A carefully-designed and engineered casting can assist the manufacturing engineer with tremendous time, floor space, and cost savings.

The key to success is the knowledge of the casting process and its capability to achieve the required dimensional tolerances. The result: Features line up at the locations where they are required to be mounted. In addition, you achieve as-cast surface finish and smooth transitions with fillet and radii for better fatigue life and performance.

In the case of this ductile iron casting––an industrial truck bracket––the customer realized a 40% cost savings by converting a six-piece weldment to a single casting. The foundry said it provides more strength and durability and frees up capacity in multiple manufacturing areas. 

Parting and orientation (1)
•    At the start of the casting design and conversion, the design engineers must rigorously evaluate various alternatives before finalizing the parting planes for the pattern, corebox, and the key features’ orientation with regards to gravity. Subsequent casting detail design and the ultimate casting quality will depend on this upfront critical decision making!

As-cast stiffeners and cored holes (2)

•    Webs and cross ribs provide the required stiffness in place of thicker cross sections, thereby allowing weight savings to the design engineers. Cast iron mechanical properties are directly influenced by the section thickness––thinner is stronger than thicker, which can seem counterintuitive to design engineers.

•    Computer modeling and simulation of the casting process is a very effective tool to predict the microstructure and properties in critical areas of the casting before releasing the final design––and building an expensive tool.

Smooth transitions for better aesthetics and lower stress concentration (3)

•    The casting manufacturing process allows design engineers the flexibility for smoother transitions from thicker to thinner by incorporating complex blends and generous radii and fillets.  From a strength of materials point of view, the smoother transitions of varying cross sectional areas eliminate or reduce the stress concentration effects, with better component fatigue life in service.

•    With casting, all the appendages will have radii as opposed to sharp edges, and all the junctions––L, T, X and Y–– will have corner fillets for smoother transitions. 

•    The overall effect is greatly reduced stress concentration that is typically associated with sharp changes in the cross sections with weldments.