Converting this rotational and lift control post from a weld- ment (foreground) to a casting reduced cost and provided a five-times longer part life.
ing multiple pieces as one. “Te more pieces you have to weld
together, the better a casting looks, economically,” Hildebrand said. “Ge- ometry is essentially free in a casting. I can add strength where needed. It’s easy to do in a casting, much harder to do in a weldment.”
2. Other similar functioning parts are made as castings.
When Hildebrand gives customers
a background on weldment to casting conversions, he likes to show examples. Often, this sparks recognition and fa- miliarity. Te customer sees something similar to their own parts, and the
connection is made more easily for the potential of moving to a metal casting. “Te second conversion is always
easier,” Hildebrand said. “Or customers start thinking of castings [upon first product concept] and maybe design it that way from the beginning.”
3. Multiple features can be incorporated for increased op- portunity for cost reduction.
Carley Foundry (Blaine, Min-
nesota) worked with an aerospace customer to create an investment cast stator housing that was originally produced as a two-piece hogout with a pressed-in insert. Te end design
includes extensive external mounting features that act as attachment and support points for all the components of an electronic system and dual mo- tor controller. Te casting includes aerodynamic stator vanes, a motor case with ventilation holes, and a cast-in steel bearing liner. Te part also includes an integrated fan impel- ler containment ring and mounting brackets to support installation into the aircraft.
4. Weight reduction would be an advantage.
Magna Cosma International (Troy,
Michigan) worked with Ford Mo- tor Co. to design and build prototype vehicles with a 23.5% reduction in weight compared to a 2002 baseline target. As a result, seven aluminum structural body castings were designed to replace steel assemblies. Te casting process allowed for reduced mass and reduced part count. Ultimately, the castings provided a 25% weight sav- ings to the vehicle.
5. The potential benefits can make up for the initial casting design and tooling costs.
“Te volume has to be enough an-
nually to justify the tooling,” Hildeb- rand said. “Higher volumes help. Cost is an issue clearly, but we talk quite a bit about the soft advantages too. Casting can make it look better with curves and angles. We can add logos and part numbers. Or, where does the customer get skilled welders? With a casting, you can deploy those welders elsewhere in the shop.”
6. Can another material be considered?
Often steel is chosen in fabrication
Originally machined from solid billet, this cold chamber shot end plunger tip was redesigned as an investment casting for a 22% cost reduction. Casting provided the customer the ability to add as-cast internal heat transfer features not possible in machining.
because of its weldability. But if it is cast, that property is not necessary. Te material properties needed by the application might be met by another alloy choice, such as ductile iron (for better castability) or aluminum (for lighter weight). If you have a part that corresponds
with some of the points listed here, reach out to a casting supplier and invite them to your shop for an onsite review of inventory.
22 | METAL CASTING DESIGN & PURCHASING | Mar/Apr 2017
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