Now the price of magnet raw materials on the market is more and more expensive, and the project funds are limited, how to improve the efficiency of the magnet?

There is a type of magnet called pot magnet, which is a combination of a magnet and an iron shell. A magnet of the same size in an iron shell is stronger and cheaper than a separate magnet.

Why does adding an iron shell make the suction stronger?

This property, which strengthens the external magnetic field, is called paramagnetism.

Iron is also called a soft magnet because it is easily magnetized.

Iron is paramagnetism and ferromagnetism, that is, it retains magnetism when the external field is removed.

The reason for paramagnetism can be understood as there seem to be countless small magnetic needles in the material. In the absence of external magnetic field, they are arranged irregularity due to thermal motion, which cancels each other and does not show magnetism as a whole.

They line up in the direction of the external magnetic field, and as a whole they become magnetic, reinforcing the external magnetic field.

If the needles were still interacting with each other, they would remain aligned in the same direction after removing the external magnetic field, which is ferromagnetism.

That is to put the magnet across the iron plate, which is equivalent to magnetizing the iron plate.

The magnetized sheet of iron is like a patchwork of innumerable magnets, and its magnetism is so strong that it sometimes exceeds some of the magnets, and when the magnetism of the magnets themselves is added (the magnets magnetize other objects without affecting their own magnetism), their magnetism is greatly increased;

In addition, there are stronger easily magnetized objects, such as alloys and oxides containing cobalt and nickel.