Introduction to Neodymium (NdFeB) Magnets

Up to +150 degrees C, the Neodymium Iron Boron magnets are the strongest performers. Between +130 degrees C and +160 degrees C, there is an overlap in performance between NdFeB and SmCo. Above +150 degrees C, SmCo provides more excellent performance.

NdFeB Magnets Applications

The “Neo” magnets are the first choice for many applications as they offer the most outstanding performance with the smallest volume. Neodymium Iron Boron (NdFeB) magnets exist in a variety of grades. These grades not only vary in magnetic output performance, but they also vary with a temperature rating. The maximum recommended operation temperature for the “Neo” magnets is +200 to +230 degrees C. However, the exact limit depends on the magnet shape and the total magnetic circuit (so the recommended limits are only crude guideline values). This is discussed in the section called Temperature Ratings.

NdFeB Magnets Characteristics

All the Neodymium Iron Boron, NdFeB, magnets are prone to corrosion (a method similar to rusting). They will require a form of protective coating. The standard coating is a triple-layer plating of nickel copper nickel (Ni-Cu-Ni). This Ni-Cu-Ni coating is applied to the Neodymium Iron Boron magnets unless requested otherwise. It should be noted that the level of protection given by any coating depends on the environment the magnet will be subjected to and how the coating is looked after.

The magnetic output from the “Neo” magnet varies with temperature. The output falls with increasing temperature but usually returns as it cools (the degree of fall with rising temperature depends on the reversible temperature coefficients). It is possible to permanently reduce the magnetic output through too high a temperature (a permanent demagnetisation).

The level of permanent demagnetisation depends on the magnet shape, the total magnetic circuit and the actual shape of the BH curve (which will vary depending on the grade of “Neo” chosen). Neodymium Iron Boron, NdFeB, magnets are also affected by external demagnetisation fields and by radiation, both of which can demagnetise the magnet, the latter permanently demagnetising.

If the user understands the limitations of the NdFeB and their application, using NdFeB magnets can allow very compact designs with high-performance issues affecting the performance. For note, if the magnet is kept in dry conditions at all times and the plating is not broken. No external demagnetising fields are applied; the magnet theoretically can retain its magnetism indefinitely.

The following sections will show you how NdFeB magnets are made, the NdFeB grades available, the effects of temperature and how to use plus get the most out of NdFeB. Alternatively, contact us on 01442 875081 for more information.