OPERATING INSTRUCTIONS
IMPORTANT FACTS FOR THE OPERATION OF LIFT MAGNETS
LOAD CHARACTERISTICS OTHER THAN JUST WEIGHT
MUST BE CONSIDERED IN ORDER TO DETERMINE
THE LOAD THAT ANY MAGNET CAN LIFT.
This statement is true for all lifting magnets because they all operate using the same fundamental
laws of physics. Magnetic power is often pictured as lines of magnetic force flowing from north pole
to south pole. Anything that limits the flow of these magnetic lines of force obviously reduces the
magnet's lifting capacity. There are many important factors, which limit the flow of these lines of force.
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1. LOAD THICKNESS
The greater the number of lines of magnetic force that can flow from a magnet into the load,
the greater the effectiveness of the magnet. The thicker the load, the more lines of magnetic
force that are able to flow, up to the thickness where the load capacity excedes the capability
of the lift magnet.
Thin material (load) means less iron available and thus fewer lines of magnetic force flow from
the magnet into the load. As a result, the lifting capacity of the magnet is reduced. In some
cases, the magnet will attract more than one thin plate of material when set on a stack of thin
plates.
DO NOT LIFT
more than one plate at a time as the lower plate may not be held suf
ficiently.
The lifting guidelines provide the user with what minimum thickness of load is required to reach
full lifting capacity. Loads thinner than those listed will result in reduced lifting capacity of the
magnet. This is evidenced by the information in the lifting guidelines charts.
2. SURFACE CONDITIONS
Magnetic lines of force do not flow easily through air, however, they do flow very easily through
iron. As a result, anything that creates a space or an air gap between a magnet and the load
will limit the flow of magnetic lines of force, thus, reducing the lifting capacity of the magnet.
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Magnet's Lifting Surface Condition
- The lifting surfaces of a magnet must be clean,
smooth, flat and free of nicks and burrs in order to minimize the air gap between a magnet
and the load. This magnet has been designed with soft, low carbon steel lifting surfaces
in order to maximize the lifting capacity. This requires that special care be taken to protect
these surfaces. Follow the Inspection Instructions in this manual. Attaching or welding
other materials to the lifting surfaces of this magnet in order to reduce wear is not recom
mended as it will reduce the lifting capacity.
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Load Surface Condition
- Paper, dirt, rags, rust, paint, and scale act the same as air. A
rough surface finish on the load also creates an air gap between the magnet and load. Any
of these conditions will reduce the magnet's lifting capacity.
3. LOAD ALLOY
Low carbon steels, such as SAE 1020 steel, are nearly as good conductors of magnetic lines
of force as pure iron. Many alloys, however, 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
stainless steel is almost as poor a conductor of magnetic lines of force as air.
Type 416 stainless steel is considered magnetic but contains enough chromium so that a
magnet can develop only one-half as much force on a type 416 stainless steel load when
compared to SAE 1020 steel. In cast iron, the carbon content reduces the force developed to
less than one-half of that developed on SAE 1020 steel. (Chilled cast iron further reduces the
force to less than one-quarter.)
O.S. Walker Inc., Battery Powered Magnets
