Permanent Magnet in IH Rice Cookers

Demand Increase of Permanent Magnet
With the rice cooker, IH technology is bound to use a magnetic material (including neodymium n52, cobalt, nickel, etc.), many domestic and foreign manufacturers in the development and mass production of IH rice cookers, which means rare earth magnet demand will be increasing.

IH Rice Cooker – Super High-End Rice Cooker on The Market Now
IH is an abbreviation for Induction Heating, Induction means electromagnetic induction, and Heating, by definition, which is “electromagnetic heating.”

IH Rice Cookers

Electromagnetic Coil Technology
This product canceled the heating plate of the traditional rice cooker, instead, an electromagnetic coil, mounted on the inner portion and the bottom of the pot between the insulation cover, using electromagnetic induction heating to cook food, so that the inner pot is both a carrier and heat generation.

Compared With The Traditional Rice Cookers
IH rice cooker is not only fast and uniform heating, but also in environmental protection, service life and safety performance also has unique advantages, it will be the future development trend of the rice cooker.

Non-Contact Heating Technology
It works by generating a frequency of 20-40 kHz high-frequency alternating current through the control circuit, the high-frequency current flowing through the solenoid will produce rapid changes in alternating magnetic field,When an alternating magnetic field lines close through the magnetic field near the custom magnet (iron, cobalt, nickel) will drive the material’s microcrystalline structure of the metal, thus producing countless small eddy, and then let the metal material microstructure friction between itself and its own fever, achieve the purpose of non-contact heating of the metal material.

How to Recycle Magnets

The magnet made from rare earth is not a new technology. It was developed by scientists as early as 1982. Its official name is “NdFeB strong magnet”. The method is to extract Nd, Fe, and B from rare earth to form the metal body and then turn on current to magnetize.

The neodymium magnet is the most powerful magnet at present, and the loss of magnetic force is very slow, almost reaching the effect of the permanent magnet. Neodymium magnets are now widely used in computer hard drives, Halbach array, mobile phones, eardrums, speakers, and battery-powered electronic products.

Recycle Magnets

Turning old into new

Permanent magnets recycle means the extracting the rare earth elements from the magnets again. However, it is very hard and expensive.

The scientists of the Fraunhofer Project Group for Materials Recycling and Resource Strategies IWKS in Alzenau and Hanau of the Fraunhofer Institute for Silicate Research ISC are now pursuing a different approach to recycle the entire material instead of trying to regain each individual type of rare earth.

Because the composition of the material is already almost as it should be, this process only needs a few steps, and this is much easier and more efficient.

The first magnet successfully recycled
The scientists rely on the melt spinning process that already tried and tested for other alloys, also known as “rapid solidification”. The details are as below:
The researchers liquefy the magnet in a melting pot. The liquefied material, heated to more than 1000 degrees Celsius, is directed via a nozzle onto a water-cooled copper wheel that rotates at a speed of 10 to 35 meters per second. As soon as the melted droplet comes into contact with the copper, it transfers its heat to the metal within fractions of a second and solidifies.
The scientists call the emerging material formations “flakes”. The special feature is the structure formed inside the flakes. If the melted material were allowed to solidify in the normal way, the atoms would “line up in rows” in a crystal lattice. In the melt spinning procedure, however, crystallization is avoided: Either an amorphous structure is formed, in which the atoms are completely irregularly arranged, or a nanocrystalline structure, in which the atoms arrange themselves in nanometer-sized grains to form a crystalline structure.
The advantage: The grain sizes – meaning the areas with the same crystalline structure – can be specifically varied. They can be used to change the properties of the permanent magnet. In a further step, the researchers mill the flakes into a powder, which can then be further processed. “We press it into its final shape”, Diehl says

If the price of rare earth elements continues to go up, magnet recycling will be more cost-efficient and recycling permanent magnets from wind turbines and electric motors will be popular.

Now they have already set up a demonstration plant and have managed to recycle magnets there. This demo system can process up to half a kilogram of molten material and is somewhere between a lab and a large-scale plant.

In many cases, the rare earth magnets are extremely difficult to remove from the engines. So the potential ways of creating a collection cycle for used engines, and also of a design more suitable for disassembly is what the scientists want to develop.

NdfeB Magnets for Electrical Fields

With the increasing performance of permanent magnet materials, rare earth permanent magnet materials are widely used in electrical fields.
Using high-performance rare earth permanent magnet materials to make a motor, the structure does not require special electrical excitation system, which helps to improve motor efficiency and power factor, and save energy, to reduce the size of the motor.

electrical motor
Currently in the design of permanent magnet motor, the general assumption that a uniform distribution of the various parts of the magnetic field of the permanent magnet and the magnetic properties of the same batch of neodymium magnets can be the same, while the need to use a permanent magnet demagnetization curve of permanent magnet at room temperature under suppliers, intrinsic connectivity magnetic parameters, residual magnetism, such as density and maximum energy product.

