For magnetic applications, everyone pays great attention to the attraction of magnets. The attraction force of a magnet can be calculated (pull force calculator). The following formula can be used for reference. However, it should be noted that the default conditions of the formula are ideal, that is, the magnetic field distribution is very uniform. The magnetic permeability of the attracted object is very high (weak magnetism). Materials such as 300 series stainless steel and some other ferrous alloys are not applicable), the thickness and adsorption area are sufficient (increasing the thickness and area suction force will not increase, that is, regardless of magnetic leakage), even so, the calculated value can still only be used as For reference, it cannot be used as an accurate calculation.
(Among them, S represents the adsorption area, B represents the air gap magnetic flux density, and μ0 is the vacuum magnetic permeability (which is a constant, μ0=4π*10-7).)
How To Improve The Attraction Of Magnets?
1. Increase Adsorption Area
The object to be attracted should at least cover the adsorption surface of the magnet, and the object's thickness can be increased if conditions permit.
When A Magnet Attracts An Iron Plate:
The larger the adsorption area between the iron plate and the magnet, the greater the suction force between the magnet and the iron plate. When the adsorption area is equal to the area of the magnet, the tendency of the suction force to increase will gradually slow down. When the iron plate is large enough, it will increase The area of the iron plate may not improve the suction power;
When the area of the iron plate is the same, when the thickness of the iron plate is thin, increasing the thickness of the iron plate can increase the suction force. When the iron plate is thicker, the increase in suction force caused by increasing the thickness of the iron plate will gradually level off until there is no improvement.
2. Increase The Air Gap Magnetic Flux Density
From the magnetic field simulation diagram, we can see that after the magnet is changed to bipolar magnetization, the magnetic flux leakage is significantly reduced, and a large part of the magnetic field lines form a closed magnetic circuit loop inside the adsorbed iron piece.
If the number of poles is further increased and a magnetic conductive sheet is added to the bottom of the magnet, the magnetic leakage will be further reduced and the suction force will be further improved.
The current design trend of magnetic parts is to maximize the utilization of the magnetic field. Through the design of multi-pole magnetic circuits or Halbach magnetic circuits, or with the guidance of some materials with high magnetic permeability, the magnetic field can pass through as much of the object as possible. Attracting objects forms a closed loop of the magnetic circuit. Typical applications include:
Rubber magnets are designed for multi-level magnetization, some are double-sided multi-pole, and some are single-sided multi-pole. The magnet performance of rubber magnets is very low, but after a multi-pole magnetic circuit design, the magnetic field is densely distributed on the surface. The magnetic leakage is very small during adsorption, resulting in better adsorption effect;
Magnetic devices such as door suction devices are guided by magnetic permeable sheets. When adsorbing, the magnetic circuit is almost formed from the object to be adsorbed. In this way, the utilization rate of the magnetic field is very high. The intuitive experience is that of a small magnetic suction device. , the suction force is huge when in direct contact.