Life cycle assessment of selective-laser-melting-produced hydraulic valve body with integrated design and manufacturing optimization: A cradle-to-gate study

Selective laser melting (SLM), a relatively advanced additive manufacturing (AM) technique, enables high design flexibility and manufacturing complexity; therefore, it can facilitate improvement in the environmental performance of a complex component throughout its life cycle. However, existing studies have been unable to conclusively determine whether the environmental impacts of parts produced via AM are lower than those of conventionally manufactured parts. Moreover, few studies have investigated industrially applicable parts with complex inner shapes fabricated via SLM whilst simultaneously considering the design and manufacturing optimization involved thereof. In this study, an industrial hydraulic valve body was investigated in consideration of the part design, material preparation, and part fabrication with respect to their influence on the life-cycle impacts of SLM and conventional manufacturing (CM). The part was first re-designed to achieve a lightweight structure and optimized process parameters. Subsequently, an optimized and a non-optimized sample part were fabricated via SLM. A cradle-to-gate study of this part was conducted, involving a comparison employing life cycle assessment (LCA) for the case of CM. The life-cycle inventory data were obtained from the relevant enterprise, literature, databases, and our experiments. According to our results, the environmental impact of SLM without optimization was 37.42% lower than that of CM with respect to a hydraulic valve body, and the SLM-optimized design can lead to a 10-23% reduction in environmental impacts. Of all the life-cycle stages, the powder preparation stage was observed to exert the highest impact per part. Moreover, the electricity requirement for SLM is the main reason for environmental damage. With the optimization of the valve body design, the proportion of environmental impact caused by SLM processing increases. This indicates that when a part has a high lightweight potential, the SLM process will have a more significant cradle-to-gate environmental impact. In this case, manufacturing optimization will play a more important role. The results can be used to guide AM practitioners to improve the life-cycle environmental performance of AM-fabricated industrial parts through integrated design and manufacturing optimization.