RESHAPING AS NOVEL CIRCULAR ECONOMY STRATEGY FOR SHEET METAL BASED END-OF-LIFE COMPONENTS

Making materials consumes about 21% of the global energy demand a specifically metals production, it accounts for about 8% of total global energy consumption. In fact, in the past few decades, the use of lightweight alloys has become increasingly widespread in many major industrial sectors thanks to the weight reduction associated with their applications. Most lightweight materials like aluminum alloys are characterized by high-energy demands primary production cycles that are responsible for a relevant share of the global CO2 emissions. Circular economy strategies such us longer life, more intense use, repair, product upgrades, modularity, remanufacturing, component re-use and open/closed loop recycling are strategies to put in place urgently to reduce the environmental impact. Although recycling of is metals the most used strategies and is being improved in terms of efficiency, it is mandatory moving towards more virtuous circular economy strategies, such us product/component reuse. A potentially effective strategy would be the incorporation of metal reuse techniques that would enable material recuperation at low environmental costs and in consequence, reducing the environmental impact of material production. Several researchers have bought forward strategies in response to the metal reuse question. In this dissertation, a novel reuse strategy for sheet metal-based End-of-life components is proposed. Specifically, a proposal towards the use of Single Point Incremental Forming for the Reshaping of End-of-Life sheet metal components has been presented. In particular, the suitability of this strategy as a circular economy enabler, has been studied with a particular focus on the technical feasibility of the SPIF process for the function of Reshaping, the quality of the end products of Reshaping and the energy efficiency along with the equivalent CO2 emissions of this strategy has been focused upon. Dissertation Structure Chapter 1, titled “Introduction”, deals with the general introduction to the metal recycling issues and capabilities, with particular focus on the lightweight alloys. The first subsection 1.1 introduces the concept of circular economy, followed by the metal reuse framework (section 1.2) which discusses the existing state of art on the various approaches proposed and studied in the past. Section 1.3 provides an introduction to the Single point Incremental forming process and it’s mechanics, followed by the proposed approach explained in section 1.4. Chapter 2, titled “SPIF used as a Reshaper: Technical Feasibility”, contains the analysis of the technical feasibility of the proposed Reshaping strategy. Section 2.1 provides an introduction to the Deep Drawing process and technical aspects of the same. Section 2.2 details the procedure adopted, in terms of the experimental campaigns, and the results of analysis conducted. The discourse is then shifted towards the study of the effectiveness of Reshaping using conventional forming processes (section 2.3). The final sub-section of this chapter is a discussion of the overall outcome of the technical feasibility analysis and the direction towards which the research would focus after having obtained the said results (Section 2.4). The work presented in this chapter was published as: 1) Ingarao G, Zaheer O, Campanella D, Fratini L (2020) Re-forming end-of-life components through single point incremental forming. Manufacturing Letters, 24:132-135. 2) Zaheer O, Ingarao G, Di Lorenzo R, Fratini L (2021) On the effectiveness of SPIF process to re-form End-of-Life components as compared to conventional forming approach. SHEMET 2021. Chapter 3, namely “Formability and Geometrical Accuracy Performances”, focuses on the analysis of the geometrical accuracy of the Reshaping technique. The first section 3.1 deals with the analysis of the geometrical accuracy of the End-of-Life component, in terms of the non-worked zones of the component during the Reshaping process. This research work was also focused on analyzing the effects of different process parameters (those of the original forming process, as well as, those of the Reshaping process) on the geometrical accuracy of the End-of-Life component. Section 3.2 was rather focused on the variation of the SPIF process formability when used as a Reshaper for different kinds of End-of-Life parts (Sheet metal components having different types of pre-strainings). Consequently, the geometrical accuracy of Reshaping pertaining to the different types of End-of-Life components was also analyzed in order to better understand the correlation between the pre-straining type/level and the obtainable geometry by SPIF. Finally, in section 3.3 the key findings of this chapter are summarized. The work presented in this chapter was published as: 1) Zaheer O, Ingarao G, Pirrotta A, Fratini L (2021) Geometrical deviation of end-of-life parts as a consequence of reshaping by single point incremental forming. International Journal of Advanced Manufacturing Technology, 115:1579-1588. 2) Zaheer O, Ingarao G, Di Lorenzo R, Fratini L (2021) Understanding formability and geometrical accuracy of SPIF process used as Reshaping approach. ESAFORM 2021. Chapter 4, titled, “Energy Efficiency Analysis”, covers the performance of the Reshaping strategy in comparison to two other recycling techniques (Conventional and solid state recycling). This study was carried out in light of the overall energy consumption and the CO2 emissions relative to the entire process cycles. Section 4.1 covers the cumulative energy demand and CO2-emission analysis followed by the system boundary identification and assumptions. The energy demands and CO2 emissions of the three routes are compared to using experimental measurements of necessary data and LCI techniques in section 4.3. The results of these analysis and their relative discussions are elaborated in sections 4.4 and 4.5. This work presented in this chapter was published as: 1) Ingarao G, Zaheer O, Campanella D, Di Lorenzo R, Fratini L (2020) An energy efficiency analysis of single point incremental forming as an approach for sheet metal based component reuse. Procedia CIRP, 90:540-545. 2) Ingarao G, Zaheer O, Fratini L (2021) Manufacturing processes as material and energy efficiency strategies enablers: The case of Single Point Incremental Forming to reshape end-of-life metal components. CIRP Journal of Manufacturing Science and Technology, 32:145-153. Chapter 5, titled “Reshaping by Hydroforming: Feasibility Analysis”, focuses on the studying the potential of carrying out the Reshaping strategy using an alternative forming process, i.e. Hydroforming. Section 5.1 cover the description of the designed experimental campaign and the technical parameters utilized. The results of this research (section 5.2) detail the key findings of the study and the influence of the process parameters on the process efficiency and quality of the obtained Reshaped components. Chapter 6, titled “Conclusion”, provides a summary of the general results obtained for the entire research scope, highlighting the advances of the state of the art enabled by the research presented in this dissertation (section 5.1). Section 5.2 finally provides a general outlook of the investigated process, the milestones yet to be studied and a focus on the possible future developments of this work.