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

Stack Melter
Like many plants melting aluminum alloys onsite that participated in the analysis, Lost Foam
Foundry-1 uses natural-gas-fired reverberatory furnaces for its melting operations. As noted in
the analysis of Die Casting Facility-1 (page 36), these furnaces have an efficiency that ranges
from 20 to 25% because of high energy losses that occur through the flue gases. Additionally, the
melt losses in reverberatory furnaces tend to be between 3 to 5% in aluminum. 57
Since stack melters preheat the incoming charge with flue gas, they have a relatively high
efficiency of 40 to 50%. Replacing the three reverberatory furnaces with stack melters will
improve the facility’s melting efficiency and reduce its natural gas use. Although this is a capitalintensive
recommendation, in light of the rising price of natural gas the increased efficiency
should make the economics of such replacement feasible. The assessment team recommended
the plant to conduct a detailed cost/benefit study.
Casting Pressure
Personnel at this facility indicated that the lost foam casting process is limited by its inability to
produce engine castings with the higher fatigue strength needed for the next generation of high
horsepower/pound of lightweight engines. However, other research developments and
modifications to the lost foam process have proven otherwise (see Aluminum Casting Facility-1
case study on page 75).
The team recommended that Lost Foam Facility-1 investigate the benefits of adding pressure to
its casting process during the pouring phase. Adding pressure not only can reduce porosity
defects but also increase the tensile strength of the castings. This can help the foundry in
developing new, stronger aluminum engine blocks and heads capable of higher horsepower
output.
3. Conclusion
ITP-sponsored research has contributed to the engineering success of the lost foam process and
has encouraged students to enter the metal casting industry. Lost Foam Foundry-1 has utilized a
number of the research results from the Lost Foam Consortium at the University of Alabama –
Birmingham. Foundry management found the results of this work to benefit its manufacturing
process and to help mitigate its risks. Participation in ITP-sponsored research has enabled Lost
Foam Foundry-1 to lower its energy bills. The only major additional energy-saving opportunity
identified by the assessment team at this facility was the replacement of reverberatory furnaces
with more efficient stack melters (which was a common recommendation in this project for all
aluminum facilities).
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