Cast Alnico Magnet Manufacturing Method

Cast Alnico Magnet resources

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Alnico Magnet is consisting primarily of iron, aluminum, nickel, cobalt, with minor amounts of other elements including copper and titanium. Cast Alnico Magnet manufacturing Method was called Sand Casting. They are shaped by using resin bonded sand molds, metal waters (Melting furnace´╝ë get into sand molds and cooling. Then break the sand molds and wipe off the pouring gates will get the magnet have been shaped. Then they will be heat treated to make magnetic properties. And then Machine them by grinding, linear cutting, and some other machine method

1. Cast Alnico Magnets’ Raw Materials need to be prepared, And before Melting, all the raw materials need to be check and clean ,to stop the raw materials be polluted that take some issues on final elements.
2. Formula, it is the important process for the magnetic properties of Cast Alnico Magnet, if the formula was wrong, the elements are out of control, we cannot get the magnetic properties we would like to have. Usually There will be a certain amount of Alnico Scrap will be used for the new magnet, so the formula need to be calculated carefully and double-check on the formula and weigh the materials carefully.
3.Melting, the materials will be melt in a melting furnace, and the slags will be take out, the slags are usually that oxidized materials and when melting them, the oxide cannot be melt, and floating upon the hot metal water.
4. Moulding Casting, before that, Sand moulds have been ready, the moulds are made from Resin Bonded Sand, The sand we use is a type of White Sand, with some Resin, they will be shaped in a metal mould, then heated. And the sand can be reused. The hot metal water fill into the sand mould then wait for their cooling.
5. Heat treatment, it is an important process for making magnetic properties, the heat treatment incl. solid solution, isothermally treated´╝îmagnetic field solution and back fire for different Grades.
6. Magnetic test, The samples will be test on all parameters for the magnetic properties, comparing with standard parameters of the grades. the Residual induction,the Coercive Force, the product energy are the three important parameters for the material. And there also will stand a lowest standard of this magnet, for the final comparing inspection of magnetic flux.
7. machining for the dimensions and the surface performance, the machining methods incl. grinding, linear cutting, and sometimes drilling and some other method, because cast Alnico magnet are brittle, especially the grades have high Coercive force like Alnico 8 or Alnico 8H, there will be a limited for machining. We will think about this to choose the correct method to machine them to the dimension and surface performance our customer required.
8. Magnetic comparing inspection, there will be 2 types of inspection, closed circuit and open circuit, most of Alnico magnets will be only comparing test in Closed Circuit for the flux density,but some Alnico magnet will be comparing tested for the open circuit. After checking their performance in flux density, (the standard was decided by the process of Magnetic test by all parameters of Br, Hc and BHmax, and find the lowest level the magnet should be reach), 100% Alnico magnet will be OK for customers’ requirement. That is the most important differences from the manufacturer from other countries, with 100% manual inspection and check, there will be 100% OK on Magnetic performance.
9. Dimension inspection, it is a conventional inspection for magnets, the different requirement will be taken some different inspection method and percent. Some important dimension also will be taken to a 100% inspection.
10. Packing, there will be magnetized or unmagnetized as customers’ requirements. And they will be packed by different way to protect magnets to be destroyed.


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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