Based on the above information, it can be summarized as follows: According to the principle of electromagnetic induction, a strong current can generate a strong magnetic field. By using a strong magnetic field, ferromagnetic materials can be magnetized. Due to the different magnetization characteristics of different materials, some materials are easy to magnetize and are not easy to lose magnetism (lose magnetism), allowing them to maintain magnetism for a long time. Magnetizing this material produces a magnet. Use a magnetizer to magnetize hard magnets.

According to the principle of electromagnetic induction, current can generate a magnetic field, and using a strong magnetic field to magnetize hard magnetic materials is generally referred to as the magnetic material of a magnet. In fact, there are several different things: the most common magnet, such as the magnet used in general speakers, is a ferrite magnet. They are produced by using iron scales (in the form of flakes of iron oxide) that fall off the surface of steel billets during the hot rolling process in steel mills. After impurities are removed, crushed, and a small amount of other substances are added to the steel mold for pressure forming. Then, they are sintered in a reducing electric furnace (through hydrogen) to reduce some of the oxide to ferrite, cooled, and magnetized in an exciter.

What is more upscale than them is magnetic steel: magnetic steel is real steel, composed mainly of high nickel content in addition to iron. It is usually melted in a medium frequency electric furnace (each furnace weighs only a hundred or ten kilograms) and cast into shape. Due to precision requirements on certain surfaces, it is generally processed by grinding with a grinder. Then magnetize it to become a product. This type of magnetic steel is used in various types of electricity meters for measuring electricity. A more advanced magnetic material is neodymium iron boron magnetic material. They are substances containing rare earth elements neodymium, iron, and boron. The production is made by the method of hard alloy: through powder making, mixing, molding, sintering, precision processing, and magnetization. This type of magnetic material has the highest magnetic field strength, the best performance, and the most expensive price. It is only used in national defense, military industry, and precision equipment. The rotor of the stepper motor in the electronic watch is. Ah, the maglev train must be using this kind of magnetic material. Ferrite permanent magnet materials include strontium ferrite permanent magnet materials and barium ferrite permanent magnet materials, which can be divided into isotropy and anisotropy. Speaker magnets generally use ferrite permanent magnet materials; Metal permanent magnet materials mainly include aluminum nickel cobalt permanent magnet materials and rare earth permanent magnet materials. Rare earth permanent magnet materials can be divided into samarium cobalt permanent magnet materials and neodymium iron boron permanent magnet materials. Rare earth permanent magnet materials are made through powder metallurgy technology. Magnetic strength? I haven't found any convincing information yet.