details DESIGN


Ribs and Pockets Add Stiffness, Reduce Weight


JITEN SHAH, PRODUCT DEVELOPMENT & ANALYSIS, NAPERVILLE, ILLINOIS CASTING PROFILE


Cast Component: Front engine support.


Casting Process: Green sand casting.


Material: 65-45-12 ductile iron. Weight: 18.6 lbs.


Dimensions: 25.8 x 10.2 x 4.7 in.


C


onverting to ductile iron castings saved Paccar, Bellevue, Wash., more than $400,000 annually for a heavy truck front engine support cast by Neenah Enterprises Inc., Neenah, Wis. T e cast- ing eliminated two parts, provided a 55% weight reduction over previous versions and eliminated the risk of galvanic corrosion.


As-cast pockets provide improved stiffness and reduced weight.


• Pockets with corner fi llets and radii were designed for lower weight without weaken- ing the component for structural strength.


Casting parting plane


• Typically, lightening pockets requires additional cores. In this case, by design- ing locations strategically with reference to the parting plane, it was possible to achieve as-cast pockets using the cope and drag mold patterns.


• T e casting design achieves smooth transitions in the lightening pockets with fi llets and radii in the low stress areas. Smooth transitions, as opposed to sharp corners inherent with machined pockets, eliminate the stress concentration eff ect, which leads to better fatigue life.


18 | METAL CASTING DESIGN & PURCHASING | May/Jun 2013


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