A piece is considered magnetized when it acts as a magnet, attracting ferrous (ferromagnetic) particles. This is the most evident effect of a magnetized piece.
A ferromagnetic material reacts to an external magnetic field. It is attracted to or attracts a magnet or a magnetized material. Most steels, except for many stainless steels, and cast iron are ferromagnetic.
Demagnetizing means removing the residual magnetism from a ferromagnetic material, reducing its ability to attract ferrous particles.
A ferromagnetic component can become magnetized due to several reasons:
- Proximity to a magnet (e.g., lifting magnets, magnetic clamping tables used in grinding)
- Proximity to a magnetized ferromagnetic piece (e.g., in storage, during transport)
- Electric current passing through the piece
Non-destructive testing (e.g., magnetic particle inspection, induced currents) - Alignment of a long piece along the north-south axis
- Mechanical processing (e.g., cutting, bending)
Yes, if the initial cause of magnetization is not removed, the piece can remagnetize. If only part of the piece is demagnetized (e.g., one end or just the outer layers), the remaining magnetic portions can remagnetize the demagnetized areas.
It will continue to be attracted to or attract the magnet. Demagnetization alters its ability to attract ferrous particles or iron pieces, not its interaction with the magnet.
If only part of the tube/bar was demagnetized, the untreated part will remagnetize the treated part. If the entire length was demagnetized, it may have been only superficially, allowing the subsurface areas to remagnetize the surface.
Magnetic, “magnetized,” and “calamitized” are synonyms, meaning the piece can attract or be attracted to magnets and other magnetic pieces. “Ferromagnetic” means the material can be attracted to or attract magnets and other magnetic pieces.
No, this is not possible.
Mechanical processing can magnetize a piece. It is also possible that the piece was not thoroughly demagnetized, leaving residual magnetism that emerges during cutting.
Residual magnetism that escapes from the piece can be measured; but unfortunately, the magnetism that remains hidden within the piece, which only comes evident after mechanical processing, cannot be measured. The most accurate method to measure residual magnetism is with a digital measuring instrument called a gaussmeter or teslameter. For large pieces, analog magnetic field indicators called gausstests are particularly convenient. A simple but approximate method is to use steel paper clips stacked together: if they are attracted to the piece, it indicates residual magnetism is present in that surface area.
Our team is available to demagnetize your components at our facility or on-site.
Demagnetizer and demagnetiser refer to the same device, with the former being the American spelling and the latter being the British spelling.
Residual magnetization of steel parts is measured, depending on the required level of precision, using either analog instruments (such as gausstests) or digital devices (such as gaussmeters or teslameters).
It is advisable to conduct the measurement in a neutral environment, meaning one that does not interfere with the measurement. Examples of neutral environments include areas far from large ferromagnetic masses, magnets, electromagnets, or electrical panels. If necessary, measurements should be carried out in a properly shielded environment.
For long parts, it is recommended to position them in an East-West orientation to minimize the influence of the Earth’s magnetic field.
See the answer to the question “How is residual magnetism measured?”.
See the answer to question “Why does magnetization occur?”.
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