Divergence and lifecycle offsets in product families with commonality

Commonality, or the reuse and sharing of components, manufacturing processes, architectures, interfaces, and infrastructure across the members of a product family, is an often leveraged strategy targeted at improving corporate profitability. Commonality strategies are widespread in the literature and in industrial practice, but a clear gap exists: The literature has a distinctly positive bias towards the benefits of commonality, whereas industrial success with commonality has been mixed. This article explores two phenomena, divergence and lifecycle offsets, that may prevent companies from properly assessing and realizing the potential benefits of commonality. Using a multiple case study approach, we trace commonality levels through the lifecycles of seven complex product families that span the aerospace, automotive, semiconductor capital equipment, and printing industries. The case studies indicate that commonality tends to decline over time, a phenomenon we title divergence. In contrast to the prevailing concept of parallel development in product families, we find that lifecycle offsets, or temporal separations between the development, manufacturing, operations, and/or retirement phases of two or more products, are prevalent in industrial practice. Through this exploratory study, we find that lifecycle offsets may reduce the potential benefits of commonality, make the realization of benefits much more difficult, delay the realization of benefits, and reallocate potential benefits across individual products. We predict that lifecycle offsets exacerbate divergence. We propose a framework for categorizing parts‐level changes that explicitly recognizes the potential for divergence. We conclude with guidance for product family managers, namely, that commonality be managed dynamically throughout the product family lifecycle, rather than as a static property. Additionally, we articulate the need to make commonality decisions from a product family perspective, a perspective that may lead to decisions that create near‐term costs for one variant but result in larger long‐term savings for a second variant and for the product family as a whole. ©2012 Wiley Periodicals, Inc. Syst Eng 16