Magnetic Pulling Power or Pulling Force is the force required to pull a magnet free from a flat steel plate while holding plate parallel to the surface. While there are equations and formulas specifically to determine this strength, they are not useful for the “everyday” user of a magnetic sweeper or industrial magnet. Pulling force is going to also vary based upon the shape of the object being lifted. It is much easier to attract a flat, square object as opposed to a cylindrical object as there is less surface area on the cylindrical object. Large, heavy objects are actually sometimes easier to lift than small ferrous objects as they contain more surface area to attract.
It is also important to note that pulling force will diminish if the metal is an alloy and not pure ferrous. There are magnetic “Pull-Testers” available on the market which can pull in pounds, kgs or other force units. Also available to measure specific magnetic force are Gaussmeters which measure the Gauss strength of a magnetic field. Reputable magnetic manufacturers and distributors will have the Gauss ratings readily available if asked to provide such. For standard, practical usage when testing the pulling force of a magnetic sweeper or tow behind magnetic sweeper, most common testing is done using a flat, 100 lb steel plate.