The Most Popular Motor Magnets-Neo Arc Magnet

Arc segment motor magnet has advantages of easy manufacture and low cost compared with radial ring magnets. It’s still the most common motor magnet shape, especially for PM DC motor and magnet rotor.

As we all know, permanent Magnet is the core of PM motor.
In order to ensure the steadily electrical performance and long-term safe and reliable operation of electric vehicles, it requires the magnetic property of permanent magnet material remains stable. Considering magnetic performance influenced by the work environment, temperature and time, the reliability of permanent motor magnets can be divided into thermal stability, time stability, chemical stability, and magnetic stability.

rare earth magnet

1. Temperature stability can be shown by Curie temperature and the maximum operating temperature. As the temperature rises, the magnetic properties gradually reduce. When raises to a certain temperature, the magnetization disappears. This certain temperature is the Curie temperature of the permanent magnet materials, also known as the Curie point. The deficiency of NdFeB permanent magnet is relatively low Curie temperature, but higher temperature coefficient. Therefore neodymium magnets will be lost much magnetic force if work under high temperature. Due to the high-temperature coefficient of NdFeB permanent magnet, the magnetic properties are poor. To this end, it must pay more attention to Max. working temp.of sintered NeFeB magnet when you select a magnet grade. The test method of magnet temperature stability is the aging test

2. Chemical stability refers to the anti-oxidation and corrosion-resistant of permanent magnet material. Compared with the traditional ferrite or samarium cobalt (Smco) or alnico magnets, the chemical stability of sintered NdFeB magnet is the worst. Currently, the primarily solution is adding some alloy elements such as Co, Ni, Al and Cr, etc., while in the sintering process, increasing the density and reducing the porosity of magnetic material. Another approach is made certain magnet surface treatment such as electroplating. This can obtain a practical corrosion resistance for the magnet.

3. Time stability is putting the permanent magnet at a certain temperature for a long time, observing the change of its magnetic properties over time. These NdFeB permanent magnets added Co + Dy + Nb will obtain better time stability.

4. Magnetic stability is based on the magnetic material, and also affected by temperature, time, external magnetic field, chemical corrosion, radiation, mechanical vibration or shock and other factors.

Compared with electro-magnetic, we can list more advantages of segment arc motor magnet:
1. Simplify the structure of the motor
2. Easy maintenance
3. Light weight
4. Small volume
5. Operational reliability
6. low energy consumption

How to choose motor segment material?
For traditional AC motor, ferrite and AlNiCo segment magnets are most applied. With the higher request on motor power, more and more motor manufacturers use ndfeb and smco magnet which have super high magnetic energy product. However, they are more expensive because neodymium magnet and samarium cobalt magnet segments belong to rare earth magnet.

How to join neodymium arc magnets, which are diameter magnetized, to create a cylindrical ring that is radially magnetized?
The general approach is to make a sleeve or frame to put neo arc magnets in that will keep them in order and don’t jump around. The sleeve here has to be made of something sturdy and nonmagnetic, such as aluminum, copper or Q235 low carbon steel. Due to a strong repelling force, it’s better to operate by those experienced workers. If you are the first time to assemble segment magnets, just be careful. Halbach array magnets also utilize a frame or other tools to overcome the strong magnetic repulsive force between the same pole sides of two magnets and keep them fixing together.

Poles of Spherical Magnets

We know that the poles of bar magnets are actually at both ends, and the poles of horseshoe magnets are at both ends. But what about spherical magnets? If one is in the center of the sphere, one is in some part of the surface or on the sphere, it is obviously not tenable, because, in this way, there is no magnetic field around the spherical magnet. If we say that there are two relative points on the sphere, then obviously there can be countless magnetic poles, which is also impossible.

In fact, the magnetic poles of neodymium sphere magnets in nature are usually at both ends of a certain diameter, such as the NS poles of the earth. Of course, there may be a slight deviation, but it will not be much worse in general. As for artificial spherical magnets, their poles are related to the direction of magnetization during manufacture. There are many kinds of materials for artificial magnets, but no matter which kind of material is made into a certain shape and then magnetized. Therefore, its magnetic pole position is determined by the magnetizing method. When the direction of magnetization is determined, the magnetic poles are at both ends of the sphere diameter in that direction.

magnetic poles

We can also think about it through an ideal experiment. If a bar magnet is separated symmetrically from left to right by a straight line from N to S, then a very small piece is cut off on the left side and a very small piece is cut off on the right side at the same time. Then the remaining large N and S poles remain primitive. Repeat the action until the magnet is spherical. At this time, the magnet must still retain the original orientation of N and S poles. That is to say, the magnetic pole of a spherical magnet should be the same as the magnetic field of the earth, in effect, as a long magnet. The magnetic force line emits from the N pole and forms an arc in the outer space, pointing to the S pole. Inside the magnet, the line of force points from the S pole to the N pole.

ball magnets

Similarly, the external magnetic field of a hollow spherical magnet is the same as that of a solid sphere, and the magnetic poles are distributed at opposite poles. In the internal space, it is also a polar magnetic field.

