Learn about magnetic materials in one article

1. Why are magnets magnetic?

Matter is mostly made up of molecules, which are made up of atoms, which in turn are made up of nuclei and electrons. Inside the atom, the electrons rotate incessantly and revolve around the nucleus, and both of these movements of the electrons produce magnetism. But in most matter, the direction of electron movement is varied and chaotic, and magnetic effects cancel each other out. Therefore, most substances are not magnetic under normal conditions.

Ferromagnetic substances such as iron, cobalt, nickel or ferrite are different, and the electron spins inside them can be spontaneously arranged in a small area to form a spontaneous magnetization region, which is called a magnetic domain. After the ferromagnetic material is magnetized, the internal magnetic domains are arranged neatly and in the same direction, so that the magnetism is strengthened, and the magnet is formed. The magnet magnetizes the magnet, and the magnetized iron and the magnet have different polarities of attraction, and the iron is firmly "glued" to the magnet.

2. How to define the performance of a magnet?

There are three main performance parameters to determine the performance of the magnet:

Remanent Br: After the permanent magnet is magnetized to technical saturation and the external magnetic field is removed, the retained Br is called the residual magnetic induction intensity.

Coercivity Hc: The reverse magnetic field strength required to reduce the B of a permanent magnet magnetized to technical saturation to zero is called magnetic coercivity, or coercivity for short.

Magnetic energy product BH: represents the magnetic energy density established by the magnet in the space of the air gap (the space between the two poles of the magnet), that is, the magnetostatic energy per unit volume of the air gap.

3. How to divide metal magnetic materials?

Metal magnetic materials are divided into two categories: permanent magnet materials and soft magnetic materials. Generally, the material with an intrinsic coercivity greater than 0.8kA/m is called a permanent magnet material, and the material with an intrinsic coercivity less than 0.8kA/m is called a soft magnetic material.

4. Comparison of the magnitude of the magnetic force of several types of commonly used magnets

The magnetic forces are arranged from large to small as: NdFeB magnets, Samarium Cobalt magnets, Alnico magnets, ferrite magnets.

5. What is the valence analogy of different magnetic materials?

Ferrite: low and medium performance, lowest price, good temperature characteristics, corrosion resistance, good performance-to-price ratio

NdFeB: the highest performance, the price, good strength, not resistant to high temperature and corrosion

Samarium cobalt: high performance, highest price, brittleness, excellent temperature characteristics, corrosion resistance

Alnico : low and medium performance, medium price, excellent temperature characteristics, corrosion resistance, poor interference resistance

Samarium cobalt, ferrite, NdFeB can be manufactured by sintering and bonding methods, the sintering magnetic properties are high, the molding is poor, the bonding magnet formability is good, and the performance is reduced a lot. AlNiCo can be manufactured by casting and sintering methods, casting magnets have higher performance and poor formability, and sintered magnets have lower formability and better formability.

6. Characteristics of NdFeB magnets

NdFeB permanent magnet material is a permanent magnet material based on the intermetallic compound Nd2Fe14B. NdFeB has extremely high magnetic energy product and correction force, and the advantages of high energy density make NdFeB permanent magnet materials widely used in modern industry and electronic technology, so that it is possible to miniaturize, lightweight and thin instrumentation, electroacoustic motors, magnetic separation magnetization and other equipment.

Material characteristics: The advantage of NdFeB is that it is cost-effective and has good mechanical properties; The disadvantage is that the Curie temperature point is low, the temperature characteristics are poor, and it is easy to pulverize and corrode, and its chemical composition must be adjusted and the surface treatment method must be adopted to improve it in order to meet the requirements of practical application.

Manufacturing process: NdFeB is manufactured using powder metallurgy process.

Process flow: batching→ smelting ingot→ milling→ profiling→ sintering tempering→ magnetic detection→ grinding→ pin-cutting processing→ electroplating→ finished products.

7. What is a single-sided magnet?

Magnets have two poles, but in some working positions need a single-sided pole magnet, so it is necessary to wrap one side of the magnet with an iron sheet, so that the magnetism of the other side of the iron sheet is shielded, and the magnet on the other side is enhanced by the refraction of the iron sheet, and such magnets are collectively called single-sided magnets or single-sided magnets. There is no such thing as a true single-sided magnet.

The materials used in single-sided magnets are generally arc-shaped iron sheets and NdFeB strong magnets, and the shape of NdFeB strong magnets used in single-sided magnets is generally disc-shaped.

