The Production Process of Neodymium Bar Magnets

1. Preparation and pretreatment of the raw materials of neodymium bar magnets

Pretreat raw materials such as weighing, crushing, breaking and rust removal.

2. Melting of neodymium bar magnets

The pretreated raw materials such as neodymium, pure iron, 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 uniform in composition, high in crystal orientation, good in organizational consistency, and avoids the formation of ɑ-Fe.

3. The hydrogen explosion of neodymium bar magnets

The hydrogen explosion process of neodymium bar magnets 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, burst and shatter. The cracking along the neodymium-rich phase layer 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.

4. The powder making of neodymium bar magnets

Jet mill powder is pulverized by the high-speed collision of the material itself. There is no wear and pollution to the inner wall of the grinding chamber, and the powder can be prepared with high efficiency.

5. The forming orientation of neodymium bar magnets

The function of the orientation of the neodymium bar magnets 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 a large remanence. The main purpose of pressing is to press the powder into a green compact of a certain shape and size, while maintaining the degree of grain orientation obtained in the magnetic field orientation as much as possible. Our designs are overmolded using forming magnetic field presses and isostatic presses. For special-shaped magnets, special mold tooling is used for direct molding. The sintered neodymium bar magnets can be put into use only after a little surface treatment, which greatly saves materials and subsequent processing costs.

6. The sintering of neodymium bar magnets

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 post-forming process of the material, which has an extremely important influence on the density and microstructure of neodymium bar magnets.

7. The machining of neodymium bar magnets

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

8. The surface treatment of neodymium bar magnets

Various shapes of rare earth permanent magnets, such as electrophoresis, zinc plating, nickel, nickel copper nickel and phosphating, are surface treated to ensure the appearance and corrosion resistance of the product.

9. The inspection and packaging of neodymium bar magnets

Various magnetic properties, corrosion resistance, high temperature properties, etc. of neodymium bar magnets products are tested, and then packaged to meet the various needs of customers.