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What Do Magnets Do

Magnets consist of iron, cobalt, nickel and other atoms. The internal structure of the atoms is quite special, and they have magnetic moments themselves. Magnets can generate magnetic fields and have the characteristics of attracting ferromagnetic materials such as iron, nickel, cobalt and other metals.


Different magnets have different uses.

Classification of magnets:

Shape magnets: block magnet, arc magnet, special magnet, cylindrical magnet, ring magnet, disc magnet, bar magnet, magnet frame magnet.

Attribute magnets: samarium cobalt magnet, neodymium magnet (strong magnet), ferrite magnet, aluminium nickel cobalt magnet, ferrochromium cobalt magnet.

Industry magnets: magnetic components, motor magnet, rubber magnet, plastic magnet 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, while soft magnets are added with electricity. (It’s also a way to add magnetism) If the soft iron is removed by the equal current, it will gradually lose its magnetism.

shape magnets

Use of different types of magnets:

1. Nd-Fe-B permanent magnet is a modern magnet with strong magnetism and is widely used.

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

2. Permanent magnet ferrites are used as constant magnets in meters, generators, telephones, loudspeakers, TV sets and microwave devices. They are also used in recorders, pickups, loudspeakers, magnetic cores of various instruments, radar, communication, navigation, telemetry, and other electronic devices.

3. Samarium-cobalt magnets have been widely used in detectors, generators, radar, instrumentation, and other precision science and technology fields because of their high working temperature of 300 degrees, corrosion resistance and oxidation resistance.

4. Aluminum-nickel-cobalt magnets are heat-resistant and corrosion-resistant. They are mainly used in motors, sensors, medical instruments, hand tools, loudspeakers, and various instruments.

5. Rubber coated magnets are different and heterosexual, and their homosexual attraction is weak. They are mainly used for propaganda (refrigerator stickers, car stickers, etc.), decorative gifts, refrigerator stickers, toys, teaching materials, etc. Heterosexual magnets can be used in small motors, sensors, magnetic adsorbents, etc.

Understanding the use of different magnets is very important for enterprises. Making full use of the characteristics of different magnets can better improve product performance.

Multiple Uses of Neodymium Disc Magnets Domestically

Neo magnets are super strong and very useful all around the house, office and workshop. Neodymium disc magnets are particularly sold for domestic use. Although they are small, these discs are still very hazardous and should be handled with care and kept out of reach of children.

neo disc magnets

Additionally, one should handle separate magnets with care as they can snap back and pinch the skin. An NdFeB disc is a permanent magnet that will retain its magnetism for several years. This is particularly if used in a favorable environment that cannot interfere with its plating or coating. They are made of neodymium, iron and boron and this is the strongest manmade alloy. A neodymium disc magnet, as mentioned above, has many uses around the office, house, garage or workshop. Some of the uses are summarized as shown below.

• Door catches. Small neodymium disc magnets are capable of pulling a twisted cabinet door straight. It can also hold it locked
• Use on fixtures, hardware and jigs
• Hanging items. These magnets are so strong that they can even be used on a corner dry wall that has a metal core.
• Neo disc magnets can be used in wood and other surfaces as long as they are backed by steel.
• Refrigerators
• Holding tools on the edge of a workbench for easier retrieval

Neodymium disc magnets should be kept from electronic devices such as, televisions, computer hard discs, floppy discs, cassette tapes, bank cards, credit cards and related items. This is because their strong magnetic fields can wipe out data on some of the electronic items mentioned above as they store it magnetically. Because drilling, screwing and machining these small items is a sensitive task, it should be done professionally.  Neodymium is very breakable even though hard. So if machined with the wrong equipment it can break easily and become waste.

To attach these discs to a particular surface use special adhesives made for use with neodymium magnets. Epoxy glue could also be used. Finally, customers should pay attention to the sizes of NIB magnets. These will depend on the applications one has. One thing is for sure though, that a very tiny neo disc magnet will hold an item that is two or more times heavier. One will find that the pull force of each magnet is indicated. For instance, neodymium disc magnets measuring ¼ x1/10 inches have magnetic strength of 2.5 lb.