8. What is the purpose of a single-sided magnet?

(1) It is widely used in the printed matter industry, and there are single-sided magnets in gift packaging boxes, mobile phone packaging boxes, tobacco and alcohol packaging boxes, mobile phone packaging boxes, MP3 packaging boxes, moon cake packaging boxes and other products.

(2) It is widely used in the leather goods industry, and there are single-sided magnets in bags, briefcases, travel bags, mobile phone cases, wallets, etc.

(3) It is widely used in the stationery industry, and there are single-sided magnets in notebooks, whiteboard buckles, folders, magnetic nameplates, etc.

9. What are the precautions during the transportation of magnets?

Pay attention to the humidity in the room, which must be maintained at a dry level. Do not exceed room temperature; Products in the state of black blocks or blanks can be properly oiled when stored (general engine oil is sufficient); Electroplating products should be vacuum-sealed or isolated from air storage to ensure the corrosion resistance of the plating; Magnetizing products should be attached together and packed into boxes for storage to avoid sucking up other metal bodies; Magnetizing products should be stored away from disks, magnetic cards, tapes, computer monitors, watches and other objects sensitive to magnetic fields. The magnet should be shielded when it is transported in a magnetized state, especially when it is transported by air.

10. How to achieve magnetic isolation?

Only materials that can be adsorbed to the magnet can play a role in isolating the magnetic field, and the thicker the material, the better the magnetic isolation effect.

11. Which ferrite material conducts electricity?

Soft magnetic ferrite is a magnetically permeable material, with high permeability and high resistivity, which is generally used at high frequencies and is mainly used for electronic communications. Like the computers and televisions that we touch every day, there are applications in them.

Soft ferrite mainly includes manganese-zinc and nickel-zinc, etc., and the magnetic permeability of manganese-zinc ferrite is greater than that of nickel-zinc ferrite.

12. What is the Curie temperature of permanent ferrite?

It is reported that the Curie temperature of ferrite is about 450 °C, usually greater than or equal to 450 °C. The hardness is around 480-580. The Curie temperature of NdFeB magnets is basically between 350-370 °C. However, the use temperature of NdFeB magnets cannot reach the Curie temperature, and the magnetic properties of the temperature exceeding 180-200 °C have been attenuated a lot, and the magnetic loss is also very large, which has lost its use value.

13. What are the effective parameters of the core?

Cores, especially ferrite materials, come in a wide variety of geometries. In order to meet the requirements of various designs, the size of the core is also calculated to fit the optimal requirements. These existing core parameters include physical parameters such as magnetic path, effective area, and effective volume.

14. Why is the radius of the corner circle important for winding?

The angular radius is important because if the edge of the core is too sharp, it is possible to cut through the insulation of the wire during precise and tight winding. Take care to ensure that the edges of the core are rounded. Ferrite cores are molded with a standard radius of roundness, and these cores are sanded and deburred to reduce the sharpness of their edges. In addition, most cores are painted or covered to not only blunt the corners but also make the winding surface smooth, while the powder core has a pressure radius on one side and a deburring semicircle on the other. For ferrite materials, an additional edge covering is provided.

15. What type of core is suitable for making transformers?

The core that meets the needs of the transformer should have a high magnetic induction strength on the one hand, and keep its temperature rise within a certain limit on the other hand.

For inductors, the core should have a certain air gap to ensure that it has a certain level of permeability at higher DC or AC drives, the ferrite and the core can be treated with an open air gap, and the powder core has its own air gap.

16. What kind of core is best?

It should be said that there is no answer to this question, because the selection of the core is determined according to the application occasion and application frequency, and the selection of any material has market and other factors, for example, some materials can ensure that their temperature rise is smaller, but their price is expensive, so that when the material is selected for a higher temperature rise, it is possible to choose a larger size but lower price material to complete such a job, so the so-called best material selection should first be aimed at the application requirements of your inductor or transformer, From this point of view, the operating frequency and cost are important factors, and the optimal selection of different materials is determined according to the switching frequency, temperature rise and magnetic flux density.

17. What is an anti-interference magnetic ring?

Anti-interference magnetic rings are also known as ferrite magnetic rings. For example, electronic products are subject to external disorder signals and invade electronic products, so that electronic products receive external disorder signal interference and fail to operate normally, and anti-interference magnetic rings can just have this function, as long as the product is added with an anti-interference magnetic ring, it can prevent external disorder signals from invading electronic products, can make electronic products operate normally, and has an anti-interference effect, so it is called an anti-interference magnetic ring.

