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1. Aadvantages of Segment Arc Motor Magnet
2. The Performance of Magnetic Segment Impact on Motor
3. How to Choose Motor Segment Material?
4. Permanent Magnet: the Core of PM Motor
5. How to Join Neodymium Magnet Arcs Into a Radially Ring?
6. Motor Magnet Customized Service

We recently highlighted radially magnetized ring magnet for micro motor rotor in our previous blog. However, this does not mean that the traditional arc segment motor magnet will disappear gradually. Segment motor magnet has advantages of easy manufacture and low cost compared with radial magnet ring. It’s still the most common motor magnet shape, especially for PM DC motor.

1. Compared with electro-magnetic, we can list more advantages of segment arc motor magnet:

1. Simplify the structure of motor
2. Easy maintenance
3. Light weight
4. Small volume
5. Operational reliability
6. low energy consumption

2. The performance of magnetic segment impact on motor or generator:

1. Br (residual magnetic flux density): high Br can ensure that the motor has a high speed, high torque and high output power. Then the motor will have a high efficiency. Such as for starter motor, high Br magnet arc will provide high instantaneous start-up force.
2. Hcb: high Hcb can provide enough electromotive force needed for motor output, making the operating point of motor close to the maximum energy product to take full use of magnetic property.
3. Hcj: high Hcj can ensure there is a strong resistance against the demagnetization caused by motor overload, against the anti-aging, and against the low temperature. If you need durability motor, then choose high HC motor segment magnets.
4. Magnetic energy product (BH) max.: the higher (BH) max. , the better working coefficient of permanent segment magnets in the motor actual operation.
5. Magnetic flux: the bigger the better; it will greatly improve the work efficiency of the motor.
6. The rectangle degree of the demagnetization curve: the higher rectangle factor , the smaller the dynamic losses in the motor.
7. The higher resistivity, the smaller the eddy current losses.

3. 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. Please click here to get more analysis of different magnet material.

4. Permanent Magnet: the core of PM motor

In order to guarantee 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 work environment, temperature and time, the reliability of permanent motor magnets can be divided into thermal stability, time stability, chemical stability and magnetic stability.

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 disappear. 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.Thus neodymium magnet will lost much magnetic force if work under high temperature. Due to the high temperature coefficient of NdFeB permanent magnet, the magnetic properties is poor. To this end, it must pay more attention to Max. working temp.of sintered nedfeb magnet when you select an magnet grade. The test method of magnet temperature stability is aging test
2. 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.
3. 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 make certain magnet surface treatment such as electroplating. This can obtain a practical corrosion resistance for magnet.
4. Magnetic stability is based on magnetic material, and also affected by temperature, time, external magnetic field, chemical corrosion, radiation, mechanical vibration or shock and other factors.

5. How to join neodymium magnet arcs, 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 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 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 frame or other tools to overcome the strong magnetic repulsive force between the same pole sides of two magnets and keep them fixing together.

6. Motor Magnet Customized Service

According to special requirement of different motors or generators, there is few standard segment rotor magnets available on the market for customers to choose. Every motor manufacturer will design different product based on their technology, market direction, therefore segment magnets of motor rotor need to be customized. China Magnets Source Material Ltd a professional magnets manufacturer for many years and specialized in motor NdFeB magnet. When you ask for a quote, please provide detailed information as follow:

1. Material: Sintered Neodymium Iron Boron Magnets or bonded ndfeb magnet or samarium cobalt or alnico magnet or ferrite magnet
2. Grade: please click here and select from our table
3. Coating: please click here and select from our table
4. Size: drawing is needed for segment magnet
5. Magnetize or Not:
6. Magnetized Direction: please show on drawing
7. Quantity: we don't have MOQ, but price will be cheaper if you order more at a time