Fri, 20 Jul 2018 07:25:29 +0000

Introduction NdFeB production process

1. Raw material preparation and pretreatment:
Process description: Pretreatment of raw materials such as weighing, crushing, breaking and derusting, etc.
Process equipment: steel cutting machine, drum polishing machine, etc.

2.Smelting:
Process introduction: After pretreatment, the raw materials praseodymium, pure iron, boron iron, and others 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 or vacuum strip casting furnace

 

Introduction NdFeB production process

 

3.Hydrogen decrepitation:
Process description: The hydrogen decrepitation (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, , and cracks along the rich phase layer to ensure the integrity of the main phase grains and the intergranular boundaries. The HD process makes the bismuth of NdFeB strip very loose, greatly improving the milling efficiency of the jet mill and reducing the production cost.
Process equipment: vacuum hydrogen treatment furnace (hydrogen decrepitation furnace)

4. Powder making:
Process description: Airflow grinding 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: airflow grinding

5.Forming 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 press profile is to compress the powder into a shape and size while maintaining the degree of grain orientation obtained in the magnetic field orientation as much as possible. The forming magnetic field press and the isostatic press are used for the secondary forming. For the special-shaped magnet, the special mold tooling is used for direct molding, and the sintered magnet only needs a slight surface treatment to be put into use, which greatly saves materials and subsequent materials 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

 

vacuum melting furnace

7. Mechanical processing:
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.

Key words: NdFeB, vacuum sintering furnace, vacuum melting furnace, vacuum strip casting furnace, vacuum hydrogen treatment furnace (hydrogen decrepitation furnace)