Characteristics, selection and processing of permanent magnet magnets2018-08-21
Ferromagnetic materials are non-metallic, also known as ceramic magnets. The speaker in the general radio is made of ferrite magnets. The magnetic properties of ferrite are not high, and the magnetic energy product is only one tenth of that of NdFeB. It can only be 4MGOe. The company's favorite to use it as a production accessory is because it has one of the biggest advantages, that is, the price is low. At present, the scope should be widely used. Because ferrite is ceramic. Therefore, the main surface of the processing is similar to ceramics. Ferrite magnets are formed by molding and sintered. If the mechanical finishing is very difficult, most of the ferrite magnets are simple in shape, such as square, round, and have large positive and negative tolerances. The square shape can be ground. Circular, generally only grinding two planes. Other dimensional tolerances are given as a percentage of the nominal size. Ferrite magnetic products, many manufacturers now have ready-made conventional shapes and rings, squares and other products to choose from. Ferrite is a ceramic property, so the finished product does not require surface treatment and it is not easily corroded.
Samarium cobalt magnet
Samarium-cobalt magnets are mainly composed of two elements, lanthanum and cobalt. Since the two materials themselves are relatively expensive, the samarium-cobalt magnet is also the most expensive one in the magnet, and the number of people used is relatively small. The magnetic energy product of samarium-cobalt magnets can now achieve 30MGOe. The samarium-cobalt magnet has high coercive force and high temperature resistance, and can reach a high temperature working environment of 350 degrees Celsius. Therefore, many of them need to use high temperature work. The samarium-cobalt magnet is one of the powder metallurgy. The manufacturer will sinter into a square blank according to the size and shape required by the customer, and then cut it into a finished size with a diamond blade. Samarium cobalt can be wire cut because it is electrically conductive. The corrosion resistance of the samarium-cobalt magnet is also very good as that of the ferrite. If the customer does not require it, the appearance does not need to be electroplated or painted. It is also important to note that samarium-cobalt magnets are fragile and require great care when machining small shapes.
Neodymium iron boron magnet
NdFeB is now the fastest growing magnet product (the NdFeB is currently used in RC motors). It has only been 20 years since the invention. In addition to its very high magnetic properties, it is easy to process and the price is moderate, so development should be fast. Commercialized NdFeB magnets, magnetic energy product can reach 50MGOe. NdFeB is also a powder metallurgy class, processing and samarium cobalt phase similar. The maximum working temperature of NdFeB can be around 220 degrees Celsius. NdFeB is easily corroded. Unlike ferrite and samarium cobalt, it needs to be plated or coated. General customer requirements: nickel plating), galvanizing, epoxy, phosphating and other treatments. Due to the high magnetic properties of NdFeB, many small products use it, such as mobile phones. Both samarium cobalt and neodymium iron boron have good processability. Therefore, the positive and negative tolerances of the product size are much smaller than the ferrite.
AlNiCo It can be made by both casting and sintering processes. AlNiCo has a magnetic energy product of up to 9MGOe, which is more resistant to high temperatures than samarium cobalt and can reach temperatures of 550 degrees Celsius during operation. However, AlNiCo is easily demagnetized in the case of a reverse magnetic field. If you combine the two poles of the two AlNiCos, the magnetic field of one of the magnets will be reversed or reversed. Therefore, it is not suitable for working in a reverse magnetic field such as a motor. AlNiCo is very hard, and the cost of grinding and wire cutting is very high. It is generally either ground or not. The sensor should have more points.
Rubber magnetic strip
Rubber magnetic is composed of magnetic powder and synthetic rubber material. It is made by special processing, compounding, extrusion molding, calendering and injection molding. It is soft, twistable and very elastic. magnet. Plasticity is also very good, such as refrigerator door seals, water dispenser door seals, magnetic drawing boards, sealing strips, relay switches, micro-motors, disinfection cabinets, cabinets, stationery, advertising and other industries are used in Jiangyan City. The rubber magnetic material can be homogenous or heterogeneous. It consists of ferrite magnetic powder, CPE and other trace elements. It can be adjusted in size according to the required size. Rubber magnetic can also be laminated according to customer requirements, PVC, adhesive, Apply UV oil and so on.
There are a few big details to be aware of when choosing to use a magnet:
1. Don't simply think that as long as the highest performance is achieved, it is recommended to provide the working environment and the requirements of the application to the manufacturer. Because there are still many comprehensive factors to consider, the manufacturer can give you advice and choose the right magnet. material.
2. The operating temperature difference between different types of magnets is very large. The same material, different performance is different, this should also be considered comprehensive.
3, the magnet is generally fixed by bonding. Now the performance of the adhesive is very good, basically there is no need to worry about the problem of disengagement between the magnets. The way in which the bismuth iron mechanically fixes boron is as perforated.
4, most of the texture of the magnet is relatively easy to brittle, easy to damage. Therefore, use it carefully during manufacturing.
5, the common processing methods of magnets are diamond blade cutting, wire cutting, and grinding. Cold cutting is generally not recommended because of the hard texture.
6, the benefits of permanent magnet materials to the industry: electromagnetic can sometimes be replaced by permanent magnets. If there is no power consumption and no heat, you don't have to worry about power off. For example, the electromagnetic coil is most afraid of power failure protection. Therefore, electromagnetic lifting generally requires an uninterruptible power supply, and the use of a permanent magnet chuck can also reduce costs.
7, the decision to use the magnet depends on two major elements: corrosion and demagnetization.
8, the application of the magnet needs to be clear before the magnetic material can be fixed, such as permanent magnet motor, magnetic jack, magnetic sucker, magnetic actuator, magnetic spring, sensor, iron remover, concentrator, daily necessities, toys, tools, Clothing, medical, aviation, electronics and so on.