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Selection of
Magnetic Lifter |
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As three types of
magnetis are available for handling purpose |
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Permanent Magnetic Lifter |
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Advantages |
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Manually Switched On-Off |
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No Electricity required, 100%
safe for handing |
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Disadvantages |
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Can be made upto 2000 Kgs
Capacity only |
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Operator to reach to switch the
magnet |
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Cannot be operated at odd space,
height and location |
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Electro Magnetic Lifter |
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Advantages |
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Remote Switched On-Off |
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100% time Electricity required to
Keep Magnet On |
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Can be made in any size,
dimension and capacity |
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Can work with high Air Gaps &
Only magnet suitable for Scrap Handling |
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Disadvantages |
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Load drops if Electric power or
Electrical Controller component fails |
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Magnet gets heated due to
continuous running - needs rest if continuously used |
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Battery Back up support against
power failure, but have no protection if the battery fails or
the cable cuts etc |
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No Protection against winding
coil failure |
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Electro Permanent Magnetic Lifter |
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Advantages |
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Remote Switched On-Off |
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Electricity Pulse (for 2 Seconds)
required only to Switch the Magnet ON and then to switch the
Magnet Off |
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Can be made in any size,
dimension and capacity |
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Disadvantages |
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No disadvantages except these
cannot work with high Air Gaps & not suitable for Scrap
Handling |
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Choosing of Magnetic
Lifter as per requirement |
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While the surface condition i.e
the area of contact is very important, but in general a smooth
flat surface as supplied by Major Steel Plant is good enough.
The magnet should always be hanged from centre of the job i.e
used in equilibrium as far as possible. |
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A magnet can lift 1000 Kgs of
Solid Steel Plate providoed the plate is more than 50 mm thick
and the maximum size is 2000 x 2000 mm. A Magnet can lift 100%
at plate > 50 mm thick and will lift only 60% when the
thickness is 25 mm. So the magnet capacity is to be derated
depending upon the plate to be handled |
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If the thickness is less, the
magnetic induction in steel is less and so the lifting
capacity is reduced |
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The overhanging of the plate from
the Magnet should not be more than 1000 mm in any case
provided the plate is more than 25 mm thick and it does not
bend when lifted by the Magnet. |
So if the thickness is less and
the length is more than 2000 mm, then instead of high capacity
magnet, more than one magnet of lower capacity is used making
sure that the overhanging on width is not more than 800 mm and
length 1000 mm.
for Example if you have to lift a plate of say 6000 x 2000 x
12 mm thick, you need to hang atleast 4 Sets of magnets (Each
set consist of 2 Nos. magnet side ways) and they are hanged
from a spreader beam of 4000 mm x 1000 mm. |
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For handling plates of various
sizes, generally we make telescopic Plate Handling System
which is basically a spreader beam having 2 sets of fixed
magnets and 2 set of magnets moving between 800 to 1100 mm
each side. |
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The magnets are hanged by Spring
suspension box with loose chain so that it takes care of the
bendness of the plates available in market. Such handling of
plates commercially available is no problem |
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