Anti-interference magnetic rings are also known as ferrite magnetic rings, because ferrite magnetic rings are made of ferrite materials such as iron oxide, nickel oxide, zinc oxide, copper oxide, etc., because these materials contain ferrite components, and the products made of ferrite materials are like a ring, so they are called ferrite magnetic rings over time.

18. How do I demagnetize the core?

The method is to apply 60Hz alternating current to the core so that it starts with enough drive current to saturate both the positive and negative ends, and then gradually and slowly reduces the driving level, repeating several times until it reaches 0. This will revert back to its original state.

19. What is magnetoelasticity (magnetostriction)?

After the magnetization of the magnetic material, a small change in geometric dimensions will occur. The size of this change should be in the millionth of a millionth level, which is called magnetostriction. For some applications, such as ultrasonic generators, the advantages of this feature are used to obtain mechanical deformation by magnetostriction with magnetic excitation. In other applications, when working in the audible sound frequency range, there will be a kind of whistling noise. Therefore, low shrinkage materials can be applied in this case.

20. What is magnetic mismatch?

This phenomenon occurs in ferrite and is characterized by a decrease in permeability that occurs when the core is demagnetized. This demagnetization can occur after the operating temperature is higher than the Curie point temperature, and the amplitude of alternating current or mechanical vibration is gradually reduced.

In this phenomenon, the magnetic conductivity first increases to its original level, and then exponentially decreases rapidly. If there are no special conditions to be desired for the application, then the change in permeability will be minimal, as many of the changes will change within a few months of fabrication. High temperatures accelerate this reduction in permeability. Magnetic disharmony will recur after each successful demagnetization, so it is not the same as aging.

Craft knowledge

1. What are the characteristics and processing technology of ferrite magnets?

Features: Its main raw materials include BaFe12O19 and SrFe12O19. It is made by ceramic process, the texture is relatively hard, it is a brittle material, and it has become the most widely used permanent magnet because the ferrite magnet has good temperature resistance, low price and moderate performance.

Characteristics: High magnetic properties, good time stability and low temperature coefficient.

Ferrite magnet application site: widely used in electricity meters, meters, motors, automatic control, microwave devices, radar and medical equipment.

Ferrite magnet magnet magnetization direction: can be magnetized axially, radially or as required.

Ferrite magnet shapes: cylindrical, toroidal, cuboidal, flat, tile, axe-shaped.

2. Characteristics and processing technology of Alnico magnets

Alnico magnet characteristics: It is an alloy composed of aluminum, nickel, cobalt, iron and other trace metal elements. The casting process can be processed and produced into different sizes and shapes, and the machinability is good. Cast Alnico permanent magnets have the lowest reversible temperature coefficient and can operate at temperatures above 600°C. Alnico permanent magnet products are widely used in various instrumentation and other applications.

Alnico magnet classification: It can be divided into two categories: cast Alnico and sintered Alnico magnets.

Alnico application site: Cast Alnico products are mainly used in auto parts, instrumentation, electroacoustics, motors, teaching, aerospace and military fields, with the advantages of low temperature coefficient, high temperature resistance, humidity resistance, not easy oxidation and good working stability. Sintered alnico is produced by powder metallurgy, which is suitable for the production of complex, light, thin and small products, and is widely used in instrumentation, communication, magnetoelectric switches and various sensors.

Alnico magnet shapes: cylindrical, toroidal, cuboidal, flat, tile, horseshoe shapes.

3. What are the characteristics and processing technology of samarium cobalt magnets?

Samarium cobalt magnets are also known as samarium cobalt magnets, samarium cobalt permanent magnets, samarium cobalt permanent magnets, samarium cobalt strong magnets, rare earth cobalt permanent magnets, etc. It is a magnetic material made of samarium, cobalt and other metal rare earth materials by proportioning, melting into alloy, crushing, pressing and sintering. It has a high magnetic energy product and a very low temperature coefficient. The maximum working temperature can reach 350 °C, the negative temperature is not limited, and the maximum magnetic energy product, temperature stability and chemical stability of the working temperature above 180 °C exceed that of NdFeB permanent magnet materials. It has strong resistance to corrosion and oxidation; Therefore, it is widely used in aerospace, national defense and military industry, microwave devices, communications, medical equipment, instruments, meters, various magnetic transmission devices, sensors, magnetic processors, motors, magnetic cranes, etc.

