Additive manufacturing for the automotive industry: on the life-cycle environmental implications of material substitution and lightweighting through re-design

The automotive sector has recently been taking measures to reduce fuel consumption and greenhouse gas emissions for the mobility of ground vehicles. Light-weighting, via material substitution, and the re-designing of components or even a combination of the two, have been identified as a crucial solution. Additive manufacturing (AM) can be used to technologically complement or even replace conventional manufacturing in several industrial fields. The enabling of complexity-for-free (re) designs is inherent in additive manufacturing. It is expected that certain benefits can be achieved from the adoption of re-design techniques, via AM, that rely on topological optimisation, e.g., a reduced use of resources in both the material production and use phases. However, the consequent higher specific energy consumption and the higher embodied impact of feedstock materials could result in unsustainable environmental costs. This paper investigates the case of the light-weighting of an automobile component to quantify the outcomes of the systematic integration of re-designing and material substitution. A bracket, originally cast in iron, has been manufactured by means of a powder bed-based AM technique in AlSi10Mg through an optimized topology. Both manufacturing routes have been evaluated through a comparative Life Cycle Assessment (LCA) within cradle-to-grave boundaries. A 69%-lightweighting has been achieved, and the carbon dioxide emissions and energy demands of both scenarios have been compared. Besides the use-phase-related savings in terms of both energy and carbon footprint due to the lightweighting, the results highlight the environmental trade-offs and prompt the consideration of such a manufacturing process as an integral part of sustainable product development

A structured comparison of decentralized additive manufacturing centers based on quality and sustainability

Companies are increasingly adopting decentralized manufacturing strategies to manage multiple, geographically scattered manufacturing centers that are characterized not only by similar types of equipment, working methods, and productions, but also by variable mixes and volumes. This trend also applies to additive manufacturing, a well-established technology that allows the flexibility and customization of production to be increased, without significantly increasing the per unit cost. Thus, the need arises to monitor the performance of individual centers in a structured way, and to make practical comparisons of such centers. However, achieving this task is not so straightforward, given the inevitable differences in the characteristics of manufacturing centers and their productions. This paper presents a methodology that can be used to analyze and com-pare the production performance of a plurality of manufacturing centers from two different viewpoints: (i) quality, through a multivariate statistical analysis of product data concerning conformity with geometrical specifications, and (ii) process sustainability, with the aim of achieving a reduction in energy consumption, carbon dioxide emissions, and manufactur-ing time, through regression models pertaining to the selected metrics. The proposed methodology can be adopted during regular production operations, without requiring any ad hoc experimental tests. The description of the method is supported by an industrial case study

Additive manufacturing for an urban vehicle prototype: re-design and sustainability implications

Additive Manufacturing (AM), allowing the layer-by-layer fabrication of products characterized by a shape complexity unobtainable with conventional manufacturing routes, has been widely recognized as a disruptive technology enabling the transition to the Industry 4.0. In this context, the design of a Portable Assisted Mobile Device (PAMD) prototype was considered as a case study. The best practices of the re-design for AM were applied to three of the main structural components, and the most sustainable manufacturing approach between AM processes and the conventional ones was identified with respect to cumulative energy demand, carbon dioxide emissions and costs. The paper aims to promote the debate concerning the correlation between design choices, process selection and sustainable product development

Multi-criteria environmental and economic impact assessment of wire arc additive manufacturing

Wire arc additive manufacturing (WAAM) is a fusion- and wire-based additive manufacturing technology which has gained industrial interest for the production of medium-to-large components with high material deposition rates. However, in-depth studies on performance indicators that incorporate economic and environmental sustainability still have to be carried out. The first aim of the paper has been to quantify the performance metrics of WAAM based manufacturing approaches, while varying the size and the deposited material of the component. The second aim has been to propose a multi-criteria decision-analysis mapping to compare the combined impacts of products manufactured by means of the WAAM-based approach and machinin

Performance assessment of a vibro-finishing technology for additively manufactured components

Metal components produced by Additive Manufacturing (AM) technologies usually exhibit a rough surface, that in certain applications can result detrimental for the part’s functionality. Thus, it is of great interest to study the finishing processes that can be applied to the surfaces, both external and internal, of AM components. The aim of this work is the evaluation of the capabilities of a vibro-finishing process in the treatment of samples produced by Laser-Powder Bed Fusion (L-PBF) from AlSi10Mg powders. In this research, the abrasive media is identified, and the surface quality improvement is analysed in terms of surface roughness and modifications induced by the finishing treatment (i.e., edge rounding, material loss) against finishing duration. The cost of the treatment is also evaluated

Wire arc additive manufacturing of Ti-6Al-4V components: the effects of the deposition rate on the cradle-to-gate economic and environmental performance

Wire Arc Additive Manufacturing (WAAM) is a direct energy deposition process based on a wire-shaped metal feedstock which is melted by means of an electric arc to produce and/or repair components in a layer-wise manner. WAAM has shown to be suitable for producing large components, in particular those with a near-to-net shape, at relatively high productivity levels. The aim of this work has been to assess the effects of the WAAM deposition rate on economic and environmental sustainability metrics. A life cycle assessment has been performed under cradleto-gate system boundaries. Three components, with different geometrical characteristics (i.e., dimensions, masses, and solid-to-cavity ratios) and made of Ti-6Al-4V, have been considered as case studies. The effects of different deposition rates have been evaluated on the Cumulative Energy Demand, CO2 emissions, manufacturing times and costs. The conventional manufacturing route for the production of the same components, that is, machining from massive workpieces, has been considered as a benchmark for a process performance comparison. The results show that an increase in the deposition rate determines a significant reduction (up to 25%, on average) in the production time and, consequently, in the manufacturing costs

An appraisal of the cradle-to-gate energy demand and carbon footprint of high-speed steel cutting tools

The awareness of the environmental impact of the manufacturing sector has increased over the last few decades. This paper presents the results of an LCA-based approach used to evaluate the production of a threading tool (i.e., an M10 × 1.25 spiral point tap) made of high-speed steel. The cumulative energy demand and CO2-equivalent emissions have been quantified throughout the entire tool manufacturing process. Both the pre-manufacturing steps and the upstream/downstream flows of the used material have been accounted for, considering cradle-to-gate (plus end-of-life) system boundaries. The results show that the share of primary energy employed to produce the tool is mainly imputable to the manufacturing processes. Therefore, this analysis could contribute to fostering the development of structured assessment frameworks that would allow cutting tool manufacturers to identify the weak points of their production routes to be optimized