Laminated magnet

What is laminated magnet

Laminated Magnet is a special magnetic assembly, which is also called insulated magnet or glued magnet because it is made of several individual thin permanent rare earth magnets bonded to each other by insulated glue .For example, rare earth magnets are glued to each other or onto a steel plate with the same polarity across the entire stack. Laminated magnets can reduce eddy current losses in high-efficiency motors and enhance the performance of electric machines. Less eddy current loss refers to less heat and waste that preventing the magnets from overheating. Laminated Samarium Cobalt permanent magnet and laminated Neodymium Iron Boron magnet are proven to obviously reduce the eddy current loss for the high efficiency motors. The electrical resistance of bonded magnets could be 102 to 104 times more than conventional sintered magnets due to the existence of binder glue. So laminated magnet is the ideal solution for improving the efficiency of motors, which is widely used in the aerospace, motorsport, automotive, etc.

Mag Spring can supply both SmCo and NdFeB Laminated magnet:

1. Neodymium magnets have many grades with different magnetic energy that range from 30MGOe (230KA/m3) to 55MGOe (438KA/m3) and working temperature from room temperature to 280 C, which can be used in many types and purposes of electric motors. Laminated Neodymium magnets with high Hcj are used in new energy motors, aerospace, etc.
2. Samarium Laminated Magnet is the ideal magnetic material where the magnets are required to be used in a stable magnetic field or a corrosive environment. Because of its outstanding thermal stability, (Br) low to -0.03 %/oC and (Hcj) low to -0.2%/oC and excellent corrosion resistance, surface treatment is not necessary.

The advantage of laminated magnets:

1. Epoxying Coating is available to prevent NdFeB magnets from rusting or decrease the risking of SmCo Magnets Chipping
2. Working temperatures is up to 200 C;
3. The unique production way increases the competitive advantage in the production efficiency, manufacturing accuracy and cost control;
4. The individual magnets are insulated from each other to form an assembly;
5. The thickness of insulating layers is from 0.025mm to 0.10mm(25um-100um);
6. Magnet material SmCo or NdFeB is avaibale;
7. Magnet shape in block, segment or wedge is available;
8. Avoid the irreversible demagnetization and increase safety, stability of motor work by decreasing electromagnetic eddy current loss in laminated structure form.

Disadvantage of Laminated Magnets:

1. Max working temperature is no more than 200 C because of the working temperature limit of glue max;
2. Production way is complicated and lead time is not short as well as the unit cost is very high;
3. Laminated Neodymium Magnets need protective coating because it is easy to rust. After gluing, Epoxy coating or Painting cannot is available while NiCuNi or Zn coating is not acceptable. Laminated Samarium Magnets do not need protective coating; however, it is easy to chip due to its brittleness that comes from the physical properties of Samarium Cobalt Magnets.

Why Laminated Magnets are expensive

1. Both raw material of Samarium Magnets and Neodymium Magnets are not cheap especially, the price for both Cobalt and Neodymium in 2021 have been increasing more than two times.

2. To achieve a good binder power, high-level insulation, resistance, and high temperature, the cost for high quality glue is not low
3. The laminated magnet is not simply glued by the thin parts together as what are seen. Many factors have to be taken into consideration during the manufacturing process because the tolerance of finished magnets is very strictly; our staff have to use bigger size of green magnets for gluing, which have to be sliced into thin pieces before gluing, and many steps of machining process are necessary according to different shape and size after gluing. Therefore, the waste for the expensive SmCo and Neodymium magnet materials is higher and the steps of machining process is more. Above of which leads to the much higher cost than common SmCo or NdFeB magnets.

Laminated Magnets Application

Mag Spring s Laminated Magnets are mainly used in servo motors, traction motors, linear motors and elevator motors, etc. Because it can reduce the eddy current loss for the high efficiency motors by each magnets insulated. Fewer eddy current loss means lower heat and higher efficiency for motor.