On tolerance analysis of precision rotating assemblies in aeronautics

Product developers are always eager to pursue strategies to develop the best product right for the first time with minimal variation. In this regard, one of the most effective tool, being used for variation prediction and evaluation, is tolerance analysis. Tolerance analysis has been at the heart of precision assembly design during recent times in aerospace industry. It has not only gained ultimate imperativeness and effectiveness by improving the product quality but also provided a tremendous support towards quantifying the deviations of precision assemblies. Deviations are indispensable to every phase of product's life cycle: design, manufacturing, assembly and assembly operation. Tons of literature has been published vis-à-vis tolerance analysis of static structures, however, less attention has been paid to the assemblies in motion. Gear based transmission mechanisms are a popular choice for development of precision rotating assemblies. In order to achieve peak performance and accuracy for assembly rotation, centre to centre distance is a critical factor. A cast-off and out of size centre to centre distance may lead to catastrophic errors in product's functionality and performance. In this regard, there is always a need to analyze it at early design stage in order to ensure the assembly (rotational) accuracy. In this paper, tolerance analysis of a precision spur gear based assembly has been performed focusing center to centre distance, results have been analyzed and design recommendations have been provided.