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Boosting Motor Performance with Laminated Magnets: Reducing Eddy Current Losses for Enhanced Efficiency

At Tengye, we employ advanced magnet lamination and insulation technology to manufacture laminated NdFeB magnets that meet the specific needs of our clients' motor applications. Our laminated magnets help to enhance motor efficiency, reduce heat generation, and extend the lifespan of the motor.

Introduction of Laminated Magnet

Laminated magnets, also known as segmented magnets, consist of two or more individual magnets that are bonded and insulated to each other. They were developed to enhance the performance of electric machines by preventing the magnets from overheating. Laminated NdFeB magnets are commonly used for this purpose, but Sm2Co17 magnet also serves as a fundamental magnetic material for magnet segmentation technology.

laminated magnets

Technical Background of Laminated Magnet

As electric motors for vehicles and generators for wind power constructions continue to develop, there is a growing demand for sintered NdFeB magnets. These magnets are essential components in these devices, allowing them to operate at high speeds. However, the high-speed operation also produces eddy currents in the magnets, causing them to heat up and demagnetize at a certain point. To address this issue, complete NdFeB blanks are segmented and laminated together with adhesive to create independent magnet parts that are insulated from each other. This helps to significantly reduce eddy current loss and maintain lower temperatures within the NdFeB magnets during motor operation.

How Magnet Segmentation Conquers Demagnetization

A drawback of NdFeB magnet is its poor resistance to high temperature. NdFeB magnets demagnetize at high temperature. By laminating and insulating NdFeB blank, eddy current path is broken into multiple paths. Thus, it reduces eddy current density and eddy current loss decreases as well. To provide you with a better understanding, we recommend JMAG’s article – Analysis of the Eddy Current in the Magnet of an IPM Motor.

simulation comparison of laminated and non-laminated magnets

Types of Laminated Magnets

Laminated NdFeB magnets can be formed by gluing individual NdFeB magnets together, either before or after coating depending on the technical requirements of the application. 

In the “after-coating type”, individual magnets are coated first and then glued together to form a larger unit, as seen in the segmented magnets mounted on the rotor above. “Before-coating type” can be found in axial flux motors, as shown in the picture on the right. However, the manufacturing process of laminating these magnets is intricate and expensive.

neodymium block magnet
7 single neo magnets
24011639218933 .pic hd
magnet block composed of 2x7 unit
segmented magnets rotor
PMSM rotor with segmented magnets

Essential Manufacturing Process of Laminated Magnets

First, NdFeB blanks are sliced into equal-thickness single pieces and then laminated with insulation glue. The fully laminated blank is then cut, sliced, and ground to the desired geometry and size, creating a complete laminated NdFeB magnet. The bonding adhesive typically achieves a maximum insulation rate of 95%. However, due to the adhesive, electroplating is not possible, as the magnet body is no longer electrically conductive. As an alternative, common coating solutions include epoxy-painting (usually black) or phosphorization.

manufacture of laminated magnets

Licensed Laminated NdFeB Magnets

To avoid potential legal issues, companies selling products containing NdFeB magnets in North America or Japan are strongly advised to use Hitachi licensed neodymium magnets. In China, there are only eight Hitachi authorized NdFeB manufacturers. At Tengye Magnetic, our strategic partnerships with some of these authorized manufacturers allow us to efficiently and affordably source licensed magnets, even in low volume, ensuring compliance with local laws and regulations.

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