High Temperature Can Make Magnets Lose Magnetism Quickly
A magnet will lose some magnetism immediately when it encounters a high temperature that exceeds its own tolerance. How much high temperature does it need? This depends on the coercive force of the magnet, which is usually expressed by the letter after the magnet grade, such as N40H, the maximum magnetic energy product is 40, and H represents the temperature resistance of 120°C. The higher the coercive force, the more metal dysprosium content is added to the magnet. .
How much magnetism will it lose?
It depends on the degree of its magnetic protection, if there is some iron around it will help. Of course, it depends on the temperature. But this is a highly non-linear effect. It does not lose any magnetism until it reaches a certain temperature, and then loses all magnetism quickly. Please note that the amount of magnetism it loses depends on how high the temperature is, not the length of time at a particular temperature. After the magnet reaches a certain temperature, it will lose all the magnetism that it can reach at that temperature.
Fire roasted magnet
How long does it take?
For a specific small volume of magnet, demagnetization will occur immediately. However, even in a small magnet, it takes time for heat to transfer from the outer surface to the center. For example, a 1 cm3 part takes several minutes. However, the part of the magnet near the surface will immediately lose its performance. 200°, whether in Fahrenheit or Celsius, is very high for a magnet. Unless you have a special, very advanced magnet (UH or AH or better), you will completely ruin it.
Introduction to the coercivity of each grade of magnet;
Grade n neodymium magnet: low coercivity
Grade m neodymium magnet: medium coercivity
Grade H neodymium magnet: high coercivity
SH grade neodymium magnet: extra high coercivity
Uh grade neodymium magnet: ultra high coercivity
EH grade neodymium magnet: extremely high coercivity
Neodymium magnet grade parameters;
Magnetic property parameters of sintered Nd-Fe-B
High temperature resistant magnets are recommended;