Implementation of Metal Casting Best Practices - EERE - U.S. ...

Another alternative for the facility is to evaluate the benefits of replacing traditional crucible
furnaces with induction furnaces. Induction melting has a thermal efficiency of 59-76%, which is
significantly more efficient than a crucible furnace at 7-19%. Induction melting also has a
significantly lower melt loss when melting aluminum (i.e., 0.75-1.25%). 66 This is much lower
than the 6-7% loss currently experienced at the facility. The analysis that the facility conducts
should examine its current and projected alternative fuel costs (i.e., natural gas versus electricity),
and should factor in the following:
• Number & size (exposed diameter) of the melting crucibles
• Crucibles that use blowers vs. compressed air
• Actual pounds of castings sold per year vs. purchased ingots
• Number and size of air compressors
• Data on natural gas use for melting (if it is available) in summer vs. winter
This analysis will enable the facility to make a business decision as to whether it would be in its
financial advantage to undertake such a large project.
Heat Treating Furnaces
Aluminum Casting Facility-2 heat treats approximately 90% of its castings using conventional
natural gas-fired furnaces. The assessment team recommended that Aluminum Casting Facility-2
perform a combustion gas analysis on these furnaces. The facility should also examine using heat
exchangers to capture waste heat from the furnaces. In the past, heat exchangers have been a
capital-intensive investment and their economics were not attractive. However, rising natural gas
prices could change that conclusion.
Sand Heater
The no-bake line at Aluminum Casting Facility-2 does not utilize a sand heater. The assessment
team recommended that the facility reconsider installing one of these heaters because of the
potential differences in summer versus winter cure times caused by low sand temperatures.
Chemical reaction rates double with each 10ºC increase in temperature. Cold sand temperatures
in the winter will either slow down production while waiting for sand to cure or, if cure times are
not adjusted, cause castings to be poured into under-cured molds which often causes gas-related
defects.
Die Steels
Currently Aluminum Casting Facility-2 utilizes H-13 die steels for its permanent mold and die
material. The assessment team recommended that the facility consider some of the die steel
research performed by Case Western Reserve University that has identified a number of
commercially available steels that can outperform conventional H-13 steel.
3. Conclusion
Aluminum Casting Facility-2 has actively participated in DOE-sponsored research. Participating
with CANMET in their E-SMARRT activity has proven beneficial to the facility by bringing a
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