The elegant investment casting incorporates dozens of as-cast features and serves as a stunning example of what is possible in cast design. SHANNON WETZEL, SENIOR EDITOR
B
ruce Willson, sales manager for O’Fallon Casting, O’Fallon, Mo.,
spends a lot of his time teaching current and potential customers how to design for the casting process. In the case of an electronics housing for the defense industry, the customer conducted a casting design lesson of its own. “Tis is just one of the finest designs
I have ever seen, and I have been in the industry for close to 35 years,” Willson said. “Every part of that casting serves some function. Tey make [O’Fallon Casting] look really good.” Te customer, who wished to
remain anonymous due to the confi- dentiality of the part and application, has partnered with O’Fallon and other casting suppliers often, and that expe- rience culminated in the 2.2-lb. alumi- num casting—the winning design in the 2013 AFS/Metal Casting Design & Purchasing Casting Competition. “Just look at it and say, ‘Wow,’” said
one of this year’s casting competition judges. “Te fins, the holes, the need for dimensional stability—electron- ics housings will continue to demand more features as more electronics are jammed into smaller spaces.” Te ultimate goal of the electronics
housing, which measures 7.5 x 7.5 x 10 in., was to make it rigid and strong while also as light as possible. “The driving factor was weight, so the customer began with weight restraints,” Willson said. “It’s a portable device; an individual would have to carry this. So it started with, ‘How can we make this as light and rigid as we can?’” Because investment casting is a near-net-shape casting process, it provides a wide range of freedom of
ELECTRONICS HOUSING ELECTRONICS HOUSING
O’Fallon Casting, O’Fallon, MO Material: A356-T6. Process: Investment casting. Weight: 2.2 lbs. Dimensions: 7.5 x 7.5 x 10 in. Application: Defense industry.
• The customer avoided hours of fabrication and assembly by combin- ing multiple parts and features into a single, rigid piece. It is lighter and more precise than a comparable fabrication; secondary machin- ing was minimized.
• Thin walls (0.06 in.) keep the weight low, while a lattice of ribbing provides rigidity. Holes and slots further remove unnecessary material.
design. Draft and drawback (a part of a sand mold drawn back to clear overhanging portions of the pattern) are not necessary to include in the design. For the electronics housing, the customer cast in undercuts throughout the part to sculpt out material. Holes in the upper structure also serve to remove excess metal. “Tey were looking for grams of
material to remove,” Willson said. Checkerboard ribbing on parallel
walls reinforces and provides further stiffness. Two bosses are connected with a rib to provide further rigidity. Te rib has a dual function, as its presence helps
ONLINE RESOURCE
Browse through a gallery of all of 2012’s Casting of the Year candidates at
www.metalcastingdesign.com.
June 2013 MODERN CASTING | 21
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