Overlapping design and build cycles in product development

Product development time is a major component of the total time it takes to bring a product to market. Overlapping is the process of starting a downstream operation (such as manufacturing) before completing the upstream operation (such as design), There is an inherent risk in overlapping as a build-assembly may not be compatible with a subsequent assembly, requiring reconciliation work on the overlapped tasks. The ensuing trade-off between this risk, and the project time saved, is shown to possess some unique characteristics among different modes of overlapping. We study the optimization model of the trade-off in general, and analyze some special cases to establish interesting insights on overlapping. These include: advantage of overlapping in different scenarios, special properties of optimal overlap, and impact of parameter values on overlapping decisions. We show, that several properties of a single overlap can be extended to multiple overlaps, and establish a limit to overlapping based on administrative cost of implementing overlap and shapes of cost functions. The critical role of the administrative cost (of coordinating overlaps) is also borne out by the model. (C) 2001 Elsevier Science B.V. All rights reserved.