Magnets are ubiquitous in our environment. From the tiny magnets that can hold your sticky notes on your fridge to the big magnets used in factories, there are a variety of sizes and applications. Not all magnets are made the same, though: they vary in strength of force, material, and magnetising effect.
Everyone knows what Magnet is, but did you know that there are various kinds of magnets with specific properties and usage? To the permanent magnets in regular tools, to the driving of computers with electromagnets, to the temporary magnets; each has a different purpose.
All kinds of magnets are different and have different properties, powers, and uses. Our article today is going to look into how many classifications they have, how they are different, and what their use is in our lives. By the end, you’ll not only know what type of magnet will work for you, but also why they are still necessary in today’s world. Ready to explore?
What is a Magnet?
A magnet is a material that produces a magnetic field, which attracts or pushes away many ferrous metals. Its interior is made up of tiny rotating atoms. As these atoms spin, they create small magnetic moments that combine to create the magnet’s overall magnetic field.
The magnetic field of a magnet has a north pole (N) and a south pole (S). The magnetic field lines emerge from the north pole and then loop back to the south pole.
From a material perspective, magnets can be divided into soft magnets and artificial magnets (made from paramagnetic materials placed in a strong magnetic field). The atoms of easily magnetized materials such as iron, steel, neodymium, nickel, and cobalt are arranged into small units called domains. Each domain, although tiny in size, contains hundreds of billions of atoms, each functioning as a small unit. When these magnetic materials are placed in a strong magnetic field, the individual domains pointing in different directions will unify the magnetic field direction according to the magnetic environment. When most of the domains align with the magnetic field, the material becomes a magnet. The principle of this process lies in the interaction of moving electric charges, as described by the laws of electromagnetism.
Magnets are essential in countless applications, from refrigerator magnets to electric motors, generators, and even medical devices. Due to their special functions and scientific principles, magnets are indispensable in everyday life and even in the development of advanced technologies.
Three Major Classifications of Magnets
From common fridge magnets and earphone magnets to permanent magnets, we all integrate a variety of magnets into our lives. To understand more clearly the functionality and types of magnets, from the perspective of how magnetism is created and stored, magnets can be categorized into three classes. There are soft magnets, temporary magnets and permanent magnets. Not only is this a useful classification for determining their distinctive properties, but it also reflects their significance in different usage scenarios.
Soft magnetic materials are the materials that only attract under the influence of an external magnetic field. On the opposite side to the permanent magnets, they lose their magnetism as soon as the magnetic field is removed. The initially magnetized state is typically entirely random, unlike most hard magnetic materials. They are widespread in technology where speed, flexibility and control matter the most.
Soft magnets are flexible enough that magnetic fields can penetrate them easily, making them highly efficient for electromagnetic applications. For example, silicon steel sheets, like those we see in electrical transformers, minimize losses by decreasing hysteresis and eddy currents. For example, soft magnetic cores (which enable magnetic performance without leaving a magnetic signature) have become a key element in devices like inductors and solenoids.
This type of magnet is used for the speed at which they will magnetically demagnetise and magnetise, which is convenient for moving devices such as electric motors, generators and relays. Also, because of their speed and short life span, they are used in many industries.
Temporary magnets only become magnetic under the influence of strong magnetic fields. This magnetism disappears as soon as the external magnetic field disappears. For example, look at how everyday objects such as nails or paper clips become temporary magnets in the presence of a strong magnetic field and temporarily attract other ferromagnetic materials. This happens because the magnetic domains of the material are forced into alignment by the external magnetic field, but they return to their random alignment after the field is removed.
The categories of temporary magnets and soft magnets can sometimes be linked, for example, temporary magnets require an external force to show magnetism. However, soft magnets are specifically designed for industrial and technological efficiency, while temporary magnets can only be used as an occasional or impromptu pleasure.
Permanent magnets have a stable magnetic field and don’t require any external power. They are magnetic because the material inside is ordered such that its atoms align so that they have the ability to stay magnetised. The permanent magnet is permanently magnetised, so long as it’s not subjected to something that demagnetizes it, like high temperatures, powerful opposing magnetic fields, etc. Examples include: Examples include:
- Alnico Magnets: Known for their excellent temperature stability.
- Samarium-Cobalt (SmCo) Magnets: Highly resistant to corrosion and high temperatures.
- Ferrite Magnets: Cost-effective and widely used in everyday applications.
