A. M. Helvey, M. T. Schaefer, The Boeing Company, St. Louis, MO; R. L. Hanks, Advanced Manufacturing R&D, Boeing – Phantom Works, St. Louis, MO; S. Fox, TiMet Corporation, Henderson, NV; T. Tuohy, H. Camden, GKN Aerospace, St. Louis, MO

Summary:

The fabrication of large (72 inch x 144 inch), thin step-lap picture frame structures from Ti-6Al-4V for bonding with polymer matrix composites has primarily been accomplished by machining side pieces and welding them together. This requires long lead times, the need for extensive weld fixtures, and special order of precision ground stock. Plate flatness tolerances, machining tolerances, and high buy:fly ratios have prevented the used of monolithic machinings. As a part of the Metals Affordability Initiative Program, manufacturing development was undertaken to fabricate these structures from a single piece of Ti-6Al-4V plate rolled from single-melt electron beam cold hearth melted ingot. Ingot breakdown, rolling, machining development, and the final machining practice and results are presented.