However, since the manufacturing process and the level of the plant and other reasons, there is a temperature in each portion of a permanent magnet hereinafter actual performance differences and the performance of the same group of permanent magnets is different.

The magnetic properties of the permanent magnet
The permanent magnet motor in normal operation can be closely related to the magnetic permanent magnet.
The strong magnet motor can directly determine whether reliable operation.
When the permanent magnet motor is running, sometimes the rotor temperature is high and NdFeB irreversible demagnetization will happen, causing permanent magnet synchronous motor efficiency and power factor and other performance indicators deteriorated.

What is Halbach Array Motor

Halbach array is a new type of permanent magnet arrangement combined with the radial and tangential array, which can increase the magnetic field on one side of and weakened the magnetic field on the other side.
Using Halbach array in permanent magnet motor can increase the magnetic flux in the air gap and decrease the magnetic flux in the rotor yoke, and it is most suitable for the inner or outer rotor of the external permanent magnet.
At present, the permanent magnet motor is developing toward high power, high function, and miniaturization. The high power density and high efficiency are the basic requirements for all types of permanent magnet motor design.
According to the principle of magnet motor design, the increase of magnetic loading is to increase the motor gap magnetic flux density, which can reduce motor size and improve the power density.

Halbach array motor

For permanent magnet motor, generally, there are two measures to increase air gap flux density in the motor.
1. Change magnetic material: try to use permanent rare earth magnet with higher residual magnetic flux density. But restricted by magnet material performance and price, the actual alternatives are few.
2. Change magnet structure and arrangement

In brief, its application in the permanent magnet motor has great advantages:
1. The sine wave of air-gap magnetic field
2. Good magnetic shielding effect
3. High power density
4. Lightweight
5. Small in size

Neodymium magnets play a very important role in the renewable energy market. So we believe this magnet motor could find a broad range of industrial and automation applications, from electric vehicles, aerospace, independent power generation to other occasions.

The magnetic rotor assemblies are complex, including a wide variety of permanent magnets:
1. Samarium Cobalt (SmCo)
2. Neodymium Iron Boron
3. Ferrite
4. AlNiCo

What is Permanent Magnet Motor?

Magnetic Assembly—Permanent Magnet Motor

The Permanent Magnet Motor includes
– armature with split ring commutator at one end
and a dual slip-ring commutator at the other
– field magnet, shaft and brush assembly
– maintenance items
– manual
ceramic magnet

The Permanent Magnet Motor can be used to demonstrate the operation of a DC motor. The Permanent Magnet Motor can be used to determine the speeds of maximum power and maximum efficiency of a DC motor by varying the load while simultaneously measuring the speed, torque, and armature current.

magnet motor

The field magnets are permanent magnets possessing a north pole and a south pole that interact with the north and south poles of the armature (an electromagnet when connected to an electric current). Like poles repel, while unlike poles attract. The armature rotates until its north pole is as close as possible to the south pole of the permanent magnet (and also as far as possible from the north pole). Inertia carries the armature past this point.

However, as the armature passes this point, the commutator reverses the direction in the coils, so that the poles of the coils are suddenly repelled by the nearby field magnets. Thus another half-turn occurs, and this process occurs again and again.

A better explanation involves an understanding of fields. The field magnets produce a magnetic field that passes through the gap between the pole pieces. When current passes through the turns of the armature in the presence of the field, forces act to cause a torque that rotates the armature.

Inertia carries the armature past the position of no torque to the point where the torque would force the armature back in the other direction. However, at that point the commutator reverses the direction of current in the armature so the torque continues to act in the original direction.

How to start a simple motor?
The motor is not self-starting. Immediately after you apply the power, start the motor manually by grasping the black plastic bushing at the top of the armature assembly between your thumb and forefinger and spinning the armature.

With the Permanent Magnet Motor configured as either a DC or universal motor, almost any attempt you make at spinning the armature will result in successfully starting the motor; only the direction of the spin is important.

When configured in an AC synchronous mode, the motor must be spun at a speed that approximately matches the frequency of the power source.

What Should We Know About Magnets?

Magnets are composed of iron, cobalt, nickel and other atoms, the internal structure of the atom is relatively special, it has a magnetic moment. Magnets can produce magnetic fields and attract the properties of ferromagnetic materials such as iron, nickel and cobalt.

Different types of magnets have different uses.

Classification of magnets:

Shape magnets: square magnet, arc magnet, special-shaped magnet, cylinder magnet, ring magnet, disc magnet, bar magnet, magnetic frame magnet.

