Development of a Degausser
(System for erasuring magnetic recorded data)
Degaussers are devices with a strong magnetic field for erasuring magnetic stored data in hard disc drives and magnetic tapes.
The requirements to the strength and spatial dimension of this field are derminated by
- the properties of the hard magnetic storage layers and
- the geometric dimensions of the data media (hard discs drive, magnetic tape cassettes)
In general magnetic air-fields are generated
- in air coils by current pulses from capacitor discharges or
- in the air gap of yokes
A powerful degausser with a magnetic field in the air gap of a yoke with electromagnetic excitation was developed by Magnettechnik Kleine.
A flux density of B ≥ 1.2T is achieved within a rectangular volume
- over a width (perpendicular to the field direction) of 100mm and
- a length (along the field direction) of 30mm
The value of B is determined with HALL sensors on several tracks during the transport of the data-media through the field.
The degausser is operated by a touchscreen. As power supply a 230V-net (16A) is sufficient.
The developed degausser can be converted to a system for other tasks by a few changes / additions, such as for
- the determination of the specific saturation magnetisation σS according to IEC 60404-14
- to magnetising hard magnetic ferrites
(see passage “own solution”).
The field strength can be clearly increased for these applications by reduction of the air gap size.