Design flexibility allows product parameters such as weight and effectiveness to obtain a superior life cycle performance
[36]. Though size limitation is one of the key constraints, the potential of 3D printing technology for the construction sector is considered based on the findings gained from each work phase, particularly the case studies analysis
[37]. The authors declared that the goal of many manufacturers and academics was the long-term viability of the built environment in terms of economic, environmental, and social advantages. The environmental performance of a revolutionary additive manufacturing technique, known as rapid mask-image-projection-based stereolithography, was assessed using a life cycle evaluation to find damage to ecosystems and human health
[38]. The study was conducted in different approaches to decrease economic risks, carbon and ecological footprints, and environmental impacts of 3D printing technology to minimize the environmental impacts and costs associated with traditional manufacturing methods
[39].
AM technique is used as the standard manufacturing process to find the lack of end-of-life data and a modest influence on maintenance and fuel efficiency and examine the impact on the environment on output. As demonstrated in
[3], to improve the design features of DfAM, the research must focus on the early design stages to reduce environmental impacts. The authors in
[46] created a methodology to supplement the LCA of an AM material to minimize hazards, human health, and ecological implications. A feasibility study was carried out by
[47] to evaluate the applicability, manufacturing time, and production costs of AM versus CM of specified metallic construction components. Second, the authors’ analysis of LCA examined the environmental implications of AM and CM. The researchers in
[48] compared conventional manufacturing processes with AM, exposed the AM system emissions, the impact of raw materials utilization, and operating parameters, and developed suitable control measures and best practices for hazard reduction. Four LCAs were also conducted
[49] for mold core production techniques, including casting with low-melting alloy, milling from plaster-like substance Aqua pour, additive manufacturing with high-impact polystyrene (HIPS), and additive manufacturing using powder materials such as salt. The study also analyzed the environmental consequences of traditional and additive mold core manufacture in CFRP production.
An LCA-based study was also conducted
[63] using powder bed fusion (PBF) of metal components of an engine in a light distribution truck. Conventional manufacturing was contrasted with 3D-printing scenarios, one indicating the current stage of development of 3D-printing technology and the other a probable future state. The authors in
[64] researched the evaluation of new materials for paste extrusion printing. LCA technique was used to compare their whole-system environmental implications to typical ABS extrusion: testing also evaluated material strength, printability, and cost. The reported research on AM’s environmental impact emphasizes gaps and places where more study is needed. Finally, the effects of reusing metallic powder and the waste disposal processes were investigated
[65].
The LCA for an inkjet fusion printer with unusually high spatial utilization capability was performed in
[66], which compared with earlier LCAs of nine printers produced with eight materials. However, when evaluated in the same usage situations, the inkjet fusion printer had a more significant environmental effect per component than other printers due to its high energy consumption.
The investigation was carried out, and a comparison of AM data from the literature on lifecycle evaluation was made with traditional industrialized data from the Granta EduPack database. According to the authors
[67], the AM had considerably larger CO
2 footprints per kilogram of material produced than casting, extrusion, rolling, forging, and wire drawing. When this pertains to the manufacture of medical implants, this study analyzed whether AM is more environmentally friendly than CM. The environmental impact of producing the femoral component of a Ti-6Al-4V knee implant was examined. For the fabrication of this component, one AM process, i.e., electron beam melting (EBM) and milling operation, were investigated
[68]. The authors in
[69] undertook a life cycle environmental comparison of two different versions of a product fabricated utilizing additive technology. The products’ structures were the same, and the study trials involved modifying the materials used in additive manufacturing (from PLA to ABS). The impacts of adjustments on environmental factors were noted, and a direct comparison of the effects in the various components was performed. The life cycle assessment is accomplished in the brick-making process to assess environmental impacts considering conventional production systems and olive mill wastewater
[70].
Overall, it is vital to assess the actual environmental impact of new manufacturing methods. The LCA, among other things, facilitates opportunities to build sustainable products and processes, provides information to decision-makers in businesses and government organizations, selects environmental performance indicators, and assists with green manufacturing and marketing.
3. Energy Modeling in Additive Manufacturing
Energy models in additive manufacturing allow determining which aspects of the machine contribute the most to global environmental effects to reduce energy consumption. The modeling approach involves simulating each machine characteristic that influences the environment.
