Apart from electromagnets, neodymium magnets are the strongest in the world. Their adhesive force is very high even with small designs and should never be underestimated. Ferrite magnets are nowhere near this strength. But what are neodymium magnets and how are these super magnets actually made? You can find information on this in this guide.
The surface treatment turns a blank into a magnet
The cooled magnets are technically finished after sintering, but they don’t really look high quality yet. Two further steps are necessary to refine the surfaces of the neodymium magnets after production. First, they are sanded to remove rough spots and bumps. According to the given tolerances, the material can still be made to the desired size.
If the magnet has the correct dimensions, the surfaces must be sealed with a protective layer. The material must be thoroughly cleaned and dry for this step. There are many different magnetic coatings for neodymium magnet production. The most frequently used coating is a Ni-Cu-Ni coating, i.e. a composition of nickel-copper-nickel. Other possible coatings are:
- Gold plating (Ni-Cu-Ni-Au)
- Chromium (Ni-Cu-Ni-Cr)
- Copper (Ni-Cu)
- Epoxy resin (Ni-Cu-Ni epoxy)
- Zinc (Zn)
Now the only thing missing is the actual magnetization. This neodymium magnet production process is implemented with a magnetic coil, the magnetic force of which is at least three times the desired strength of the new magnets. The batch with custom magnets bulk must be fixed well before the process begins, because otherwise they will immediately repel or attract each other after magnetization. The coil emits a magnetization pulse to the raw magnets, which causes the crystals to be realigned inside. From this point on, the blanks are permanently magnetized.
Why are neodymium magnets so strong?
Neodymium magnets are also often referred to as super magnets. They are, compared to ferrite magnets, much more attractive. Some of them hold six hundred times their own weight. The energy density is given in kilojoules per cubic meter (kJ / m3). A numerical example is useful to illustrate the difference between ferrite and neodymium magnets: ferrite magnets normally have an energy density of approx. 30 kJ / m3. In contrast, neodymium magnets have a maximum energy density that is almost 20 times as high, namely approx. 500 kJ / m3. These are usually not used in the private sector, but preferably in industry or similar work areas. The reason for their enormous adhesive force lies in the chemical connection and the crystal structure. This has a large anisotropy and extremely high coercive field strengths.
How dangerous are neodymium super magnets?
The use of neodymium magnets should always be well thought out. If handled carelessly, their extremely high adhesive strength can lead to severe bruises, bruises or even broken bones. The metals often have hard edges that can hurt the skin if handled incorrectly. Therefore, you should wear padded gloves for all magnetic applications. When bringing two magnets together, you should also keep in mind that they attract themselves from a certain distance and can lead to unexpected dangerous situations. The neodymium alloy is brittle in this state. Due to the high forces, metal chips can chip off the magnets in the event of an impact and thus also injure the skin.
