Grades of Neodymium Magnets

Neodymium Magnet Grades

When buying neodymium (NdFeB) magnets, you’ll notice terms like N35, N42, or N52. These refer to the magnet’s grade, indicating its magnetic strength. The higher the number next to the ‘N’, the stronger the magnet. For instance, N42 has a stronger magnetic field than N35.

In some cases, you may also see letters after the grade, such as in N45SH. These letters represent the magnet’s resistance to demagnetisation forces like extreme heat or magnetic pulses, which is known as coercivity. Here are the common letter grades used:

1. M (Medium) – Can withstand temperatures up to 100°C before losing magnetism.
2. H (High) – Can withstand temperatures up to 120°C.
3. SH (Super High) – Can withstand temperatures up to 150°C.
4. UH (Ultra High) – Can withstand temperatures up to 180°C.
5. EH (Extra High) – Can withstand temperatures up to 200°C.
6. AH (Advanced High) – Can withstand temperatures up to 230°C.

These letter grades ensure the magnets are suitable for various applications, especially those involving exposure to high temperatures or demagnetisation forces.

What Is The Strongest Grade?

The strongest grade of neodymium magnet available is N58, a very recent advancement in technology. Other high-performance grades include N54, N55, and N56. While N58 is cutting-edge and still emerging, N56 and below can be reliably produced, though it is less commonly made compared to lower grades. These higher-grade magnets provide exceptional magnetic strength but are more expensive, making them ideal for situations where power is the top priority.

Technical Definitions

• Remanence (Br) – This is the measure of a magnet’s ability to retain magnetism after being magnetized to saturation and the external magnetic field is removed. The higher the remanence, the stronger the magnetic field the material can retain.

• Coercive Force (Hc) – This is the measure of the material’s resistance to demagnetisation. It indicates the strength of an opposing magnetic field required to reduce the magnet’s magnetization to zero.

• Intrinsic Coercive Force (Hci) – This measures the resistance of a magnet to irreversible demagnetisation. It indicates the strength of an opposing magnetic field required to completely demagnetize the magnet to zero internal magnetization, not just reducing it to zero in an external field.

• Maximum Energy Product (BH)max – This represents the maximum amount of magnetic energy stored in a magnet. It is an indicator of the magnet’s strength and is commonly expressed in MegaGauss Oersteds (MGOe). The higher the value, the stronger and more efficient the magnet is.

• kG (KiloGauss) – 1 Kilogauss equals 1,000 Gauss. Gauss is a unit of magnetic flux density that measures how much magnetic field passes through a given area.

• T (Tesla) – 1 Tesla equals 10,000 Gauss. Tesla is another unit of magnetic flux density, used to measure the strength of magnetic fields in scientific and industrial contexts.

• Oe (Oersted) – Oersted is a unit that measures magnetic field strength, specifically the amount of magnetizing force or field intensity in a material.

• kA/m (Kiloampere per Meter) – 1 Kiloampere per Meter equals approximately 12.57 Oersteds. This is another unit of magnetic field strength used primarily in the International System of Units (SI).

• MGOe (Maximum Energy Product) – This unit measures the strength or power of a magnetic field in terms of energy per unit volume, often used to describe the performance of permanent magnets.

• kJ/m³ (Kilojoules per Cubic Meter) – 1 Kilojoule equals 1,000 Joules. This unit measures energy density, and in the context of magnets, it represents the amount of energy stored in a given volume of the magnetic material.