Low Frequency Generators
If you wish to achieve good degaussing results, it is not sufficient to have a strong magnetic field, but you also need the appropriate degaussing frequency. In many cases, just the standard line voltage of 50 / 60 Hz is used, since this is the less costly source of energy.
However, it is not sufficient to degauss the surface only if permanent degaussing is to be achieved. The remaining residual magnetic fields in the centre of a work piece will emerge outwards with the result that, after a few days, the residual magnetism existing before the degaussing procedure will again be measurable. For reliable degaussing of work pieces with a wall-thickness > 10 mm, a considerably lower frequency than the standard 50/60 Hz is required for hard steels. Degaussing at low frequency allows the reduction of the secondary eddy currents inside a work piece, as well as larger penetration depths into the forced magnetic field. When degaussing large work pieces (i. e. extruded forms, railroad tracks, punching devices and others), frequencies of down to 0.5 Hz are necessary to keep the work piece magnetically neutral throughout. This is also valid for hard steel bars or large axles and tubes.
The below diagram shows the recommended degaussing frequency in relation to material thickness and material hardness:
Other reasons for the use of low frequencies are metal product carriers, punched / perforated pallets or grid baskets which are creating eddy currents within the degaussing fields and thus produce antagonizing fields shielding the work piece (in process of degaussing). We offer divers maintenance-free generators supplying low frequency.