Casting and Chill`n - Dr. Daan Maijer, University of British

Casting and Chill’n
Spare some sympathy for the manufacturers of engine blocks
and cylinder heads. These major components are large and
bulky, to be sure, but they are intricate as well. Their
performance depends on precisely defined channels and
openings, which are expected to hold up to high pressures and
high temperatures. And, in the interests of making our vehicles
lighter and more fuel efficient, the walls surrounding those
channels and openings are expected to be thinner than ever
before, but without compromising tensile strength or fatigue
resistance.
That amounts to a tall order for manufacturers, but casting
methods have evolved to meet the challenge in recent decades.
Among the most sophisticated is the Cosworth process, a sandcasting strategy developed in the late 1970s, which uses
pressure pumping to inject metal into the mould. This approach is
fast and efficient, improving the ultimate accuracy of the casting
and making it possible to create the lighter, stronger components
so eagerly sought by the automobile industry.
Dr. Daan Maijer has been looking at further enhancements to this
process. The University of British Columbia professor of
materials engineering, along with his colleagues at UBC campus,
Ryerson University, and the University of Waterloo, are
examining the way in which the mould is cooled, a critical step
that determines the underlying structure of the metal as it
solidifies.
“If you bring the temperature down faster, there’s less
porosity, there are fewer holes in your metal,”
he explains. “And the actual structure that makes up the grains
and the dendrites is smaller and finer, which means it’s stronger.
It also leads to better fatigue performance, and since this is an
engine block we’re talking about, it can go through many more
cycles without failure.”
Unfortunately, he adds, it is possible to bring the temperature
down too soon. In the case of an engine block, if you apply chill
technology — targeted, high intensity cooling — before the metal
has successfully settled in all those intricate channels and
openings, the entire structure will be compromised. According to
Dr. Maijer, the key is timing, knowing exactly how long to leave
the casting hot then cooling it down immediately.
Dr. Maijer leads the AUTO21 project Advanced Chill
Technology for Powertrain Components.
Credit: Wendy McHardy/UBC Faculty of Applied Science
He is leading an AUTO21 project to examine how to optimize the
application of chill technology. This research is taking advantage
of UBC’s well established relationship with various industry
partners, in this case General Motors and powertrain maker
Nemak.
“We’ve worked with these kinds of manufacturers for about 15
years,” says Dr. Maijer, crediting this collaboration with vital
insights into just how casting proceeds in this kind of full-scale
industrial setting. He can only replicate some aspects of that
setting in a more modest casting facility on the university campus,
which has already yielded some findings on how rapid chill
techniques affect simple wedge components. The researchers
are now turning to more complex castings that would mimic
slices of an engine block, with the aim of compiling a scalable
computer model.
“If we can do this properly, where we can characterize the
cooling that we get, then we can model it,” he concludes. “We
use the data from the slice castings to ensure that we are able to
model it accurately, then we apply that to the industrial case.”
AUTO21 is supported by the Government of Canada through a Networks of Centres of Excellence program
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