Their dimensions, angles, magnetization directions, grades, coatings, and tolerances are often determined by the requirements of the motor, rotor, or magnetic assembly in which they are used.
Unlike standard block or disc magnets, Neodymium arc magnets are usually defined by the structure in which they will be used. Their shape is influenced not only by size requirements, but also by the magnetic circuit, system geometry, pole arrangement, magnetization pattern, and assembly method.
In many cases, even small changes in arc angle, thickness, curvature, or magnetization direction can affect how the magnets fit into the final design. This is why Neodymium arc magnets are often developed as custom parts rather than selected from standard dimensions.
Their design usually needs to balance magnetic performance, available space, machining feasibility, and assembly requirements. For this reason, Neodymium arc magnets are more project-specific than many other common magnet shapes.
For radial flux applications, Neodymium arc magnets are more commonly made in regular arc shapes or in other optimized profiles designed to fit the rotor or magnetic assembly structure. These magnets are typically used in systems where the magnetic flux is arranged perpendicular to the axis of rotation, such as conventional motors, generators, and many magnetic couplings.
In practice, the final shape of a Neodymium arc magnet is determined not only by dimensional fit, but also by the magnetic circuit, assembly method, and performance target of the system. This is why arc magnets used in different applications may vary considerably in angle, thickness, curvature, and overall profile.
Neodymium arc magnets can be magnetized in several different directions depending on the magnetic system, flux path, and performance target of the application. The most common options include diametrical magnetization, radial magnetization, chord magnetization, and axial magnetization. Each of these magnetization patterns produces a different magnetic field distribution and is selected according to the structure in which the magnet will be used.
In radial flux systems, diametrical magnetization and radial magnetization are the most commonly discussed options, while chord magnetization may also be used in certain segmented layouts or Halbach-type configurations. In axial flux systems, fan-shaped arc magnets are often axially magnetized, although chord magnetization can also be used in some specialized magnetic array designs. Because magnetization direction affects not only flux distribution, but also manufacturability and cost, it is usually determined together with the shape and configuration of the magnet.
Neodymium arc magnets are not usually formed directly to final shape during pressing. Because sintered Neodymium magnets are pressed under an external magnetic field, it is difficult to achieve the precise arc geometry and dimensional accuracy required by practical applications at the pressing stage alone. For this reason, sintered blanks normally need additional machining before they can be used as finished arc magnets.
Compared with common shapes such as discs, blocks, or rings, Neodymium arc magnets generally require more specialized machining. In most cases, the final arc shape is produced by either wire-cutting or profile grinding, depending on the required geometry, batch size, and cost target.
Wire cutting is especially suitable for arc magnets with more complex profiles. It offers greater flexibility in shape control, making it useful for prototypes, small-batch production, and deeply curved designs. Multi-wire cutting can also improve efficiency in larger-volume production of arc magnets with relatively lower bow and larger span.
Profile grinding, by contrast, can offer advantages in efficiency and cost for suitable dimensions, but it is less flexible when the shape becomes more complex. In practice, the machining method is usually selected according to the required curvature, dimensional complexity, and production volume of the arc magnet.
Neodymium arc magnets play an important role in motor applications, where both geometry and magnetic performance affect overall efficiency. Beyond material properties and surface treatments, magnet geometry itself can have a direct impact on motor behavior. In slotted motors, for example, the interaction between the magnets and the stator teeth can create cogging torque, which leads to torque ripple, vibration, and noise. To reduce these effects, arc magnets used in both radial flux and axial flux motors are often designed with skewed shapes, helping improve running smoothness and overall motor performance.
Another important consideration is eddy current loss. Eddy currents can generate heat inside the magnets, causing temperature rise and increasing the risk of demagnetization, which may reduce motor efficiency. To address this problem, laminated arc magnets made of multiple thin magnetized layers bonded together are increasingly used in motor designs. This structure helps reduce eddy current loss while maintaining the required magnetic performance, making it a practical option for improving both efficiency and thermal stability.
At SDM, we support custom Neodymium arc magnet projects based on actual application requirements. Because arc magnets are usually developed for specific rotating magnetic systems rather than selected as general-purpose parts, the design process often starts from the working structure, magnetic target, and assembly method of the application.
To help us evaluate a project more efficiently, customers can provide available information such as drawings, key dimensions, magnetization direction, material grade, coating, operating temperature, and the intended application structure. For motor and magnetic coupling projects, details related to pole arrangement, assembly layout, or performance targets can also be helpful. If complete drawings are not yet available, samples, reference dimensions, or a basic description of the application can still provide a useful starting point.
Based on this information, we can work with customers to discuss suitable arc magnet shapes, magnetization options, manufacturing methods, and other project-specific requirements. Whether your project is at the prototype stage or moving toward production, feel free to contact us to discuss your custom neodymium arc magnet requirements.