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How to Separate Strong Magnets

Many people want to find a way to separate the magnets from an old hard disk due to the strong magnetic force among permanent magnets.

Well, how to merge and separate strong magnets?

It is a big and serious problem while people working with them.
The strong magnet is NdFeB magnet. Compared with ferrite magnets, AlNiCo, and SmCo magnets, Nd-Fe-B magnets can absorb 640 times weight of their own, so neodymium magnets are often called powerful magnets by outsiders.

The role of powerful magnets:

1. refers to the north and the South

2. attract small objects

3. electromagnet can be used as an electromagnetic relay.

4. motor

5. generator

6. electroacoustics

7. magnetic therapy

8. magnetic levitation

9. nuclear magnetic resonance

In daily life, strong magnets should be placed away from easily magnetized items, such as floppy disks, credit cards, computer monitors, watches, mobile phones, medical devices, etc. The magnet should be far away from the pacemaker. For larger size magnets, plastic or cardboard gaskets should be added between each piece to ensure that the magnets can be easily separated. Magnets should be stored in a dry and constant temperature environment.

Sintered neodymium magnets, even with small sizes, have the very strong magnetic force that will surprise you definitely. Permanent magnets belong to the dangerous object; when you handle them:
1. You should get some magnet safety-danger tips.
2. Do some clean-ups in the workplace to keep iron items away.
3. Prepare some tools like work glove, safety glasses, and woodblock, the wood block is a good spacer for big strong magnets.
4.Although demagnetizer is a way to separate magnets. But it will lose magnetic force. So it is very important to know the principle of separating magnets as below picture:

separate strong magnets

Due to the long shape of neodymium cylinder magnets to let you have the area to grab, you can separate two small cylinder magnets by hand. But for small thin neodymium disc magnets or other very big strong magnets, the first method is the right way. Here are the reasons:
1. Seek leverage from another object such as desk and/or find a better way to grab the magnets
2. Separate magnets apart parallel, which requires less force.

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What Material to Choose? – Neodymium Magnet, SmCo, AlNiCo, Ferrite

When you choose the permanent magnetic materials, you need to consider the following aspects:

permanent magnetic materials

1. Magnetic Performance
BHmax is the point where a magnet delivers more energy to the minimum volume. If you want to compare the magnetic performance of different types and degrees of permanent magnets, the most convenient method is to consider your BHmax.

magnet BHmax

Another parameter that must be taken into account is the flux density at the pole face of a rare earth magnet. This value is often confused with the Br, but in fact, it is purely the induction in a closed circuit. The following table shows the typical densities of the four pole flow point when working at about its BHmax points.

pole face magnet

2. Maximum working temperature
Effects of temperature can be classified into two categories, reversible and irreversible. Reversible changes with temperature have nothing to do with the shape, size or working point of the demagnetizing curve. They depend on the composition of the material. Irreversible losses will not appear in a certain temperature is not exceeded. In addition, they can also be limited by operating at high as a possible work point. But when the outside temperature exceeds the Curie temperature of a magnet, metallurgical changes occur inside the magnet and there will be irretrievable losses.

Maximum working temperature
The working point in the circuit determines the maximum working temperature of a magnet. The higher the working point is, the higher the magnet temperature can operate.

Working Temperature

3. Effects of exposure on Magnetic Stability
Although the high temperature is the greatest threat to magnetic stability, exposure to high external fields also has an effect on certain types of magnets. The following table shows the effects of different grades:
Magnetic Stability

Shock and vibration effects
The traditional magnets have always been affected by shocks and vibrations, but now it has little effect on modern magnetic materials, except for more closely calibrated devices. However, the mechanical impact will cause the magnetic materials to be brittle and fractured. SmCo is the most fragile magnet.

Effects of Radiation
Magnets are used in particle beam deflection applications and those with an upper HCI are more suitable for use in such environments. According to some tests, SmCo magnet has significant losses when exposed to high levels of radiation (109-1010 rads). Losses at low levels of radiation are basically the same as the loss of temperature. It is notable that some magnetic materials have Cobalt in them, and Cobalt can retain the radiation after exposure.

Effects of Shape
The performance and stability of a magnet are also affected by its shape. The shape of the magnet determines its working point along the degaussing curve. The higher the operating point, the more difficult it is for the magnet to be demagnetized. Magnets that have a longer length or are used in an enclosed magnetic circuit have better performance and magnetic stability.

Some methods may be adopted to improve the stability of magnetic performance, such as demagnetization sites and high-temperature aging treatment. After exposing the magnet in advance for possible negative influences, the unstable texture and magnetic domains disappear and the magnet may be magnetically more stable.

