Important Considerations When Buy Curved Magnets

Arc magnets (magnetic tiles) are widely used in devices such as brushless motors, permanent magnet motors, fans, and water pumps, but they are typical "non-standard custom parts". Many procurement issues arise not from the price itself, but from incomplete technical information or misunderstandings, ultimately leading to assembly difficulties or substandard performance. Therefore, it is essential to clarify the material and grade before procurement, such as sintered neodymium iron boron, ferrite, or bonded neodymium iron boron, while confirming the magnetic performance level (such as N35, N42, N52 or high-temperature SH, UH series) and actual operating temperature requirements. Otherwise, issues such as insufficient magnetic force or high-temperature demagnetization may occur.

The dimension parameters are one of the most common pitfalls for curved magnets. In addition to the conventional outer diameter, inner diameter, and thickness, it is also necessary to specify the curvature (central angle), pairing method, and assembly clearance requirements. Since curved magnetic tiles are used in a circumferential fit, if the tolerance control is not good, it is easy to encounter problems such as difficulty in installation, excessive clearance, or rotor eccentricity, which can lead to motor vibration, increased noise, and even decreased efficiency. For high-speed motors, dimensional consistency is more critical than individual magnetic performance.

Motor rotor using neodymium arc magnets

The method of magnetization is also a core risk point. Radial magnetization, tangential magnetization, and multipolar magnetization are common for curved magnets, and different motor designs correspond to completely different magnetization methods. If the magnetization direction is incorrect, even if the dimensions are perfectly correct, it cannot be used normally. In addition, it is necessary to confirm the arrangement of poles (distribution of N poles and S poles), whether they are supplied in pairs, and whether they match the motor stator design. For this part, it is recommended to directly provide drawings for the manufacturer to verify and confirm.

Surface treatment and corrosion resistance cannot be overlooked, especially for sintered neodymium iron boron magnetic tiles, which have a relatively weak corrosion resistance. Common treatments include nickel plating, zinc plating, epoxy coating, etc. Different usage environments require different treatments. For example, humid or outdoor environments often require stronger protection or salt spray testing requirements. If this point is overlooked, problems such as rusting, plating loss, and even magnetic performance degradation may occur in the later stages.

Lastly, the most overlooked aspects of arc magnets are batch consistency and the manufacturer's process capability. Qualified samples do not necessarily indicate stable batches. The real factor affecting motor performance is the ability to control consistency, including dimensions, magnetic properties, magnetization angles, and appearance consistency. It is recommended to prioritize selecting manufacturers with experience in motor magnetic tile production and conduct sample verification before mass production. This can minimize assembly risks and cost losses in the later stages.

Selection of curved magnets; 

Arc-shaped neodymium rare-earth magnets

Ceramic ferrite arc-shaped magnets