tray were added to the one-piece casting design, while still keeping the component’s total projected weight to 20 lbs. The additional features were added to the model casting requirements, and the technical data package (TDP) was modified accordingly. Benet sent a request for quote (RFQ) and TDP to a number of investment casters with the requirement to provide one prototype casting for testing, and then the project hit a snag. Benet received a few bids that were unacceptably high in price and lead time. Many investment casters who did not bid provided the fol- lowing reasons: • The walls were too thin. • The thin-to-thick cross sections were difficult (0.08-in. walls to 1.5- in. x 1.75-in. mounting areas).
The deflector tray casting had difficult thin-to-thick sections where walls transitioned from 0.08-in. to 1.5 x 1.75-in. mounting areas.
• The casting was too rangy to readily be straightened.
• Grade B and C X-ray require- ments were too difficult for the casting configuration. After careful consideration by
the team, it was determined the deflector tray still was a viable casting design, and TDP require- ments could be produced. HAB, with 85 years of experience in the tooling casting industry and extensive work with many casting facilities, took the lead and sent out a more detailed RFQ. HAB selected Acme Cast-
ings, Huntington Park, Calif., to produce the part based on an agreement that HAB would supply the stereolithography (SLA) pat- terns, rigging and design and take total responsibility for the finished casting, paying for it regardless of meeting all requirements.
From Order to Completion
Benet issued a purchase order and the manufacturing process was started. Heat treatment of rangy parts is prone to cause distortion. The first process was to develop a means to achieve the dimensional requirements. HAB added tie bars, which would be cut off prior to straightening, to the casting model
44 | MODERN CASTING February 2014
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