Here, the design changes at the top of the casting are shown with the red model representing the original drawing and the white model being the new design. The arrows indicate areas of the cross-section where changes were made.


“We originally had a drain hole in the


rear,” Sigelakis said. “We eliminated the drain hole and instead created two chan- nels under the tongue [to allow drainage]. Additionally, it protects the tongue and helps hold the core in place.” Applegate said several other chang- es completed the reduction in the num-


ber of cores used, including a change in the draft on the front cap at the top of the hydrant so that the cores could be drawn naturally (i.e., removed from the sand mold without damaging it). On the interior of the casting, the engi- neering team cored the hole where the ball screw would go to reduce porosity.


Finally, mass was removed from the inside channels so those cores could be drawn naturally, as well. “The cost of the tooling was much less after the redesign,” Sigelakis said. “Much, much less.” The new core design also eliminated a significant number of man-hours at


JULY/AUGUST 2011


METAL CASTING DESIGN AND PURCHASING


43


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