Magnetostriction

Magnetostriction describes the elastic deformation of the molecular structure in ferromagnetic materials such as iron, nickel, cobalt, and their alloys when exposed to external magnetic fields. Ferromagnetic materials consist of a multitude of small elementary magnets that are grouped into so-called “Weiss domains” with the same magnetic orientation. In the unmagnetized state, the alignment of these domains is random.

When an external magnetic field acts on the material, some of these domains spontaneously align themselves in the direction of the magnetic field. The number of domains that reorient themselves depends both on the strength of the external magnetic field and on the mechanical properties of the ferromagnetic material.

This physical property forms the basis for magnetostrictive linear position transducers. A ferromagnetic material with pronounced magnetostrictive properties, which serves as a so-called “waveguide,” is housed in a robust enclosure along the measuring path. A Position marker that generates an external magnetic field marks the measuring position. The interaction between the magnetic field and a short current pulse in the waveguide initiates spontaneous magnetization and triggers the torsional wave. The time that elapses between the excitation and the reception of the torsional wave in a wave transducer is electronically converted into the corresponding position value.

Magnetostrictive technology is a non-contact, wear-free measurement principle that enables robust and absolute displacement measurement with micrometer resolution—ideal for demanding industrial displacement measurement.