Difference between Surface Gauss, Pull Strength, and Remanence
Discussing neodymium magnets can sometimes be tedious because several terms refer to different values, all of which contribute to their performance and efficiency. Three of those terms are surface gauss, pull strength, and remanence.
The surface gauss refers to the strength or density of a neodymium magnet right at its surface. If you can get a magnetometer up to its skin, the rating you will get here is the surface gauss, and it can be a good indicator of how well the neodymium magnet will perform in its application.
The surface gauss is usually lesser than the gauss at its core, so it’s essential to measure the surface gauss of the neodymium magnet to ensure its compatibility with the intended application.
The pull strength, as described above, refers to the force required to separate a neodymium magnet from a steel plate. This value depends mainly on the neodymium magnet’s maximum energy product or BHmax, i.e., the sheer strength of the magnetic force the neodymium magnet generates.
A neodymium magnet’s pull force also depends on the neodymium magnet’s shape and size. That is, a larger neodymium magnet will have the capacity to attract objects at a farther distance than a smaller neodymium magnet and will also have a higher pull strength regardless of whether they are of the same rating.
Certain factors may affect the actual pull force of a neodymium magnet during application. They include the surface of attachment, the permeability of the material, placement of the neodymium magnet, and air gap, which refers to any non-magnetic material between the neodymium magnet and the ferromagnetic material, e.g., coating, paint, foam, wood, paper, and others.
Remanence, derived from the word “remain,” refers to the amount of magnetic field left in a saturated magnetic material after exposure to an external magnetizing field. It is also the residual magnetic induction or residual flux density.
Among neodymium magnets’ qualities are their high remanence and coercivity, i.e., the ability to retain magnetism permanently and high resistance against demagnetization forces. A neodymium magnet’s remanence also determines the strength of its magnetic field because the magnetic field gets weaker as it covers a larger area.