Attribute magnets: SmCo magnets, NdFeB magnets (powerful magnets), ferrite magnets, AlNiCo magnets, Fe-Cr-Co magnets;
Industry magnets: magnetic components, motor magnets, rubber magnets, plastic magnets and so on.

Magnets are divided into permanent magnets and soft magnets. Permanent magnets are added with strong magnets, so that the spin of magnetic materials and the angular momentum of electrons are arranged in a fixed direction. Soft magnets are added with electricity. It is also a way of adding a magnetic force. If the current is removed, the soft iron will slowly lose magnetism.

powerful magnets

The use of different types of magnets:

1. Neodymium iron boron permanent magnet is a modern permanent magnet with strong magnetism, and its application is also extensive.

It is mainly used in electroacoustics, permanent magnet rotor, communications, automotive electronics, magnetic machinery, aerospace, computer, household appliances, medical equipment, office automation, toys, packaging boxes, leather products, magnetic accessories and other fields.

custom neo magnets

2. Permanent magnet ferrites are used as permanent magnets in electric meters, generators, telephone sets, loudspeakers, television sets and microwave devices. They are also used in recorders, pickups, loudspeakers, and magnetic cores of various instruments. They are used in radar, communications, navigation, telemetry and other electronic devices.

3. SmCo magnets can operate at temperatures up to 300 degrees, and have corrosion resistance and oxidation resistance. They have been widely used in detectors, generators, radar, instrumentation, and other precision science and technology fields.

4. Al-Ni-Co magnets are high temperature resistant and corrosion resistant. They are mainly used in motors, sensors, medical instruments, manual tools, loudspeakers and various instruments.

5. Rubber coated magnets have the same and different characteristics, the same suction is weak, mainly used for publicity (refrigerator stickers, car stickers, etc.), decorative gifts, refrigerator stickers, toys, teaching materials and other areas.

What Neodymium Magnets Used For

Neodymium magnet is a permanent magnet material based on intermetallic compound Nd2Fe14B. NdFeB permanent magnets have been widely used in modern industry and electronic technology due to their high magnetic energy product and coercivity, and high energy density, which makes it possible to make instruments, electroacoustic motors, magnetic separation, and magnetization equipment small, lightweight and thin.

Neodymium has the advantages of high-cost performance and good mechanical properties; the disadvantages are low Curie temperature point, poor temperature characteristics, and easy to pulverize and corrode. It must be improved by adjusting its chemical composition and adopting surface treatment methods to meet the requirements of the practical application.

The sintered NdFeB permanent magnets are made by powder metallurgy. The melted alloy is made into powder and pressed into compacted embryos in the magnetic field. The compacted embryos are sintered in inert gas or vacuum to achieve densification. In order to improve the coercivity of magnets, aging heat treatment is usually needed.

permanent magnets

Applications of neodymium magnets

At present, the main application fields are permanent magnet rotor, generator, nuclear magnetic resonance imager, magnetic separator, acoustic loudspeaker, magnetic levitation system, magnetic drive, magnetic lifting, instruments and meters, liquid magnetization, special-shaped magnet magnetotherapy equipment and so on. It has become automobile manufacturing, general machinery, petrochemical, electronic information industry.

Comparison between NdFeB and other permanent magnets

NdFeB permanent magnet is the strongest permanent magnet in the world at present. The magnetic energy product of special-shaped magnet is ten times higher than that of ferrite, about twice as high as that of the first and second generation rare earth magnets (samarium-cobalt permanent magnet), and is known as “the king of permanent magnets”. Instead of other permanent magnets, It can double the volume and weight of the device. Because of the abundant neodymium resources, compared with the samarium-cobalt permanent magnet, the special-shaped magnet replaces the expensive cobalt with iron, which makes the products cheap in price and good in quality, so it has been widely used.

magnet rotor

The principle of ferromagnetic NdFeB

1. Ferromagnetic materials such as iron, cobalt, nickel or ferrite are different. The electron spins in them can be arranged spontaneously in a small range to form a spontaneous magnetization region, which is called a magnetic domain. Ferromagnetic materials after magnetization, the internal magnetic domains neatly arranged in the same direction, so that the magnetism is strengthened, constituting a magnet. The magnet’s absorption process is the magnetization process of the iron block. The magnetized iron block and the magnet produce attraction between different polarities, and the iron block is firmly attached to the magnet.

2. Matter is mostly made up of molecules, molecules are made up of atoms, and atoms are made up of nuclei and electrons. Inside the atom, electrons spin and revolve around the nucleus. These two motions of electrons generate magnetism. But in most substances, electrons move in different directions, in disorder, and the magnetic effects cancel each other out. Therefore, most substances do not exhibit magnetism in normal conditions.

3. Determined by the characteristics of the magnet, if interpreted by the atomic current, it is the magnetic field generated by the current magnetizing other objects, magnetizing objects produce an electric field, then the electric field has interaction force.

