1,721,103 research outputs found
A comparative assessment of energy demand and life cycle costs for additive- and subtractive-based manufacturing approaches
Full text linkThe applicability domain of Additive Manufacturing (AM) processes, apart from technological and quality results, relies on environmental and cost performance. These aspects still need to be better understood. To this aim, comparative analyses with conventional manufacturing routes are needed. In this paper, empirical cost and energy requirement models are suggested to assess subtractive- (machining) and additive- (Electron Beam Melting) based manufacturing approaches for the production of Ti-6Al-4V components. A life-cycle perspective is adopted, and all the steps from the input material production to the post-AM processing operations and the use phase are included. The analyses have been carried out considering the shape of the component, the light-weighting capabilities and the utilization time as the main factors of influence. The proposed modelling effort has allowed different decision-support charts, which are suitable for identifying the most energy-efficient or economically-advantageous manufacturing approach, to be obtained. The results have revealed that, for the considered case study, EBM could be a more energy-efficient approach than conventional machining, even without re-designing the component, due to the higher efficiency in raw material usage. As far as cost is concerned, the additive-based approach only becomes the preferable solution when the cost savings during the use phase are accounted for
Multi-material based functionally graded billets manufacturing through friction stir consolidation of aluminium alloys chips
No full textNew deal of Friction Stir Consolidation (FSC) is its evolution from Recycling technique towards Upcycling. In this paper, the potential of FSC to manufacture Functionally Graded billets is proved. Processing chips of two different aluminium alloys (AA7075, AA2011-T3), graded hardness distributions were obtained along the longitudinal direction of the manufactured billet. Material flow was analysed by EDX analyses and numerical simulations; mechanical properties were assessed through hardness measurements. The influence of material's position, mass fraction of each material and process parameters was considered. Results reveal that FSC offers a proper control in the design of billets with graded properties
Manufacturing processes as material and energy efficiency strategies enablers: The case of Single Point Incremental Forming to reshape end-of-life metal components
No full textMaking materials consumes about 21% of the global energy demand; concerning metals production, it accounts for about 8% of total global energy consumption. Circular economy strategies such as longer life, more intense use, repair, product upgrades, modularity, remanufacturing, component reuse, and open/closed-loop recycling are strategies to put in place urgently to reduce the environmental impact of raw material production. Although recycling of metals is the most used strategy and is being improved in terms of efficiency, it is mandatory moving towards more virtuous circular economy strategies, such as product/component reuse. In this paper a novel reuse strategy for sheet metal based End-of-life components is proposed; to be more specific the suitability of Single Point Incremental Forming (SPIF) to reshape End-of-life aluminum components is presented. An experimental approach is used to change the shape of a square box, previously obtained by deep-drawing processes, by means of single point incremental forming processes. The paper aims at outlining the environmental impact of the proposed reshaping approach presenting a Cumulative Energy Demand and CO2-eq. emissions comparative analysis. Three different routes are analyzed and compared to one another: SPIF based reshaping, conventional recycling and Solid State Recycling (SSR) routes. The SPIF based approach proved to be the most environmentally friendly strategy, the energy and emissions saving are ascribable to the fewer process steps and the less material involved with respect to the analyzed recycling strategies
Friction stir consolidation of aluminium chips: A new approach to overcome the inhomogeneous properties of the consolidated billet
Full text linkThe need to improve the recycling process of metals to achieve sustainability goals is reflected in the growing interest in solid-state recycling approaches. One of these is the Friction Stir Consolidation (FSC), able to directly transform chips into consolidated billets. The main features of this process are the pressure and the rotational speed of the tool which compresses and heats up the chips collected inside a designed die. During the consolidation process, the friction between the tool and chips surfaces plays an important role because it is the main source of heat, therefore the heat transfer starts near the tool to the bottom of the billet resulting in an inhomogeneous material property. This aspect leads to both inhomogeneous microstructure and hardness characterization of the consolidated billet. To improve the effectiveness of the friction stir consolidation recycling process, this study focused on a numerical approach by proposing a new setup in which the structure where the die and the chips are placed on, namely backing plate, was heated up aiming to activate a heat flow also from the bottom
Sustainability for 3DP operations
No full textSustainability is an essential consideration in manufacturing, and within this chapter a detailed appraisal is given to sustainability for 3D printing. An in-depth review of existing research is provided, and a cradle-to-grave assessment technique is shown to assess the environmental impact of 3D printed part
Guidelines to compare additive and subtractive manufacturing approaches under the energy demand perspective
Full text linkIn order to characterise the environmental performance of additive manufacturing (AM) processes, comparative analyses are required. Different manufacturing approaches (such as additive and subtractive ones), besides adopting different equipment, use different kinds and amounts of material. Therefore, the material-related flow has to be followed throughout the entire product life. Differences in environmental impact arise at each step of the life cycle: material production, manufacturing, use, disposal, and transportation. A life cycle-based methodology able to take due account of all the factors of influence on the total energy demand for the production of metal components is given in this paper. Decision support tools for identifying the most sustainable manufacturing route (subtractive versus AM-based approaches) are presented for different scenarios. The aim of the present paper is to contribute to the debate concerning the environmental impact characterisation of AM processes
Optimization of the sheet hydroforming process parameters to improve the quality of reshaped EoL components
Full text linkThe reshaping of End-of-Life (EoL) components by means of sheet metal forming
process has been considered largely attractive, even from the social and economic point of view.
At the same time, EoL parts can be often characterized by non-uniform thicknesses or alternation
of work-hardened/undeformed zones as the results of the manufacturing process. Such
heterogeneity can hinder a proper reshaping of the EoL part and residual marks on the re-formed
blanks can be still present at the end of the reshaping step. In a previous analysis, the authors
evaluated the effectiveness of reshaping a blank with a deep drawn feature by means of the Sheet
Hydroforming (SHF) process: it was demonstrated that residual marks were still present if the deep
drawn feature was located in a region not enough strained during the reshaping step. Starting from
this condition and adopting a numerical approach, additional investigations were carried out
changing the profile of the load applied by the blankholder and the maximum oil pressure.
Numerical results were collected in terms of overall strain severity and residual height of the
residual marks from the deep drawn feature at the end of the reshaping step. Data were then fitted
by accurate Response Surfaces trained by means of interpolant Radial Basis Functions,
subsequently used to carry out a virtual optimization managed by a multi-objective genetic
algorithm. Optimization results suggested the optimal value of the output variables to reduce the
marks from the deep drawn feature without the occurrence of rupture
Re-forming end-of-life components through single point incremental forming
No full textApplying Circular Economy strategies is mandatory to face material demand while minimizing the environmental impact. Manufacturing processes are to be thought as means to enable material/component reuse strategies. This paper presents the suitability of Single Point Incremental Forming (SPIF) to re-form End-of-life sheet metal components. Deep drawing followed by SPIF process on aluminium alloys were carried out to simulate reforming processes chain. The resulting thinning and strain distributions were experimentally analysed for different configurations. The research proves that the local action and enhanced formability nature of SPIF allow non-homogeneously thinned and reduced formability parts to be successfully re-formed
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