be a candidate where temperature stability is especially important. Its suitability still depends on the grade and design. Ask for the relevant supplier data rather than applying a universal maximum temperature.

Compare under the same conditions.

Ask an engineer to evaluate the materials against the same magnetic and environmental requirements. Include coating needs, handling, testing, supply route and delivery in the comparison.

Material references: Arnold: NdFeB and Arnold: SmCo. These are educational references, not confirmation of our supply or a commercial relationship.

This guide is an introduction. Final selection and acceptance criteria need to be agreed for your application.