| 1. |
- Amir, Saman, et al.
(författare)
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Toward a Circular Economy: A Guiding Framework for Circular Supply Chain Implementation
- 2024
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Ingår i: Springer Series in Supply Chain Management. - Cham : Springer Nature. ; , s. 379-404, s. 379-404
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Bokkapitel (refereegranskat)abstract
- This chapter presents a guiding framework for circular economy implementation in supply chains. Closing the loop for resource efficiency is a well-known practice in the industry. To concretize the circular economy implementation strategies, closed-loop thinking requires innovation and adaptation. Circular supply chains (CSCs) are one of the key enablers in closing the loop by design or intention for value recovery and profit maximization. CSC is an emerging area, and the view of CSC where forward and reverse supply chain is seamlessly integrated with the overall aim to achieve system-wide circularity is missing in the academic debate. By offering a cross-functional and systemic perspective of circular supply chains, we present a guiding framework to structure and understand the underlying complexities and highlight the crucial elements of circular supply chain implementation. The framework categorizes the circular supply chain into four building blocks: systemic approach, main drivers, levels of decision making, and mechanisms to manage the full loop closure and minimize the inherent uncertainties of a complex system. We conclude the chapter by illustrating the applicability of the circular supply chain framework using two industrial cases that are transitioning toward the circular economy.
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| 2. |
- Amir, Saman, et al.
(författare)
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Towards circular economy : A guiding framework for circular supply chain implementation
- 2022
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Ingår i: Business Strategy and the Environment. - : Wiley. - 0964-4733 .- 1099-0836.
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Tidskriftsartikel (refereegranskat)abstract
- Closing the loop for resource efficiency is a well-known practice in the industry. Toconcretize the circular economy implementation strategies, closed-loop thinkingrequires innovation and adaptation. Circular supply chains (CSCs) are one of the keyenablers in closing the loop by design or intention for value recovery and profit maxi-mization. CSC is an emerging area, and the view of CSC where forward and reversesupply chain is seamlessly integrated with the overall aim to achieve system-wide cir-cularity is missing in the academic debate. By offering a cross-functional perspectiveof CSC, this paper presents a CSC guiding framework to structure and understandthe underlying complexities and highlight the crucial elements of the CSC implemen-tation. Thus, this framework lays the basis for CSC within the systemic implementa-tion of CE by closing the loop by design or intention. The framework categorizes theCSC into four building blocks, namely, systemic approach, main drivers, levels of deci-sion making, and mechanisms to manage the full loop closure and minimize the inher-ent uncertainties of a complex system. The building blocks of the framework aresynthesized from various streams of supply chain literature and recurring concepts inthe circular economy literature. The CSC framework applicability is illustrated usingtwo industrial cases that are transitioning towards the circular economy.
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| 3. |
- Roci, Malvina, et al.
(författare)
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Multi-method simulation modelling of circular manufacturing systems for enhanced decision-making
- 2022
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Ingår i: MethodsX. - : Elsevier. - 1258-780X .- 2215-0161. ; 9, s. 101709-101709
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Tidskriftsartikel (refereegranskat)abstract
- Circular manufacturing systems (CMS) constitute complex value networks comprising a large and diverse set of stakeholders that collaborate to close the loop of products through multiple lifecycles. Complex systems modelling and simulation play a crucial role in providing quantitative and qualitative insights into the behaviour of such systems. In particular, multi-method simulation modelling that combines agent-based, discrete-event, and system dynamics simulation methods is considered more suitable to model and simulate CMS as it allows to capture their complex and dynamic nature. This paper provides a step-by-step approach on how to build a CMS multi-method simulation model in order to assess their economic, environmental, and technical performance for enhanced decision-making. To model and simulate CMS three main elements need to be considered: • A multi-method model architecture where the CMS stakeholders with heterogeneous characteristics are modelled individually as autonomous agents using agent-based, discrete-event, and system dynamics. • An agent environment defined by a Geographic Information System (GIS) to establish connections based on agents’ geographic location. • The product journey resulting from the product's interaction with various CMS stakeholders in the circular value network is traced throughout its multiple lifecycles.
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| 4. |
- Roci, Malvina, et al.