- Neodymium-Iron-Boron (NdFeB) Magnets: Extremely powerful and used in advanced technologies like wind turbines and electric vehicles.
These kinds of permanent magnets we’ll look at in more detail later. Keep Reading!
What Types Of Permanent Magnets Are There?
Permanent magnets are today’s most common, and they are also classed into different types by nature and composition. There are three primary classes of permanent magnets: metal alloy magnets (Alnico, Iron-Chromium-Cobalt), rare earth magnets (Neodymium, Samarium-Cobalt) and ferrite magnets (ceramic or rubber magnets). Every type has different characteristics due to the materials they are made from which type is strong, temperature resistant and so on. They come in different forms with different functions and properties. Now let’s see what each permanent magnet can do and why it’s so special.
Metal Alloy Magnets.
Metal alloy magnets include a metal compound of elements that when mixed together form very strong magnetic properties. The metal alloy permanent magnets are mainly classified into four types: Alnico (Aluminum-Nickel-Cobalt) magnets, Iron-chromium-Cobalt magnets and Platinum-Cobalt magnets sets. These alloys offer various advantages in terms of magnetic strength, temperature stability and corrosion resistance.
- Aluminium nickel cobalt magnets (Alnico Magnets or ALNiCo) are a combination of aluminium, nickel, cobalt, iron and some other metals. They are cast into various sizes and shapes, and so they are easy to work with. Such magnets are extremely sensitive to low temperatures and can be operated at high temperatures up to 600 degrees Celsius. They’re found in a lot of instruments and applications. There are two types of them namely cast aluminium nickel cobalt magnets and sintered aluminium nickel cobalt magnets. Cast Alnico Magnets are often used in automotive parts, tools, and warfare because they are not affected by moisture and oxidation. Powder metallurgy sintered Alnico Magnets are ideal for small, lightweight or complex shapes and are used in communications equipment, sensors, and magneto-electric switches.
- Iron-chromium-cobalt magnets are composed of iron, chromium, and cobalt, which together provide good magnetic strength and excellent corrosion resistance. Although the magnetic strength of permanent magnets made from these alloys is not as good as that of rare earth magnets, they can maintain their magnetism under harsh conditions and are very suitable for applications that require strong corrosion resistance.
- Platinum-cobalt magnets are made of platinum and cobalt and have a different magnetic behaviour because of their atomic structure and high interatomic attachment. They have high magnetic strength and long stability at high temperatures because they are powered by the principles of ferromagnetism: the atoms’ magnetic moments are lined up to form a strong permanent magnetic field. Since they’re rare and expensive, the only use for platinum-cobalt magnets is in research, precision instruments and specialised devices where performance and stability matter.
Ferrite Permanent Magnets
Ferrite magnets (also referred to as BaFe12O19 and SrFe12O19) are also brittle and hard. They’re prized for being cheap, high-temperature resistant, and highly stable in magnetic performance, with very little temperature dependence. They were also the only type of magnets with the superior ability to hold magnetic power over time. Unlike many other permanent magnets on the market, ferrite magnets can be made into a variety of shapes and sizes, thanks to their flexible sintering and bonding processes. The biggest benefit of this type of permanent magnet is that it is affordable and safe, making it an ideal choice for many everyday low-magnetic needs. Ferrite magnets are divided into two main types due to the different manufacturing processes: ceramic magnets and rubber magnets.
- Ceramic Magnets (Sintered Ferrite):
Ceramic magnets are a great option for a wide range of applications thanks to their impressive performance and affordable cost. They’re made by combining iron oxide (Fe2O3) with either barium carbonate (BaCo3) or strontium carbonate (SrCo3) to create a highly magnetized metal powder. There are two main types of ceramic magnets – isotropic and anisotropic. The anisotropic ones can be further divided into dry and wet varieties. Regardless of the specific type, ceramic magnets offer some fantastic benefits. They deliver uniform, stable, and permanent magnetism, making them ideal for use in small or uniform-volume components. And with iron oxide as the main raw material, they’re inexpensive to produce while also boasting excellent insulation and resistance properties. - Rubber Magnets (Bonded Ferrite):
Rubber magnets are produced by mixing ferrite powder with a flexible binder, such as rubber or plastic. These magnets are different in that they not only are elastic, but also adaptive to a wide array of shapes of strips, rolls, sheets, blocks, rings and so on that can be fabricated by extrusion, calendering or injection molding using the adaptability. The final product is a soft with twistable magnet that’s very easy to manipulate. What makes rubber magnets stand out is their adaptability. Although they are also flexible, they are surprisingly rigid when compared to sintered magnets. Their lightweight and pliable nature makes them extremely useful in both creative and functional applications, making them ideal for advertising displays and various decorative projects where flexibility and ease of use are key. One can also tailor the surface itself, by adding, for instance, PVC wrapping, adhesive layers, UV oil finishes, or even printed patterns. Furthermore, seeing as they can be bent, twisted, and rolled, they can be adapted to almost any requirement. With a magnetic energy product from 0.60 to 1.50 MGOe, they provide a robust magnetic response for such a soft material.
