## 3 Sustainability of Additive Manufacturing
### Sustainability Assessment  
In recent years, environmental issues of manufacturing processes have been at the center of attention due to the importance of resource-saving and environment protection. Therefore, sustainability studies are essential for AM before being commercially utilized [131]. Reducing fuel consumption in goods transportation and material wastes in manufacturing are the two large challenges in AM sustainability. Comprehensively overcoming these challenges and assessment of their real impacts result in a reduction in overall product cost and sustainability improvement [132]. Sustainability dimensions are progressively identified as an applicable tool for public communication and policy in order to carry information about country and corporation performance [121]. Reduction in energy/material consumption and transportation/packaging systems through different life cycle analysis (LCA) methods have been performed on AM processes in order to make them more sustainable  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Advantages** & **Challenges** \\ \hline \hline
**Product redesign** & \\ \hline \hline Design freedom & Integrating sustainability using the design for \\ \hline \hline Optimized geometries and performance & environment or eco-design \\ \hline \hline Reduced cost and time & Training of designers and engineers concerning \\ \hline Improved product functionality and durability & the potential utilization and benefits of AM \\ \hline Simplified assemblies and products & Certifying new components \\ \hline Upgradable and democratized design & \\ \hline \hline
**Material input processing** & \\ \hline Improved resource efficiency of raw & Resource efficiency improvements and recycling \\ material processing & potential restricted to specific materials \\ \hline Decreased toxicity of material processing & Increasing the percentage of recycled content in \\ By-products from the waste flow & material inputs \\ \hline Upcycling and recycling of waste materials & Lack of knowledge of the environmental performance of \\ Localized material recycling & material processing techniques \\ \hline
**Component and product manufacturing** & Restricted speed and reliability of AM \\ \hline Decreased energy consumption & Restricted quality of products \\ \hline Decreased waste production & High machine costs \\ \hline Improved access to digital designs and & Improving cost-effectiveness and energy efficiency at \\ manufacturing systems & higher production volumes \\ \hline Decreased material inputs & Lack of knowledge of the environmental \\ \hline Simplified assemblies and supply chains & Performance of AM technologies and supply chains \\ \hline Improved productivity, cost and resource efficiency & Requirements for standards and regulations \\ \hline
**Product use** & \\ \hline Lightweight products & \\ Improved operational efficiency & Uncertain performance of products and components due \\ Improved functionality and durability & to low maturity of AM technologies \\ Repair, remanufacturing and recycling & Certifying repair and remanufacturing processes \\ Decreased waste produced during the repair process & Performing maintenance systems \\ Decreased process time for repair & Restricted recyclability of plastics due to quality losses \\ Improved product utilization through repair & Non-recyclability of AM-produced multi-material goods \\ and remanufacturing & \\ Improved material efficiency through recycling & \\ Increased acceptance of recycled material content & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Summary of benefits and challenges of sustainable AM process [13].  
regarding their economic, environmental, and social impacts. Figure 9 summarizes all aspects of the sustainability of AM processes based on three main dimensions.