Magnetizing fixtures must provide not only sufficient field strength, but also the field direction and distribution required by the magnetic materials, component geometries, and intended pole configurations. They therefore act as the interface between the magnetizing equipment and the magnets or magnetic assemblies being magnetized.
Permanent magnet materials must be exposed to external magnetic fields to establish their intended magnetization directions or pole patterns. These fields may be produced by permanent magnets or by electrical currents.
The field strength required for magnetization depends on the magnetic material, its coercivity and magnetization characteristics, the component geometry, and the magnetic circuit of the fixture. AlNiCo and ferrite magnets generally require lower magnetizing fields, while modern rare earth magnets such as Neodymium (NdFeB) and Samarium Cobalt (SmCo) magnets normally require much stronger fields to reach the intended level of magnetization.
Several methods can be used to magnetize permanent magnet materials, including permanent magnet magnetization, direct current (DC) magnetization, and impulse magnetization. Permanent magnets may be suitable for materials with relatively low coercivity or for simple magnetization requirements, although the applied field cannot be switched off or readily adjusted. Direct current magnetization produces a steady magnetic field, while impulse magnetization generates a much stronger field over a short period and is therefore widely used for high-coercivity permanent magnets.
Impulse magnetizing systems generally consist of magnetizers and magnetizing fixtures. Magnetizers store electrical energy in capacitors or capacitor banks and release it as controlled high-current pulses through the fixtures. Magnetizing fixtures convert these current pulses into magnetic fields with the strength, direction, and distribution required by the magnets or magnetic assemblies being magnetized.
Magnetizers and magnetizing fixtures must therefore be matched to each other. Magnet materials, component dimensions, magnetization directions, pole configurations, fixture inductance, and required field strength can all affect the voltage, current, and stored energy needed for the magnetization process.
Magnetizers can often be used for different magnetic products within their voltage, current, and energy capabilities. Magnetizing fixtures, however, are normally designed around specific magnets or magnetic assemblies. Their configurations depend on factors such as magnetic material, component geometry, magnetization direction, pole number, pole pitch, and whether magnetization is performed before or after assembly.
Magnetizing fixtures can also be integrated into automated loading and part-handling systems to support fully automated magnetization processes. These systems may incorporate in-line magnetic inspection, safety controls, and other process functions to improve consistency, operational safety, and production efficiency.
Magnetizing fixtures are generally developed according to specific magnets or magnetic assemblies rather than selected only from standard specifications. Important project information may include component drawings, magnetic material and grade, magnetization direction, pole number and pole pitch, and the required magnetic field distribution.
It is also necessary to confirm whether magnets will be magnetized individually or after assembly, as surrounding components, air gaps, and assembly structures may influence the fixture configuration. Production volume, loading method, magnetic inspection requirements, and any planned integration with automated handling systems may also need to be considered.
For customers purchasing magnets or magnetic assemblies, SDM can also support related magnetizing fixture requirements. Based on component structures and intended magnetization patterns, suitable fixture configurations can be discussed together with magnet supply and project requirements.
