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Metal casting isn't the technical term for what Imperial Storm Troopers did to Han Solo in "Star Wars." Actually, it refers to the manufacturing process that creates the countless metal parts used in machines across hundreds of industries. Essentially, technicians pour molten hot metals into molds known as casts, allow them to cool, and then break them out of the casts. After machinists inspect – and often modify – these parts, they’re built into the complex machines that power our economy.
However, the metal casting process is extremely energy intensive. In fact, metal casting across all industries in the United States represents approximately 1 percent of all manufacturing energy use.
“Metal casting was identified as one of the top 10 energy users in manufacturing,” says Tom Prucha, vice president of technical services at the American Foundry Society.
Thus, efficiency improvements in the metal casting field offer a significant opportunity for innovative companies to help manufacturers save money and help the environment.
A metal casting technique called lost foam metal casting demonstrates one way that manufacturers have started improving their approach.
In the lost foam process, highly complex parts can be cast in one piece, reducing the need for machining and assembly. It uses an expendable polystyrene pattern, coated by sand, then surrounded by a casting mold. When workers pour molten-hot metal into these molds, it vaporizes and replaces the foam pattern, forming a casting that’s identical to the original pattern.
But at first, like all new technologies, it didn’t work quite right. When the process initially came on the manufacturing scene, “the scrap rates were very high,” Tom says. “We essentially abandoned utilizing the process because of that.”
For the last 10 years, the Energy Depatment has co-funded research to further develop lost foam metal casting with an industry consortium at the University of Alabama at Birmingham that includes foundries, suppliers and end users. That effort has already yielded significant results. It has helped reduce an estimated 9.4 million tons of solid waste between 1994 and 2005, which saved industry an estimated 3 trillion Btu, roughly the same amount of energy the entire state of Oregon produced with wind power in 2006.
The technology represents a 20- to 25-percent reduction in production costs and uses 7 percent fewer materials than traditional processes. The possibility for savings is huge.
“We identified that there’s a 25- to 30-percent energy savings potential with the process,” Tom says. “There’s also almost a 50-percent improvement in labor productivity.”
Because most companies that use metal casting are small businesses with fewer than 100 employees, the type of intensive research needed to overcome those hurdles required a big capital investment. That’s where the government sponsorship came in.
“Being able to match funds,” Tom says, “knowing that they could leverage that and get a bigger bang for their buck, created a vehicle where we could get the consortium going.”
Another benefit of the project has been involvement from UAB students. “On any of these project tasks, there are typically both undergraduate students and graduate students assisting,” he says. “At least 10 or more students have graduated out of that program and are now working in the industry.”
One So not only is the consortium making the manufacturing processes more energy efficient and reducing waste, but also it’s training a new generation of industry engineers.
“They see that there’s direct correlation to the work they’re doing to the industry,” Tom says. “The students aren’t just making a presentation at a conference to other academics – [they] interact with the people in the process.”