it allows you to do whatever types of changes are necessary inexpensively.” It turned out the design changes
made with the aid of the stress simulation proved on target. Te first pour of the gray iron part using the 3-D-printed core package was suc- cessful. Eventually, the entire pro- totype order of 20 pieces was made without defect using the 3-D-printed cores, and the lead-time was reduced to a few days rather than several weeks if produced with metal tooling. “Te success of the part required
two leaps of technological faith: stress analysis and using printed cores,” Burita said. “Both worked out great.” After the first success using
No cracks were found in the final castings.
Making Up Lost Time Because the prototypes were going
into production, Dalton had originally built metal tooling. Te 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. Te 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. Te 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 Foundry turned to new technology to solve the problem. Te metalcaster 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.” In the customer’s situation,
Dalton Foundry saw how it could take advantage of the ability to print directly from the model without upfront tooling cost, particularly with a prototype that had a history of crack defects. If more changes were necessary, they could be done
42 | MODERN CASTING September 2015
quickly and a new core could be printed within days. “Speed is a factor,” said Harold
DeVaux, national account manager, Neenah Enterprises Inc. “You can turn these 3-D-printed cores around in a short amount of time. Accuracy is very close to production-likeness. Using the customer’s model, you get a casting that is going to be very close to the production model, plus
the printed cores, Dalton Foundry decided to try its next prototype for a different customer using the same method. Now, just about every proto- type the metalcasting facility makes is via 3-D sand printing. “We had been looking at 3D
printing for awhile and this issue provided us the perfect opportunity to try it out in our own process,” said Chuck Fennell, program manager, Dalton Foundry. “It was the catalyst for us to do all our prototypes now with the new technology.”
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.
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