AlNiCo Ring Magnet

An AlNiCo ring magnet can be produced using either casting or sintering methods. The sintering process enables the creation of an AlNiCo ring magnet that is near net-shape, requiring little additional machining. However, sintered AlNiCo magnets have restricted dimensional applicability and are typically suited for small-sized or thin-walled ring magnets due to their manufacturing constraints.

Cast AlNiCo magnets are coarse-grained, hard, and brittle, making them incompatible with standard machining techniques like drilling. Low-precision holes are usually rough cast during the foundry stage, with the magnets cast close to their final size. Additional machining ensures required tolerances. For high-precision holes and grain-oriented AlNiCo ring magnets, such as those with columnar or semi-columnar crystal growth, wire-cutting or grinding is applied to meet precise specifications.

Certain AlNiCo magnets are isotropic, allowing magnetization in any direction, but most commercial AlNiCo magnets are anisotropic, with a preferred direction of magnetization. This orientation forms during the heat treatment of cast and sintered AlNiCo ring magnets, after shaping. During this process, the magnets are heated to a specific temperature and cooled under an alignment magnetic field to set the orientation.

Once magnetized, an anisotropic AlNiCo ring magnet cannot be magnetized in directions other than its set orientation, making reorientation nearly impossible. However, various pole configurations can be achieved without opposing the magnet’s fixed orientation, enabling diverse application possibilities.