What are the Types of Magnets?

There are many kinds of magnets, generally divided into permanent magnets and soft magnets.

Permanent magnet is divided into two categories:

The first category is: metal alloy magnets include NdFeB, SmCo and AlNiCo magnets.

The second category is ferrite permanent magnet.


1. Neodymium-iron-boron magnet: It is the most commercially available magnet, known as the magnet king, with extremely high magnetic properties, its maximum magnetic energy product is more than 10 times higher than that of ferrite. Its mechanical properties are quite good. The working temperature can reach up to 200 degrees Celsius. Moreover, its texture is hard, its performance is stable, and its cost performance is very good, so its application is extremely extensive. But because of its strong chemical activity, the surface layer must be treated.

2. Ferrite magnet: its main raw materials include BaFe12O19 and SrFe12O19. It is a brittle material with hard texture. Ferrite magnet has been widely used because of its good temperature resistance, low price and moderate performance.

magnets assembly

3. Aluminum nickel cobalt magnet: an alloy consisting of aluminum, nickel, cobalt, iron and other trace metals. The casting process can be made into different sizes and shapes, with good workability. The cast aluminum nickel cobalt permanent magnet has the lowest reversible temperature coefficient, and the working temperature can reach up to 600 degrees Celsius. Al Ni Co permanent magnet products are widely used in various instruments and other applications.

4. Samarium cobalt (SmCo) is divided into SmCo5 and Sm2Co17 according to their components. Because of the high price of materials, their development is limited. SmCo, as a rare earth permanent magnet, not only has a high magnetic energy product, reliable coercivity, and good temperature characteristics. Compared with NdFeB magnets, samarium cobalt magnet is more suitable for working in a high-temperature environment.

The Strongest Permanent Magnet-Neodymium Magnets

At room temperature, the neodymium magnet is the most powerful permanent magnet.

But this is only at room temperature. Early Neo magnets had an annoying flaw: they were sensitive to temperature, and when the temperature rose, the magnetism dropped dramatically, and when it was above 100 degrees Celsius, it was completely demagnetized. But now an improvement has been found by adding a small amount of dysprosium, another rare earth metal, which is less sensitive to temperature changes.

neo magnets

At the same time, a technological revolution driven by permanent magnets opened the curtain. Anywhere you want to produce the strongest magnetic field with the least amount of material, Neo permanent magnets are preferred: car engines, spindle motors on CD and DVD readers, electric signals converted into sound diaphragms in headphones and speakers, and super magnetic fields needed in medical magnetic resonance technology… By 2010, even though cheaper ferrites still dominated the market, neodymium permanent magnets were worth more than a dozen or even hundreds of times more than ferrites in terms of volume.

However, when Neo permanent magnets were developed, the demand for rare earth metals surged. Rare earth metals aren’t really rare on the planet — they are a few parts per million in the earth’s crust — they’re “rare” because they’re hard to find.

Search for new permanent magnet materials

Each computer needs only 50 grams of Neo permanent magnet. It doesn’t seem like much, but given the number of computers around the world, it’s almost an astronomical number. Now, with the rise of green energy technology, the consumption of computers has become a great mystery. Turbine motors in wind farms, as well as electric cars and bicycles, require lightweight and powerful permanent magnets, and only Neo magnets currently meet the requirements. Each electric vehicle consumes 2 kilograms of Neo permanent magnets. The power of megawatt wind turbines will consume 2/3 tons of Neo permanent magnets. Therefore, it is imminent to develop new and stronger permanent magnets. It is better to reduce the number of rare earth metals. The ideal situation is to stop using rare earth metals.

Neo magnet

The United States has invested huge sums of money in finding new permanent magnets. At present, scientists are trying to improve the performance of Fe Ni alloy permanent magnets. Usually, when two magnetic metals, iron and nickel, are fused together, they form disordered structures in which it is difficult to align electrons in the same direction. One exception, however, is that iron and nickel atoms are arranged in regular layers in a mineral called cubic nickel rubble. Once a magnetic field is applied, the electron spins tend to move in the same direction.

But this mineral is very difficult to form under natural conditions, especially on the earth. In fact, the only orthoclase sample in the world today comes from a meteorite that took at least billions of years to form. One billion years is certainly too long for us. The goal of scientists is to synthesize it in the laboratory and do what nature needs to do in billions of years.

Another ongoing attempt that seems to be completely different is to use carbon as a permanent magnet. It is well known that graphite and diamond are nonmagnetic, and the incorporation of carbon into pure iron also makes it lose its magnetism. But making compounds of carbon and other elements into nanoparticles is another matter. Scientists found that the material showed strong magnetism. For commercial secrecy, what the material is and how to make it is not convenient for scientists to disclose. But they say the permanent magnet will one day beat neodymium at both performance and price.

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