An air inlet scoop for electronic cooling in a fighter aircraft pod manufactured by Uni-Cast, Londonderry, NH took the Aerospace Airframe Award in the Investment Casting Institute’s 2005 Casting Contest.
The military has often funded and encouraged industry to push the envelope of producibility in order to bring sophisticated product to market faster. While castings are a favorite component of many defense contractors due to high functionality, low weight and high stiffness, impediments to incorporating a complex casting during the development stage includes high tooling costs and long lead time. The 19″ x 18″ x l7″ aluminum component was produced initially from a stereolithography (SLA) prototyping pattern, thus eliminating initial tooling cost. While prototypes were being produced, Uni-Cast was concurrently developing the production injection mold. The mold was made available three months after prototypes were delivered. The customer benefited from the lead time advantage by saving costly program qualification delays.
The components were needed fast, but had to meet strict requirements regarding NDT soundness, surface finish and dimensional accuracy (wall thickness tolerance +/- 0.010″; aerodynamic smoothness 0.007″ per inch for the flow path areas; +/- 0.020 to +/- 0.040 depending on location to datum).
The design incorporated precise interfaces where cast and assembled sheet metal components must meet up.
In order to guarantee results for castings produced from SLA patterns, Uni-Cast designed and built an inspection fixture utilizing a centralized cast datum structure and the drawing tolerances. Castings were verified and guaranteed to machine without issue.