Category II: Manufacture-Driven Design Considerations
Design for Manufacture: The trade-off study is concerned with the appropriate process required for parts fabrication, including cost-versus-material selection, process selection, the use of NC machines, parts commonality, and modularity considerations to facilitate assembly. A key issue in the conceptual design stage is a low parts count to reduce assembly time. The lowest parts count may not be the least expensive method – compromise may be necessary.
Design for Assembly: This is concerned with the fewest manhours required to assemble parts. Traditional practices in aircraft assembly include numerous components and a complex organizational structure in the engineering, logistics, and management disciplines. This results in an inefficient use of factory floorspace, and quality is compromised due to the unnecessary operations and fasteners required to join mating parts. DFA minimizes manufacturing costs by optimizing engineering methods using innovative best-practice techniques of jigs and tool design, whether a manual or computerized assembly method. Product configuration and the detailed design of parts are important in the assembly process.
Design for Quality: Adherence to the specification requirements is the essence of quality control. One example is meeting the aerodynamic surface – smoothness requirements through surface-tolerance specifications at the component final assembly. Currently, many quality issues are addressed in the post-conceptual design stage; they should be advanced to the conceptual design stage.