Samarium cobalt magnet production process: ingredients → smelting ingots→ milling → profiling → sintering tempering → magnetic detection → grinding processing → pin cutting processing → finished products.

Samarium cobalt magnet shapes: discs, rings, squares, squares, tiles, and special shapes can be processed according to requirements.

4. Magnetic field orientation and pressure forming

Powder magnetic field orientation is one of the key process technologies for the manufacture of high-performance sintered magnets. The purpose of magnetic field orientation is to make the easy magnetization direction (c-axis) of each powder particle to be oriented in the same direction, and to make an anisotropic magnet, then there is a maximum remanence Br along the direction of the c-axis orientation of the powder particles, and then the maximum magnetic energy product of the magnet is increased. The orientation of the powder has an important effect on the remanence Br and the maximum energy product (BH)max of the magnet. There are two purposes of powder molding: one is to press the powder into a certain shape and size of the press blank according to the user's needs; The second is the degree of crystal orientation obtained in maintaining the orientation of the magnetic field. At present, there are three commonly used profiling methods: molding method, molding and cooling isostatic pressing, and rubber molding (cold isostatic pressing). The profiling process is the main process of oxygen absorption by magnetic particles, so there are strict anti-oxidation measures in the molding process, and the magnetic particle weighing or pressing process is required to operate under the protection of inert gas. The equipment used in this process is a forming press.

5. What is the orientation of the magnet?

Sintered NdFeB permanent magnets are anisotropic magnets. Orientation direction: The direction in which the anisotropic magnet can obtain the best magnetic properties is called the orientation direction of the magnet, also known as the "orientation axis" and "magnetization axis".

6. How to determine the magnetization direction of a magnet?

Magnetic pole test plates can be used. The principle of the magnetic pole test piece is actually to put some iron powder in the compartment and then clamp it with a transparent object. When there is a magnetic force, the magnetic particles in the interlayer will be attracted to it, and there is no magnetic area, that is, there is no magnetic particles, so that the distribution of the magnetic poles can be observed.

7. Which magnet can be used in water?

Depending on the material, not every magnet can be used in water. A corroded and rusty magnet can be a hazard to aquatic life. Ferrite has strong corrosion resistance and oxidation resistance, and can be used normally in water.

8. What is a magnetic tile?

Magnetic tile is a type of tile-like magnet in permanent magnets, which is mainly used in permanent magnet motors.

9. What are the production processes of ferrite magnetic tiles?

Ferrite magnetic tiles are mainly sintered ferrite.

The production process of sintered ferrite magnetic tile is mainly divided into wet pressure anisotropy, dry pressure isotropy, and dry pressure anisotropy, and the difference between the opposite and the isotropic is whether there is an oriented magnetic field when the press is formed. Here we mainly introduce the process of wet pressing anisotropy.

The wet pressing process is as follows: raw material → pre-sintering→ coarse grinding (primary ball milling), → batching→ secondary ball milling (wet grinding), → magnetic field forming→ sintering→ grinding→ cleaning → magnetization.

Because the molding slurry contains moisture, the molded particles are easy to turn in the magnetic field, so it has a higher degree of orientation than the dry pressing properties, and its performance is higher.

10. NdFeB magnetic tile production process

Sintered NdFeB magnetic tile: batching→ smelting→ crushing→ pulverizing→ magnetic field forming→ isostatic pressing→ vacuum sintering and tempering→ wire cutting and other processing→ electroplating→ magnetization.

11. What is the choice of workpiece cleaning method?

The way the workpiece is placed in the cleaning tank has a great relationship with the cleaning quality, and its placement method is related to the size, shape and structure of the workpiece. In general, overlapping stacks between workpieces, or stacking too many parts at once, can affect the cleaning effect.

Although NdFeB magnetic materials have different shapes, they are mostly small parts. It can be placed on a nylon net and shaken in the cleaning tank, which helps the dirt on the surface of the workpiece to fall off, and also helps the water film destruction of the workpiece with blind holes, so that the cavitation effect is easy to occur in the blind holes. Another way to place the workpiece is to flatten the workpiece directly on the bottom plate of the cleaning tank (i.e. the radiant plate of the ultrasonic transducer), so that the workpiece is subjected to strong ultrasonic impact. Practice has proved that this method of directly placing the workpiece on the base plate for cleaning has the best cleaning effect and the highest efficiency.

