Magnets to carry out the process, the Chinese 1000 years ago with iron bars and friction magnet magnetized, produced the world's first compass.
About 1100 Chinese applied magnet needle and bearing plate even in together, make the magnet type guide device, used for navigation.
In 1820, the Danish physicist found current induced magnetic.
Japan 30 s found nickel, aluminum, cobalt mixed elements of the new magnet.
In Japan in the 70 s scientists created the neodymium magnets, this new magnet for & quot;
5000 years ago people found the natural magnet.
2300 years ago the Chinese natural grinding magnet into ladle, on a smooth air, under the action of magnetic, spoon handle guide, for the king of the world's first permanent magnet guide apparatus.
Manufacturing process of permanent magnets, magnet shape of sand mold casting to make demand, will be able to cast magnets, materials including: copper, cobalt, sulfur, nickel, iron, aluminum and titanium.
Metal into the electromagnetism stove, heated to 1600 ℃ above, all metals are melted into liquid.
Pour the solution into sand mold, the mold was put out, due to the hardening of the flammable gas inside the sand.
Pried open with a hammer casting mill, let air into the casting cooling inside information, make gas burn out.
The metal from the sand block points out, after casting metal or ordinary iron, do not have any magnetic force.
Tied a metal piece on the copper pipe, into a larger pipe, the copper pipe in the middle position, closely around the silicon with sand, with concrete seal both ends on both ends of the copper tube.
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