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Gianluca Buffa,Dario Baffari,Giuseppe Ingarao,Livan Fratini 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.5
Conventional metal chips recycling processes are energy-intensive with low efficiency and permanent material losses during re-melting. Solid state recycling allows direct recycling of metal scraps into semi-finished products. It is expected that this process category would lower the environmental performance of metals recycling. Friction Stir Consolidation is a new solidstate technique taking advantage of friction heat generation and severe plastic deformation to consolidate chips into billets. In this research, the feasibility of Friction Stir Consolidation as aluminum chips recycling process is analyzed. Specifically, an experimental campaign has been carried out with varying main process parameters. Three main aspects have been evaluated in order to highlight products quality and environmental impact of the process: (i) metallurgical and mechanical properties of the consolidated products; (ii) primary energy demand, as compared to conventional processes; (iii) forgeability of the consolidated products, as compared to parent material. Results revealed that a proper process parameters selection results in fully consolidated aluminum disk with satisfactory mechanical properties. Also, the new recycling strategy allows substantial energy savings with respect the conventional (remelting based) route.
Gianni Campatelli,Filippo Montevecchi,Giuseppe Venturini,Giuseppe Ingarao,Paolo C. Priarone 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.1
Over the last years, additive manufacturing (AM) has been gathering momentum both in the academic and in the industrial world. Besides the obvious benefits in terms of flexibility and process capabilities, the environmental performance of such processes has still to be properly analyzed. Actually, the advantages of additive manufacturing over conventional processes are not obvious. Indeed, different manufacturing approaches result in different amounts of involved material and in different processing energy demands. Environmental comparative analyses are hence crucial to properly characterize AM processes. In this paper, an energetic comparison between the emerging wire arc additive manufacturing (WAAM) process and a traditional machining-from-bulk solution to produce a steel blade is presented. A methodology accounting for all the material and energy flows of the whole component life cycle is proposed. Experimental measurements and environmental databases are used to quantify the primary energy demand at each stage of the life cycle. The results reveal that, for the analyzed case study, an integrated additive (WAAM)-subtractive manufacturing route enables significant material and primary energy savings with respect to traditionally applied approaches.
Gianluca Buffa,Davide Campanella,Muhammad Adnan,Umberto La Commare,Giuseppe Ingarao,Livan Fratini 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.11 No.4
Friction stir extrusion is one of the most promising solid-state chip recycling techniques because of its relative simplicity and high efficiency. One of the most straightforward applications for the process is the production of recycled wires to be utilized as filler material in welding or welding-based additive manufacturing processes, in order to create an industrial symbiosis link, fostering a circular economy and enhancing the technology readiness level of the process. The scalability of the process to the thin wires needed for such applications has not been investigated so far. In this paper, an experimental and numerical analysis was developed. A dedicated numerical model was first validated and then used to design the tool geometry. The effect of tool rotation and tool force on both “standard” mechanical properties, as Ultimate Tensile Strength and microhardness, and specific properties for the envisaged application, as the wrapping around reels with different radii, was investigated. The numerical model results were used to explain the influence of the process parameters on the material flow as well as on the distribution of the primary field variables, namely temperature, strain, and strain rate. Finally, the energy demand was measured, and the specific energy consumption (SEC) was evaluated. It was found that a conical shoulder surface favors the conditions for effective solid bonding. Low values of the extrusion force have detrimental effects on the wires properties as they result either in insufficient strain, or hot cracking defects. High values of extrusion force results in lower SEC, unlocking the potential of the process as symbiotic link enabler.