Introduction to the manufacturing process of NdFeB magnets

NdFeB magnets are the third-generation rare earth permanent magnet materials with high cost performance. NdFeB magnets are widely used in energy, transportation, machinery, medical, IT, home appliances and other industries. Then you know its production process, the following editor will briefly introduce it to you:

1. Raw material preparation and pretreatment:

Process introduction: Pretreatment of raw materials such as weighing, crushing, breaking and rust removal.

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

2. Smelting:

Process introduction: The pretreated raw materials, such as praseodymium neodymium, pure iron, and ferroboron, are batched according to the proportion, put into the vacuum melting furnace, and smelted at high temperature under the protection of argon, and then stripped. It makes the product composition uniform, the crystal orientation is high, the structure consistency is good, and the formation of ɑ-Fe is avoided.

Process equipment: vacuum melting furnace

3. Hydrogen explosion:

Process introduction: The hydrogen explosion (HD) process uses the hydrogen absorption characteristics of rare earth intermetallic compounds to place the NdFeB alloy in a hydrogen environment, and the hydrogen enters the alloy along the Nd-rich phase thin layer, causing it to expand and burst. It is broken and cracked along the neodymium-rich phase layer, which ensures the integrity of the main phase grains and the intergranular phase between the neodymium-rich grains. The HD process makes the NdFeB flakes very loose, which greatly improves the pulverizing efficiency of the jet mill and reduces the production cost.

Process equipment: vacuum hydrogen treatment furnace

4. Milling:

Process introduction: Jet mill powder is pulverized by the high-speed collision of the material itself, which has no abrasion and pollution to the inner wall of the mill, and can prepare powder with high efficiency.

Process equipment: jet mill

5. Forming orientation:

Process introduction: The function of orientation is to turn the c-axis of the easy magnetization direction of the chaotically oriented powder particles to the same direction, so as to obtain the maximum remanence. The main purpose of pressing is to press the powder into a certain shape and size, while maintaining the degree of grain orientation obtained in the magnetic field orientation as much as possible. We design using a forming 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 only need a little surface treatment before they can be put into use, which greatly saves materials. and subsequent processing costs.

Process equipment: magnetic field press, isostatic press

6. Sintering:

Process introduction: Sintering is a series of physical and chemical changes that cause crushing to occur at high temperature. It is a simple and cheap method to change the microstructure of materials to improve the magnetic properties of materials. Sintering is the final forming process of the material and has an extremely important effect on the density and microstructure of the magnet.

Process equipment: vacuum sintering furnace

7. Machining:

Process introduction: The NdFeB magnets obtained after sintering are all blanks, which require further machining to obtain products of various sizes, sizes and shapes. Because NdFeB magnets are relatively brittle and have poor mechanical properties, generally only grinding and cutting can be used.

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

8. Surface treatment:

Process introduction: Surface treatment of various shapes of rare earth permanent magnets, such as electrophoresis, zinc plating, nickel, nickel copper nickel and phosphating, etc., to ensure the appearance and corrosion resistance of NdFeB magnet products.