Rare-Earth Permanent Magnets
Rare-earth magnets are permanent magnets having a composition of alloys manufactured from rare earth elements (mostly elements from lanthanide series, and alloys). They were developed in the 1970s and 1980s and are the strongest types of permanent magnets. They produce magnetic fields that are quite stronger than other types of magnets like alnico and ferrite magnets. Rare earth magnets have a field strength of more than 1.4 Tesla, whereas ceramic and ferrite magnets have fields of 0.5 to 1.0 Tesla. They offer unique benefits like magnetism, stability in temperature and corrosion resistance that make them an indispensable material in electronics, aerospace and renewable energy.
- Neodymium-Iron-Boron Magnets (Nd2Fe14B):
NdFeB magnets are often referred to as the “King of Magnets” and are highly regarded for their incredible strength. Their magnetic force is more than ten times that of ferrite magnets in the same volume. This high strength is critical in applications where small size and high magnetic output are required, and they are the highest magnetic energy magnets available among commercial magnets today.
Although it does have its limitations in some directions, such as susceptibility to corrosion and poor thermal stability, these can be addressed by adding protective coatings and material modifications. The production process adopts a series of manufacturing processes such as ingredients, smelting and ingot making, powder metallurgy & Hydrogen Decrepitation, magnetization, pressing, etc. The basic alloy composition is Nd2Fe14B, but materials can be customized to produce neodymium magnet models corresponding to grade specifications according to specific usage conditions. Click to view a more detailed neodymium magnet grade table. - Samarium-Cobalt Magnets (SmCo):
SmCo magnets perform best where magnetic energy and temperature resistance are needed: 350°C or higher. They are also far more stable and reliable than NdFeB at high temperatures even at a higher price point. These are made of samarium, cobalt, and other rare earth metals that have high durability and magnetic performance and are often the best choice for demanding use. Their demagnetisation and corrosion resistance also proves them for specialized applications. - Iron-Nitrogen and Iron-Carbon Magnets (Re-Fe-N and Re-Fe-C):
These experimental magnets are potential superconducting magnets but lack the manufacturing process that permits their practical use. Scientists are still playing with their power, hoping to beat these barriers and use them in technologies of the future.
There are many magnets out there so do your homework on what’s best for you. Retentivity, coercivity and magnetic stability are the properties of permanent magnets, remember. Retention ability, after you take the outside magnetism out of it, means how magnetic it is by itself. The greater the retentivity, in this scenario, the more efficient that magnet will be. Coercivity refers to immunisation against demagnetisation by external fields. Magnetic stability is the reliability of a magnet at varying temperature or through stresses due to mechanics etc. If you want to know more about the key indexes for measuring magnet performance, you can leave us a message and we will consider publishing a special issue to explain it to you.
Permanent magnets are an ideal solution, because they are very adaptable and, if you know what you’re looking for while doing your research, then you can make a good decision. Two things come into play when choosing a magnet to buy. You’ll first have to know about types of permanent magnets, which we’ve got for you. In second place, you have to consider product quality and durability. Buying cheap can be tempted, but then again, cheap is always low quality. The cheap magnet will cost you more later when repaired or replaced so it’s best to buy a better one in the first place.
When you decide to go with us for custom magnets, you have 100% control of the entire process. Our responsible sales staff will take the time to understand your needs and apply their expertise to help you solve problems. Working from your perspective to responsibly advance everything from material selection to magnet quality and durability testing so that our products meet your application.
Comparison of differences between common permanent magnet types.
Different permanent magnets have different magnetic strengths due to their different basic materials and production processes. The axis of strongest to weakest magnetic strength is very simple.
