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Comparison of injection molding (rubber plastic) magnetic and bonded permanent magnet processes

Time:2023-09-18 Views:1

The magnetic force of injection molding is weaker than that of anisotropic ferrite and stronger than that of isotropic ferrite. The process and injection molding of injection molding are basically the same as that of bonded permanent magnets. The only difference is that this process involves squeezing the heated particles into a mold through a hole to form the product, which is also rigid. The adhesive used is the same as injection molding, with a dosage of about 20% (volume). This process is generally used to produce thin or thin-walled circular magnets that are difficult to achieve by other bonding processes. It evolved from the manufacturing of injection molded plastic products. Firstly, the magnetic powder and binder are mixed evenly, then mixed and granulated to produce dry pellets. Then, the pellets are sent to a heating chamber with a spiral guide rod for heating, injected into the mold for molding, and cooled to obtain the product. The magnetic particles used are generally ferrite, neodymium iron boron, and samarium cobalt. The latter two types of magnetic particles have high hardness and severe wear on the guide rod and mold cavity, which is currently one of the issues of concern.

The magnetic properties of bonded magnets made by injection molding and bonded permanent magnets are the best. Almost all bonded neodymium iron boron permanent magnets adopt this process, which has gradually formed industrialization. The surface of bonded magnets requires coating protection, usually using cathodic electrophoresis, spraying, or other surface protection methods.