How are NdFeB magnets made?

Step 1: Raw Material Preparation and Proportioning

The first step in manufacturing NdFeB magnets is preparing the raw materials. Main elements include neodymium (Nd), iron (Fe), and boron (B). Additional metals such as dysprosium (Dy) and gadolinium (Gd) improve performance and corrosion resistance. These materials are mixed in precise proportions, which directly influence the magnet's final properties.

Step 2: Melting and Ingot Forming

The mixed materials are melted in a vacuum induction furnace to form an alloy melt. Stirring ensures uniform composition. The melt is cast into ingots under vacuum or inert gas to prevent oxidation, controlling grain size and purity.

Step 3: Powdering

Alloy ingots are crushed and ball-milled into micron-sized powder. Finer powder yields better magnet performance. The powdering process is conducted in an inert atmosphere to avoid oxidation.

Step 4: Molding and Pressing

The prepared powder is placed in a mold and compacted using a magnetic field to align the magnetic grains, creating a "green body" with low mechanical strength but directional magnetism.

Step 5: Sintering and Annealing

Green bodies are sintered at high temperatures (around 1100°C) to fuse particles and form a dense block. Annealing reduces internal stress and optimizes magnetic properties. Sintering is the most critical step for determining density and magnetic performance.

Step 6: Post-Processing and Surface Coating

Sintered magnets are cut, ground, and drilled to meet product specifications. Surface treatments such as nickel plating, zinc plating, or epoxy coating improve corrosion resistance.

Step 7: Magnetization and Testing

The magnets are magnetized in a strong magnetic field, fully aligning the domains to achieve permanent magnetism. After magnetization, rigorous testing ensures the magnets meet quality and dimensional standards.

Through these processes, each tiny NdFeB magnet is created. These high-performance magnets have enabled advancements in numerous high-tech industries, making modern life more convenient and intelligent.