China Neodymium And Ferrite Magnets Manufacturer & Supplier 
Multi-pole magnet is a magnet with more than one pole on one side of the magnet, most of these magnets are ring-based, are widely used in a variety of magnetic sensors, permanent magnet DC motors, its installation distance is of great concern, there are users who ask the multi-pole magnet from the Hall sensor is not necessary within two millimeters? Permanent magnet manufacturers Karachi small Fu on this issue to introduce.
Hall sensors and multi-pole magnets between the optimal working distance is actually not fixed, it can be 2mm, or other distances, depending on the sensitivity of the Hall sensor, the magnetic field strength of the magnet, the material, the number of poles and so on.
In terms of magnet type: Magnets made with high-performance magnetic materials such as neodymium-iron-boron (NdFeB) can provide a stronger magnetic field at longer distances, thus increasing the effective detection distance of Hall sensors.
In terms of magnetic field strength: a stronger magnetic field allows for greater distances.
Pictured are 50mm+ OD multi-pole bonded NdFeB magnets.
Sensitivity of Hall sensors: Different models of Hall sensors have different sensitivities, and higher sensitivity sensors can be slightly farther away.
Then again, the number of poles of the magnet will also have an effect on the distance between the multi-pole magnet and the Hall sensor. Multi-pole magnets (e.g., 4-pole, 8-pole, etc.) are more demanding on the distance to the Hall sensor than simple bipolar magnets, and it is usually necessary to keep the sensor tightly within 2 millimeters in order to get the best performance and accuracy.
Therefore, sometimes in order to ensure that the Hall sensor can stably detect the magnetic pole change, especially in the case of precision control or space constraints, may require the sensor and the magnet between the distance as small as possible (for example, less than 2 mm), 2 mm is considered a more reasonable value, but not necessary, the actual application, according to the specific circumstances in the range of 1-5 mm to choose the appropriate distance.
Our company is a professional supplier of multi-pole magnets, we can improve the multi-pole magnets with different magnetic poles of various materials for you, you need samples to test and evaluate the price, welcome to contact us.
More multi-pole magnets are introduced;
Difference between single sided multipole and double sided multipole