Degaussing with Coils
Degaussing coils (also referred to as degaussing tunnels) create an alternating magnetic field in the direction of their passage axis.
The density of magnetic field lines is at its maximum in the coil centre, and is strongly decreasing towards the outside. If a ferromagnetic work piece (steel) is introduced into the coil, the field lines are concentrating and flooding the work piece. The conductivity of steel is up to 800 times higher than that of air. Since the field lines inside the coil run parallel in relation to its axis, the coil is best suited for degaussing of flat work pieces containing magnetic fields in longitudinal direction. Degaussing is done during a continuous movement of the work piece, leading out of the coil. Decreasing field strength is achieved by a slow extraction from the coil.
The degaussing coils are made of a solid cast aluminium body with stainless steel covering (except small coils). This allows bolting the coil to a line. Generally, the aluminium body is sufficient for heat dissipation. For coils with extremely strong magnetic fields, a rotary axial blower is mounted on top of the housing; additionally, a temperature control system can be installed.