Can You Permanently Demagnetize a Magnet?


Hello there guys! In today’s article, we will discuss whether you can permanently demagnetize a magnet or otherwise. However, before we dive right into the article, I would like to quickly point out that all of the information provided in this article are based on reliable sources. This is done to ensure that the content supplied to you is authentic and free from factual errors. So, without wasting any more time, let’s jump right into the article.

Can You Permanently Demagnetize a Magnet

Is it Possible to Demagnetize a Magnet Permanently?

Firstly, you need to understand that magnets are formed when the magnetic dipole orientation of a particular material has the same direction. Hence, to demagnetize a specific magnet, the only thing you need to achieve is to disrupt the magnetic dipole orientation of the magnet.

It’s safe to say that it is possible to demagnetize a magnet permanently. The reason for this is that once a particular magnet has its magnetic dipole orientation disrupted, it will not possess any magnetic properties. The magnet will stay this way until you decide to align the magnetic dipole orientation in one direction. Therefore, as long as the magnetic dipole orientation is disrupted, the magnet will stay demagnetized forever.

Why Would You Want to Demagnetize a Magnet?

There are times when magnets either cause huge problems in life or have the potential to do so in the future. For instance, if you’ve used a data storage device in the past (like a magnetic tape drive) to store all of your sensitive information and you would like to get rid of it because you just bought a new one, then it’s important for you to make sure that you get rid of it properly.

This is done to prevent any unauthorized access to your sensitive information contained in your old tape drive. This is when demagnetization gets very handy in life as it helps you to strip all of the data in the tape drive, enhancing your security level. Apart from that, there’s also plenty of situations in life whereby the magnetization of metals causes problems in life.

In most cases, the main problem usually occurs from a magnetized metal that attracts other metals to it, whereas in other cases, the presence of the magnetic field itself causes unnecessary problems to arise.

Some of the things in life that are commonly demagnetized to solve problems include engine components, metal molds, flatware, heavy-duty tools, and metal parts used for welding.

Next, you may also take a look at the applications of demagnetization in Electron Beam. Magnetism is known to act on the electrons of the Electron Beam, and it causes these electrons to be directed by Lorentz force. However, these electron beams are deflected in an uncontrolled manner by the presence of an unknown magnetic field that stands in the path of the beam.

This problem leads to unwanted results such as blurry images in SEM microscopes and defective Electron Beam welding seams. Machine parts that are unintentionally magnetized in the production or an incorrect assembly of the Electron beam itself may cause this unwanted magnetism. In this case, a precise demagnetization of the Electron Beam and the machine parts involved provides a huge advantage for the industry.

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What Magnets Can Easily Be Demagnetized?

Currently, the easiest type of magnet that can be demagnetized at any time is electromagnets. Electromagnets are the easiest type of magnet that can be demagnetized at any time because they don’t require you to wait for even a second for them to be completely demagnetized. You can literally magnetize and demagnetize them at any time you want.

The only thing you need to do is switch the power on and off, and the electromagnets will instantly do their job. Unlike other types of magnets that require you to heat them all the way beyond the Curie temperature, electromagnets only require you to push that switch button for them to be demagnetized.

Can You Demagnetize a Rare Earth Magnet?

For those who don’t know it yet, a rare earth magnet is a permanent magnet with a high strength level. They are usually made from alloys of rare earth elements. Rare earth magnets are considered the strongest permanent magnets ever made as they produce stronger magnetic fields than any type of alnico or ferrite magnet.

It’s pretty challenging to demagnetize a rare earth magnet, but it’s doable, provided that you have enough money to buy the equipment needed. The primary way to demagnetize a rare earth magnet is by heating it beyond the Curie temperature of the magnet.

For example, if you need to demagnetize a neodymium-iron-boron magnet, you will need to heat it to 320 degrees Celcius. The coercivity of the magnet should be high before the heating process, and it will decrease gradually as the temperature of the magnet rise. Heating the magnet up to 320 degrees Celcius is quite challenging for some people.

Alternatively, you may also heat the magnet to 250 degrees Celcius instead, and from there, you may use an alternating current to further demagnetize the heated magnet.

