Simple Robust Formulations for Engineers: An Alternate to Taguchi S/N

Robust engineering is an integral part of the quality initiative, Design For Six Sigma (DFSS), in most companies to enable good designs and products for reliability and durability. Taguchi’s signal-to-noise ratio has been considered as a good performance index for robustness since many decades. An alternate approach that is direct and simple for measuring robustness is proposed. In this approach, robustness is measured in terms of an augmented output response and it is a composite index of variation and efficiency of a system. This formulation represents the engineering design intent of a product in a statistical sense, so engineers can understand, communicate, and resonate at ease. Illustrative formulations with case studies are discussed with respect to smaller-the-better, nominal-the-best, and dynamic responses. Confirmation runs of optimization show good agreement of the augmented response with the predictive models that are based on the additivity principle.