FORT WORTH, Texas, July 24th, 1998 -- The Metals Group of the Advanced Affordability Initiative at Lockheed Martin Tactical Aircraft Systems has been evaluating a process to reduce airframe assembly costs, and the early prognosis is good. Known as "aluminum investment casting," it is a process of melting aluminum and pouring it into a mold to create large, unitized assemblies.

The process does away with the need for sawing, stretch forming, machining, drilling and fastening to make an assembly. Lockheed Martin is looking to apply the process to support affordability goals for future aircraft such as the Joint Strike Fighter.

The forward equipment bay of the F-16 was chosen to demonstrate and validate the use of the casting technology. "We chose this assembly because it was a good example of how we could replace a number of costly, time-consuming fabrication and assembly steps with a single casting," said J.T. Amin, lead for this initiative. "Under the conventional process, assembling a forward equipment bay entails drilling and fastening almost 150 design details. With the casting process, that is no longer necessary. Also, we were able to incorporate 73 design details into one single casting design."

The casting was produced by Cercast, Inc., of Canada, owner of a new pouring and rapid solidification technique used in the process. The pouring and the rapid solidification technique is known as "Sophia Process" in the industry. Through a rapid prototyping method using stereolithography, Cercast was able to build the part quickly from computer-generated design databases. "The fabrication of the casting posed numerous challenges for Cercast," said Amin. "Given its size and complexity, the assembly is a first for aluminum investment casting. Yet despite this challenge, Cercast produced the casting in 12 weeks versus more than a year using conventional methods."

According to Ken Taylor, director of the Advanced Affordability Initiative at Tactical Aircraft Systems, "Aluminum investment casting meets two objectives of the metals program. First, it demonstrates the viability of producing large, single-unit aircraft substructures with this process. Second, it collects cost data of producing similar castings in a production environment."

Preliminary cost estimates indicate a savings of 15 to 20 percent over current processes. "Investment casting gives us the potential to make a significant contribution towards the goal of making our fighter aircraft more affordable, not only with current programs, but with future ones as well, such as the Joint Strike Fighter," said Amin.

In addition to the cost savings, investment casting also improves quality because unitized construction can eliminate potential fatigue problems associated with the numerous fastener holes required for assembling detail parts. Moreover, the designer can create shapes that are normally very difficult or impossible to machine. Shapes of this type improve load distribution and ultimate strength.

Lockheed Martin’s Fort Worth plant produces the F-16 for the U.S. Air Force and a number of foreign countries and is leading Lockheed Martin’s Joint Strike Fighter team. It also produces the mid-fuselage for the F-22 aircraft and is participating in production of Japan’s F-2 fighter.