5 Ways to Permanently Demagnetize a Magnet

In reality, the demagnetization process of a particular magnet occurs naturally but at a slow rate. There are several ways to demagnetize a magnet permanently in a safe manner. One way to do this is by heating the magnet beyond the Curie temperature. For those who don’t know it yet, a Curie temperature or point is a temperature in which a particular material (in our case, the magnet itself) permanently loses its magnetic properties.

1. Heating the Magnet Beyond the Curie Temperature

If you heat a usual magnet way above its Curie temperature, the excess heat energy that the magnet gained from the heat source will eventually cause the magnetic dipole to be freed from its fixed orientation. As a result, the magnet will no longer possess any magnetic properties. This method is by far the safest and straightforward way to demagnetize a magnet manually by yourself.

2. Brute Force

The same effect can be obtained by hitting the magnet with a hammer, dropping the magnet from a high altitude repeatedly, and applying some pressure to the magnet. All of these actions will also contribute to the demagnetization of the magnet. The reason is that the physical vibrations and disruption from these actions will eventually cause the overall magnetic dipole orientation to be disrupted, which demagnetizes the magnet.

3. Utilizing AC Current to Disrupt the Magnetic Dipole Orientation

Since alternating current can be used to make a temporary magnet, it’s also possible to use alternating current to reverse the process. To do this, make sure that you allow the flow of the alternating current to the magnet via an insulated copper wire. The magnet will eventually lose its magnetic properties because the alternating current keeps changing its direction. This will help to disrupt the magnetic dipole orientation of the magnet.

Keep in mind that you will need to start flowing the alternating current at a high level initially and gradually reduce the current as time passes until it reaches zero. The magnetic dipoles will try to fix their orientation according to the field, but it will end up randomizing the magnetic dipoles instead, demagnetizing the magnet. Please keep in mind that you cannot use a direct current to demagnetize the magnet.

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The reason is that a direct current flows in only one direction, and it’s difficult to cause a massive disruption to the orientation of the magnetic dipoles if the current doesn’t change its direction rapidly. So it’s possible that you can cause disruptions to some of the magnetic dipoles, but you will certainly not be able to affect all of them. The magnet will end up demagnetized slightly but not entirely, that’s for sure.

4. Demagnetization by Self Demagnetization

This method only requires you to store multiple magnets together in the same container. You may also rub them off together if you like. This method works because the magnetic field of each magnet will continuously affect the magnetic fields of other magnets. This will eventually cause the magnetic dipole orientation of these magnets to be disrupted.

Alternatively, you may also use a stronger magnet to demagnetize any magnet you want, provided that the other magnet is at least five times stronger.

5. Demagnetization by Polarity Positioning

This method of demagnetization is almost the same as that of self demagnetization. The difference between these two is that instead of rubbing the two magnets together, both magnets are sandwich together, separated by a block of wood.

The polarity of both of these magnets should be positioned in a specific way. The arrangement should be made so that the North pole of one magnet is kept close to the North pole of the other magnet. The same goes for the South pole of the magnets. By positioning the magnets in this manner, the magnetic field of one magnet can be used to disrupt the magnetic field of the other magnet causing both magnets to be demagnetized.

Will Magnets Lose Its Magnetism in Water?

Magnets are known to work perfectly fine in water. In fact, retrieving magnets are even used to get valuable items such as keys and jewelry that have accidentally fall into a tank full of sharks. Besides, it’s also quite easy for you to test it out for yourself at home. Simply put two magnets together in water and observe what happens.

Usually, the magnets will attract to each other even if you submerge them underwater. Just in case your magnets are made up of iron, then you might want to dry them off right after you’ve tested their magnetic strength. Otherwise, those magnets will get rusty, which in turn will cause them to get demagnetized.

How Long Does It Take For a Magnet to Demagnetize?

How long a magnet takes to demagnetize all depends on the type of magnet that you’re dealing with:

  • If you have a temporary magnet on your hand, it should demagnetize under an hour.
  • On the other hand, if you have Neodymium magnets on your hand, they should be naturally demagnetized after you have used them for at least ten years.
  • Permanent magnets such as sintered Neodymium-Iron-Boron magnets should remain magnetized for an extremely long time.
  • Last but not least, electromagnets may last for as long as there’s current flowing in the coils.

