detailset DESIGN
Choosing to produce a hole during the casting process or through secondary drilling depends primarily on the feature diameter, thickness and location with respect to the parting plane.
• Because these holes were located on the parting plane, they were cored.
• T ese holes, which are small and away from the parting plane, were drilled, as opposed to cored.
Feature placement and drafting are such that the pattern can be withdrawn from the mold without mold breakage.
• T e parting plane is where the halves (the cope and the drag) of the mold tooling will split. Casting orientation—how the mold will be split into two halves—is determined based on the ease of gating and risering, ease of core placement, the location of critical features and lettering, surface fi nish desired in critical areas and overall casting soundness required.
• Any back draft with reference to the parting plane will lock up the pattern and require additional cores or a loose piece. Both will add to the cost and dimen- sional variability.
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 2015 | METAL CASTING DESIGN & PURCHASING | 19
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