Walker Magnetics NEO-HV SERIES - Manual (Page 7)

7 O.S. Walker Inc., NEO Permanent Lifting Magnets
3. LOAD ALLOY
Low carbon steels, such as AISI 1020 steel, are nearly as good conductors of magnetic lines
of force as pure iron. However, many other alloys contain non-magnetic materials, which re-
duce the ability of magnetic lines of force to fl ow into the load. An alloy such as AISI 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 AISI 1020 steel load. Also, because of the carbon content, the force developed
on cast iron is less than one-half of that developed on AISI 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 fl at 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 magnet is greatly
reduced.
For plate lifting, where drooping often occurs, rectangular shaped magnets must be positioned
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 lifting
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 coeffi cient 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 ca-
pacity.
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).