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The residual magnetism (Br) of injection molded magnetic rings is mainly related to the following factors:

1、 Magnetic powder material

Magnetic powder types: Different types of magnetic powders have different remanence characteristics. For example, 

there is a significant difference in remanence between ferrite magnetic powder and neodymium iron boron magnetic 

powder.

Purity of magnetic powder: The higher the purity of magnetic powder, the higher its residual magnetism is usually. 

Because impurities may interfere with the magnetic domain arrangement of magnetic powder particles, thereby 

reducing remanence.

2、 Injection molding process

Injection temperature: Injection temperature can affect the melting of magnetic powder and the arrangement of 

magnetic domains. Appropriate injection molding temperature helps to fully melt magnetic powder particles and 

orderly arrange magnetic domains, thereby improving remanence. However, excessively high injection molding 

temperatures may cause magnetic powder oxidation or degradation, reducing residual magnetism.

Injection pressure: Injection pressure can also affect the arrangement and density of magnetic particles. Higher 

injection pressure helps to tightly arrange magnetic powder particles, thereby increasing remanence. However, 

excessive pressure may also cause the breakage or deformation of magnetic powder particles, affecting remanence.

3、 Post processing technology

Annealing treatment: Proper magnetic treatment during the annealing process can change the remanence of the 

magnetic ring. By adjusting the annealing temperature and magnetic field strength, the arrangement of magnetic 

domains can be optimized, thereby improving remanence.

Other post-processing techniques, such as surface coating treatment and heat treatment, can also affect the remanence

 of the magnetic ring. These treatments can alter the surface state or internal structure of the magnetic ring, thereby 

affecting its magnetic properties.

4、 The size and shape of the magnetic ring

The size and shape of the magnetic ring can also affect its remanence. Larger magnetic rings usually have higher 

remanence because there are more magnetic powder particles and the arrangement of magnetic domains is easier 

to achieve orderliness. Meanwhile, the shape of the magnetic ring also affects the distribution of the magnetic field 

and the arrangement of magnetic domains, thereby affecting the remanence.

In summary, the residual magnetism of injection molded magnetic rings is closely related to multiple factors such 

as magnetic powder materials, injection molding processes, post-treatment processes, and the size and shape of 

the magnetic rings. When designing and manufacturing injection molded magnetic rings, it is necessary to 

comprehensively consider these factors to optimize the remanence performance.