How do magnets work? Which ones should you get? And what’s the difference between neodymium magnets and other permanent-magnet materials? The right answer depends on the application, required force, temperature, corrosion exposure, geometry and available space.
Permanent Magnets and Electromagnets
Permanent magnets create a persistent magnetic field without electrical power. Common permanent-magnet materials include neodymium (NdFeB), samarium cobalt (SmCo), ferrite/ceramic and Alnico. Electromagnets create a magnetic field when electrical current flows through a coil and can be switched or controlled electrically.
Understanding Magnetic Strength
Magnet performance is not defined by one number alone. Engineers may consider surface Gauss, remanence (Br), coercivity, maximum energy product (BHmax), geometry, air gap and pull force. Two magnets with similar surface field measurements can perform very differently in a real assembly.
Measuring Magnetic Performance
Gaussmeters and other magnetic test equipment can be used to evaluate field strength, but measurements depend heavily on probe position, fixture geometry and test method. For purchasing and quality control, the magnet grade, dimensions, magnetization direction and agreed measurement method should be clearly specified.
Working Safely With Neodymium Magnets
Neodymium magnets can produce very high forces for their size and should be handled carefully. Strong magnets can pinch fingers, chip or shatter if allowed to snap together, and interfere with some electronic or medical devices. Review the magnet’s technical data, operating-temperature limit and handling requirements before use.
