of its initial casting design iterations. After his visit, Hudson returned to
Illinois to make modifi cations to the solid model. “With his new knowledge of how
a casting is made, he could make some of the [castability] changes without us having to bring it up,” Downing said. Hudson said one of the main things he learned during his visit was the importance of avoiding burnt-in sand and how to do so. Many of the bosses on the weldment design were blended together to make the cores simpler and reduce the chances of the defect. “You don’t want small fi ngers [of
material] in the casting if you don’t need them for the function of the part,” Hudson said. T rough 10 design iterations, Cat-
erpillar and Monarch moved tubing and passageways, combined bosses and simplifi ed shapes to improve cor- ing and molding. “Once [Hudson] made some of
the changes, we realized if we took it further, we could eliminate some loose inserts or drop a core,” Downing said. T e open communication estab- lished with Hudson’s visit at the start of the project gave Monarch the freedom to suggest design changes to improve castability. “Typically as a foundry, you get a
drawing from the customer, and you don’t really know what’s important or what’s critical. You quote to print,” said Mark Hildebrand, director of market- ing at Monarch. “Knowing the applica- tion, we were able to question some design aspects because it could cause casting issues. And knowing the casting issues, Darryl was able to tell us if a feature wasn’t necessarily important.” Hudson said the conversion was the most experience he has had in changing a design to better fi t the casting process. “A lot of pieces I’ve worked on are
smaller and simpler,” Hudson said. “But since the Monarch job, I have already applied what I’ve learned with this part to other projects.”
Increasing Time to Market Monarch Industries applied past
Torque Converter Housing Monarch Industries Ltd., Winnipeg, Canada
Material: G3000 gray iron. Process: Nobake. Weight: 610 lbs. Dimensions: 37.8 x 29.2 x 26.9 in. Application: Housing for 2,300-hp transmission for fracture oil drilling.
Converted From: Weldment.
• Converted from a 36-piece weldment, the single casting cut total lead time in half. Part numbers, revision numbers, customer logos and date codes were cast-in.
• The casting reduced the high scrap rate suffered by the weld- ment due to leaks in the many feet of welding in each part.
• By reducing labor, lead time and scrap rate, the casting in- creased the customer’s overall manufacturing capacity.
• Radii, fi llets, curves and increased wall thickness were added where needed to give the casting strength.
lessons of its own on the torque converter housing. The metalcaster had produced a similar casting before and, based on that experi- ence, opted to rotate the new part’s orientation 90 degrees and move the parting line. “T is way, we were able to utilize
smaller coreboxes that we preassem- bled before dropping the entire core- pack into the mold,” Hildebrand said. T e smaller corebox design allowed Monarch to produce the nobake cores with its automatic coremak- ing machine, which helped increase coremaking and molding speed. “Because we were able to confi gure
the cores the way we wanted, we can mold two of the castings in the same time as one casting with the old mold design,” Hildebrand said. For Caterpillar, the reduced time
from molding to delivery was a fur- ther improvement on already short- ened lead times. Hudson typically schedules casting orders a month or two out (the weldment took up to 12 weeks) but likes the ability to receive parts sooner when in a bind. “We don’t typically require this tight of a turnaround, but we know Monarch could pour the casting one week and send it to the machining supplier the next week,” he said.
May/Jun 2012 | METAL CASTING DESIGN & PURCHASING | 27
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