NdFeB process

- Aug 21, 2018 -

1. Raw material preparation and pretreatment

Process Description: Pretreatment of raw materials such as weighing, crushing, breaking and derusting.

Process equipment: steel cutting machine, drum polishing machine, etc.

 

2. Smelting

Process introduction: The pretreated raw materials 镨钕, pure iron, boron iron, etc. are proportioned, added to the vacuum melting furnace, and smelted under high temperature smelting under argon protection. The product composition is uniform, the degree of crystal orientation is high, the structure consistency is good, and the formation of bismuth-Fe is avoided.

Process equipment: vacuum melting furnace

 

3. Hydrogen explosion

Process Description: The hydrogen explosion (HD) process utilizes the hydrogen absorption characteristics of rare earth intermetallic compounds. The neodymium iron boron alloy is placed in a hydrogen atmosphere, and the hydrogen enters the alloy along the thin layer of the rich phase, causing it to expand and burst and break. Cracking at the rich phase layer ensures the integrity of the main phase grains and the intergranular boundaries. The HD process makes the bismuth of NdFeB very loose, greatly improving the milling efficiency of the jet mill and reducing the production cost.

Process equipment: vacuum hydrogen treatment furnace

 

4. Milling

Process Description: Airflow milling powder is pulverized by high-speed collision of the material itself. It has no wear and no pollution to the inner wall of the grinding chamber, and can prepare powder with high efficiency.

Process equipment: jet mill

 

5. Molding orientation

Process Description: The role of orientation is to make the easy magnetization direction c-axis of chaotically oriented powder particles turn in the same direction, so as to obtain the maximum remanence. The main purpose of the profile is to compress the powder into a shape and size while maintaining as much as possible the degree of grain orientation obtained in the orientation of the magnetic field. We design a shape magnetic field press and an isostatic press for secondary molding. For special-shaped magnets, special mold tooling is used for direct molding. The sintered magnets can be put into use only with a slight surface treatment, which greatly saves materials. And subsequent processing costs.

Process equipment: magnetic field press, isostatic press

 

6. Sintering

Process Description: Sintering is a series of physicochemical changes that occur at high temperatures. It is a simple and inexpensive way to change the microstructure of materials to improve the magnetic properties of materials. Sintering is the final forming process of the material and has a very important influence on the density and microstructure of the magnet.

Process equipment: vacuum sintering furnace

 

7. Machining

Process Description: NdFeB magnets obtained after sintering are blanks that require further machining to obtain products of various sizes, sizes and shapes. NdFeB magnets are relatively brittle and have poor mechanical properties. Generally, they can only be used for grinding and cutting.

Process equipment: surface grinder, double grinder, chamfering machine

 

8. Surface treatment

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

 

9. Finished product inspection and packaging

Process Description: The product's various magnetic properties, corrosion resistance, high temperature performance, etc. are tested and packaged to meet the various needs of customers.


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