Can magnets be demagnetized?

Can you demagnetize magnets? Yes, you can. You can also just "turn off" them temporarily, but if they don't work anymore, go for demagnetizing them completely. However, it is more technical than just a yes or a no with a short explanation, because there are many factors that come into play - e.g. magnet type. And it is not always that a loss of strength is permanent. But we promise you that it will be very inspiring to spend 4-5 minutes reading this post, as you will get an insight into magnets and magnetism that you hardly learned in physics classes.

Impact of high temperature

There are several factors that apply when you want to demagnetize a magnet using high temperature. Firstly, it matters whether it is a neodymium magnet or a ferrite magnet - ferrite can withstand higher temperatures than neodymium. In addition, it is important for the size of the magnet, because it is only when the core reaches too high a temperature that the magnet is completely demagnetized. In addition, there is a difference between N and H values ​​for neodymium. As a guideline, we have a max.  working temperature indicated on most ferrite magnet product cards as 250°C and on N-value neodymium magnets as 80°C. But if you take a larger neodymium magnet on e.g. 20x20 mm., can it withstand slightly higher heat than a 2x2 mm. magnet, as there is further to the core. But the time period for an excessively high heat effect does not have much to say, because it is very easy to heat up a magnet and thereby demagnetize it.

This means that you will be able to throw a neodymium magnet into a stove and demagnetize it without problems, but something more is needed to demagnetize a ferrite magnet, which is why it is also really good to use for locking mechanisms on stoves.

Influence of low temperatures

I in terms of high temperatures, ferrite had a clear advantage and could handle a lot more heat than neodymium, but it's just the opposite at low temperatures.

Neodymium: Neodymium magnets withstand well to be cooled down a lot - also using liquid nitrogen (-196°C). When neodymium is cold, the strength decreases (up to 90% strength loss at -196°C), but when the magnet returns to room temperature, it is back to full strength. You can therefore easily cool down a neodymium magnet quite strongly, as long as you allow the strength to weaken temporarily (but not disappear completely).

Ferrite: Ferrite magnets, on the other hand, lose their strength when -40°C and gradually more and more when exposed to lower temperatures than -40°C. We don't get that many questions about ferrite and sub-zero temperatures, but we're happy to investigate further on this topic if you need to know something more precise about the curve of demagnetization for ferrite at sub-zero temperatures.

Impact of rust

Neodymium: Rust on magnets is largely not a problem. As long as it's just surface rust. The challenge often lies in the fact that magnets appear weaker when they are rusted, because the rust creates distance. But if you remove the rust with fine-grained sandpaper, you again have a better contact with the magnet, and then it works fine. If, on the other hand, you take a broken magnet and leave it to rust, e.g. outdoors in wind and weather, it is quite easy to destroy the magnet and thereby obtain a much weaker magnet (though rarely completely demagnetized).

Ferrit: It is very rare, that ferrite magnets are attacked by rust. Therefore, they are also good for use outdoors. It therefore does not make as much sense to write about rust for ferrite magnets compared to having to make a magnet stop being magnetic.

Drilling in magnets

It is rarely a good idea to drill into magnets. A very special tool is needed, as they break very easily. This is also why you can find magnets in many shapes and sizes with us, so you don't have to start making the magnets. But when magnets break, they are still magnetic (and still has a north and south pole in all the new magnet parts). Each new part is just less magnetic than before, as the surface is smaller and thus also the magnetism measured in strength. You therefore do not get a demagnetized magnet by drilling into it or breaking it, but you just get some smaller magnets, each of which is less strong (but together again has approximately the same strength as originally). So avoid drilling into magnets - it's dangerous with all the splinters. And it also doesn't make much sense if the purpose is to demagnetize the magnets, which this post is about.

Magnets and welding

You often use ferrite magnets for magnetic welding equipment because they withstand such high temperatures (up to 250°C). But neodymium magnets will quickly become too hot and thereby demagnetized, so if you put neodymium magnets on an object that is heated by welding, you will quickly demagnetize your magnets.