Abstract
This paper presents a novel optimization technique in straight-build assembly to control variation propagation. The optimization technique is developed by minimizing the eccentricity stage by stage in the assembly. The straight-build assembly model is derived from connective assembly models, easily expressing the part-to-part relationships. Any measurement error or process error in the assembly can be easily incorporated in the model. This approach can be also used to predict the final assembly quality while the design is still at the conceptual stage. The straight-build assembly is validated by using statistical analysis through two case studies: a simple identical cylindrical-component assembly and a practical non-identical cylindrical-component assembly. The variation propagation can be reduced significantly for the straight-build assembly, compared to the direct-build assembly without optimization. The results show how the variation propagation control is related to process noise and measurement accuracy. The simulation results also show that minimal variation can be achieved at reduced cost by properly selecting the accuracy of measurement, according to process procedures. The information obtained provides a practical and useful approach for design engineers. The potential applications of the straight-build assembly are also illustrated.