innova iovations CASTING EGR Valve Redesign Relies on Simulation A

fter winning business from a competitor, Epcor (Cincinnati) needed to produce complex exhaust gas recirculation (EGR) valves for an automotive parts manufacturer. Most modern engines use this emissions reduction technique

to meet automotive emission standards and the valves must be manufactured to high standards. T e challenge for Epcor was to produce these parts quickly and without fl aw. T e standard approach for metalcasting is for pattern- makers to design molds based on their own experience. T is method is less than optimal for various reasons, the number one reason being that the initial design is rarely viable. In the case of the EGR valve, Epcor knew it could not meet the customer’s aggressive delivery requirements using the tradi- tional approach. T erefore, after evaluating diff erent casting simulation tools, Epcor turned to ESI QuikCAST. In ad- dition to it being an affordable solution, Epcor liked the fact that QuikCAST linked them to ESI’s more compre- hensive casting simulation program, ESI ProCAST. To begin, Paul Kiefer, Senior Design Engineer for Hitech

Shapes and Designs (an affi liate of Epcor Foundries) per- formed the simulation of the EGR valve’s casting process. Starting from a CAD model of the valve, Kiefer defi ned

the casting process parameters along with material properties and used QuikCAST to produce a simulation that allowed the team to visualize mold fi lling and solidifi cation—and eventually predict the part’s quality. From this, they deter- mined 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 solidifi cation. Kiefer determined in several critical 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. T is is what caused the shrinkage porosity. A defect like this could cause the part to fail during its usage. If they found this defect on the shop fl oor, 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 the necessary modifi cations to eliminate porosity. Kiefer considered several approaches to address the problem but settled on adding risers. In doing so, shrinkage would occur in the risers and not the casting. A fi nal run of the part with QuikCAST revealed the

problems were resolved and the mold would produce quality cast parts on the fi rst try and each time after that (Fig. 2). Ultimately, Epcor was able to build the mold design veri-

fi ed by QuikCAST. T e mold produced good parts from the fi rst 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 during the process. The startup time and throughput levels were where they needed to be at the start of a program for a complex cast- ing with tight quality requirements. The customer was very happy with our ability to launch such a complex part without any issues.” 

Fig.1: An initial QuikCAST simulation shows shrinkage porosity present in the casting.


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