Demagnetization of large-scale objects before welding
In the assembly of large steel constructions, welding processes are usually used. Often the welding seam is relevant for safety, meaning that its quality is especially important. Residual magnetism reduces the quality and durability of welding seams by interfering with the welding process (magnetic arc blow) and causing magnetic corrosion (hydrogen embrittlement induced by magnetic fields).
In this White Paper a new method for demagnetizing large steel surfaces is described.
Industrial safety and demagnetizers
Demagnetizers based on alternating field principle generate electromagnetic fields in the low frequency range. Workplaces are subject to regulations concerning occupational health and safety for areas in which electromagnetic fields are applied. Internationally, the limit value recommendations and guidelines of the ICNIRP are applied in this context. In Germany, the BGV B11 regulation is applied with regard to occupational safety. More detailed information on this topic can be found in the following white paper.
Demagnetizing before contactless torque
Torque measurements are increasingly carried out using non-contact sensors. The sensors measure the magnetic field present on the component. An applied force changes this magnetic flux, whereby the applied torque is determined. Excessively strong external inhomogeneous magnetic fields on the surrounding components lead to incorrect measurements. Therefore, a deep and homogeneous residual magnetism on these is necessary for this application. To achieve this, a powerful and process-safe demagnetization is mandatory.
Demagnetization as process preparation in the forming of metal powder
The process safe compaction of ferromagnetic powders requires low residual magnetism on the tooling. The flow of the metal powder is already reduced at residual magnetism over 2A/cm (2.5 Gauss). Powerful degaussing systems allow the effective demagnetization of powder press frames, adapters and sintered tungsten carbide punches and dies on site.
Measurement of residual magnetism
New quality requirements regarding maximum permitted levels for residual magnetism have created a need for standardized measuring methods. Under the following link is a compilation of further information on this subject.
Magnetic attraction to particles
The model calculations presented in the White Paper are intended particularly to provide a better understanding and a scientific basis for this topic for specialists in the areas of surface technology, technical cleanliness and powder metallurgy.
Demagnetization prior to cleaning
In order to reliably meet the increasing residual dirt requirements in the parts cleaning of ferromagnetic steel parts despite the most modern cleaning machines, efficient demagnetization processes are required. Further information on this topic can be found under the following link.
Demagnetization KATRIN-Hall, KIT
The high sensitivity required for experiments with the spectrometer requires an external magnetic field as low and uniform as possible in the area of the spectrometer. In the direct vicinity of the spectrometer, non-magnetic steel reinforcements were installed, but the scientists identified the more distant ferromagnetic steel reinforcements of the building shell as a disturbance variable.
Demagnetization of assembled bearings
Demagnetization processes are widely used in the rolling bearing industry. In rolling bearing production, rolling elements, outer and inner rings are individually demagnetized before assembly. However, residual magnetism that arises during assembly often goes unnoticed. Numerous known damage mechanisms that reduce service life can be attributed to residual magnetism.
Demagnetization of tungsten carbides
Carbide parts can be magnetized in production as well as in operation. In the following application report the demagnetization of carbide is considered. To demagnetize hard metal, which mostly consists of tungsten carbide with cobalt as binder, very high field strengths of often more than 200 kA/m (25 mT / 250 Gauss) are required. However, a reduction of the residual magnetism is also possible with lower field strengths.