Casting metal – that is, melting it, pouring it into a die, cooling it and sometimes shaping it while it is still soft – seems straightforward enough. But, says mechanical and mechatronics engineering professor Mary Wells, the details of how you do it make a big difference.
“There’s a strong link between the manufacturing process and the final product,” explains Wells, who is also Waterloo Engineering’s associate dean of research. The same metal poured into the same mould might not produce the same product: at the micron level, the metal’s structure depends on the rate it was cooled, the pressures it was subjected to and other details of how it was processed. For instance, the more slowly metal is cooled, the smaller the size of the grains inside it and the stronger the metal.
Wells creates mathematical models that help manufacturers design casting processes that optimize a metal’s microstucture. “These models can predict what the temperatures need to be, the compressions, the cooling rates, et cetera,” she says.
Wells is working with colleagues to perfect a new process called fusion casting. The new technique can be used to create metal sheets with a core that’s different from the surface: a core designed for strength and a surface customized to resist corrosion, for example.
They’ve already worked out how to make a certain type of aluminum alloy four times as bendable. “It’s very exciting,” Wells says. “We’re the only people in the world working on this.”