Do Magnets Lose Magnetic Strength Over Time?

Regular Magnets

A regular permanent magnet such as iron, nickel, and cobalt magnet is known to lose magnetic strength over time. The reason being is that these types of magnets are usually exposed to a minute level of heat, physical impact, and pressure that contribute to the rate of loss of their magnetic strength.

Even though these magnets usually lose their magnetic strength very slowly, it’s clear that they do lose a small percentage of magnetic strength as time passed by.

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The loss of the magnetic strength of these magnets is inevitable unless they are being placed in a contained environment where they are protected from any external factors such as heat, pressure, physical impacts, and improper storage methods.

Electromagnets

On the other hand, electromagnets are known to have the ability to provide a strong magnetic field even as time passed by. It’s hard to find an electromagnet (that is maintained properly) that could lose its strength after some time.

In most cases, electromagnets are very reliable in terms of providing a strong magnetic field provided that there is a steady supply of current. Even if an electromagnet does lose its strength after it’s been used for some time, the percentage loss of its magnetic field strength is extremely minute that most people tend to ignore it.

Rare Earth Magnets

As for the rare earth magnets, they are slightly better than a regular magnet. Rare earth magnets can last for a very long time, and it usually loses its magnetic strength once every 100 years. In most cases, rare earth magnets such as neodymium-iron-boron (NdFeB) magnets lose their magnetic field strength as much as 3% (assuming that they are being placed in an optimized environment).

Can a Magnet That Has Lost Its Strength be Re-Magnetized?

A magnet that has lost its strength is simply a magnet that has its magnetic dipole orientations to be disrupted by factors such as heat, corrosion, induction, and alternating current.

Therefore, to restore the strength of a particular magnet, the only thing you need to do is restore the magnet’s magnetic dipole orientation to its original direction. Hence, yes, it is possible to remagnetize an old magnet that has lost its magnetic strength.

How to Restore the Strength of An Old Magnet That Has Lost Its Strength?

Items Required:

  • Compass
  • Neodymium magnet
  • Old Magnet
  • Marker

First Step (Determining the Polarity of the Neodymium Magnet)

Determine the polarity of your Neodymium magnet by using a compass. Place the compass at the first end of the Neodymium magnet to determine whether it’s a South or North pole. Mark the polarity of your Neodymium magnet for future reference.

Second Step (Determining the Polarity of the Old Magnet)

Repeat the first step for your old magnet by using the compass and the marker.

Third Step (Utilizing the Magnetic Field of Rare Earth Magnet to Reset the Magnetic Field Orientation of the Old Magnet)

Place the South pole of the Neodymium magnet to the North pole of the old magnet and vice versa.

Fourth Step (Strengthening the Magnetic Field of the Old Magnet)

Repeat the third step until your old magnet has been fully magnetized and regained its magnetic strength back to its normal level. Once you have successfully restored the power of your old magnetic field, it’s crucial that you store it in a proper way and in an appropriate place. This needs to be done correctly to prevent the magnets from self demagnetized in the future.

Another Interesting Way to Remagnetize a Magnet:

How to Store Your Magnets to Avoid Demagnetization

One way to store your magnets is by keeping the North pole of one magnet to the South pole of the other magnet and vice versa. This way, the magnetic field of each magnet can be strengthened instead of being disrupted.

Exception for Electromagnets

However, please keep in mind that these steps cannot be applied to electromagnets. The reason being is that electromagnets are completely different from other types of permanent magnets. Unlike permanent magnets, electromagnets require copper coils and a steady flow of current to even have their magnetic fields.

In most cases, the copper coils are wrapped around one ferromagnetic metal such as iron, cobalt, and nickel to enhance the strength of its magnetic field. For you to remagnetize an electromagnet, there is only one way to do that so far, and that is by ensuring there’s a constant flow of current to the solenoid. You shouldn’t give yourself a hard time remagnetizing an electromagnet if you have access to a high level of electricity.


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