12. What are the precautions during the transportation of magnets?

Pay attention to the humidity in the room, which must be maintained at a dry level. Do not exceed room temperature; Products in the state of black blocks or blanks can be properly oiled when stored (general engine oil is sufficient); Electroplating products should be vacuum-sealed or isolated from air storage to ensure the corrosion resistance of the plating; Magnetizing products should be attached together and packed into boxes for storage to avoid sucking up other metal bodies; Magnetizing products should be stored away from disks, magnetic cards, tapes, computer monitors, watches and other objects sensitive to magnetic fields. The magnet should be shielded when it is transported in a magnetized state, especially when it is transported by air.

13. What is a strong magnet?

A strong magnet refers to a NdFeB magnet. Its magnetic properties greatly surpass those of ferrite magnets, alnico and samarium cobalt. NdFeB magnets can absorb 640 times the weight of their own weight, so NdFeB is often called a powerful magnet by outsiders.

14. How do you demagnetize a strong magnet?

Depending on the use of strong magnets, a certain method can be developed to demagnetize the method.

1) High temperature demagnetization method:

The main operation of the high-temperature demagnetization method is to put the magnet into the high-temperature furnace for heating, and the magnetism of the strong magnet will be removed after high-temperature treatment, but in the heating process, because the action of high temperature will directly lead to drastic changes in the structure of the object inside the magnet, so this demagnetization method is generally used for scrapped and recycled magnets.

2) Vibration demagnetization method:

The operation of this method is very simple, that is, the strong magnet is vibrated strongly, and the internal structure of the magnet has changed after the operation of the vibration, so as to change the physical properties of the magnet.

3) Magnet AC demagnetization method:

This demagnetization method is to put the magnet into the space that can produce an alternating magnetic field, and after the interference of the alternating current magnetic field, the internal structure of the magnet will be disturbed, so that the effect of demagnetization can be achieved, and this method is a more common demagnetization method.

The above three methods are effective for the demagnetization of strong magnets, but in ordinary times, we still have to prefer AC demagnetization, which has a better demagnetization effect than the high-temperature demagnetization method and vibration demagnetization method, and the efficiency is also high, and it is the most used method in industrial production at present.

15. How to check the quality of the plating?

The quality of the coating directly affects the service life of NdFeB, and the main methods for detecting the quality of NdFeB coating are:

1. Visual inspection of appearance

The exterior is mainly observed by the naked eye, and is best observed in natural light (daylight, not direct), or under a fluorescent lamp with an illuminance equivalent to 40W. There should be no blistering, peeling, partial plating and uneven tone, stains, water stains, etc.

2. Coating thickness measurement

3. Drop test (mainly for galvanized products)

4. Grid test (generally used for nickel plating products)

5. Chilling and heat stimulation test

6. PCT pressure test

7. SST salt spray test

8. Constant temperature and humidity test, etc

16. What should be paid attention to when measuring the particle size distribution of NdFeB powder with a laser particle size analyzer?

NdFeB particles have strong magnetic properties, and the average particle size is generally measured by the air permeability method, and is currently mainly used for dry laser particle size analyzer to measure particle size distribution. NdFeB powder has the characteristics of spontaneous combustion in the air, and when the ambient temperature is slightly higher, its concentration reaches a certain level, and it will spontaneously combust, which often ignites the vacuum cleaner pipeline and filter and burns the vacuum cleaner. The following measures should be taken to prevent spontaneous combustion: (1) using inert gases such as high-pressure nitrogen as the gas source; (2) The vacuum cleaner tube should be replaced with a polyethylene tube with a smooth surface, so that the particles are not deposited in the pipeline; (3) Use a vacuum cleaner with water filtration.

17. Which motors will use NdFeB magnetic watts?

NdFeB is a permanent magnet material, but also an indispensable component of permanent magnet motors, rare earth permanent magnet motors are the largest application field of NdFeB magnets, accounting for about 70% of the total magnets, computer hard disk supporting the ring motor (VCM) accounts for 40% ~ 50%, so the computer industry is the largest user of permanent magnet motors.

Common permanent magnet motors are: permanent magnet DC motors, permanent magnet AC motors.

Permanent magnet DC motors include: brushed DC motors, brushless motors, stepper motors, etc.

