Rochester Magnet stocks neodymium and samarium cobalt rare earth magnets in a range of standard sizes, with custom sourcing available in weeks. Whether you need a single disc or thousands of blocks, you can buy directly from our online store or request a quote for custom specifications.
The strongest permanent magnets that are commercially available. Our neodymium earth magnets come in disc, block, ring, and rectangular forms, with standard grade N35 nickel-plated stock ready to ship. Higher grades (up to N52) and high-temperature ratings (H, SH, UH, EH) are available by request.
Built for high-temperature and corrosive environments where neodymium cannot perform. SmCo magnets are available in standard sizes and grades, with custom options for specialized applications in aerospace, military, marine, and industrial systems.
Pre-applied adhesive on neodymium discs makes installation fast for packaging closures, point-of-sale fixtures, and assembly applications. Available with adhesive on the north or south face for proper magnet-to-magnet alignment.
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Rare earth magnets are permanent magnets made from alloys of rare earth elements, a group of 17 metallic elements found in the Earth’s crust. Despite the name, these elements are relatively abundant, but the mining and refining processes required to produce magnet-grade material are complex.
Two types of rare earth magnets dominate commercial and industrial use: neodymium iron boron (NdFeB) and samarium cobalt (SmCo). Both produce magnetic fields far stronger than ferrite (ceramic) or alnico magnets, which is why engineers and manufacturers turn to them when performance requirements exceed what conventional magnets can provide.
The key advantage of rare earth magnets is their energy density. A neodymium disc the size of a coin can generate enough pull force to hold several pounds, allowing product designers to use smaller magnets without sacrificing performance. This makes them critical components in applications where size, weight, and magnetic strength all factor into the design.
Both neodymium and samarium cobalt are rare earth magnets, but they perform differently under real-world conditions. Understanding the tradeoffs between them will help you select the right material for your application.
Neodymium magnets offer the highest magnetic energy product of any permanent magnet. Standard grade N35 provides strong resistance to demagnetization at ambient temperatures and covers a wide range of applications. For projects that require even greater pull force, grades up to N52 are available, packing more energy into the same physical footprint.
The primary limitation of neodymium is heat. Standard grades begin to lose magnetization above 176°F (80°C). High-temperature grades (designated H, SH, UH, and EH) push that ceiling higher, but neodymium still falls short of samarium cobalt in sustained high-heat environments. Neodymium magnets also contain iron, which makes them susceptible to corrosion. A nickel or epoxy coating is applied during manufacturing to protect against moisture and oxidation.
When to choose neodymium: Your application operates at or near room temperature, maximum pull force per unit size matters, and cost efficiency is a priority.
Samarium cobalt magnets trade some raw strength for superior temperature stability and corrosion resistance. SmCo operates continuously at temperatures from 250°C to 350°C, depending on the grade, and in some formulations even higher. Because these magnets naturally resist corrosion, they typically ship uncoated and unplated.
SmCo is available in two series: SmCo 1:5 (with energy products of 16 to 25 MGOe) and Sm2Co17 (with energy products of 20 to 32 MGOe). The higher cost of samarium cobalt is justified in applications that demand thermal stability, corrosion resistance, or both.
When to choose samarium cobalt: Your application involves sustained heat above 176°F, exposure to moisture or chemicals, or environments where long-term magnetic stability is non-negotiable.
Not sure which material fits? Rochester Magnet’s team works with engineers and procurement teams daily to match materials to operating conditions. Contact us to discuss your application.
Neodymium discs are a popular choice for magnetic closures in packaging applications. Small discs (often 3/8″ diameter) can be applied exposed with pre-applied adhesive or buried beneath a surface layer for a concealed finish. Their high pull force creates a secure, satisfying closure in a compact footprint.
When two magnets face each other in a closure, adhesive is applied to the north face of one and the south face of the other to ensure proper alignment.
In applications where full magnet-to-magnet strength is unnecessary, a cold-rolled steel disc or custom strike plate can serve as the receptive surface.
Several variables determine how much pull force a magnet for your specific application will produce:
Rare earth magnets are significantly stronger than ferrite or flexible magnets and require careful handling.
Neodymium and samarium cobalt magnets are both brittle. If two magnets snap together from a distance, they can shatter on impact, sending fragments outward. Larger neodymium magnets can pinch skin or cause bruising if fingers are caught between attracting surfaces. Always slide magnets apart rather than pulling them directly, and keep loose magnets separated during storage.
Store rare earth magnets away from electronic devices, credit cards, and pacemakers. While the field from a small disc is unlikely to cause problems at a short distance, direct contact with magnetically sensitive items should be avoided.
Rochester Magnet can advise on handling procedures and packaging methods for your specific magnets. Contact our team for guidance on safe integration into your product or process.
Grade selection depends on the pull force your application requires and the operating temperature. N35 is the most widely used grade and handles most ambient-temperature applications well. If you need maximum strength in the smallest possible footprint, consider N42 or N52. For applications involving heat, look at high-temperature designations like N35H or N35SH, which maintain their magnetization at elevated temperatures. Our team can help you balance strength, size, cost, and thermal requirements.
Yes. Rochester Magnet sources custom neodymium and samarium cobalt magnets based on your engineered drawings. We can accommodate custom shapes, non-standard dimensions, specific grades, and particular magnetization directions. Custom orders typically take weeks to fulfill rather than months.
SmCo magnets cost more than neodymium, but they justify that cost in specific scenarios: sustained operating temperatures above 176°F, exposure to moisture or corrosive chemicals, or applications where magnetic stability over a wide temperature range is essential. In aerospace, defense, marine, and certain industrial motor applications, SmCo is often the only viable option.
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