A magnet consists of varying amounts of aluminum, iron, cobalt, nickel, and other rare elements like neodymium, dysprosium, and samarium. It’s made of atoms and molecules that reinforce each other. So, where do magnets come from? They are made by exposing nickel and iron (ferromagnetic metals) to magnetic fields.
Magnets are made to suit specific applications and performance requirements. This explains why the materials are important in the manufacturing process. But again, that depends on whether you’re talking about manmade or natural magnets. No matter the type of magnet you have, you expect a force of propulsion due to the arrangement of electrons.
Where Do Magnets Come From?
The first natural magnets were discovered in Greece (Magnesia) 2000 years ago. They were rich in a mineral called magnetite (the main source of lodestone). About 800BC, man discovered how to create weapons through iron and steel. With time, he realized that hammering iron caused some magnetic domains to align the earth’s surface. It was later discovered that hitting lodestone could magnetize the iron.
That said, permanent magnets are made from iron ferrite that delivers magnetism from the earth’s magnetic field. In the 1970s, researchers discovered how to make magnets with materials that are more magnetically aligned. Lodestone exhibited a better arrangement of atoms and magnetic domains. The natural alignment makes the magnetic forces stronger.
Another weakly magnetic material is pyrrhotite. It mainly consists of iron sulfide and has varying amounts of iron. Some people refer to natural magnets the same as permanent magnets. They have positive and negative charges and maintain the same distance from each other. Pyrrhotite is a naturally occurring magnetic material with a weak amount of magnetism but strong to attract some paper clips.
In the 1980s, some researchers discovered how to make magnets using powdered neodymium iron boron. The magnetic forces are 70 times stronger than magnetite. It’s no surprise these are the most powerful magnets produced commercially today.
When a natural magnet is suspended, it rests in the north-south direction. And this is what sailors used to navigate ships in ancient times.
Other Ways to Get Natural Magnets
Hematite
Research has shown that hematite crystal exhibits tiny magnetic force. For the mineral to be fully magnetic, it must be heated until it granulates. When a strong magnetic material is applied, the molecular poles form a magnet.
Earth
Did you know the earth exhibits the properties of an electromagnet? While the crust has some permanent magnetization, it can still generate its magnetic field. But for magnetization to occur, the temperature must reach several thousand degrees.
While the mechanisms used to generate magnets are a bit murky, physicists believe that some objects rotate past each other. So as the earth rotates, they rub against each other, creating a magnetic field.
Magnetar
It’s touted as the most powerful magnet in the universe and can rotate over 100,000 miles. It has the benefit of being close to the other than other magnetic forces. What’s a Magnetar? It’s a short name for magnetic stars and is known to be the cause of some of the mysterious radio bursts. Since the magnetic field lines are so strong, they squish the atoms.
Where Exactly are Natural Magnets Found on Earth?
Natural magnets are found in nature and won’t lose their magnetic power. They can be found in sandy areas around the world. You can easily identify lodestone as it exhibits black color. And tend to align with the earth’s North-Pole.
If you visit a mineral show, you’ll always find some lodestone on display. You can check the strength of the magnetism.
How is a Magnet Created? The 8 Step Process
1. The manufacturing process
Since magnets are made of different materials, the manufacturing process also differs. For flexible permanent magnets, the materials are mixed and forced under pressure. Others are formed through the metallurgy process, where metal is forced through magnetic forces to form heat. The manufacturing process usually takes 4-6 weeks. Here’s a step-by-step guide to the process.
2. Preparing the metal
Some varying amounts of iron, boron, and neodymium are heated in a vacuum. This ensures there’s no chemical reaction between the melting material – the air can contaminate the final alloy. Once the metal is cooled, it’s crushed into small pieces. Then, the pieces are round together to form a fine ball.
3. Pressing and heating
The powdered metal is placed in a die then a magnetic force is applied. After that, the powder is placed on mechanical or hydraulic rams and compressed to the intended thickness. Typical pressures are usually 10,000 PSI, but some materials require 15,000 PSI. You can make some shapes by placing the materials in an airtight container. This is referred to as Isotactic compaction.
To convert the compressed material to solid metal pieces, the material is heated at a low temperature. But to drive off other contaminants, the temperature is raised to about 70% melting point.
Then, the material is cooled with a step-by-step temperature increment.
4. Annealing and finishing
The sintered material passes through annealing (heating and cooling). This helps to remove any residual stress before cooling it. The annealed material is close to the finished shape, and you can cut to the dimensions required. To produce a smooth surface, the product goes through the machining process.
There are three main types of magnets – bar, horse, or needle magnet. But due to the advancement in technology, manufacturers can now produce electromagnets. They are powerful and can be used when an intense field is needed.
For a large volume, it’s economical to produce more pieces into shape. This is because the grinding swarf and material scrap are minimized.
5. Magnetizing
While the material is exposed to a magnetic force, it’s still not yet magnetized. The piece is taken through the poles of a powerful electromagnet. It’s then energized by a group of atoms to make a strong magnet.
6. Performance testing
Several things contribute to magnetic strength. Each of the factors is measured and tested. The magnetic strength and pulling force is summarized as follows:
- Remanence – This refers to the magnetism that remains after an external force is applied to magnetize it.
- Maximum energy – The maximum energy indicates the strength of the magnet. Higher energy means a better magnetic field.
