An Ecodesign approach for the lightweight engineering of cast iron parts

Lightweight engineering is a current topic in mechanical industry. The mass reduction is a common design objective to reduce product cost and environmental impacts. Virtual prototyping tools are widely applied to study new lightened solutions and check the compliance with regulations and standards. However, an integrated approach, involving simulations and life-cycle analysis, is necessary to support design optimization and decision-making. The scope of this study concerns the definition of an Ecodesign approach to support the lightweight engineering of cast iron parts through the redesign of the product shape. In particular, this paper deals with the optimization of a ductile cast iron manhole. The test case shows a redesign method which considers structural analysis with environmental impacts. The structural analysis has been evaluated using a finite element method tool. In particular, the simulation results have been compared and validated with physical tests. The environmental analysis is based on the methodology provided by the standardized ISO 14040:2006 and ISO 14044:2006. The proposed LCA study considers the phases of manufacturing and transport related to one ductile iron product. The described manufacturing phase is related to a Chinese foundry which produces roughly 12,000 tons of ductile cast-iron castings. The results show the possibility to achieve about 20% of mass reduction for one casting. Considering such mass decreasing, the related reduction in terms of carbon emission is about 7%. Summarizing, this paper shows a design approach to integrate the structural improvements with the reduction of the environmental impacts related to a lighter weight casting.