Spreading Magnets0 pages

www.thyssenkrupp-magnettechnik.com

ThyssenKrupp Magnettechnik

Spreading Magnets
When piles of sheets of different thickness are unloaded, double sheets could occur despite the
use of spreading magnets (fanners), and this all the more, the thinner the sheets. The effects
of a spreading magnet -either according to the electromagnetic or the permanentmagnetic
principle- are based on a magnetic flux admitted to the sheet so that magnetic poles of the
same kind are generated in the sheet which then repel in the same way as two magnetic north
or south poles would do. This repulsion effect isolates two sheets lying directly upon each
other. This is especially required if the blanks were oiled before and have been under pressure
for some time with the sheets showing a strong sticky effect. This cannot be avoided in the
usual processes, because the sheets must be protected against corrosion until the following
process stage begins. As a general principle two different kinds of spreading magnets are
differentiated:
The purely permanentmagnetic
electromagnetic one.

spreading

magnetic

system

and

the

purely

1. Permanentmagnetic Spreaders ( Fanners )
As the name already indicates, this kind of spreaders only consists of permanent magnets. The
front view can be seen in figure 1 and has the following arrangement:
iron plate

magnet

sheet

Figure 1: Typical outline of a permanentmagnetic fanner
The outline of the fanners can be seen. It represents an iron plate with permanent magnets
sticking to them with the polarity specified; ‘north’ designates the north pole of the magnet
which should be homogeneous on the complete area; ‘south’ designates the south pole of the
other magnet. The sheet should stand perpendicularly on this area. The area of the magnets is
covering about 90% of the working area.
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