detailset DESIGN
As-cast cored pockets can reduce weight while maintaining the structural strength of a casting. • T e key driver in this application was reduce weight and cost by designing as- cast cored pockets as opposed to a very expensive machined slot.
• Generally, the investment casting process allows thinner wall thicknesses and features compared to sand. T e shell mold is preheated, so the liquid metal fl ows for longer distances with a smaller temperature drop.
A smooth transition in the strengthening rib helps avoid localized stress concentration for better fatigue life. • Fillets and radii are key features for reducing stress concertation and achieving better fatigue performance.
• Risers are located by heavy masses for better directional solidifi cation. Properly designed steel castings, in which direc- tional solidifi cation is promoted, will be sound and free of shrinkage porosities and hot tears.
Jiten Shah is president of Product Development & Analysis (PDA) LLC (
www.pda-llc.com), (Naperville, Illinois), and a 25-year casting design and manufacturing veteran.
Nov/Dec 2016 | METAL CASTING DESIGN & PURCHASING | 19
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