facilitating part inspection dur- ing the straightening process. Te team decided to design an inspection fixture using go/no- go gages on critical features. A conventional metal inspection fixture was deemed too costly with too great a lead time for a single casting. As an alternative, the check fixture was designed to use the conventional metal go/ no-go gages. HAB created the gating design using CAD model- ing, but did not perform verifica- tion with solidification software due to the high cost and long lead time estimates received. Instead, the company relied on its extensive tool- ing experience and ability to produce a sound casting. After inspection, HAB shipped
poured to HAB-specified shell and metal temperatures. Upon shakeout and cleanup,
The rim of the casting features 0.08-in. walls.
the SLA patterns to Acme Castings, along with a gating design model that included fully dimensioned gating drawings and all wax gate bars cut to size and identified. Te
metalcaster gated the part according to HAB’s design, dipped the ceramic and fired the shell. Te shell was cleaned to remove ash residue from the sintered SLA material, sealed and wrapped with k-wool insula- tion in the locations on the drawing provided by HAB to ensure proper solidification. Te ceramic shell was heated in an oven and the castings
the casting exhibited some minor misruns and nonfills along the rim of the 0.08-in. walls. Tese areas were weld repaired and cleaned, and the casting was sent to hot isostatic pressing (HIP) to help ensure metal quality and meet the nondestructive test- ing (NDT) requirements. After heat treatment, Acme Castings removed the tie bars and set the casting up for straighten- ing. Upon placing the casting
in the printed inspection fixture, the metalcaster discovered the cast- ing had hardly moved at all and minimal straightening was required. After straightening, the casting was inspected in the fixture using go/no- go gages and then sent to final heat treatment. An outside lab performed NDT X-rays to Grade B in critical areas and Grade C in the balance of
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