details DESIGN
Smooth transitions and generous fi llet and radii of- fer better fl ow of sand during molding. This produces sounder mold sections with deep pockets, which other- wise may break off or become dislodged and result in a casting with sand inclusions. • Complex green sand castings require generous fi llet, radii for smoother transitions.
• Smoother transitions allow reduced turbulence of liquid iron while fi lling into the mold cavity.
Machined
Overall casting quality and dimensional accuracy increase with reduced number of cores. Fewer cores also reduces the overall cost of the casting and the lead time. • T e decision to incorporate as-cast vs. drilled features is based on the feature size (diameter and depth), section wall thickness in the vicinity, and the location with respect to the parting plane. T e design engineer determines to make the holes as-cast or cast solid and then drilled.
• Mounting holes on the vertical surface here are cast-solid and drilled later on.
Cross ribs replace the thick wall along the parting plane to achieve the same stiffness with reduced weight.
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.
May/Jun 2017 | METAL CASTING DESIGN & PURCHASING | 17
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