Tapered Hole Automation for Hard Metals – Enabling Producibility 2020-01-0006
Assembly of the F-15 wing utilizes the Taper-Lok fastening system which requires precise preparation of conical holes to enable tapered fasteners to provide a uniform interference fit. The controlled interference fit directly affects fastener preload to reduce stress and improve fatigue life. Traditional methods for generating tapered holes in thick aluminum and titanium structures require heavy duty tooling. Fixtures are clamped to aircraft structure which hold large power feed to complete the hole generation processes in multiple steps. Manual drilling for Taper-Loks is labor intensive, non-ergonomic, and requires extreme care to ensure quality holes are produced. Automated hole generation was a logical solution to the complex Taper-Lok fastening system, however replicating traditional drilling methods proved challenging. Extensive testing was completed to ensure hole quality generated with automation would meet or exceed existing power feed equipment. Once process capabilities were proven and equipment requirements were generated, an articulated arm-based drilling system was developed and implemented. The automation was designed to accurately position and complete the hole preparation process in a single pass by the use of multiple high-torque spindles and a hybrid coolant system. Other functions include automated temporary fastening, auto-normalization, and automated cutting tool exchange. This paper presents complexities of the hole generation process and the automated solution that provided ergonomic, quality, and efficiency improvements to F-15 wing production.
Trevor Hartnagel, Russell DeVlieg
The Boeing Company, Electroimpact Inc.