Support for the analysis of the chains of tolerance (tolerance management)

Abstract

The sum of all tolerances results from the combination of machine accuracy and dimensional accuracy of the components, depending on the respective process. Hence, we have compiled the main sources of tolerances within this report. Already during the design phase and the definition of the process chain, the requirements for parts and process specific constraints with initial assumptions on accuracy were compiled. For machine accuracy, we distinguish between absolute and relative accuracy. For the actual shape of geometric features, such as pad-ups/local patches and their ramps, the absolute accuracy of the tow deposition is decisive. We have thus measured the absolute accuracy of our multifunctional robot cell. Also, certain deviations arise from the tools or end-effectors mounted to the robot. Measuring the machine accuracy aided in distinguishing the main sources of deviation and deduce respective compensational and optimization measures. Considering the part deviations, with the first set of stringers delivered by AERNNOVA and frames delivered by Premium AEROTEC in December 2020, DLR had the chance to 3D measure the geometrical features. In general, a high quality of the press molded was found.