Production technology of Nd-Fe-B magnet

1. Raw material preparation and pretreatment:

Process Description: pretreatment of raw materials such as weighing, crushing, material breaking and rust removal.

Process equipment: steel bar cutter, drum polishing machine, etc

2. Melting:

Process Description: the pretreated raw materials praseodymium neodymium, pure iron, ferroboron, etc. are proportioned and added to the vacuum melting furnace. After high-temperature melting under the protection of argon, the belt is thrown. The product has the advantages of uniform composition, high crystalline orientation, good microstructure consistency and avoiding ɑ- Formation of Fe.

Process equipment: vacuum melting furnace

3. Hydrogen explosion:

Process Description: hydrogen explosion (hd) process is to use the hydrogen absorption characteristics of rare earth intermetallic compounds to place the neodymium iron boron alloy in a hydrogen environment. Hydrogen enters the alloy along the thin layer of neodymium rich phase, causing it to expand, burst and break, and crack along the layer of neodymium rich phase, ensuring the integrity of the main phase grains and the boundary phase between neodymium rich grains. HD process makes the flapping of Nd-Fe-B very loose, which greatly improves the pulverizing efficiency of air mill and reduces the production cost.

Process equipment: Vacuum hydrogen treatment furnace

4. Pulverizing:

Process Description: air flow grinding powder is crushed by the high-speed collision of the material itself, which has no wear and pollution on the inner wall of the grinding chamber, and can prepare powder 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 to the same direction, so as to obtain the maximum remanence. The main purpose of molding 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 to use forming magnetic field press and isostatic press for secondary forming. For special-shaped magnets, special mold tooling is used for direct forming. The sintered magnets can be put into use only after a little surface treatment, which greatly saves materials and subsequent processing costs.

Process equipment: magnetic field press, static press, etc

6. Sintering:

Process introduction: sintering is a simple and cheap way to change the microstructure of materials to improve the magnetic properties of materials. Sintering is the final forming process of materials, which has a very important impact 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 blank, which need further machining to obtain products of different sizes, sizes and shapes. Nd-Fe-B magnet can only be ground and cut because of its brittleness and poor mechanical properties.

Process equipment: surface grinder, double end grinder and chamfering machine

8. Surface treatment:

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

9. Finished product inspection and packaging:

Process Description: test various magnetic properties, corrosion resistance, high temperature performance, etc. of the products, and package them after reaching the standard, so as to meet various needs of customers.