Magnetism and magnetic field measurement
Magnetic field strength, remanence, magnetic flux - what exactly are they?
Various measured variables can be determined in connection with magnets. As there is often confusion, here is a brief overview. The exact definition and the physical principles can be found in the specialist literature.
Magnetic field strength (H)
The unit of magnetic field strength is A/m (A/cm or kA/m are more commonly used to report values), formerly Oersted (Oe). Since magnetic flux density B, measured in Gauss (Gs) or Tesla (T), can be converted with a constant factor, magnetic field strength and flux density (and thus the units A/cm, kA/m, Oe, Gs, T) can be used alternately in practice.
Devices for measuring magnetic field strength are known as magnetometers, magnetic field meters, gaussmeters or teslameters.
Remanence / Residual Magnetism
Remanence or residual magnetism is a special consideration of magnetic field strength, i.e., the remaining magnetic field strength after the action of a magnet or after a demagnetization process.
Remanence can also be measured using magnetic field meters, gaussmeters and teslameters.
Magnetic flux
Magnetic flux (Phi, Φ) describes the total strength of a magnet. The unit of measurement is the volt-second (Vs), also known as Weber (Wb) or formerly Maxwell (Mx).
A flux meter is required to measure magnetic flux. These instruments are more complex than handheld magnetic field or permeability meters; they are often laboratory instruments, but can also be handheld instruments with a Helmholtz torque coil attached.
What causes unwanted magnetism on steel parts?
Magnetic steel parts can cause problems in further processing. The cleanliness of the parts is compromised. For example, iron filings can stick to the part, causing tool wear. Or sensors can be disturbed. What causes magnetism?
There is no general answer. Steel parts can be easily magnetized by the earth's magnetic field, whereby the elementary building blocks of the material align themselves in the direction of the magnetic field. For example, it can be observed that a steel bar is easily magnetized by vibrations during transportation.
However, if you use magnetic load handling attachments that are universal and gentle on the material, you have a possible source of residual magnetism. First step: Determine the residual magnetic field strength. Is it within your tolerances? If not, you must either demagnetize the parts or dispense with the magnetic crane. Demagnetizing is best done before the finished part is installed to minimize the effects of transport on remanence.
Electromagnetic high frequency fields
Magnetic field measuring devices from List-Magnetik are suitable for measuring direct and alternating magnetic fields up to a maximum of 20 kHz with a measuring range from a minimum of 0.01 mT (= 10 µT) to a maximum of 5 T. These are fields with a strength of at least the earth's magnetic field.
However, they are not suitable for measuring electromagnetic high-frequency fields in the sense of an EMC test or electrical fields in the range of a few µT.
There are special EMC measuring devices on the market for this purpose, which we do not sell.
