What does the term demagnetization mean?
The reduction or removal of magnetization in a ferromagnetic body, such as the iron parts of a sensitive mechanical device, is called demagnetization. Magnetized components made of ferromagnetic materials are usually demagnetized before devices and fixtures are assembled, for various reasons. For example, it may be necessary to remove the effects of residual magnetic fields on measuring instruments or the adhesion of ferromagnetic particles to the components. A strong magnetic field can be used to reduce or completely destroy magnetization. Alternatively, where feasible, the material can be heated to a temperature above its maximum Curie temperature and then brought back to room temperature in the absence of an external magnetic field.