Investigating and Managing Design Margins throughout the Product Development Process

Abstract

The automotive industry, like other sectors, faces a number of technological challenges in terms of meeting different legislations and developing products highly customised with a short lead time. They also have to manage the trade-offs between the price for the customer and the overall cost of the product development. This thesis argues that design margins are a decisive factor with regard to many trade-offs that engineers may wish to make. These margins represent room for manoeuvre in the developing design. On the other hand, design margins allow engineers to accommodate new requirements without leading to costly engineering changes. If a change becomes necessary, the engineers might modify parameters where there are still margins with respect to the new requirements. Therefore engineers can avoid major redesigns to their existing components and systems. Ultimately this has the potential to enable control of the resulting development time and cost. While margins are an intuitive concept, no clear and consistent definitions exist. The concept is relatively under-investigated area of design research. A comprehensive literature review and an empirical study at Volvo Global Truck Technology, emphasised the main issues and showed that there is a strong industrial need for support with margins, especially to understand how margins shape the design process. The concept of design margins, consisting of buffer and excess is developed. The key to managing product development is the transition from buffer to excess throughout the design process. This gives designers and engineers a rich way to express and communicate information about the forthcoming design to other team members, other teams and suppliers. The thesis proposes a conceptual framework to investigate and capture design margins. The overall model indicates that a clear elicitation and an explicit documentation of design margins can help decision makers implement more efficiently the necessary changes involved in product development: design margins are seen as a critical aspect of product design and development