A Study of the Evolution of Uncertainty in Product Development as a Basis for Overlapping

Overlapping new product design process is widely applied in industry. However, selections of appropriate overlapping strategies based on the prediction of process performance can be problematic due to insufficient understanding on the dependence between design processes and its effect on the performance. This paper introduces a new model for a product design organization that is based on the evolving nature of the design process, the dependence between up and downstream design specifications, and the design technology being adopted. The model presents an evaluation method for quantifying the downstream evolutionary behavior. Through an industrial case study, it is applied to evaluate how the design performances vary under different overlapping strategies and how to determine an optimal overlapping; the results imply that the performance is contingent on the strategy, and no single strategy outperforms in overall performance measures. Furthermore, the model measures process dependency - a quantification of the downstream work that is indifferent to the change of the upstream. This quantification can be applied to determine the rework probability or rework function proposed by other studies. The model also addresses the rationale of how improving design technology efficiency can lead to an upgrading of design performances.