Walker Magnetics CER SERIES - Manual (Page 7)

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O.S. Walker Inc., CER Lift Magnet
3. LOAD ALLOY
Low carbon steels, such as SAE 1020 steel, are nearly as good conductors of magnetic
lines of force as pure iron. However, many other alloys contain non-magnetic materials
which reduce the ability of magnetic lines of force to flow into the load. An alloy such as
SAE 300 series of stainless steel is almost as poor a conductor of magnetic lines of force
as air.
 Type 416 stainless steel is considered magnetic, but it contains enough chromium
so that a magnet can develop only one-half as much force on a type 416 stainless
steel load as it can on a SAE 1020 steel load. Also, because of the carbon content,
the force developed on cast iron is less than one-half of that developed on SAE 1020
steel. (Chilled cast iron further reduces the force to less than one-quarter.)
4. LOAD LENGTH OR WIDTH
As the length or width of a load increases, it ceases to remain flat when lifted and the
edges begin to droop. This drooping or sagging of the load can create an air gap between
the load and the magnet. This is called peel. If this occurs, the lifting capacity of the mag-
net is greatly reduced.
For plate lifting, where drooping often occurs, rectangular shaped magnets must be posi-
tioned so that the length of the magnet is parallel to the width of the load.
5. POSITION OF MAGNET’S LIFTING SURFACE
As the position of the magnet’s lifting surface changes from horizontal to vertical, the lift-
ing capacity of the magnet decreases. When the magnet’s lifting surfaces are vertical, the
lifting capacity of the magnet is minimum and dependent upon the coefficient of friction
between the magnet’s lifting surface and the load.
6. PORTION OF MAGNET SURFACE IN CONTACT WITH
LOAD
The full surface of the magnet must contact the load if the magnet is to achieve rated lift
capacity.
7. LOAD TEMPERATURE
The temperature of the load can cause damage to the magnet and, if high enough, can
even change the magnetic characteristics of the load. For Standard Lift Magnets, Walker
should be consulted if the load or air temperature exceeds 110° F (43° C).