N52 Rare Earth Magnets are actually permanent magnets because they lose their magnetism or are naturally demagnetized, about 1% per century. They usually operate in a temperature range of -215°F to 176°F (-138°C to 80°C). For applications requiring a wider temperature range, Sa cobalt (SmCo) magnets are used.
Since uncoated sintered N52 Rare Earth Magnets will corrode and chip when exposed to the atmosphere, they will be sold with a protective coating. The most common coating is made of nickel, although other commercially available coatings are also resistant to high temperatures, high humidity, salt spray, solvents and gases.
N52 Rare Earth Magnets have different grades, corresponding to their magnetic field strength, ranging from N35 (the weakest and cheapest) to N52 (the strongest, most expensive and more brittle). The N52 magnet is about 50% stronger than the N35 magnet (52/35 = 1.49). In the United States, consumer-grade magnets in the range of N40 to N42 are usually found. In mass production, if size and weight are not the main considerations, N35 is usually used because it is cheap. If size and weight are key factors, a higher grade is usually used. The price of the highest grade magnets has a premium, so compared with N52, it is more common to use N48 and N50 magnets in production.