Stainless Steel Isn't Magnetic, or Is It?
4th of 10 Magnetic Separator Myths
The vast majority of stainless steel used in plants processing foodstuffs, chemicals, plastics and handling bulk materials whether in solid, liquid or powder form, is non-magnetic.
Or is it?
Traditionally, Magnetic Separators were installed to remove any ferrous metal. Today, this has expanded to include any magnetically susceptible material, including magnetic plastic, used for gloves and even tools. Magnetically attractable metals come in the form of steel or iron and are strongly attracted to the surface of a magnet.
However, as the attractive strength of permanent magnets, such as Rare Earth Cartridge Magnets has increased, analysis of the captured metal has shown that stainless steel is present. So how is that so?
Most stainless steel ending up in a process line originates from broken or worn processing equipment and is often small in size. During the process of being broken or worn, this abraded stainless steel has been work-hardened. This results in a slight change in the metal causing it to be very weakly magnetic.
With the right design and strength of Magnetic Separator, weakly magnetically susceptible materials such stainless steel can be attracted to the magnet face and captured. Even ‘non-magnetic’ stainless steel bolts are found to be very weakly magnetic on the head of the bolt, especially if a spanner or socket has been used for tightening and loosening.
So even though a Magnetic Separator will not capture all stainless steel, those with a high magnetic attractive force (eg Rare Earth Magnets) will attract and capture a high percentage. This is ideal when trying to reduce the amount of metal passing through final stage Metal Detection.
Other articles in the series of blogs looking at Magnetic Separator Myths include:
- The highest gauss Magnetic Separator is not always the strongest;
- Are all Rare Earth Magnetic Separators the same?
- Should you always use the strongest magnet?
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