Strong Neodymium Magnets Process Steps

Neodymium magnet, also known as NdFeB magnet, is a tetragonal crystal formed by neodymium, iron, and boron (Nd2Fe14B). In 1982, Sumitomo Sasakawa found a neodymium magnet. The magnetic energy product (BHmax) of this magnet is larger than that of the SmCo magnet, which was the largest material in the world at that time. Later, Sumitomo special metals successfully developed the powder metallurgy process, and General Motors successfully developed the melt spinning process, which can prepare NdFeB magnets. This kind of magnet is a permanent magnet which is next to the absolute zero holmium magnet, and it is also the most commonly used rare earth magnet. NdFeB magnets are widely used in electronic products, such as hard disks, mobile phones, headphones, and battery-powered tools.

Neodymium iron boron magnet is divided into sintered neodymium iron boron and bonded neodymium iron boron. Bonded neodymium iron boron is magnetic and corrosion-resistant in all directions. However, sintered neodymium iron boron is easy to corrode and needs to be coated on its surface, generally including zinc plating, nickel, environmental zinc, environmental nickel, nickel copper-nickel, environmental nickel, etc. The sintered NdFeB is generally divided into axial magnetization and radial magnetization, which are determined according to the required working face.

Process Step of Neodymium magnet

1. Raw material preparation and pretreatment
Process Description: the raw materials are pre-treated by weighing, crushing, breaking and derusting.
Process equipment: steel cutting machine, drum polishing machine, etc.

2. smelting
Process Description: the raw materials such as praseodymium neodymium, pure iron, and ferroboron after pretreatment are proportioned, added into the vacuum smelting furnace, and the belt is thrown after high-temperature smelting under the protection of argon. The results show that the product has uniform composition, high crystal orientation, good microstructure consistency and avoids the formation of λ – Fe.
Process equipment: vacuum melting furnace

3. hydrogen burst
Process Description: The hydrogen explosion (HD) process is to use the hydrogen absorption characteristics of rare-earth intermetallics to place the neodymium iron boron alloy in the hydrogen environment. Hydrogen enters the alloy along with the neodymium rich phase thin layer so that it expands, bursts and breaks, and cracks along with the neodymium rich phase layer, ensuring the integrity of the main phase grains and the neodymium rich intergranular phase. HD technology makes the Nd-Fe-B casting very loose, which greatly improves the efficiency of airflow mill and reduces the production cost.
Process equipment: Vacuum hydrogen treatment furnace

4. flour milling
Process Description: airflow grinding is to use the high-speed collision of the material itself to pulverize, without abrasion and pollution to the inner wall of the grinding chamber, so the powder can be prepared efficiently.
Process equipment: air mill

5. Forming orientation
Process Description: the function of orientation is to turn the easy magnetization direction c axis of disorderly oriented powder particles in the same direction, so as to obtain the maximum remanence. The main purpose of pressing is to crush the powder into a certain shape and size while maintaining the grain orientation obtained in the magnetic field orientation as much as possible. We design and use the forming magnetic field press and isostatic press for the secondary forming. For the special-shaped magnet, we use special mold tooling to directly form. After sintering, the magnet can be put into use only with a little surface treatment, which greatly saves the cost of materials and subsequent processing.
Process equipment: magnetic field press, isostatic press

6. sintering
Process Description: sintering is a simple and cheap way to change the microstructure of materials and improve the magnetic properties of materials. Sintering is the final forming process of materials, which has a very important influence on the density and microstructure of magnets.
Process equipment: vacuum sintering furnace

7. Machining
Process Description: the Nd-Fe-B magnets obtained after sintering are all blanks, which need further machining to obtain products of different sizes, sizes, and shapes. Because of its brittleness and poor mechanical properties, NdFeB magnets can only be ground and machined.
Process equipment: surface grinder, double face grinder, chamfering machine

8. Surface treatment
Process Description: surface treatment of various shapes of rare earth permanent magnets, such as electrophoresis, zinc plating, nickel, nickel copper-nickel, and phosphating, to ensure the appearance and corrosion resistance of products.

9. Inspection and packaging of finished products
Process Description: to test all kinds of magnetic properties, corrosion resistance, high-temperature performance, etc. of the products, and pack them after reaching the standard, so as to meet the needs of customers.

AISEN MAGNETS focused on the development and manufacturing of a Neodymium magnet, has more than 10 years of manufacturing experience in producing various sizes, different shapes, and surface coating. Over 45 different grades of neodymium magnet (strong magnet)  widely used in many industries.

Our Production line including vacuum melting, Jet mill, Isostatic press, vacuum sintering, machining, and magnetization. Our annual design output is 1000tons, currently, the output is 800tons.  Our experienced engineers work closely with the customer to find out the best possible solutions to meet your requirements.

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Harper Harrison

Harper Harrison is a reporter for The Hear UP. Harper got an internship at the NPR and worked as a reporter and producer. harper has also worked as a reporter for the Medium. Harper covers health and science for The Hear UP.