Sustainability Assessment of Additive Manufacturing Processes
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Additive Manufacturing (AM) processes were developed in the 1980s to reduce the time for the realization of prototypes. Nowadays, AM processes are considered as real manufacturing techniques suitable to build end-use products. As for any new technology, research efforts aiming to process planning and optimization within a sustainable development framework are needed. In particular, the application of the sustainable manufacturing principles requires the creation of products that use processes that minimize negative environmental impacts, conserve energy and natural resources, are safe for employees, communities, and consumers, and are economically sound. In this work, the three aspects of sustainability, namely environmental, economic and social sustainability are critically analyzed for AM. For each topic, an analysis of models that can evaluate the consumption of energy and CO2 emissions, costs and the impact on workers' health is carried on. The functional redesign of a mechanical object, with the aim of reducing its mass and trying to keep unchanged the constraint conditions imposed is accounted for. A critical analysis of the impacts on workers' health focusing on the hazardous aspects related to the animal and human exposure to metal powders is presented. Considerations on body weight, cancer, cardiovascular, dermal, endocrine, gastrointestinal, hematological, hepatic, musculoskeletal, neurological, ocular, rheumatologic, renal, reproductive, respiratory effects are reported for different elements as Cobalt, Chrome, Nickel, Titanium and for each kind of exposure (inhalation, oral, dermal). Methods for the comparison and evaluation of an inventory s dissimilar pollution loads have been proposed and are critically analyzed. Considerations on the possible workplace maintenance techniques to be followed for handling metal powders (such as those according to ASTM, NFPA and OSHA standards) are also evaluated. Whatsoever, it is possible to consolidate a new technology in the industrial scenario only if it is economically sustainable and profitable. A critical study of the evolution of the main economic models is reported. In addition, approaches that can take into account also the pre-process and post-process phases as well as the production of different objects in the same built are presented. Moreover, in this work, several examples and comparisons of the sustainable performance of different AM techniques are discussed. A critical study of models that can evaluate the amount of CO2 emissions during the production of part via AM techniques is studied. A model for the calculation of CO2 emissions from the consumption of electricity is also detailed. The above mentioned models have been applied to selected case studies before and after the redesign phase. NX and ANSYS software were used to perform the geometrical optimization. An experimental study was then conducted to validate the results.