SmCo and NdFeB are rare-earth permanent-magnet materials. Choosing between them requires the magnetic output at the working gap, operating temperatures, environment and finished geometry. A room-temperature grade or a quoted maximum temperature alone does not establish suitability.
Compare proposed grades at the same operating temperature and magnetic working point. NdFeB is often considered where a high room-temperature energy product is useful; SmCo is often considered where temperature stability is a priority. Validate either material in the intended assembly.
For shapes, specifications and quotation details, see our custom neodymium (NdFeB) magnets and custom samarium cobalt (SmCo) magnets.
SmCo vs NdFeB: Compare the Operating Requirements
Compare remanence (Br), intrinsic coercivity (Hcj), energy product and the demagnetization curves at the intended temperature. The field at a sensor or working gap also depends on magnet shape, magnetization direction and the surrounding magnetic circuit. A material-grade value in gauss is not a pull-force rating.
What Are Samarium Cobalt Magnets (SmCo)?
SmCo magnets are commonly grouped into SmCo5 and Sm2Co17 families. Their commercial grades have different magnetic properties and temperature limits. Arnold Magnetic Technologies’ SmCo grade reference illustrates those differences; its published values describe its own materials and are not specifications for a Magnetstek quotation.
SmCo is often considered for improved resistance to ordinary atmospheric corrosion, but this does not establish compatibility with every chemical, cleaning process or salt exposure. Whether a finish or encapsulation is needed should be reviewed for the actual environment.
What Are Neodymium Magnets (NdFeB)?
NdFeB magnets contain neodymium, iron and boron and are offered in grades with different coercivity and temperature behavior. An 80°C rating for a particular grade does not mean that every NdFeB magnet loses all magnetism above 80°C. Maximum use temperature and Curie temperature are different limits. See K&J Magnetics’ explanation of temperature and neodymium magnets.
How Temperature Affects Magnets
Heating can produce a reversible change in output and, under unsuitable operating conditions, irreversible demagnetization. The risk depends on grade, geometry, the magnetic working point and opposing fields. Specify continuous and peak temperature, exposure time and the allowable change in magnetic output. Our SmCo temperature selection guide explains the information needed for a high-temperature inquiry.
About Coatings on Magnets
NdFeB often needs surface protection in humid conditions. Nickel-based plating, epoxy and other finishes are options to evaluate against the application. Arnold’s NdFeB material reference discusses grade selection and corrosion protection. A coating name alone does not prove waterproofing, salt resistance or a service life.
Corrosion Resistance Depends on Exposure
Describe the actual exposure: humidity, salt, chemicals, cleaning agents, contact materials, temperature and duration. Neither material family provides a blanket guarantee for a corrosive environment.
If a finish is required, state its material, coverage, thickness allowance and acceptance test. Account for edges, holes and assembly damage that could expose the base material. Confirm compatibility with adhesives, housings and mating parts.
Check the finished assembly after the specified environmental exposure. Agree how magnetic output, appearance and dimensions will be measured and what constitutes a pass.
For regulated or safety-critical equipment, provide the applicable qualification requirements. The magnet material name alone does not establish medical, aerospace or device approval.
What to Include in a SmCo or NdFeB RFQ
Drawing and magnetic requirements: provide finished dimensions and tolerances, quantity, pole faces and magnetization direction. State the required field or force at a defined working gap and give the measurement method. If you are comparing materials, use the same assembly constraints for both quotations.
Operating and inspection conditions: include continuous and peak temperatures, opposing fields, exposure conditions, coating requirements and acceptance criteria. Identify any assembly, stabilization or first-article testing that the supplier must review. Compare the total quoted scope rather than assuming one material is always cheaper.
Verify the Proposed Grade Before Production
Request a current datasheet and the relevant temperature-dependent curves for the proposed grade. Confirm the drawing revision, finish, magnetization, test conditions and approval record before production. Our first article inspection checklist provides a starting point for agreeing those checks.
Request a Material-Specific Quote
For a part-specific comparison, send an SmCo vs NdFeB inquiry with the drawing and operating requirements. Magnetstek can review the applicable material and supply scope; grade availability, price, minimum order and lead time are confirmed with the quotation.
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