Dimensional management for aerospace assemblies: framework implementation with case-based scenarios for simulation and measurement of in-process assembly variations

Tolerances within an assembly are defined during the setting of engineering specifications in the design phase. However, during assembly process execution, certain assembly variations arise from the individual components, manufacturing imperfections, material compliance, the means by which they are fastened and the assembly sequence used. The implementation work reported in this article utilises in-process assembly measurement information for predicting dimensional variation of the aero structure assembly process. A framework is exploited in the case study for predicting the dimensional influence of (1) designed tolerances, (2) designed assembly processes and (3) component and sub-assembly level measurement data for revising the assembly sequence if any concessions were issued on manufactured components. Considerable learnings are achieved while managing dimensional variation of in-process aerospace assembly structure. Dimensional variation simulation is found to be overestimating variation spread even after considering compliance of non-rigid components. Thus, in-process measurement data (component and sub-assembly level) has to be integrated in the variation analysis in order to reduce variation spectrum. Case-based scenarios are discussed where design and measurement data can be utilised for estimating dimensional variation of the in-process assembly.