simulation helped prove that to the customer. Seeing the actual picture really sold it.” Based on the simulation
Shown is the modified casting at shakeout (left) and after shot-blasting.
Due to the urgency for the customer to receive replacement parts, Dalton utilized 3-D- printed core technology to reduce lead times from several weeks to a few days.
results, Dalton engineers, along with the customer’s engineers, began making modifications to the design, eventually working through 10 design changes before settling on one that indicated zero stress issues in the simulation. The final, successful gear case housing design featured thin- ner ribs that were more curved in shape with a little more draft angle, which provided a more solidification-friendly transition from the diameter of the cast- ing’s top, around the windows of the rim, and down to the massive base on the bottom.
Making Up Lost Time Because the prototypes were
going into production, Dalton had originally built metal tooling. The plan was to cut the metal tooling again, but because of the time it took to redesign the part, the customers were in urgent need of the cast parts as soon as possible. The gear case housing was one of five prototype parts Dalton Foundry was producing for the customer’s final assembly. Four of the parts were ready. The customer wanted to move on to the next stage of development for its assembly to stay on schedule for production in late 2016. Metal tooling modifications
in the corebox would have taken several weeks. Like the use of stress simulation, Dalton Found- ry turned to new technology to solve the problem. The met- alcaster opted to make the mold and cores without tooling using 3-D sand printing. “Our customer was up against
the wall needing parts. We were aware of 3-D printing and that a printed core could be turned around in less than a week,” Burita said. “But this was our first use.”
28 | METAL CASTING DESIGN & PURCHASING | Sept/Oct 2015
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