Do you know the production processes of NdFeB magnets?
Publish Time: 2024-08-22 Origin: Site
Neodymium magnets, also known as neodymium iron boron (NdFeB) magnets, are the most powerful permanent magnets in the world today and are widely used in electronics, automobiles, medical equipment, and wind power generation. Their superior magnetic properties and wide range of applications make neodymium magnets play an indispensable role in the development of modern industry and technology. However, many people know little about the production process of neodymium magnets.
The production process of neodymium magnets is extremely complex and technically demanding, involving multiple key steps. The first is the selection and processing of raw materials. Raw materials such as neodymium, iron, and boron must be precisely proportioned and smelted at high temperatures to form an alloy. Next is the powder metallurgy process, which presses the alloy powder into shape and sintering it at high temperatures to give it high density and excellent mechanical properties.
On this basis, magnetic performance processing is also required. Through multiple magnetic field magnetization and demagnetization processes, the neodymium magnets can achieve the expected magnetic performance indicators. Finally, through cutting, grinding, and coating treatment, ensure that the shape and size of the neodymium magnets meet the design requirements and have good corrosion resistance and mechanical strength.
This article will introduce several common production processes of neodymium magnets in detail, giving you an in-depth understanding of the birth of this core component of modern industry.
Production process of neodymium magnets
Neodymium iron boron (NdFeB) magnets are the most widely used permanent magnetic materials in modern industry. Due to their excellent magnetic properties, they are widely used in electronics, automobiles, medical equipment, energy and other fields.
According to different production processes, NdFeB magnets are mainly divided into sintered NdFeB magnets, bonded NdFeB magnets and hot pressed NdFeB magnets. The following is a detailed introduction to the production processes and characteristics of these three magnets.
1. Sintered NdFeB magnets
Sintered NdFeB magnets are the largest and most widely used type of NdFeB magnets, mainly produced by powder metallurgy. Its production process includes the following steps:
Raw material preparation: Derusting, weighing and crushing the main raw materials of Ndfeb magnet according to the process formula table, to avoid impurities unrelated to the formula mixed with raw materials.
Melting: Pretreated raw materials such as praseodymium, neodymium, pure iron, boron and iron are added into the vacuum melting furnace in proportion. After high-temperature melting under the protection of argon, the casting band is carried out to make the product have uniform composition, high crystallization orientation and good organization consistency.
Hydrogen Decrepitation: According to the hydrogen absorption properties of rare earth metal compounds, the ndfeb alloy in the tank of the sealed container, after the hydrogen reaction for chemical reaction, alloy volume expansion blowout, reach the purpose of broken. Created conditions for jet milling and improved production efficiency.
Jet Milling:The alloy powder is crushed and grinded into fine powder by high -speed collision driven by high -speed air flow.
Pressing Forming: Press the powder into a mold, orient the magnetic direction through an external magnetic field, and then sinter at high temperature to fuse the magnetic powder together to form a dense magnet.
Sintering: Sintering is a process where the blocks are placed in a furnace at a very high temperature just below the melting point of the metal. Sintering had a very important effect on the density and microstructure of the magnet.
Machining: The magnet is processed into the required shape and size. Common processing methods include grinding, slicing, laser processing and electrical discharge machining (EDM).
Surface treatment: Since sintered NdFeB magnets are prone to oxidation and corrosion, surface treatment such as phosphating, electroplating, chemical plating, etc. are required. Common coatings include zinc plating, nickel plating, nickel-copper-nickel plating and epoxy resin.
Sintered NdFeB magnets have high magnetic energy product and high coercivity, but the production process is complicated and the cost is high.
2. Bonded NdFeB magnets
Bonded NdFeB magnets are made by mixing NdFeB magnetic powder with a binder and then pressing it in a magnetic field. This production process includes the following steps:
Magnetic powder preparation: NdFeB alloy is ground into powder and mixed with polymer binder.
Molding: According to the specific process, the molding method such as injection molding, extrusion, calendering or pressing is selected.
Injection molding: The molten thermoplastic compound is injected into the mold and cooled to form the desired shape.
Extrusion: The mixture is passed through a heated barrel and a mold, pressed and formed, and then cut into appropriate lengths.
Calendering: The mixture of powder and binder is pressed into a continuous magnet sheet by a hot roller.
Pressing: The mixture is pressed into a mold to form, which is suitable for small motors and electronic products.
Post-processing: Electrophoretic coating or spraying process is carried out as needed, which is often used in different applications and environmental conditions.
Bonded NdFeB magnets have the advantages of low cost, high dimensional accuracy, and large shape freedom, but their magnetic properties are relatively weak.
3. Hot-pressed NdFeB magnets
Hot-pressed NdFeB magnets are produced by hot pressing molding process, with high density and excellent magnetic properties. Its production process includes the following steps:
Magnetic powder preparation: NdFeB alloy powder is refined.
Molding and hot pressing: The powder is pressed into a mold and hot pressed under high temperature and high pressure to form a high-density magnet.
Heat treatment: The hot-pressed magnet is tempered to improve its strength and coercive force.
Machining: Due to the poor mechanical properties of hot-pressed NdFeB magnets, they need to be carefully handled and processed. They are currently mainly used in automotive motors and other fields.
Hot-pressed NdFeB magnets have high magnetic properties and high heat resistance, but due to the complex production process and high cost, only a few companies have achieved mass production.
About us
BMAG is a professional NdFeB magnet manufacturer located in Ningbo, China, with advanced manufacturing technology and strict production process. The company focuses on the research and development and production of high-performance NdFeB magnets, and its products are widely used in electronics, automobiles, medical equipment and energy.
BMAG is committed to providing high-quality magnet solutions and has passed ISO9001:2015 quality management system certification. Its products comply with CE, Reach, ROHS and SGS standards. With its excellent product quality and professional service, the company has won the trust and praise of customers around the world.