How to demagnetize NdFeB magnets? How long does a strong magnet demagnetize?
Nd-Fe-B is widely used, there are always all kinds of problems, such as how to demagnetize Nd-Fe-B magnet? How to make the powerful magnet demagnetize for a short time? Can NdFeB magnets be magnetized after demagnetization beyond working temperature or Curie temperature?
What are the methods of strong magnetic demagnetization of NdFeB?
1. AC demagnetization of magnets
This way of demagnetization is to put the NdFeB magnet into the space which can produce AC magnetic field. After the interference of AC magnetic field, the internal structure of the magnet will be disturbed, so as to achieve the effect of demagnetization. This method is a common method of demagnetization.
2. High temperature demagnetization method
The main operation of high-temperature demagnetization method is to put the magnet into the high-temperature furnace for heating. After high-temperature treatment, the magnetism of the strong magnet will be removed. However, in the heating process, because of the effect of high temperature, the structure of the object inside the magnet will change greatly. Therefore, this demagnetization method is generally used for scrap and recycled magnets.
3. Vibration demagnetization method
The operation of this method is very simple, that is, the strong Nd-Fe-B magnet is vibrated violently. After the vibration operation, the internal structure of the magnet is changed, so as to change the physical properties of the magnet. Generally speaking, this demagnetization method has little effect, only a small amount of magnetism can be removed.
How to make the powerful magnet demagnetize for a short time?
- 1. There is a “critical temperature” of magnetic material. When it reaches the critical point, the magnetism can disappear, and when it is lower than this temperature, the magnetism can recover; but if the temperature is too high, the magnetism of the magnet will disappear forever.
- 2. For the magnetic watch base used in the mechanical processing industry, the way to make the magnetism disappear is to “short circuit” the north and south poles with soft iron (with strong magnetic conductivity). The magnetic field of the magnet only passes through the soft iron, and the magnetism disappears externally. When the short-circuit soft iron is removed, the magnet shows magnetism externally.
Can NdFeB magnets be magnetized after demagnetization beyond working temperature or Curie temperature?
- 1. There will be a small amount of magnetic loss after cooling beyond the working temperature (according to the brand nmsh eh uh ah th, there are several working temperatures of 80-100-120 — 150-180-200-250)
- 2. However, if the Curie temperature exceeds 312 ℃, there is no way to magnetize.