Sintered Alnico Magnet manufacturing Method

Sintered Alnico magnet produced by a process of powder metallurgy,but it is different from the process of Neodymium and Samarium cobalt. Sintered Alnico magnet have isotropic and anisotropic materials with different grades, comparing only anisotropic materials of Sintered Neodymium and Sintered Samarium cobalt. Anisotropic Sintered Alnico magnet are oriented during a process called heat treatment, which is a key process for making its magnetic properties. Sintered Neodymium and Samarium cobalt oriented during press and form process, and they are made their magnetic properties also in the sintering furnace, in same process of sintering, but sintered Alnico need to be heat treated. The differences are decided by the different physical characteristics, alnico magnets have excellent performance of temperature, high curie temperature etc.

1.Sintered Alnico magnet was produced by powder metallurgy, that need to prepare kinds of powder materials, but some materials are easy to be oxidized that they need to be made to alloy first, so the raw material would be some powder but some alloys.2.In China, the middle alloy usually is Al-Co, and Ti-Fe, it is different from the technology used in Europe. We will smelt these material in a vacuum furnace, that to make them alloy. It will stop them oxidized and also make them easy to add into the Alnico alloy. 3.powder, it is easy to be understood, all the materials would be powder to press, so the alloy we made by last process need to be powder, and there will be an standard on the powder size of the powder.4. Press process is a process to shape the alnico magnet, different from Neodymium or Samarium cobalt magnet that they usually can be shaped directly to the final shape we would like to have. it is because they don’t request to oriented their magnetic direction in this process, and usually it is not big part, because the big Alnico part will be produced by another cheaper method, Cast Alnico. And the big advantage is that sintered Alnico can be easy to control the rough part on close tolerance. The key parameter is to control the shaped height and density. 5.Sintering process is the key process of Alnico magnet, they will be sintered to alloy, in China, we usually use vacuum sintering furnace, but in Europe, it usually the gas shielding furnace,this different will be that the rough part Chinese company produced will contain more oxide. 6. Heat treatment is the key process of making magnetic properties. the magnetic properties decide by the elements, temperature control and the time of these process. The technologies of heat treatment usually decide by the percent of some important elements like Ti, Al etc. 7.Then the magnetic properties will be test and check. The detail parameters will be tested and comparing with the standard of this material. 8. machining, sintered alnico magnet are usually brittle after heat treatment, and the machining method is usually grinding and linear cutting, other method need to back fire the part first or prior to heat treatment. and some methods can not be used that easy to crack. 8. inspection of magnetic flux comparing, and dimension inspection. In China, they usually will be inspected 100% by flux, that is different from the European companies. It will make sure 100% magnets are satisfied your requirement. but on another hand, it shows that Chinese companies have not enough abilities to control the magnetic properties just through processes, and need to final inspection 100% to prevent the bad part mixing into.9. Plating is available but usually Alnico don’t need to be plated in most application. 10. Magnetized or unmagnetized by requirement of cusomters. 11. Packages, sintered Alnico usually will be packaged by skin package or vacuum packages.


I am the founder and director of Ningbo Jack Magnetics Co.,Ltd. Our mission is to give you best support on buying and using permanent magnets, save your money and time on your magnetic applications.

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