ITP Metal Casting: Advanced Melting Technologies: Energy Saving ...

molten metal between furnaces or to the casting station is a critical step in the casting process
that could be improved for energy efficiency. With the rising gas and electric prices, maintaining
the temperature of the metal between the melting furnace and the pouring station can be
expensive. If the distance between the melting room and pouring room is short or negligible,
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then less heat would be needed to do so. Thus, close proximity of the furnace to the pouring
location can add up to substantial annual savings and improved safety.
4.4.1 Dosing Furnaces
Dosing furnaces are closed holding furnaces with a
spout for direct metal delivery (Exhibit 27). They are
used to dispense an accurate amount of molten metal
to
the die casting machine or mold line. The advantage of
the dosing furnace is that because of the closed
structure, it minimizes heat loss and protects the molten
metal from excessive oxidation. These furnaces require
only about one-fifth of the energy to hold 2,000 pounds
of aluminum in comparison to an open crucible furnace,
and one-third of the operating costs of a comparable
holding furnace. In Europe, dosing furnaces are
replacing ladle furnaces in die casting because of their
ability to pour accurate amount of molten metal at
the
right temperature. 71
4.4.2 Electro-Magnetic
Pump Systems
Source: Case Western Reserve University
Exhibit 27: Schematic of dosing
furnace
An electromagnetic pump (EMP) may be used to
circulate hot metal through a patented scrap charging
chamber (Exhibit 28).
g of
72 The pump circulates the
molten bath in the reverberatory furnace at a maximum
flow rate of approximately 10 tons/minute. Meltin
metal inside wells, supplied with molten metal from
electro-magnetic pumps, has become more common
since the mid-1990s.
EMP systems offer two opportunities to improve
melting
efficiency: temperature homogeneity of the
melt pool and side-well melting. The melt pool in most
furnaces is stagnant, which contributes to the
http://www.sovereign-publications.com/emp.htm development of a vertical temperature profile in the
Exhibit 28: Electro-magnetic pump
pool. When the surface temperature of the molten
system
metal is different from the floor temperature, it creates
inefficiency since radiant energy from the roof and conductive energy from the hot flue gases is
being directed at the hot side of the metal pool. Stirring of the pool with electro-magnetic pumps
can eliminate the vertical temperature profile, enhancing efficiency and productivity. Also EMP
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