China Neodymium And Ferrite Magnets Manufacturer & Supplier 
When selecting or using magnets, many people wonder: Do magnets with the same performance rating and volume necessarily have the same magnetic force? With this question in mind, let me explain.
First, it is certain that the magnetic pull varies. To determine which pull is strongest, we must refer to the definition of maximum magnetic energy product. When a magnet's operating point is near its maximum magnetic energy product, it possesses the greatest capacity to perform work. A magnet's adhesive force is also a manifestation of this work capacity, meaning the corresponding magnetic pull is at its peak. It is important to note that the object being attracted must be sufficiently large to completely cover the size of the magnetic pole. This ensures that factors such as the material, dimensions, or shape of the object can be disregarded.
How to determine if a magnet's operating point is at its maximum coercive force point? When a magnet is in direct contact with the material it attracts, its holding force depends on the air gap magnetic field and the contact area. Taking a cylindrical magnet as an example, when H/D≈0.6, its center coercive force Pc≈1. Near the maximum coercive force operating point, the holding force is greatest. This aligns with the design principle of magnets used as attachments, which are typically shaped relatively flat. Taking an N35 D10*6 magnet as an example, FEA simulation calculates its holding force on an iron plate at approximately 27N. This nearly reaches the maximum value achievable for a magnet of equivalent volume, equating to 780 times its own weight.
Square magnets, similar to circular magnets, exhibit a magnetic energy product (Pc) of approximately 1 when directly adhering to the attracted material. This position is near the maximum magnetic energy product operating point, where the adhesive force reaches the maximum value achievable for magnets of equivalent volume.
Magnetic Field Lines Diagram of Single-Pole and Double-Pole Magnets
Of course, the above describes only the magnetic attraction of a single-pole magnet. When magnetized with multiple poles, the magnetic force is entirely different. The magnetic force of a multi-pole magnet is significantly greater than that of a single-pole magnet (assuming a small distance between the magnet and the object being attracted).
Why does the magnetic force vary so significantly when magnets of the same volume are magnetized with multiple poles? The reason lies in the fact that the adhesion area S remains unchanged, while the magnetic flux density B passing through the attracted object increases substantially. As shown in the magnetic field line diagram above, the magnetic field lines passing through the iron plate are noticeably denser in a magnet with multiple poles. Using the N35, D10*6 magnet as an example again, when magnetized as a dual-pole magnet, the FEA simulation shows its adhesive force on the iron plate is approximately 1100 times its own weight.
Therefore, when selecting magnets, in addition to considering grade and volume, one should also comprehensively evaluate shape design, magnetization direction, and application scenarios. This ensures the magnet's holding force meets requirements under actual operating conditions.
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