The total collapse of the composition will also cause loss of performance. Corrosion can break the magnet structure down, and from neodymium magnets, exposure to hydrogen will lead to structural breakage as well.

4. Corrosion resistance without coating
The coating can prevent the shape of magnets from being corroded. There are many protective coatings available. NdFeB often has nickel, zinc, varnish, epoxy resin or Parylene as a protective layer. Normally Alnico does not need coating, but the powder coating and galvanizing can be used when needed.
Corrosion Resistance

5. Price Comparison
There are several factors that affect the price of a magnet, such as a shape, tolerances, and quantity. However, the most important effect is the cost of the basic raw material. When there is a need for new sizes and production volume of magnets, tooling should be considered at times. In addition, accessories are sometimes required for near-machining tolerance.
Price Comparison

6. Properties of magnetic force lines
• The magnetic lines of force form closed loop outside the magnet is directed from the north pole to the south pole and inside the magnet from the south pole to the north pole.
• Magnetic force lines always look for the path of least resistance between opposing magnetic poles.
• Magnetic force lines can never cross. They repel each other when they travel in the same direction.
• Normally magnetic force lines always move along curved paths.
• Magnetic force lines will always follow the shortest path through any medium.
• Magnetic force lines always enter or exit a magnetic material at right angles to the surface.
• All ferromagnetic materials have limited capacity for power lines. When they reached their limit, they behave as if they were not there, such as an airspace or similar.

7. Useful Project Suggestion
• Always pay attention to the working temperature of the material you need.
• Temperature has the most significant effect on magnetic stability, so always take this into consideration as part of your design and your choice of material.
• The strongest one may not be the best.
• Beside flow resistance, there are still many other magnetic drawing factors to consider.
• Magnet performance can be improved with a steel pole.

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What are the Different Shapes of Magnets?

There are probably few limits to the shapes that magnets can be formed into. The factor that determines the shape that a magnet is formed into is the desired shape of the magnetic field that comes from the magnetic poles.

Uses of Different Shaped Magnets and Strengths:
Each magnet is designed and manufactured for its use and purpose to fit in for its use and the real strength of the magnet comes from the magnetic material, each shape of the magnet have the effect on the strength of the magnet and shape of the magnet is very important and significant.

magnet shape

The most common shapes you will see are rectangular prisms, cylinders, spheres, and rings, however, there are few limits to what shapes you can have with a magnet. You can buy neodymium arc magnets, neodymium bar magnets, neodymium block magnets, neodymium cylinder magnets, neodymium disc magnets, neodymium ring magnets, square pyramid magnets, conical magnets, triangular prism magnets, heart-shaped magnets, etc.

Now, let’s see what are different shapes of magnets now in detail about shapes of magnets:
Blocks and Bars:
These blocks and bars magnets have fully with the flat surface and in shape of perpendicular to each other.
Threaded Tiny Magnets:
Threaded magnets are partial with the use of their threaded shaped through magnetic rings and wooden plates and these include countersunk holes design and threaded shape which helps in holes to perfectly fit in with the threaded shape.
Rubber Coated:
Rubber coated magnets which are used for magnet keepers and used for protection purposes, these are tiny and generate and contact with large fields and these plastic coated magnets are used against the rust without irritations.
Bar Magnets :
Bar magnets are one of the weakest magnets of all shaped magnets.
Horseshoe Magnets :
Uses of horseshoe magnets and Horseshoe magnets are just barred magnets bent in u shaped and the U shaped magnet makes stronger by bending them in U shape just pointing the poles in the same direction which makes them stronger. As it is named horseshoe it can be used to collect pins, industrial materials etc.
Disc Magnets :
Disc magnets are mainly used for holding applications where the drilled hole plays an important role and it is recessed into the hole. There are lot of things we can do with disc magnets. The use of Disc Magnets is shaped in thin flat circular magnets and its thickness does not exceed the diameter.
Cylinder Magnets:
Cylindrically shaped magnets are used as rods and used in medical treatment as well sometimes for multiple surgeries, using this shape of the magnet in human spine bone and etc. Cylindrically shaped magnets posses the high level of magnetism from relatively small surface pole area rod shape with a ball end shape.
Ring Magnets:
Ring magnets are widely used in science experiments and they are used in various daily use products like the vacuum cleaner, motors, generators etc.
Pyramid Magnets:
Pyramid magnets with its shape in pyramid help to produce and designed in a way to fabricate or generate with huge flux density with it.
Sphere Magnets :
The main use of sphere magnets is for toys, and novelty products as it is shape and structure in the sphere and the magnetic flow in shape of sphere flows from north pole on the sphere to south pole on the sphere.