Is the magnetic field at the inner circle of the magnetic ring very weak?

Magnetic rings have both inner and outer circular surfaces. Some customers may encounter rings where the inner surface exhibits weak magnetism and assume this is the norm. But is that really the case?

Whether the magnetic field inside the inner circle of a magnetic ring is “very weak” cannot be generalized; it depends crucially on the specific magnetization method.

Magnetic poles in axially magnetized (thickness-direction magnetized) magnetic rings are primarily distributed across the upper and lower end faces. Magnetic flux paths predominantly close axially. In this configuration, the inner circular side walls are not the primary working surfaces for magnetic poles. Consequently, measurements taken with a Gauss meter on the inner circular surface often indicate a weaker magnetic field. Such magnetic rings are better suited for applications involving end-face force or induction, such as magnetic adhesion and positioning, rather than those relying on the magnetic field within the inner bore.

Radial Multipole Rotor Magnet

Another type involves radial magnetization of the magnetic ring's outer diameter, with magnetic poles concentrated on the outer surface. Magnetic flux primarily diverges outward into space and closes on the outer side. This configuration is commonly used in motor rotors, where the magnetic force on the inner surface is very weak.

However, there is a special type known as internally magnetized (inner-diameter magnetized) magnetic rings. In this type, the magnetic poles are directly distributed on the inner circular surface, with magnetic flux radiating outward from the inner bore. The inner circle becomes the primary working magnetic surface, and the magnetic field is not weak. Many fan motors, for instance, utilize this type of inner-diameter multi-pole magnetized ring magnet.

Therefore, the strength of the magnetic field on the inner circular surface of the magnetic ring does not depend on "whether it is a magnetic ring" but rather on the magnetization direction. When magnetized axially or radially outward, the inner circular magnetic field is relatively weak. However, with an inner diameter magnetization design, the inner circular magnetic field can be made very strong and concentrated.

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