Sometimes the problem does not come from a “wrong” magnet, but from a magnet that only appears to be correct.
It happens quite often: the sample works, the component has the required dimensions, and the declared material is the expected one. However, once it is assembled in the real application, the performance is not the same.
The force is different.
The behaviour changes.
The holding strength is not as expected.
Or the magnet loses performance over time.
This is because the performance of a magnet does not depend only on its shape, dimensions and declared material, but on a series of technical factors that are not always visible to the naked eye.
The magnetic grade makes the difference
Saying that a magnet is made of “neodymium”, “ferrite” or “SmCo” is not enough.
Within the same material family, there are different grades with different performance levels.
In the case of neodymium, for example, an N35 and an N52 magnet may have the same geometry but behave very differently in the final application.
Parameters such as Br, Hcj and BHmax help to read these differences from a technical point of view.
If you would like to learn more about the meaning of these values and how to interpret them in a technical datasheet, you can find the full article in last week’s blog post.
The production process also matters
With the same declared material, the production process can change the final result.
Pressing, orientation, sintering, heat treatments and machining all influence the magnetic characteristics of the component.
This is why two magnets that look the same can perform differently if they are produced with different processes or controls.
Magnetization and orientation
A magnet must be magnetized in the correct way for the application.
Magnetization can be axial, diametral, radial, multipolar or produced according to specific geometries.
Tolerances, coating and distance
Even small dimensional differences can have an impact.
Thickness, chamfers and tolerances can modify the behaviour of the magnet inside the assembly.
The same applies to the coating: even a few tenths of a millimetre can increase the distance between the magnet and the counterpart.
And when the distance increases, the available magnetic force can be significantly reduced.
Why proper checks are needed
For industrial applications, it is not enough for the magnet to be compliant on paper.
It is important to check dimensions, attraction force, magnetic field, magnetization direction, coating and batch characteristics.
Conclusion
Two magnets may look identical but perform differently for many reasons: magnetic grade, production process, magnetization, tolerances, coating, temperature and real operating conditions.
That is why, when choosing a magnet, it is important not to stop at its shape or declared material.
The component must be evaluated in its real application context, with the right checks and proper technical support.
At ODB Magneti, we support companies precisely at this stage: helping them choose the most suitable magnet for the real application, not just the one that appears to be similar.