4 What materials are NdFeB composed of?
The main raw materials of rare earth NdFeB permanent magnets of Nantian Magnet are rare earth metal neodymium (Nd) 32%, metallic element iron (Fe) 64% and non-metallic element boron (B) 1% (a small amount of dysprosium (Dy), terbium ( Tb), cobalt (Co), niobium (Nb), gallium (Ga), aluminum (Al), copper (Cu) and other elements). The NdFeB ternary permanent magnet material is based on the Nd2Fe14B compound, and its composition should be similar to the molecular formula of the compound Nd2Fe14B. However, when the composition ratio of Nd2Fe14B is completely proportioned, the magnetic performance of the magnet is very low, or even non-magnetic. Only when the content of neodymium and boron in the actual magnet is more than the content of neodymium and boron in the Nd2Fe14B compound, better permanent magnetic properties can be obtained.
5 How long can the magnetic properties of NdFeB last?
NdFeB magnets have very high coercivity, and will not demagnetize and magnetically change under natural environment and general magnetic field conditions. Assuming the environment is suitable, the loss of the magnetic properties of the magnet will not be significant even after prolonged use. Therefore, in practical applications, we often ignore the influence of the time factor on the magnetic properties.
6 About the orientation direction
Orientation direction: The direction in which the anisotropic magnet can obtain the best magnetic properties is called the orientation direction of the magnet. Magnets are divided into 1 isotropic magnets: magnets with the same magnetic properties in any direction 2 anisotropic magnets: different magnetic properties in different directions; and there is one direction, the orientation direction, in which the highest magnetic properties are obtained. magnet. Sintered NdFeB permanent magnets are anisotropic magnets, so the orientation direction (magnetization direction) needs to be determined before production.
7 Factors affecting the magnetic force of NdFeB magnets?
Ambient temperature, since sintered NdFeB is extremely sensitive to working temperature, the instantaneous maximum temperature and continuous maximum temperature of the environment may cause different degrees of demagnetization of the magnet, including reversible and irreversible, recoverable and unrecoverable.
8 What is the working temperature range of NdFeB magnets?
The temperature limitation of NdFeB magnets has led to the development of a series of magnet grades to suit different operating temperature requirements. Please refer to our performance catalogue to compare the operating temperature ranges of various grades of magnets. The maximum operating temperature needs to be confirmed before selecting NdFeB magnets.
9 How to shield the magnetic field?
Generally, we use ordinary iron plates to shield the magnetic field. Magnetic shielding requires a high permeability material, and the material that meets this requirement is an iron-nickel alloy, which has a high permeability. When the magnetic field that needs to be shielded is very strong, only using a single layer of shielding material will either fail to meet the shielding requirements, or saturation will occur. At this time, one method is to increase the thickness of the material. But a more efficient approach is to use a combination shield, placing one shield inside the other with an air gap between them. The air gap can be filled with any non-permeable material for support, such as aluminum. The shielding effectiveness of the combined shield is much higher than that of a single shield, so the combined shield can attenuate the magnetic field to a very low degree.
10 What are the precautions for storage and transportation of magnets?
When storing magnets, keep the room ventilated and dry, otherwise the humid environment will easily cause the magnets to rust. The ambient temperature should not exceed the maximum working temperature of the magnet; unplated products can be properly oiled to prevent rust; magnetized products should be stored away from magnetic disks, magnetic cards, magnetic tapes, computer monitors, watches and other objects sensitive to magnetic fields. The material of the magnet is relatively brittle. During transportation and electroplating (coating), it should be ensured that the magnet is not subjected to severe impact during installation. If the method is improper, it may cause magnetic damage and cracking; the magnet should be shielded when transported in a magnetized state, especially in aviation Transportation must be completely shielded.
11What are the precautions for the operation of the magnet?
The magnet should ensure that the workplace is clean during use, otherwise it is easy to absorb small magnetic particles such as iron filings and affect the use; the characteristics of NdFeB material are hard and brittle, and its suction force can reach more than 600 times its own weight, which is very easy to attract Collision damage. In the operation process, care should be taken to avoid bumping and damage for small sizes, and personal safety and protection should be paid more attention to for large sizes.
12 What are the reasons for the peeling of the coating and the causes of rust spots?
For qualified electroplating products, under normal circumstances, the electroplating coating should not have rust spots. When it is too humid, the air circulation is not good, and the temperature difference changes greatly, even the products that pass the salt spray test are stored in a harsh environment for a long time, and rust spots may occur. When the electroplating product is stored in a harsh environment, the base layer will further react with the condensed water, which will reduce the bonding force between the base layer and the plating layer. Electroplating products should not be placed in a place with high humidity for a long time, but should be placed in a cool and dry place.
13 How to measure the level of magnetic performance?
There are three main parameters: remanence Br (Residual Induction), unit Gauss, after removing the magnetic field from the saturation state, the residual magnetic flux density represents the magnetic field strength that the magnet can provide to the outside world; coercive force Hc (Coercive Force), unit Oersteds is to place the magnet in a reverse external magnetic field. When the external magnetic field increases to a certain strength, the magnetism of the magnet will disappear. The ability to resist the external magnetic field is called coercive force, which represents a measure of the anti-demagnetization ability; magnetic energy The product BHmax, unit Gauss-Oersteds, is the magnetic field energy generated by the unit volume of material, and is a physical quantity of how much energy a magnet can store.
14 Commonly used magnetic measuring instruments
Commonly used magnetic measuring instruments are: flux meter, Tesla meter (also known as Gauss meter), magnetic measuring instrument. The fluxmeter is used to measure the magnetic induction flux, the teslameter is used to measure the surface magnetic field strength or the air gap magnetic field strength, and the magnetometer is used to measure the comprehensive magnetic properties. Before using all instruments, read the manual carefully, preheat according to the requirements of the manual, and operate according to the requirements of the manual after preheating.
15 How is NdFeB made?
Nantian Magnet's sintered NdFeB permanent magnet is an iron-based permanent magnet material manufactured by powder metallurgy process. The main processes are: formula, smelting, milling, forming orientation, sintering, machining, electroplating and so on. Among them, the control of oxygen content is an important indicator to measure the technological level. The high-vacuum smelting furnace, sintering furnace and advanced automatic control jet mill are selected in our company's production equipment, which ensures the basic oxygen-free operation of the production process, and makes a breakthrough in the performance and operating temperature of the product.
16 Factors affecting the processing cost of magnets?
The processing cost of magnets is mainly affected by the following factors: performance requirements, batch size, specification shape, and tolerance dimensions. The higher the performance requirements, the higher the cost. For example, the price of N45 magnets is much higher than that of N35; the smaller the batch, the higher the processing cost; the more complex the shape, the higher the processing cost; the tighter the tolerance, the higher the processing cost.
17 About rare earth permanent magnet materials
Rare earth permanent magnet material is a rare earth permanent magnet alloy composed of samarium, neodymium mixed rare earth metal and transition metal, which is pressed and sintered by powder metallurgy method and magnetized by a magnetic field.
As a high-performance functional material, rare earth permanent magnet materials are widely used in energy, transportation, machinery, medical, IT, home appliances and other fields, and have become the basis of many high-tech industries. The NdFeB rare earth permanent magnet material has become the fastest growing and most industrialized industry due to its high performance-price ratio.