(författare)
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Towards Circular Manufacturing Systems implementation : A Complex Adaptive Systems perspective using modelling and simulation as a quantitative analysis tool
- 2022
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Ingår i: Sustainable Production and Consumption. - : Elsevier BV. - 2352-5509. ; 31, s. 97-112
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Tidskriftsartikel (refereegranskat)abstract
- A transition towards circular manufacturing systems (CMS) has brought awareness of untapped economic and environmental benefits for the manufacturing industry. Conventional manufacturing systems already present a high level of complexity in terms of physical flows of materials and products as well as information and financial flows linked to them. Closing the loop of materials and products through multiple lifecycles, as proposed in CMS, increases this complexity manifold. To support practitioners in implementing CMS through enhanced decision-making, this research studies CMS from a complex adaptive systems (CAS) perspective and proposes to exploit methods and tools used in the study of CAS to characterise, model and analyse CMS. By viewing CMS as CAS composed of autonomous, interacting agents, this research proposes a multi-method model architecture for modelling and simulating CMS. The different CMS stakeholders are modelled individually as autonomous agents by integrating agent-based, discrete-event, and/or system dynamics modules within each agent to capture their diverse and heterogeneous nature. The applicability of the proposed multi-method approach is illustrated through a case study of a white goods manufacturing company implementing CMS in practice. This case study shows the relevance and feasibility of the proposed multi-method approach as a decision support tool for the systemic exploration and quantification of CMS. It also shows how a transition towards CMS necessitates a lifecycle approach in terms of costs, revenues and environmental impacts to identify hotspots and, therefore, design circular systems that are viable in both economic and environmental terms. In fact, the analyses of the simulation results indicate how decisions in terms of business models, product design, and supply chain affected the CMS performance of the case company. For instance, implementing a service-based model led to a high number of usecycles (on average six usecycles per washing machine), which, in turn, led to high lifecycle costs and emissions due to more frequent transportation and recovery operations. Similarly, the deployment of long-lasting washing machines, which is a core principle of CMS, led to high manufacturing costs. Due to the high initial costs and a time mismatch between revenues and costs in the service-based model, it required a longer time for the company to reach the break-even point (approximately 23 months). Overall, the case study shows that multi-method simulation modelling can provide decision-making support for a successful implementation of CMS.
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| 5. |
- Abdullah Asif, Farazee Mohammad, 1980-, et al.
(författare)
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A practical ICT framework for transition to circular manufacturing systems
- 2018
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Ingår i: Procedia CIRP. - : Elsevier. - 2212-8271. ; , s. 598-602
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Konferensbidrag (refereegranskat)abstract
- The transition towards a circular economy has become important. Manufacturing industry being a major stakeholder in this transition has started exploring the potential of this transition and challenges in implementation. Ambitious companies such as Gorenje d.d. has taken the circular economy transition seriously and aims to become a pioneer in implementing circular manufacturing systems. One vital step in this transition is the business model shift from the linear (sales model) to a circular model such as 'product as a service'. This brings new challenges to Original Equipment Manufacturers (OEMs) that have never been experienced in their conventional businesses. One of the challenges is to establish an information communication and technology (ICT) infrastructure that enables information management and sharing as well as establishes a real-time communication between relevant stakeholders. Outlining such an ICT infrastructure is the objective of this paper.
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| 6. |
- Bejjani, Roland, et al.
(författare)
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Variations in the Surface Integrity of Ti-6Al-4V by Combinations of Additive and Subtractive Manufacturing Processes
- 2020
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 13:8, s. 1-24
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Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing (AM) has recently been accorded considerable interest by manufacturers. Many manufacturing industries, amongst others in the aerospace sector, are already using AM parts or are investing in such manufacturing methods. Important material properties, such as microstructures, residual stress, and surface topography, can be affected by AM processes. In addition, a subtractive manufacturing (SM) process, such as machining, is required for finishing certain parts when accurate tolerances are required. This finish machining will subsequently affect the surface integrity and topography of the material. In this research work, we focused on the surface integrity of Ti-6Al-4V parts manufactured using three different types of AM and finished using an SM step. The aim of this study was to gain an understanding on how each process affects the resulting surface integrity of the material. It was found that each AM process affects the materials’ properties differently and that clear differences exist compared to a reference material manufactured using conventional methods. The newly generated surface was investigated after the SM step and each combination of AM/SM resulted in differences in surface integrity. It was found that different AM processes result in different microstructures which in turn affect surface integrity after the SM process.
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| 7. |
- Hira, A., et al.
(författare)
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Shifting to Circular Manufacturing in the Global South : Challenges and Pathways
- 2022
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Ingår i: Journal of Developing Societies. - : SAGE Publications. - 0169-796X .- 1745-2546. ; 38:3, s. 310-335
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Tidskriftsartikel (refereegranskat)abstract
- As the Global South shifts towards increased manufacturing, the negative effects on climate change and environmental pollution raise serious concerns. These global effects are increasingly felt locally, as reflected in health surveys throughout the Global South. The world cannot afford to wait for a natural development process to take place in which rising incomes might curb pollution. This article examines the challenges of reforming manufacturing in the Global South towards more sustainable practices. It also focuses on the lessons of the Sustainable Manufacturing and Environmental Pollution Program (SMEP) which has funded a series of environmental improvement projects across sub-Saharan Africa and South Asia aimed at reducing pollution in the manufacturing process. The lessons learned from these projects include the need to improve the tracking of the negative effects of the environmental damages caused by manufacturing and analyze the manufacturing supply chain processes to better identify potential points of intervention; as well as the need for more external financial and technical resources to expand these projects.
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| 8. |
- Holmberg, Jonas, 1976-, et al.
