How Are Neodymium Magnets Made? Neodymium magnets are made by a sophisticated process that includes some very high-tech metallurgical methods comprising powder metallurgy and advanced process metallurgy.
Dozens of process steps must be followed very precisely to make Neodymium magnets –also known as NdFeB -for the chemical symbols of Neodymium, Iron and Boron.
Process variations are used to achieve the properties necessary for various grades. These variations include compositional differences, morphological (crystal shape) differences and process differences.
Below, we will walk through many of the major processing steps.
Manufacturing Process Steps of Neodymium Magnets
Let’s review the processing steps. The production of Neodymium magnets depends on advanced materials engineering and processes. Here are the main steps:
- Rare Earth Ore is discovered and mined.
- Ore is processed and refined
- Refined metal has elements added to create rare earth alloy
- Melting (raw material) and strip casting
- Hydrogen Decrepitation
- Jet Milling
- Pressing Under External Magnetic Field
- Cold Isostatic Pressing
- Machining and Grinding
- Packing and Shipping
Neodymium Magnet Processing Steps
There are many major production steps –plus numerous sub steps- in the manufacture of high-quality, high-tech Neodymium magnets. Each step is highly important, and each step is an essential part of a highly refined operation.
Here are the major steps.
How are neodymium magnets made
NdFeB Compositional and Processing Differences
High-temperature Neodymium magnets generally require the addition of Heavy Rare Earth Elements (HREE) like Dysprosium and Terbium. The HREEs improve the magnet’s resistance to demagnetization at high-temperatures and in the presence of opposing magnetic fields.
The relative rarity of the HREEs has led a few of the leading NdFeB companies to develop methods and processes for reducing or eliminating the need for HREEs in high-temperature NdFeB magnet grades.
Grain Boundary Diffusion
In recent years, a few leading NdFeB magnet manufacturers have created high-temperature/higher Coercivity grades of NdFeB magnets without HREEs (or with greatly reduced HREE) by improving control of grain size and shape, and through the use of Grain Boundary Diffusion.
Grain Boundary Diffusion (GBD) is a method of selectively introducing HREE into the Grain Boundary phase of the magnet. GBD creates high Coercivity with greatly reduced quantities of HREE like Dysprosium and Terbium, alleviating concern over the use of these rare and expensive HREEs.
Crystalline Shape and Size
In many metallurgical systems, the material’s properties are influenced by the shape of the individual crystals –or grains- in the metallic structure, as well as the average shape and size of the grains throughout the microstructure. Tight controls on processes can lead to improvements in magnetic properties at high temperatures while reducing the need for HREEs.
Each manufacturing process must be carefully monitored to verify that each step is carried out with precision to achieve quality, performance and economy.
Production of NdFeB Magnets Require a Large Capital Investment
These processes require large capital equipment investments. For example, vacuum strip casters, hydrogen decrepitation equipment, jet milling equipment, magnetic orienting presses, cold isostatic presses, and sintering and annealing furnaces are required just to make magnet blocks. Each of these is a major CAPEX cost.
Very precise cutting, machining and grinding equipment make the magnet blocks to size. Since the magnet material is prepared by a powder metallurgy process and may other processes, a substantial amount of value has been added to the parts by the time they get to machining and grinding processes.
Cutting is planned very carefully. Wire cutting is done with very thin wire to minimize kerf losses. Grinding is used when necessary, but it is well-planned to keep material losses as small as possible.
Electroplating and other coating operations all require significant capital in order to produce high-quality products in an economical and environmentally-friendly way.
Neodymium Magnets are Being Used for More Applications
Neodymium magnets power so many devices that it’s easy to lose track of them all. Almost every Hybrid and Electric Automobile depends on Neodymium magnets. Wind power turbines, marine propulsion, air conditioners, mobile phones, audio devices and many more applications all depend on Neodymium magnets to achieve sleek form factors that create downstream economies in many new systems.
Industrial motors made with NdFeB magnets configured for high up-time with efficiencies over 95% are saving electricity and conserving natural resources. Neodymium (NdFeB) magnets are creating more capabilities in smaller spaces in more applications than ever before.
NdFeB magnets deliver the highest performance in the smallest volume of material, making them a very attractive choice for designers of an increasing number of demanding applications.
Cost-Per-Unit-Weight –There’s More to the Story
A simple price-per-kg calculation doesn’t tell the whole story when evaluating a highly engineered material like NdFeB. Many winning designs factor in the cost-per-unit of magnetic field strength, which brings a ripple-effect of system cost saving throughout the system.
For example, if an engineer designs a permanent-magnet-based system that has high power requirements coupled with size or space constraints, there is a strong likelihood that the system will use Neodymium magnets. Neodymium magnets offer nearly 20 X’s the magnetic field-per-unit-volume that ferrite magnets offer, and they do it at nearly 1/10 the weight, so a design that uses NdFeB magnets will potentially create a ripple effect that reduces the size of the entire system.
Of course, each type of magnet has its place, and there are many winning designs that use different types of magnets.
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