How Are Neodymium Magnets Made?


Magnets have been around for thousands of years in human society, with records of the ancient Greeks noting the properties of iron ore in the first millennium BC.

How Are Neodymium Magnets Made?

However, it is only in the last century or so that we have started to get a grip on this particular field of physics and science, especially when it comes to understanding how and why they work exactly.

It is also only in the last hundred years that we have also started creating the most powerful magnets that we have ever created, and are being used in everything from construction, to manufacture, to medical care.

One of the most famous of this new wave of powerful magnets is Neodymium.

But what exactly is neodymium? When was it first made? What are its properties? And, importantly for us, how exactly are these super-powerful magnets made?

Well, that’s what we’re here to tell you!

In this short guide, we are going to give you the basics of everything you could want to know about neodymium, from its origins to its manufacturing, to plenty more!

What Are Neodymium Magnets?

So, before we start taking a deep dive into everything neodymium-related, we should probably first explain what exactly it is in the first place.

Neodymium is an incredibly powerful type of magnetic metal that is part of the wider family of powerful magnets known as Rare-earth magnets.

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This collection of magnets is all created from materials that are rarely found on earth.

(On a slight tangent, while the term is a little misleading, as some rare earth metals aren’t hard to find in decent quantities, they do not appear in veins or strips in the same way that metals like iron, gold or copper do, hence the name.)

Rare earth magnets can come in two forms: Either Samarium-Cobalt magnets or Neodymium magnets.

Composition

Neodymium magnets are not made from pure neodymium but are created from an alloy of neodymium ore, iron, and boron.

Origins

Neodymium was first noted and discovered in the early 1980s when the original compound was discovered by both General Motors and Sumitomo Special Metals scientists separately.

Both companies would go on to produce this magnetic compound in various forms, from bonded Neo magnets to isotropic Neo powders forms.

Because it is often used in the construction of wind turbines, neodymium has been recognized as a potentially major material and source of competition for companies and nations that are moving towards renewable energy sources.

Properties

One of the most notable things their most notable properties, of neodymium magnets, are their incredibly strong magnetic fields.

Flux Density/ Magnetic Field Strength

Many neodymium magnets will be somewhere around 13,000 to 14,500 gauss, which is significantly stronger than virtually any other everyday magnets that most people would use.

For context, a well-made iron ceramic magnet will have a strength of around 100 gausses, and an everyday fridge magnet has a gauss rating of just 10! These are seriously strong magnets, make no mistake!

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High Resistance To Degradation

Outside of their incredible magnetic properties, neodymium has incredibly strong coercivity properties too, meaning that it doesn’t just have an incredibly powerful magnetic field and flux density, but it will also maintain those properties for an incredibly long time.

Weakness To Corrosion

Neodymium is also known to easily corrode, however, meaning the magnet usually has to be treated or coated in some way to prevent it from rusting or otherwise corroding easily.

How They Are Made

So, we’ve covered plenty of material when it comes to this humble little magnet.

How Are Neodymium Magnets Made?

Now, we can finally start discussing the process through which this incredible material is made!

As we’ve already established the chemical composition needed to make neodymium magnets is iron, boron, and neodymium, which when combined, forms the compound Nd2Fe14B.

Step 1: Mixing 

The first step when creating a neodymium magnet is to mix all the composite materials in a vacuum induction furnace so that they are all melted into a liquid state that will better allow the final compound to form.

(It should be noted that the ratios between the amounts of each material can vary depending on the strength that a person is looking to have in their magnet.)

Once the alloy has been mixed, the molten metal is then cooled into ingots until they have solidified. Once at that point, the ingots are then ground down into fine tiny grains, with each grain only being 3 microns across in size.

Step 2 Pressing

From here, the metal grain can now be pressed!

The grain is pressed in a mold that is charged with a magnetic field that is equal to the mold.

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The molded grains are finished when the molded metal has the same magnetic direction as the charge that was passed through it.

Step 3: Sintering

At this point, you might assume that the magnet was finished.

However, at this stage it would be far too easy to disintegrate or crumble, so the magnet is then demagnetized, then reheated to just below the ally’s melting point.

This allows the individual grains to fuse, forming a solid lump of metal that will hold its shape.

Step 4: Cooling

From this point, the alloy magnet is then rapidly cooled, which will help improve the overall performance of the magnet. Diamond-plated tools are needed to cut the neodymium into the desired shape at this point.

Step 5: Plating

The magnet is now starting to take its final shape.

However, in this state, it is still prone to chipping and corrosion, especially now that the magnet itself is super hard.

At this point, the alloy is coated with another alloy compound, which can vary depending on what the final product will be.

Step 6: Re-magnetizing

Now, the magnet can be re-magnetized and is done so through a magnetic field that is 3 times stronger than what the final products will be. After the final step is done, you’ll have your completed neodymium magnet!

Final Thoughts

And there you have it! You now know how these magnets are made, or at least one method of creating them!

Magnet Fishing Adventure

Anthony is passionate about magnet fishing. He likes to go out magnet fishing with his friends. On this site he shares his knowledge, experience, and details about magnet fishing gear and research with you.

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