What do N35, N42, N48 and N52 mean?

Anyone looking into neodymium magnets will soon come across designations such as N35, N42, N48 or N52. These codes can be found on product pages, technical datasheets and magnet packaging. For many users, they seem like arbitrary product codes, but in reality, they tell us something fundamental about the material from which the magnet is made.

These designations belong to the so-called magnet grades. They indicate how much magnetic energy a particular material can store, and thus provide an important indication of the magnet's ultimate performance.

While it is often assumed that a higher value is automatically better, the reality is more nuanced. The choice of a particular magnet grade depends on many more factors than just maximum strength.

The origin of magnet grades

Neodymium magnets are made from an alloy of neodymium, iron and boron, often abbreviated as NdFeB. Since the introduction of this material in the 1980s, various grades have been developed, each with its own properties.

To distinguish between these grades, a classification system is used where the letter N is followed by a number. This number refers to the maximum energy product of the material, a technical property that indicates how much magnetic energy per unit volume can be stored.

The higher this number, the greater the amount of magnetic energy that can be present in the same material volume.

What does the letter N mean?

The letter N refers to neodymium, the main constituent of the most powerful permanent magnets commercially available today.

The number after the letter indicates the magnetic grade of the material. An N52 grade magnet contains more magnetic energy than an N35 grade magnet, provided both have the same dimensions.

However, this does not mean that an N52 magnet is always the best choice. The performance of a magnet is not solely determined by the magnet grade, but also by shape, dimensions, temperature and application.

The difference between N35 and N52

When two identical magnets are made from different magnet grades, the magnet with the highest N-value will generally have the greatest holding force.

Suppose two disc magnets have exactly the same diameter and thickness. If one magnet is made of N35 material and the other of N52 material, the N52 version will produce a stronger magnetic field and deliver a higher holding force under ideal conditions.

However, the difference is less spectacular than many people expect. In practice, the difference is often a few tens of percent, not hundreds of percent.

For many applications, a larger N35 magnet can therefore be more effective than a smaller N52 magnet.

Why are there different magnet grades?

The world in which magnets are used is very diverse. A magnet in a loudspeaker is exposed to different conditions than a magnet in an electric motor, sensor or industrial machine.

Some applications require maximum force within a limited space. Other applications place high demands on temperature resistance or durability.

For this reason, different magnet grades are produced, so that designers and engineers can choose a material that optimally suits the desired application.

Temperature and magnet grade

In addition to the well-known N-values, designations such as N42H, N42SH or N35EH also exist.

These additions do not refer to extra magnetic force, but to the maximum operating temperature of the material.

Neodymium magnets lose some of their magnetic properties when exposed to high temperatures for extended periods. To mitigate this problem, special grades have been developed that are more resistant to heat.

This allows magnets to be used in environments where standard neodymium magnets perform insufficiently.

Why isn't N52 always chosen?

At first glance, it seems logical to always choose the highest available magnet grade. Yet, this rarely happens in practice.

A higher magnet grade entails higher production costs and does not always provide a noticeable advantage. Moreover, dimensions, design and temperature often play a greater role than magnetic grade alone.

Therefore, for each application, an optimal balance between performance, durability and cost is sought.

Conclusion

The designations N35, N42, N48 and N52 indicate the magnetic grade of a neodymium magnet. They are a measure of the amount of magnetic energy that can be stored in the material.

Although higher values generally lead to stronger magnets, the ultimate performance is always determined by a combination of material, dimensions, temperature and application. The highest N-value is therefore not automatically the best choice.

A good understanding of magnet grades helps in selecting the right magnet and prevents choices from being made solely based on the highest value.