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How Is The Magnet Made?
Oct 22, 2018

How is the magnet made?


Ferromagnetic substances such as iron, cobalt, nickel or ferrite are different. The internal electron spins can be spontaneously arranged in a small range to form a spontaneous magnetization zone. This spontaneous magnetization zone is called a magnetic domain. After the ferromagnetic substance is magnetized, the internal magnetic domains are neatly arranged and aligned in the same direction, and the magnetic properties are strengthened to form a magnet. The magnet attracting process is the magnetization process of the iron block. The magnetized iron block and the magnet are attracted to each other in different polarities, and the iron block is firmly "sticked" to the magnet.


The natural magnet is triiron tetroxide, and the artificial magnet is usually steel. After the magnet is magnetized, it will retain the magnetic properties. The natural permanent magnets are not only ferrite (ferric oxide), but also various permanent magnet materials such as iron-cobalt-nickel alloy and iron rare-earth alloy, such as aluminum-nickel. Cobalt, samarium cobalt, neodymium iron boron, these are also very common, magnetic is very strong, these substances can be magnetized by the magnetic field constant magnetic field, and magnetized itself is magnetic and does not disappear. The composition of the artificial magnet is determined according to the magnetization properties of various metals. The magnet approaches (touches) the magnetic substance, which induces a different name near one end and the same name on the other end.


Magnet classification

A. Temporary (soft) magnet

a. Meaning: Magnetic is short, and the magnet disappears when the magnet is removed. b. Example: nails, wrought iron

B. Permanent (hard) magnet

a. Significance: After magnetization, it can retain magnetism for a long time. b. Example: steel nail


According to the above information, it is summarized as follows: According to the principle of electromagnetic induction, a strong current can generate a strong magnetic field, and a ferromagnetic substance is magnetized by a strong magnetic field, and since the magnetization characteristics of different substances are different, some substances are easy to magnetize and are not easy to fall. Magnetic (loss of magnetism), can retain magnetic properties for a long time. Magnetizing this material produces a magnet. Magnetize the hard magnet with a magnetizer.


According to the principle of electromagnetic induction, a current can generate a magnetic field, and a hard magnetic substance is magnetized by a strong magnetic field. Generally speaking, it is a magnetic material of a magnet. Actually, there are several different things: the most common magnet, such as a magnet for a general speaker, is iron. Neodymium magnet. They are iron scales (sheet-like iron oxides) which are detached from the surface of the slab rolling material during hot rolling in the steel mill. After removing impurities, pulverizing and adding a small amount of other substances, they are placed in a steel mold and pressure-molded. Then, it is sintered in a reducing electric furnace (through hydrogen), and some of the oxides are reduced to ferrite, cooled, and then placed in an exciter to be magnetized.


More advanced than they are magnetic steel: magnetic steel is real steel, the composition of which has a higher content of nickel than iron. It is generally smelted in an intermediate frequency electric furnace (only one hundred kilograms per furnace), and is cast and formed. Because of the accuracy requirements of some planes, it is generally ground by a grinding machine. Then magnetize and become a product. This kind of magnetic steel is used in all kinds of meters that measure electricity. A more advanced magnetic material is a neodymium iron boron magnetic material. They are substances containing rare earth elements lanthanum, iron and boron. The production is made by a hard alloy method: by powder-mixing-molding-sintering-finishing-magnetizing. This type of magnetic material has the highest magnetic field strength, best performance and the most expensive price. It is used in defense military and precision equipment. The rotor of the stepper motor in the electronic watch is. Ah, the maglev train is definitely the kind of magnetic material used. Ferrite permanent magnet materials are: 锶-ferrite permanent magnet materials and 钡-ferrite permanent magnet materials, which are also isotropic and anisotropic. Speaker magnets are generally made of ferrite permanent magnet materials. Metal permanent magnet materials mainly include AlNiCo permanent magnet materials and rare earth permanent magnet materials. The rare earth permanent magnet material is further divided into: samarium cobalt permanent magnet material and neodymium iron boron permanent magnet material. The rare earth permanent magnet material is made by a powder metallurgy process. Magnetic strength? I have not found convincing information for the time being.


There are too many categories of magnets, so I will simply say here:


There are two main types of magnetic materials: the first is permanent magnet material (also called hard magnetic): the material itself has the characteristics of preserving magnetic force. The second is soft magnetic (also called electromagnet): the need for external power to generate magnetic force, we are talking about magnets, generally refers to permanent magnet materials.


There are also two major classifications of permanent magnet materials: the first category is: alloy permanent magnet materials include rare earth permanent magnet materials (NdFeBB Nd2Fe14B), SmCo (SmCo), Niobium NiCo (NdNiCO). The second major category is: Ferrite permanent magnet materials (Ferrite) are divided into: Sintered Ferrite, bonded ferrite (rubber magnet), injection molded ferrite (Zhusu Ferrite) The three processes are divided into isotropic and anisotropic magnets depending on the orientation of the magnet crystal.