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Avoidheating when crucible
is cold. Heat crucible slowly to dull red heat when first using,
then heat up quickly to white heat. |
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Crucible should be heated uniformly all
around to avoid bottom and chine of all crucible, heated much
faster than the top. |
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Avoid dropping of the metal ingots in
the crucible instead place the same with the help of a long
providing a gap in between in a vertical position only. |
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Crucible should be installed or removed
from the furnace with the help of clamp jaws which should be
fitted around the middle portion of the crucible with the help
of two persons instead of a long operated by a single person
by holding it near the edge. |
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While pushing the metal pieces or stirring
the melt or removing the accumulated cross with a rod, care
should be taken not to strike the rod on any part of the crucible
wall/bottom. |
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Rotate the crucible periodically to avoid
erosion of the wall near burner of the furnace. |
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Use graphite stand of suitable size below
the crucible by placing graphite or carbon powder in between
the crucible and the stand to avoid sticking of the crucible
to the stand. |
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The crucible wall should be allowed to
expand when heated hence provide suitable gap about 3 mm. or
place ceramic asbestoss cloth between wall and the supporting
brick provided in the furnace. |
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In the oil-fired furnace, ensure that
the combination of air and oil is adequate so that fuel burns
to the fullest. |
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In the oil-fired furnace.ensure that
the drought is directed towards the wall of the furnace and
not on the crucible and that the flame swirls around the crucible. |
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In the coke-fired furnace, cavities in
the furnace chamber due to uneven stocking of coke must be avoided. |
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Electric furnace must be air sealed. |
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Charge the crucible with metal only after
the crucible becomes red hot. |
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Fluxes in adequate quantity should be added
only after metal is molten. |
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The adhering slag/dross accumulated on
the inside of the crucible wall must be removed with suitable
tools after every charge while the crucible is in "hot"
condition |
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Avoid delay between subsequent heatings
and use the crucible for obtaining many melts continuously. |
Crucible
Details 
