CASTING INNOVATIONS
and Designs (an affiliate of Epcor Foundries) performed the simulation of the EGR valve’s casting process. Starting from a CAD mod- el of the valve, Kiefer defined the casting process parameters along with material properties and used QuikCAST to pro- duce a simulation that allowed the team to visualize mold filling and solidification— and eventually predict the part’s quality. From this, they determined that adjustments were necessary due to shrinkage porosity in certain locations of the part (Fig. 1). At this point, it was important to
analyze the results further in order to understand the evolution of this porosity during solidification. Kiefer determined in several criti-
cal areas the molten aluminum was solidifying early in the cooling process and creating isolated pockets of liquid metal that could not be fed through because the path to the feeders were cut. Tis is what caused the shrinkage porosity. A defect like this could cause
A final run of the part with QuikCAST revealed the
problems were resolved and the mold would produce
quality cast parts on the first try and each time after that.
the part to fail during its usage. If they found this defect on the shop floor, instead of in the design phase, it would have meant a delayed delivery, leading to a shutdown of the auto manufacturer’s line due to lack of parts.
Once the baseline simulation model was ready, Epcor could begin making modifications to eliminate porosity. Kiefer considered several approaches to address the problem but settled on adding risers. In do- ing so, shrinkage would occur in the risers and not the casting.
A final run of the part
with QuikCAST revealed the problems were resolved and the mold would produce quality cast parts on the first try and each time after that (Fig. 2). Ultimately, Epcor was able to build the mold design veri- fied by QuikCAST. Te mold produced good parts from the first run, exceeding their customer’s expectations. “Our customer was very
pleased that we were able to get the new casting up and running so quickly,” said Mike Maratta, plant manager, Epcor. “This helped avoid the downtime that our customer would have experienced if there had been significant delays dur- ing the process. The startup time and throughput levels were where they needed to be at the start of a program for a complex casting with tight quality requirements. The customer was very happy with our ability to launch such a complex part without any issues.”
Fig.2: Two simulated views show how the progression of changes in the gating and feeding system reduced the shrinkage porosity within the casting design. 42 | MODERN CASTING December 2016
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