Permanent magnet AC motors include: synchronous permanent magnet motors, permanent magnet servo motors, etc.

18. How to apply NdFeB magnetic watts in brushless motors?

As we all know, NdFeB magnetic tile or NdFeB radial magnetic ring is as important as the human heart in motor products, and the magnetic field generated by the current and coil drives the NdFeB magnetic tile or NdFeB radial magnetic ring magnetic field, so the magnetic field strength of the NdFeB magnetic tile or NdFeB radial magnetic ring is very important. Let's take a look at the advantages of brushless motors:

1. No brushes, low interference The brushless motor removes the brush, and the most direct change is that there is no electric spark generated when the brush motor is running, which greatly reduces the interference of electric sparks on remote control radio equipment.

2. Low noise and smooth operation The brushless motor has no brushes, the friction is greatly reduced during operation, the operation is smooth, and the noise will be much lower, which is a huge support for the stability of the model.

3. Long life, low maintenance cost Less brushes, the wear of brushless motors is mainly on the bearings, from a mechanical point of view, brushless motors are almost a maintenance-free motor, when necessary, only need to do some dust maintenance.

Brushless motor, as the name suggests, certainly does not need carbon brush originals, around the winding coil to form a magnetic field around the geometric axis of the motor, this magnetic field drives the permanent magnet on the rotor to rotate, the motor will rotate, the performance of the motor and the number of NdFeB magnetic tiles, NdFeB radial magnetic ring flux strength, motor input voltage and other factors, the real decision on its performance is the brushless electronic governor, a good electronic governor needs to have a single-chip microcomputer control program design, circuit design, The overall control of complex processing technology and other processes, so the price is much higher than that of brush motors.
19. How do you compare the properties of ferrite with NdFeB?

Appearance: The ferrite body is loose and has no metallic luster, generally not plating, usually black. NdFeB basically has to be electroplated, otherwise it is easy to rust. The surface has a silvery-white metallic luster.

Magnetically: According to the data, the ferrite magnetic force is usually 800-1000 gauss, and the density is 5 (g/cm3). In the state of bare magnetism, the magnetic force of NdFeB can reach about 3500 gauss. The density is 7.5 (g/cm3).

In terms of performance: the temperature resistance and stability of ferrite are very good, compared with the ordinary temperature resistance of NdFeB is only 80 degrees. And the price is also cheap. NdFeB; NdFeB has the characteristics of small size, light weight and strong magnetism, and its magnetism is completely different from that of ferrite.

Price: Ferrite is usually cheap, many of which are calculated by piece, and the price has an impact on the shape, size, and processing difficulty of ferrite. NdFeB: The price of NdFeB now changes almost every day, depending on the grade you need to use and special requirements.

20. How to store NdFeB magnetic materials?

1. NdFeB magnets should not be close to electronic equipment, because the magnet itself has positive and negative poles and a circuit circuit, which will affect the electronic equipment and control circuit and affect the use.

2. Do not store the magnet in a humid environment, so as not to oxidize, resulting in changes in appearance, physical properties and magnetic properties.

3. If a person who has a sensitive reaction to metal objects approaches the magnet, it will cause rough and red skin. If this happens, do not touch the magnet.

4. Do not place magnets near floppy disks, hard drives, credit cards, tapes, memory cards, TV picture tubes, etc. If a magnet is placed close to a device such as a magnetic recorder, the recorded data can be affected or even destroyed.

Pay attention to the following:

1. The magnet should never be placed around a strong current;

2. The magnet cannot be roasted on the fire at high temperature;

3. The magnet cannot be knocked and vibrated violently;

4. Small magnets cannot be placed together with large magnets;

5. The hoof-shaped magnet should also add a piece of soft iron to the two poles to connect the two poles, and invert the north and south poles of the adjacent magnets;

6. Small magnets (such as magnetic needles) cannot be placed together with large magnets.

When preserving NdFeB magnets, the requirements for the environment are dry, and the NdFeB magnets are not allowed to encounter chemicals such as acids and alkalis, so as not to affect the NdFeB magnets and cause corrosion, rust and other phenomena. Therefore, placing the NdFeB magnet on a layer of wood board has a good effect to avoid moisture. Always be very careful when storing magnets, as they can attach themselves to each other and may pinch your fingers. When magnets are attached to each other, there is a risk that the magnet itself may be damaged by collision (knocking off corners or cracks).