What type of magnet has a magnetic flux density of 4000 G?

What type of magnet has a magnetic flux density of 4000G? This question likely interests many people. Below is an explanation from Fu from Carichi Magnets, hoping it proves helpful.

A magnetic flux density of 4000G refers to the strength of a magnetic field. G is the unit for gauss, so 4000G indicates a magnetic field strength of 4000 gauss, equivalent to 0.4 Tesla (T). This intensity typically corresponds to very strong permanent magnets, generally achievable only by rare earth magnets such as neodymium iron boron magnets or samarium cobalt magnets. These are powerful magnets used in industrial and scientific research applications.

The accompanying image shows a high-performance rare earth circular magnet with a surface magnetic flux density exceeding 4000 Gauss.

Why not ferrite magnets?

Ferrite magnets are a class of permanent magnet materials based on iron oxide, primarily divided into hard ferrite and soft ferrite. Their maximum remanence and maximum energy product are significantly lower than those of rare-earth permanent magnets. The magnetic flux density of ordinary ferrite permanent magnets ranges from several hundred to approximately 1600 Gauss.

Key point: A magnetic flux density of 4000 G at a point indicates a strong magnetic field there, but it does not equate to the magnet itself having a remanence value of 4000 G. While these concepts are related, they are fundamentally different. For instance, a higher residual magnetization (BR) typically correlates with greater magnetic energy product density in a magnet, but it cannot be directly equated with magnetic flux density. Magnetic flux density describes the distribution of magnetism around the magnet, whereas residual magnetization (Br) refers to the internal quantity within the magnet.

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