details DESIGN
As-cast and drilled holes both are featured in the design, depending on size and location.
• Investment casting is limited to a minimum size for holes that can be cast in. T ese are drilled in after cast- ing for better positioning and cleanliness.
• On the other hand, pre-heating the ceramic shell in the investment casting process provides lower thermal gradients, which allows thin-walled casting confi gu- rations with intricate cored holes. T e surface fi nish achieved with investment casting is the best among all other casting processes due to the smooth fi nish of the wax pattern and ceramic shell.
As-cast cored features eliminated secondary machining.
MEDIA
RESOURCE Using the Actable App, scan this page
to see a video of Jiten Shah dis- cussing the part’s design details. For instructions on Actable, see p. 1. To watch online, go to
www.metalcastingtv.com.
Generous fi llets and radii provide smooth transitions throughout the casting.
• Generous fi llets and radii are essential to prevent any hot tearing or cracking and also for smoother entry of the liquid metal into the shell mold.
Undercuts and thin-walled sections with no draft reduce weight.
• Magnesium investment casting can achieve 0.06-in. thin walls with high defi nition. Cross ribs off ered the required stiff ness to the mounting bosses.
• It was possible to hollow out the underneath /back side of the fl ange.
Jiten Shah is president of Product Development & Analysis (PDA) LLC (
www.pda-llc.com), Naperville, Ill., and a 25-year casting design and manufacturing veteran.
Sept/Oct 2014 | METAL CASTING DESIGN & PURCHASING | 15
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