What Are the Differences between
a Permanent Magnet and an Electromagnet?

The biggest difference between a permanent magnet and an electromagnet in industrial applications is the on-off switch. A permanent magnet is made from a "hard" magnetic material that maintains its magnetism over long periods of time. The magnetism in an electromagnet is created by current running through a coil of insulated wire that is wound around a piece of "soft" magnetic material. With an electromagnet, when you shut off the current, you shut off the magnetism. This ability to vary, reverse, or shut off the magnetic flux of an electromagnet is very valuable in a wide variety of applications.

Overall, however, there are important advantages to both types. Permanent magnets provide constant magnetic strength, can utilize simple designs with no moving parts, and are not affected by power failures. They are capable of operating at peak efficiency at all times and generate no heat. They can be built longer and flatter, providing a greater area of magnetic coverage, and may in some cases develop more depth of field than would be possible with the same size electromagnet. For suspension up to approximately 10 inches, suspended permanent magnetic separators are more compact and lighter than comparable electromagnets, which require no power source, and operate virtually maintenance free.

Large industrial electromagnets, on the other hand, benefit greatly from the ability to control the magnetic flux. Electro lifting magnets can be positioned over materials to be moved before the magnetism is turned on, and the load can then be positioned before the magnet is de-energized. On the negative side, electromagnets require a significant DC power source, create heat, and are vulnerable to power failures. These problems are not insurmountable, however. Some electromagnets available today, for example, are up to 50% more energy efficient than any others previously available, have more efficient cooling systems, and can be purchased with rectifiers and emergency generators (or other cut-in power source) to eliminate the vulnerability to power failure.