Neodymium Magnet Information
Neodymium magnets are the strongest permanent magnets commercially available, anywhere in the world. They provide unparalleled levels of magnetism and resistance to demagnetisation when compared to ferrite, alnico and even samarium-cobalt magnets.
HISTORY OF NEODYMIUM MAGNETS
Neodymium magnets were first developed in 1982 by General Motors and Sumitomo Special Metals following the formulation of the alloy NdFeB, which is made of neodymium as well as iron and boron. Neodymium magnets were first produced in response to the high price of samarium-cobalt magnets, giving need to identify an economical, high-performance magnet. Although jointly formulated, General Motors and Sumitomo Special Metals followed different manufacturing processes with General Motors choosing to produce neodymium magnets in powdered bonded form while Sumitomo followed the sintering manufacturing process, the same process used to manufacture our range of neodymium magnets.
Neodymium magnets are also described as rare-earth magnets, because neodymium is part of the rare-earth family of elements. The term rare-earth does not mean they are scarce, neodymium is abundant in the Earth’s crust – in fact it is more common than some precious metals such as gold – the term derives from their geochemical properties, rare-earth elements are typically dispersed and not often found concentrated in economically exploitable deposits.
Neodymium is not the only element used to make neodymium magnets; neodymium is combined with boron and iron and sometimes other elements too to make super-strength magnets, just like those supplied by umagnets.com.
Neodymium Magnet Grades
It all starts with the letter ‘N’, all the names of neodymium magnets begin with ‘N’ for neodymium. The number that follows is a little more technical as this represents the maximum energy product of the magnet in ‘Mega-Gauss Oersteds’ (MGOe). This is the primary indicator of a magnets ‘strength’. Simply, the higher the maximum energy product value, the greater the magnetic field the magnet will generate in a particular application.
The grades generally available to buy, range from N30 to N52 as lower grades are generally no longer manufactured.
Neodymium Magnet – Platings/Coatings
Neodymium magnets are very hard, but very brittle. Plus, as neodymium magnets also contain iron it means they are prone to corrosion if they aren’t coated. They are so prone to corrosion that even the moisture in the atmosphere can cause an uncoated neodymium magnet to corrode over time. If a magnet corrodes it will weaken and crumble
That’s why, at umagnets.com we supply all our magnets already triple-coated (unless specifically requested otherwise). The typical coating for a neodymium magnet is a layer of nickel followed by a layer of copper and then nickel again. However there are many different coatings used with neodymium magnets including gold, rubber and Polytetrafluoroethylene (PTFE). The coating applied to a raw neodymium magnet depends on the application it will be used for, potential coatings include:
- Nickel-Copper-Nickel (Ni-Cu-Ni)
- Nickel (Ni)
- Zinc (Zn)
- Gold (Au)
- Tin (Sn)
- Titanium (Ti)
- Titanium Nitride (TiN)
- Parylene C
- Polytetrafluoroethylene (PTFE)
- Nickel-Copper-Nickel, plus Rubber
- Zinc, plus Rubber
- Nickel-Copper-Nickel, plus Parylene
- Nickel-Copper-Nickel, plus PTFE
- Tin, plus Parylene
- Zinc chromate
- Phosphate passivation
During manufacture, all our magnets are thoroughly dried to prevent moisture being captured underneath the coating during the coating and plating process.
How does temperature affect neodymium magnets?
In the application of neodymium magnets, it is critical to understand the maximum operating temperature of each grade of magnet. Neodymium magnets operate best at lower temperatures, they even get stronger as the temperature gets colder, to a point of approximately -130°C. However, some grades of neodymium magnets can also be exposed to very high temperatures before their properties begin to change and they lose their magnetism, either temporarily or permanently.
Uses of Neodymium Magnets
Neodymium magnets are the strongest magnets in the world. Because of their strength, even tiny magnets can be effective. This also makes them incredibly versatile; as each of us goes about our modern lives, we are never far from a neodymium magnet, you are likely to have one in your pocket right now, or if you are reading this article on smartphone, you might even have one in your hand!