Comparison of magnetic strength: NdFeB magnets > SmCo magnets > AlNiCo magnets > Ferrite magnets;
The strongest magnetism in daily life and commercial applications is neodymium (NdFeB) magnets. They are widely used in applications that require high magnetic and strong magnetic fields.
Following neodymium magnets are samarium cobalt (SmCo) magnets, which are slightly weaker in magnetic force but very suitable for high temperature and corrosive environments. It is an ideal magnet for certain complex high temperature application environments.
AlNiCo magnets have very high thermal stability and can be used in sensors and speakers in industry. But their magnetic force is weaker than the previous types of magnets.
Ferrite (ceramic) magnets are more economical, have moderate magnetic force, and are suitable for everyday uses such as motors and household appliances. Although they are weaker than the permanent magnets above, they are relatively cheap and easy to obtain, making them a convenient alternative in consumer products.
Copper-nickel-iron (CuNiFe) and manganese-bismuth (MnBi) alloys are used in increasingly smaller quantities and have been phased out of use due to production costs and inefficiencies.
| Type | Composition | Br (Gauss) | Hc (Oesteds) | Bhmax (Mgoe) | Density (g/cm³) | Max Operating Temp | Temp Coefficient | Advantages | Disadvantages |
|---|---|---|---|---|---|---|---|---|---|
| Neodymium | Mainly neodymium, iron, and boron | 13,000 G | 11,500 Oe | 42 MGOe | 7.4 g/cm³ | 80 °C | 0.11% | High magnetic strength, compact size, cost-effective | Prone to corrosion, low-temperature tolerance, brittle |
| Alnico | Mainly aluminum, nickel, cobalt, iron | 12,500 G | 640 Oe | 5.5 MGOe | 7.3 g/cm³ | 500 °C | -0.02% | High-temperature resistance, stable in harsh conditions | Low magnetic strength compared to other types |
| Ferrite | Ceramic materials and iron oxide (Fe2O3) | 3,850 G | 2,950 Oe | 3.5 MGOe | 5 g/cm³ | 180 °C | -0.2% | Cost-effective, corrosion-resistant, good for general use | Low magnetic strength, low energy density |
| Samarium Cobalt | Mainly samarium and cobalt | 11,000 G | 9,700 Oe | 28 MGOe | 8.4 g/cm³ | 350 °C | 0.11% | High temperature tolerance, excellent corrosion resistance | Expensive, less magnetic strength than neodymium |
| Magnetic Rubber | Strontium or barium powder and synthetic rubber or PVC | 2,000 G | 1,600 Oe | 0.8 MGOe | 3.5 g/cm³ | 50 °C | 0.2% | Flexible, lightweight, easy to handle | Low magnetic strength, limited operating temperature |
FAQs
What is the strongest type of magnet?
The most powerful magnet is the rare earth neodymium magnet (NdFeB magnet), which is currently the magnet with the highest magnetic strength. But if we want to talk about the strongest high temperature resistant magnet, it is the alloy samarium cobalt magnet.
How many types of magnets are there?
Magnets come in 3 forms: permanent, temporary and electromagnet. Permanent magnets emit a magnetic field without the need for magnetic or electrical power from elsewhere. There are also three main categories of permanent magnets: metal alloy magnets, ferrite magnets, and rare-earth magnets. Each of these categories has several subtypes.
Will magnets lose their magnetism over time?
Magnets degrade with age, but in the absence of forces, an industrial magnet alloy ought theoretically to be magnetic for centuries. But magnets in the real world face external demagnetising forces. But good permanent magnets are engineered to last a very long time in an ordinary environment.
Can a magnet that has lost its magnetism be re-magnetized?
Use a permanent magnet or an electromagnet to re-magnetize a weak magnet. Hold the weaker magnet near the stronger one and rotate it as you go along the length so the poles are in the right direction. Do this again and again to reinforce the magnetic field of the weak magnet.
Can existing magnets be made stronger?
No, after a magnet has reached saturation it cannot be strengthened. It depends on the materials and manufacturing process what strength magnetic will have and therefore once saturated cannot be increased further.
Why should neodymium magnets be coated or electroplated?
Neodymium magnets should be coated or electroplated to keep them from rusting and breaking. The untreated neodymium itself is oxidable and will deteriorate with use if not stored properly. Coatings like nickel, zinc or epoxy allow the magnet to live longer and perform properly.
