Rare earth magnets have a well-earned reputation for being the most powerful types of magnets available. However, you may be wondering how this strength is measured in the first place. Magnets have many different properties, and there are different ways to measure each of these properties. Typically, when people refer to a magnet’s “strength,” they are talking about the magnet’s holding strength or the field intensity the magnet can generate. In this blog, we will explain different properties that determine a magnet’s strength, in addition to explaining how to measure a magnet’s holding strength.
Rare Earth Magnets have Unique Magnetic Properties
If you are measuring the strength of one magnet in order to compare it to another magnet, you must take into account all of the magnetic properties of each material. Some of the most important magnetic properties are:
Remanence (Br)—a measurement of the magnetic field’s strength.
Coercivity (Hci )—a magnetic material’s resistance to demagnetization.
(Maximum) Energy product (BHmax)—a permanent magnet’s magnetic energy, which is the maximum value of magnetic flux density (B) times magnetic field strength (H) along the 2nd quadrant normal demagnetization line.
Rare earth magnets possess both high coercivity as well as high remanence. This means that not only do they have high-strength magnetic fields, but also that these magnetic fields are highly resistant to demagnetization. Rare earth magnets also have a high energy product. The combination of high remanence, high coercivity, and a high energy product result in the immense power of rare earth magnets.
Measuring Magnetic Strength
When measuring the strength of a magnet, the magnet’s field strength is typically the specific value being measured. Magnetic field strength refers to the measurement of how the magnetic field is distributed around a magnet which results on a force being applied to another magnetic material. This is commonly referred to as holding force, or the “pull strength” of a magnet. Pull strength, by definition, refers to the amount of force required to pull a magnet away from a flat steel surface the magnet is in full contact with. Pull strength may be measured using a pull test.
When the “pull force” of a rare earth magnet is listed, it is referring to the maximum weight that a rare earth magnet is able to safely hold. For example, if the pull force for a certain rare earth magnet is listed as being 100 lbs, it means the magnet is able to safely hold an object weighing 100 lbs.
If you are interested in learning more about magnetic properties and how the strength of magnets and magnetic materials are measured, contact our experts at Bunting-DuBois today.