Types and applications of permanent magnets

Currently, commonly used permanent magnets are ferrite magnets, neodymium magnets, samarium cobalt magnets, alnico magnets, rubber magnets, etc. Each of the above-mentioned magnets has its own characteristics, and their advantages and disadvantages are also different. Therefore, in this article, let us study the types of permanent magnets and their advantages and disadvantages in more depth.

Brief introduction of advantages and disadvantages of different types of permanent magnets

1. Ferrite magnet

Ferrite magnets are a non-metallic magnetic material, also known as magnetic ceramics. They have a wide range of applications. The ferrite magnet does not have high magnetic properties. Generally, the magnetic energy product (one of the parameters that measure the performance of a magnet) can only be slightly higher than 4MGOe.

Advantages of ferrite magnets

The biggest advantage of this magnet is its low price. At present, they are still widely used in many fields. For example, the horn magnets in conventional radios are made of ferrite magnets. In addition, since the ferrite magnet is made of a ceramic material, there is almost no problem of corrosion. The finished product does not require surface treatment such as plating or coating.

Disadvantages of ferrite magnets

The ferrite magnet is generally formed from a mold and then sintered. Therefore, it is difficult to process the ferrite magnet. Therefore, most ferrite products have simple shapes and large dimensional tolerances.

2. Rubber magnet

Rubber magnet is one of ferrite magnetic material series. It is a flexible, elastic and twistable magnet, made by bonding ferrite magnetic powder and synthetic rubber together, and passing through extrusion, calendering, injection molding and other processes. Typically, its energy product is 0.601.50 MGOe. Rubber magnets can be processed into bars, rolls, sheets, blocks, rings and other various complex shapes.

Application of rubber magnet

Rubber magnets are mainly used in refrigerators, teaching instruments, switches, sensor magnets, micro motors, disinfection cabinets, cabinets, toys, stationery, advertising and other industries.

3. Samarium cobalt magnet

The main components of samarium-cobalt magnets are samarium and cobalt. Because both materials are expensive, samarium-cobalt magnets are among the most expensive magnets on the market today.

Advantages of samarium cobalt magnets

The energy product of samarium-cobalt magnets can reach 30MGOe or even higher. In addition, samarium-cobalt magnets have high coercivity and high temperature resistance, and can be applied to high temperatures of 350 degrees Celsius, so they cannot be replaced in many applications. Since the samarium-cobalt magnet has electrical conductivity, it can be processed by wire cutting. In addition, samarium cobalt magnets have good corrosion resistance and usually do not require anti-corrosion plating or painting.

Disadvantages of samarium cobalt magnets

Samarium cobalt magnets are very brittle, so it is difficult to handle small size or thin wall products.

4.NdFeB

Due to NdFeB orNdFeB magnetIt has excellent magnetic properties and easy processing, so the price is relatively low. It has been widely used and developed rapidly.

The advantages of neodymium iron boron

The energy product of NdFeB magnets can reach 50MGOe, which is 10 times that of ferrite magnets. Because neodymium iron boron has excellent magnetic properties, in many cases, they can be used to replace other magnetic materials to reduce product volume.

In addition, like samarium cobalt magnets, neodymium iron boron magnets also have good processing performance. Therefore, the dimensional tolerance of neodymium iron boron products is much better than that of ferrite products. Generally, the dimensional tolerance of ordinary NdFeB products can be (/-)0.05mm.

Disadvantages of NdFeB

The maximum operating temperature of neodymium iron boron magnets is about 180 degrees Celsius. If it is in a harsh environment, it is generally recommended that the maximum operating temperature of the neodymium iron boron magnet should not exceed 140 degrees Celsius.

In addition, NdFeB is easily corroded. Therefore, most NdFeB products need to be electroplated or painted. Commonly used surface treatments include nickel plating (nickel-copper-nickel), zinc plating, aluminum plating, electrophoresis, etc. If they work in a closed environment, phosphating can also be used.

5. Alnico magnet

AlNiCo magnet is an alloy composed of aluminum, nickel, cobalt, iron and other trace metal elements, and its magnetic energy product can reach 9MGOe. Alnico magnets are widely used in the sensor field.

Advantages of alnico magnets

The biggest advantage of AlNiCo magnets is high temperature resistance, and its working temperature can reach 550 degrees Celsius.

Disadvantages of alnico magnets

Alnico magnets are very easy to demagnetize under reverse magnetic field. If the same magnetic pole direction (two N or two S) of two alnico magnets are pressed together, the magnetic field of one of the magnets will be reversed or reversed. Therefore, they are not suitable for operation in reverse magnetic fields (such as motors).