Effect of Thin Wall Machining on the Rotorcraft Industry

There is a need in the Rotorcraft industry for manufacturing methods that cost effectively produce complex Rotorcraft airframe components. New methods must eliminate built up structures that consist of many details, require the use of numerous fixtures, and are costly and time consuming to make. The complexity of the fabrication and assembly processes limit the opportunity for design changes, product optimization, and variation. Manufactures must reduce both the cost and time to market with an emphasis on design flexibility to meet customer demand. Sikorsky has been investigating new metal fabrication technologies to reduce the number of parts and complexity of rotor craft structures. By using new manufacturing processes that allow us to consolidate details into large, precise monolithic parts, it is possible to make dramatic changes in the way we assemble helicopters. Thin wall machining using a new generation of high speed machine tools is a technology being evaluated by Sikorsky for this purpose. This paper describes new machining processes and equipment that is used to create light and strong parts needed for rotor craft structures. How a new generation of machine tools allow for the replacement of thin gauge sheet metal assemblies with monolithic machined structures. Furthermore this paper will review how the combination of this technology and lean manufacturing change the assembly process. Specific examples using the Army Blackhawk multi purpose aircraft will be discussed to illustrate the application of the technology including cost differentials between the sheet metal and machined structures. We will review how the technology changes the sub assembly, major assembly, and final assembly processes with major cost drivers. Future applications of the technology on exterior skin panels using ISO grid structures will also be discussed.