Process Introduction of the Custom Neodymium Magnets

1. Raw material preparation and pretreatment:

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

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

2. Melting:

Process introduction: The pretreated raw materials of praseodymium, pure iron, boron iron, etc. are mixed according to the proportions, and put into a vacuum melting furnace, then smelted at high temperature under the protection of argon. In this way, it can make the product composition uniform, high crystal orientation, good organization consistency, and avoid the generation of ɑ-Fe.

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. The neodymium iron boron alloy is placed in a hydrogen environment. The hydrogen enters the alloy along a thin layer of neodymium-rich phase, causing it to expand, burst and break. The cracks in the neodymium-rich phase layer ensure the integrity of the main phase grains and the interphase of the neodymium-rich grains. The HD process makes the NdFeB spinner quite loose, which greatly improves the powder making efficiency of the jet mill and reduces the production cost.

Process equipment: vacuum hydrogen treatment furnace.

4. Powder milling:

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

Process equipment: jet mill.

5. Forming orientation:

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

Process equipments: magnetic field press, isostatic press.

6. Sintering:

Process introduction: Sintering is a series of physical and chemical changes that cause crushing 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, which has an extremely important influence on the density and microstructure of the magnet.

Process equipment: vacuum sintering furnace. 

7. Mechanical processing:

Process introduction: The custom neodymium magnets obtained after sintering are all blanks, and further machining is required to obtain products of various sizes and shapes. Custom neodymium magnets are generally brittle and have poor mechanical properties, so they can only be processed by grinding and cutting.

Process equipments: surface grinder, double end grinder, chamfering machine.

8. Surface treatment:

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

9. Finished product inspection and packaging:

Process introduction: The products are tested for various magnetic properties, corrosion resistance, high temperature performance, etc., and packaged after reaching the standard to meet the various needs of customers.