- Open circuit flux density – It’s the magnetic field that penetrates a specific area. The field strength must correspond to the density of a specific area. Magnets with smaller poles have a higher open-circuit flux and small magnetic strengths.
7. Stabilization and calibration
In some cases, magnets may require calibration and stabilization. Both processes need treatment in an oven but at fields below the knock-down power. Calibration helps to narrow down the output range, while stabilization requires preheating of magnets. While many processes affect stabilization, the process should be controlled to ensure proper product performance.
8. Packaging
The team of experts will package the magnets for safe transport and in perfect conditions.
Artificial magnets tend to be stronger than natural magnets and can take any shape to suit your preference.
Where do Neodymium Magnets Come From?
Neodymium magnets are made from high-tech methods referred to as powder metallurgy. While dozens of processes must be followed to achieve various grades, the variations are due to compositional differences. The production process involves the following:
Mining of the earth ore
Once a rare earth ore is mined, it’s transported to the factory with large equipment.
Processing
The earth's ore is crushed and is taken through the flotation process. It’s then mixed with water to separate the elements from tailings. And depending on the source of the ore, it could go through electrolytic refining. The concentrate passes through high temperatures and other unusable materials.
But here is the thing – the refinement process can be complex. Sometimes, the unique refinement methods require the use of chemicals. From a scientific standpoint, about 20% of magnets consist of Praseodymium.
Alloying
Alloying refers to those small additions that help to refine the final product. The microstructure of the final product can enhance the magnetic properties.
Strip casting
The alloy then goes through strip casting where pressure is applied under a cooled drum. The high cooling rate produces small grains of metal. This is what enhances the effect of downstream processing.
Hydrogen decrepitating
The alloy from strip casting must be reduced to powder to make the magnets. And this is where hydrogen decrepitating comes in. It’s the introduction of hydrogen to disintegrate the magnetic material.
Jet milling
This process uses high-end steam of inert gas to grid the pieces into powder. Then, the airflow separates the particles – this prevents the sides of the pressure vessel.
Pressing under magnetic field
Some pressure is applied between the plates to form a block of material. Then, the magnetic field orients the grain, and remains are directed to a designated area. At this stage, the magnet can be oriented in a perpendicular block. Then, it’s submerged in a cold isotactic press under pressure. This eliminates any air gaps that come out of the press.
Sintering and annealing
The pressed block is removed, sintered, and then put on a furnace (below the melting point of a metal). At greater than 1000 degrees Celsius, the atoms have a lot in motion. Generally, the blocks can develop full mechanical properties.
The blocks are treated again, but this time they are ramped to high holding temperature. Needless to say, the cooling process follows.
Cutting, machining, and grinding
After sintering, the cutting, machining, and grinding are performed using a strict control plan. What follows after that is wire cutting, and the waste material is recycled.
Some of the common applications of neodymium are linear actuators, automotive starters, magnetic separators, medical devices, and computer rigid disc drives.
Testing
Testing is an evaluation done on every magnetic material. This is done to improve product quality and boost efficiency.
Each of the above manufacturing processes is carried out with precision to achieve the best performance.
What is a Samarium Cobalt Magnet?
Another rare-earth magnet that follows the same process as neodymium magnets is samarium cobalt. It mainly consists of iron, cobalt, and samarium. The magnet is corrosion resistant and operates moderately in high temperatures. Still, you can use the magnet in applications like traveling wave tubes, satellite systems/linear actuators, and computer disc drives.
It’s worth mentioning that this material comes with quality attributes like high-temperature stability, low corrosion resistance, and resistance to demagnetization.
3 Ways to Make Temporary Magnets at Home
There are three methods for making magnets: single touch, double touch, and the use of electric current.
1. Simple touch method
This is perhaps the simplest and the most efficient method to make magnets. Because it doesn’t have a big field of attraction, you need a ferromagnetic object. To start with, you should place a big sheet of paper on a flat surface and rub the magnet over it. Follow one direction and lift over the object at least 50 times. If the process is carried out well, the surface can attract pins. The more you rub the magnet on the surface, the more powerful it will become.
2. Double touch method
It’s similar to the first method, but this time two magnets are used. You should take a large nail or any other ferromagnetic substance, a copper wire, and a D-cell. The copper oil should be tightly tied to the nail, but the ends should be left free. This setup will work for some time even after the battery is disconnected. You can test the level of magnetism using an industrial electromagnet.
3. Using electric current
You need a ferromagnetic substance, a battery, and copper wire. To prepare the setup, tie the coil around the nail and free both ends. This is an example of a magnet commonly used in salvage yards. You can test it by holding it against some iron filings. And after some time, it will be magnetized and attract the fillings.
You can as well boost the strength of a magnet by increasing the number of coils, add a transformer or increase battery voltage.
Conclusion
Natural magnets are generally weaker than artificial ones. They naturally occur in the environment and can be found in sand deposits around the world. Although they break when being formed, they never lose power. That said, the strongest magnetic stone so far is magnetite. It rotates freely on the earth’s North-Pole. On the other hand, artificial magnets can be temporary or permanent.
Temporary magnets lose their magnetism (can be activated), while permanent magnets feature a magnetic force that never fades. Of course, all artificial magnets must undergo the above manufacturing process.
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