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

H. Lost Foam Facility-2
Plant Profile
Lost Foam Facility-2 is a new facility that produces A356 and A319 aluminum components for a
variety of markets including automotive, marine, power generation, and original equipment
manufacturers. The company has developed expertise in producing complex-geometry castings
for niche markets such as snowmobiles and lawn mowers. The facility has been able to penetrate
these markets by offering low-cost lost foam casting designs for parts that would traditionally be
produced by machining or die casting.
The facility produces 2-3 million pounds of aluminum castings a year. The scrap rate at the
facility is 1-2%, primarily due to defects in the foam pattern (e.g., dents). The shop operates one
8-hour shift per day for its pouring operation, and runs the pattern shop 24 hours per day, 4-5
days per week to keep up with the demand.
The facility fabricates its patterns on site using new bead blowing and mold-making machinery.
The pattern process begins at the facility with the pre-expansion of polystyrene beads to a
controlled density, following which the beads stabilize and reach a particular pentane level. Next,
the beads are blown into an aluminum mold to create a foam pattern. The blown beads are then
heated and steamed in order for them to expand and fuse together. Finally, the mold is cooled to
stabilize the expanded beads that make up the pattern. The pattern is hung and subjected to a
controlled atmosphere for up to six hours to shrink it to a stable controlled size. The pattern
segments are glued together using a special adhesive, and multiple patterns are assembled into a
tree or cluster.
The constructed patterns are dipped into refractory slurry to ensure a uniform evaporation of the
pattern during the casting process and to prevent penetration of the foam by the molten
aluminum. Once dipped, the patterns are dried in an oven. Dried patterns are placed into a flask
and packed with mullite sand with the aid of vibration. The flask is then moved onto the
automatic pouring line, where molten aluminum is poured directly into the foam cluster
displacing the evaporated foam. Once cooled, the casting is shaken out, inspected, cleaned and
finished.
Lost Foam Facility-2 performs all of its melting in two natural gas dry-hearth reverberatory
furnaces. The facility purchases its alloys as large billets or “sows” rather than the typical ingot,
and melts these onsite. The facility has two air compressors one 75-hp and the other 100-hp, both
of which operate at 123 psi. The facility does reclaim its mullite sand, of which 10% is run
through a fluidized bed. The footprint of the facility has extra capacity to accommodate future
growth.
Onsite Assessment
The format of the one-day site visit was similar to the others, with a face-to-face meeting in the
morning followed by a tour of the facility. The facility manager was familiar with the
MotorMaster BestPractices tool; however, he was unfamiliar with the AirMaster+ and PHAST
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