. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Design Details
Cast Cradle Throttles Steel Design Jiten Shah, Product Development & Analysis, Naperville, Illinois CASTING PROFILE
Component: Cadillac CTS Engine Cradle. Casting Process: Semi-permanent mold casting. Material: A356 aluminum. Weight: 33.5 lbs.
and making welding easier. T
Cored holes support internal body core. • Cores allow the design flexibility to make a com- ponent hollow without compromising the struc- tural integrity of the casting. The cores have to be supported in the mold so they don’t move during filling and solidification. The cored holes in the cradle casting were incorporated into the original design to provide support and vent core gases.
• As long as the cored holes are placed in low stress, non-critical areas, the overall structural integrity of the casting will not be compromised.
Thin and uniform wall thicknesses optimize part weight. • The internal body core made it pos- sible to achieve 0.16-in. walls with stable dimensional accuracy.
• The fluidity of A356 aluminum and creative gating design, allowed the casting to be produced with opti- mum mold yield and no risers, which improved the casting surface finish.
his casting is welded to four aluminum extrusions to form the engine cradle for a Cadillac CTS. The part achieved a mass reduction of 40% and consolidated a 32-piece steel design into one component. By care- fully positioning cores in metal dies, the part achieved 0.16-in. wall thickness, providing a weight savings of 2.2 lbs. over previous designs
One-piece design incorpo- rates mounting brackets and other appendages. • By careful selection of the parting plane of the metal mold, gating system and stable inter- nal body core, it was possible to incorporate more than 32 pieces of steel fabrication into a one-piece casting and include as-cast mount- ing brackets, ribs and stiffeners.
Cross-hatching allows better fluidity. • For thin wall, permanent mold casting of alumi- num alloys, cross-hatching features on the casting surfaces helps break the oxide films formed during filling and allowing easier filling of thin walls.
Jiten Shah is president of Product Development & Analysis (PDA) LLC, Naperville, Ill., and a 25-year casting design and manufacturing veteran.
20 Metal Casting Design & PurChasing MarCh/aPril 2011
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