Why do punched magnets have greater magnetic force than flat magnets?

Both punched magnets and flat magnets are made of magnetic materials. The main difference between them is the shape and structure of the magnet surface. The surface of a punched magnet has many small holes, which can increase the friction of the magnet surface and ensure close contact between the magnet and the adsorbed object. The surface of a flat magnet is smooth, so it cannot achieve the same effect.

Punched magnets have greater magnetic force than flat magnets. This is mainly because punched magnets are designed to concentrate and enhance the magnetic field. By punching holes in the magnet, the distribution of the magnetic field can be changed and the density of the magnetic flux can be increased. The following points can explain why punched magnets have greater magnetic force.

1. The magnetic field distribution of punched magnets is more uniform because the small holes can make the magnetic lines of force go deeper into the magnet, thereby increasing the stability and uniformity of the magnetic force. The magnetic lines of force of a flat magnet can only flow on the surface, so its magnetic force will gradually decrease with the increase of distance.

2. The magnetic force of a punched magnet is also affected by the magnet material. Some advanced magnet materials, such as neodymium iron boron and cobalt iron ore, can produce stronger magnetic force, so punched magnets will also be more powerful. Planar magnets usually use general-purpose magnet materials with low magnetic force.

3. Magnetic flux concentration

Drilling can concentrate magnetic flux in a smaller area, thereby increasing the magnetic force density in that area, which makes the magnetic field stronger. In contrast, the magnetic lines of force of planar magnets are dispersed over the entire magnet surface, and the magnetic line density is low.

4. Reduce reverse magnetic area

Drilling reduces the area of reverse magnetization inside the magnet (reverse magnetic area), weakening the weakening effect of these reverse magnetic areas on the total magnetic field, so the overall magnetic performance is stronger.