(författare)
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Machining of additively manufactured alloy 718 in as-built and heat-treated condition: surface integrity and cutting tool wear
- 2024
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Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer Nature. - 0268-3768 .- 1433-3015. ; 130:3-4, s. 1823-1842
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Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing (AM) using powder bed fusion is becoming a mature technology that offers great possibilities and design freedom for manufacturing of near net shape components. However, for many gas turbine and aerospace applications, machining is still required, which motivates further research on the machinability and work piece integrity of additive-manufactured superalloys. In this work, turning tests have been performed on components made with both Powder Bed Fusion for Laser Beam (PBF-LB) and Electron Beam (PBF-EB) in as-built and heat-treated conditions. The two AM processes and the respective heat-treatments have generated different microstructural features that have a great impact on both the tool wear and the work piece surface integrity. The results show that the PBF-EB components have relatively lower geometrical accuracy, a rough surface topography, a coarse microstructure with hard precipitates and low residual stresses after printing. Turning of the PBF-EB material results in high cutting tool wear, which induces moderate tensile surface stresses that are balanced by deep compressive stresses and a superficial deformed surface that is greater for the heat-treated material. In comparison, the PBF-LB components have a higher geometrical accuracy, a relatively smooth topography and a fine microstructure, but with high tensile stresses after printing. Machining of PBF-LB material resulted in higher tool wear for the heat-treated material, increase of 49%, and significantly higher tensile surface stresses followed by shallower compressive stresses below the surface compared to the PBF-EB materials, but with no superficially deformed surface. It is further observed an 87% higher tool wear for PBF-EB in as-built condition and 43% in the heat-treated condition compared to the PBF-LB material. These results show that the selection of cutting tools and cutting settings are critical, which requires the development of suitable machining parameters that are designed for the microstructure of the material.
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| 9. |
- Khodaee, Alireza, 1984-
(författare)
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Innovative Manufacturing Method for Gears for Heavy Vehicle Application
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The present thesis is a summary of research result on an innovative manufacturing method for production of PM gears for application in heavy vehicle. The method uses a powder metal densifications process route to ensure full density. The thesis addresses an innovative processing route where loosely packed powder goes through a double pressing followed by double sintering combined with hot isostatic pressing at the end of the chain in order to reach the full density for the PM gear. The thesis addresses three research questions. First the feasibility of reaching full density for a gear constructed of standard modules relevant for heavy vehicles is investigated. Then the effect of gear geometry on the PM processing is studied. It is revealed that gear geometry influences the density distributions hence the final result. Therefore, the part of the research focusing on the relationship between gear dimensions and the densification results is conducted. It is shown that specific gear geometrical parameters could be more suitable to reach full density. Finally, a prediction model is proposed which can be used in order to measure the density before HIP and exclude risky geometries. A combined numerical and experimental research methodology is implemented in order to address the research questions in the thesis. A verified hardening model for one sample powder mixture is developed in ABAQUS using experimental densification tests. The model helps us to simulate the first pressing and follow the density gradients generated during the first pressing step. The density gradient will be stored in the green component and modified after first sintering and then is used as the input for the second pressing simulation. The result of the second pressing simulation is then modified to include the second sintering effects and finally it is used as the input for HIP simulation. This chain of simulations helps us to understand the gear geometry influence on the density gradients and neutral zone formation during the pressing process. It also ensures that the transition of open pores to closed pores occurs before HIP as a requirement to reach fully density in the analysis. Physical experiments were performed in order to validate FE simulations predictions. Density measurement and dimensional measurement are used to compare the results of FE simulations and physical trial results in order to validate and support the final conclusions based on FE model. Using the validated FE model, a methodology to predict the density before HIP is designed where different gear geometries are modelled and then a regression model is extracted which can predict the minimum RD in neutral zone of the gear before performing costly experiments for a specific material and gear dimensions.
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| 10. |
- Kokare, Samruddha, et al.
(författare)
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A comparative life cycle assessment of stretchable and rigid electronics : a case study of cardiac monitoring devices
- 2021
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Ingår i: International Journal of Environmental Science and Technology. - : Springer Nature. - 1735-1472 .- 1735-2630.
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Tidskriftsartikel (refereegranskat)abstract
- Stretchable electronics is a new innovation and becoming popular in various fields, especially in the healthcare sector. Since stretchable electronics use less printed circuit boards (PCBs), it is expected that the environmental performance of a stretchable electronics-based device is better than a rigid electronics-based device that provides the same functionalities. Yet, such a study is rarely available. Thus, the main purpose of this research is to perform a comparative life cycle analysis of stretchable and rigid electronics-based devices. This research combines both the case study approach and the research review approach. For the case study, a cardiac monitoring device with both stretchable and rigid electronics is used. The ISO 14044:2006 standard's prescribed LCA approach and ReCiPe 2016 Midpoint (Hierarchist) are followed for the impact assessment using the SimaPro 9.1 software. The LCA results show that the stretchable cardiac monitoring device has better environmental performance in all eighteen impact categories. This research also shows that the manufacturing process of stretchable electronics has lower environmental impacts than those for rigid electronics. The main reasons for the improved environmental performance of stretchable electronics are lower consumption of raw material as well as decreased energy consumption during manufacturing. Based on the LCA results of a cardiac monitoring device, the study concludes that stretchable electronics and their manufacturing process have better environmental performance in comparison with the rigid electronics and their manufacturing process.
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