Tolerance optimisation considering economic and environmental sustainability

Sustainability is becoming increasingly important in the development of new product and production solutions, and the eco-design movement stresses the importance of environmental considerations in all design phases and activities. One such design activity in the embodiment design phase of product development is the specification of dimensional tolerances, where designers seek to ensure high functionality at low costs. A traditional approach to this decision-making process is to minimise economic losses to the manufacturer and the consumer through a process known as tolerance optimisation. This paper presents a new approach for tolerance optimisation that considers sustainability not only in the context of economic costs but also environmental impacts, which are shown to be significantly affected by manufacturing and product quality. This new framework is formulated as a bi-objective optimisation problem to minimise economic and environmental costs, and important modelling considerations for these two types of costs are outlined and discussed. The proposed approach is explored using two example cases of design assemblies, which demonstrate the trade-offs between economic and environmental design objectives as a result of tolerances and other quality-related design decisions.