Cost-oriented process optimisation through variation propagation management for aircraft wing spar assembly
McKenna V., Jin Y., Murphy A., Morgan M., Fu R., Qin X., McClory C., Collins R., Higgins C.
Overconstrained assemblies such as aircraft sub-assemblies present a challenge to production planners, as variations in parts and processes can make it difficult to achieve all assembly Key Characteristics (KCs) simultaneously. Despite assigning tight tolerances to sub-component manufacture, part variation propagation necessitates expensive and time-consuming variation management processes such as shimming in order to ensure the final assembly is within specification. This paper presents for the first time a variation propagation model for overconstrained assemblies, and develops a novel modelling method to connect variations with production costs. This facilitates a novel process optimisation method based on variation propagation, with the ability to analyse the trade-offs between the cost and achievable variation limits of the entire manufacturing chain in order to minimise the overall manufacturing cost. An overconstrained wing spar assembly is used as a case study to validate the methodology.