The supply of critical raw materials, especially titanium, poses a significant challenge for the aviation sector. Increased circularity is often proposed as a solution by industry and policymakers. However, the effects of circular strategies remain insufficiently understood. Therefore, this paper analyses different circular strategies, namely recycling, a pure lifetime extension, and an enhanced lifetime extension that includes an engine aircraft, based on real-world data up to the year 2040. The findings indicate that recycling retired aircraft only marginally affects the required rising inflow of titanium by less than 5%. The engine upgrade strategy shows similar results. In contrast, a pure lifetime extension shows the greatest potential for mitigating supply constraints and can be further enhanced to a potential of more than 10% when combined with recycling. The results highlight the complexity of circular strategies and emphasise a stronger focus on lifetime extension for the aviation sector and other industrial sectors.

Numerous academic scholars argue for a radical transformation of the economy towards a circular model, in response to pressures from planetary and social issues such as energy, climate change, inequality, and resource depletion. This study examines how the academic community perceives the concept of a circular economy in comparison to traditional economic discourse, through the lens of conceptual metaphors. Conceptual metaphors are systematic properties that reflect one’s understanding of abstract phenomena like a circular economy. Through a structured review of the literature, seven dominant conceptual metaphors were identified that shape the understanding of traditional economics. The study also conducted a textual analysis of the ten most frequently cited academic papers on the circular economy. The analysis revealed that certain dominant metaphors from traditional economics have been influential in shaping discourse on the circular economy. The most common metaphors were the machine metaphor, competitive metaphors, the journey metaphor, and ecological metaphors. Each conceptual metaphor has its own strengths and weaknesses, which may include poorly explained areas or missing dimensions. These two aspects are referred to as misconceptions and blind spots, respectively, and the paper reflects on the implications of these for the current academic discourse on the circular economy.

In this article, we explore concrete examples of circularity strategies for critical raw materials (CRMs) in commercial settings. We propose a company-level framework for systematically evaluating circularity strategies (e.g., material recycling, product reuse, and product or component lifetime extension) in specific applications of CRMs from the perspectives of specific industrial actors. This framework is applied in qualitative analyses—informed by relevant literature and expert consultation—of five case studies across a range of industries: (1) rhenium in high-pressure turbine components, (2) platinum group metals in industrial catalysts for chemical processing and oil refining, (3) rare earth permanent magnets in computer hard disk drives, (4) various CRMs in consumer electronics, and (5) helium in magnetic resonance imaging (MRI) machines. Drawing from these case studies, three broader observations can be made about company circularity strategies for CRMs. Firstly, there are multiple, partly competing motivations that influence the adoption of circularity strategies, including cost savings, supply security, and external stakeholder pressure. Secondly, business models and value-chain structure play a major role in the implementation of circularity strategies; business-to-business models appear to be more conducive to circularity than business-to-consumer models. Finally, it is important to distinguish between closed-loop circularity, in which material flows are contained within the “focal” actor’s system boundary, and open-loop circularity, in which material flows cross the system boundary, as the latter has limited potential for mitigating material criticality from the perspective of the focal actor.

Remanufacturing offers an approach to extend product lifetime beyond its first use. After restoring products to original quality, they are reintroduced to the market. To make products more suited for this approach, and to increase resource-efficiency, design for remanufacturing can be incorporated for new product development. Academic literature points out opportunities for improved implementation particularly through early-stage design activities. This paper presents an in-depth, single case study into the opportunities and barriers to incorporate design for remanufacturing ine early-stage design. The selected case company is a producer of professional imaging equipment with an internal remanufacturing division. The company has decades of experience in remanufacturing and has introduced a company standard on design for End-of-Life. For data collection, employees from different departments were interviewed and observed. Design management theory was used to combine findings from all perspectives into a company-specific strategy map. This map shows departmental interrelations and dependencies, and exposes the opportunities for creating new value through design. At the case company, remanufacturing was found to be separate from, and secondary to, the development of newly manufactured products. If the strategy of a company is not attuned to developing products that serve multiple use-cycles, its execution will remain sub-optimal and remanufacturing will be a value-retention strategy in isolation. These findings may be valid for other companies that have remanufacturing operations, which are separate, as well.

The assessment of the criticality of raw materials allows the identification of the likelihood of a supply disruption of a material and the vulnerability of a system (e.g. a national economy, technology, or company) to this disruption. Inconclusive outcomes of various studies suggest that criticality assessments would benefit from the identification of best practices. To prepare the field for such guidance, this paper aims to clarify the mechanisms that affect methodological choices which influence the results of a study. This is achieved via literature review and round table discussions among international experts. The paper demonstrates that criticality studies are divergent in the system under study, the anticipated risk, the purpose of the study, and material selection. These differences in goal and scope naturally result in different choices regarding indicator selection, the required level of aggregation as well as the subsequent choice of aggregation method, and the need for a threshold value. However, this link is often weak, which suggests a lack of understanding of cause-and-effect mechanisms of indicators and outcomes. Data availability is a key factor that limits the evaluation of criticality. Furthermore, data quality, including both data uncertainty and data representativeness, is rarely addressed in the interpretation and communication of results. Clear guidance in the formulation of goals and scopes of criticality studies, the selection of adequate indicators and aggregation methods, and the interpretation of the outcomes, are important initial steps in improving the quality of criticality assessments.

Adopting design approaches that allow products to last multiple use-cycles supports European Commission objectives to reduce greenhouse gas emissions and reduce primary material impacts. Remanufacturing is an example of an appropriate circular strategy and it can be applied in a variety of industries that are intensive materials users. However, most companies have not yet adopted design strategies facilitating remanufacturing at scale. In this paper, we explored how design management can facilitate the implementation of Design for Remanufacturing, based on a literature review and in-depth interviews. Seven companies active in business-to-business markets were interviewed about the design-related opportunities and barriers they see for remanufacturing. We found that access to technical knowledge is not a barrier, whereas integrating this knowledge into the existing design process is. We conclude that design management can contribute to the uptake of Design for Remanufacturing for the following reasons: by making the value of Design for Remanufacturing to the company at large explicit, by building bridges between internal and external stakeholders, and by embedding Design for Remanufacturing into existing processes by means of Key Performance Indicators (KPIs) and roadmaps.