A novel approach was proposed to assess the environmental effect of all flows (materials, fluids, and power). The conventional approach is based on a predictive model of flow consumption specified by the production process and a CAD model of the item to be produced
[13]. A novel technique for assessing electric, fluid, and raw material consumption in AM processes can be done by direct metal deposition. The method assists engineers in designing environmentally friendly products for additive manufacturing
[71]. An experimental design is utilized to investigate the impact of production volume, material and operational costs, batch size, material machinability, and lowering AM processing time. The generated models give insight into how these variables impact the expenses of creating a mechanical product manufactured using AM and subtractive manufacturing (SM) technologies
[72]. In a study reported in
[73], a CAD model of a product was created, and the manufacturing program was utilized to create a prediction model of flow usage that aims to reduce production environmental effects during the design stage. A study on empirical research was conducted
[74] by presenting an optimization framework for estimating laser energy consumption in the SLS process. This study’s experimental approach included the calculation of energy consumption by measuring the whole sintering area. A comparison of a machining strategy with an integrated production path based on an AM process plus finish machining was reported in
[75], whose primary outcome was a criterion for selecting the best environmentally friendly manufacturing technique while modifying the production scenario. An energy modeling for FDM printing was also developed
[76] to investigate from a life cycle viewpoint. The steps covered in a typical FDM life cycle included material manufacturing, printing, post-processing, and associated transportation. This model uses energy for each stage and measures unit energy consumption. Thus, the objectives of the study were to create a conceptual model for manufacturing to redesign products, identify AM process adoption possibilities, and apply the AM process in production
[77]. The researchers in
[78] studied and compared several environmental production processes for components composed of aluminum alloys. Life cycle assessment methodologies were used to study and compare SLS-based AM processes, machining, and shaping operations.
4. Energy Consumption and Sustainable Design for AM
The utilization of resources without exhaustion or negative environmental impact is called sustainability. Significant sustainability challenges in manufacturing include energy use, waste creation, water usage, and the manufactured item’s environmental effect. Sustainability concerns global ecological conditions (environment), economic development (technology), and societal equality. Engineering procedures are typically associated with economic progress.
To minimize the amount of energy used in SLS of non-polymeric materials, work was reported in
[79]. The strategy of this work was to mix a temporary binder with the material, make an SLS green part convert the binder, and densify the part by chemical deposition at room temperature inside the pore network. The authors in
[80] have also compared the electrical consumption of two major polymeric SLS platforms: the 3D Systems Sinterstation HiQHS and the EOSINT P 390 from EOS GmbH. The measured energy rates were more significant than the reported and also demonstrated that the primary energy drain is entirely time-dependent energy usage. A method for developing an energy consumption model for the binder-jetting manufacturing process’s printing stage was described in
[81]. Mathematical investigations were carried out to determine the relationship between energy usage and the geometry of the produced item. This process model is a tool for optimizing part geometry design regarding energy usage. The study was conducted to improve understanding of the energy inherent in each phase of the manufacturing process. To make the helpful model, users should calculate the energy spent by their manufacturing process equipment based on the energy-per-unit production volume for each material of interest, considering both alloy composition and shape
[82].
The researchers in
[83] analyzed a range of items and industries in this study to fully grasp the function of additive manufacturing in sustainable industrial systems. Four major areas where the use of additive manufacturing is improving resource efficiency can be identified: (1) products and process design, (2) material input processing, (3) product and component production to order, and (4) completing the loop. The authors in
[84] examined AM good’s overall life cycle sustainability using the newly developed Product Sustainability Index (ProdSI) methodology. A case study was conducted with two iterations of an AM product confirming the ProdSI metrics of AM products. Furthermore, the features of additive manufacturing from the standpoint of sustainable design and the possibility of a new business model that might result in the sustainable design of consumer items were reported in
[85]. The primary environmental benefits of using AM technologies in industrial production include lower energy consumption of printers throughout the manufacturing process, ease of product decommissioning and disposal, reduced waste, and enhanced raw material recycling rate
[86]. The authors in
[7] reviewed research initiatives that were carried out at the University of Exeter to improve the long-term viability of AM. These research efforts included: (1) sustainable product design through internal lightweight structure optimization, (2) process efficiency improvement through AM process parameter optimization, (3) energy consumption reduction through in situ thermite material reaction, and (4) sustainable production of individualized chocolates. Research on electric energy consumption of various processes was conducted
[87], followed by some extensive studies that considered raw materials and all the process processes’ flows. The study provided a novel approach for accurately evaluating the environmental effect of a part based on its CAD model. The researchers
[88] experimented and identified the machine effects, and aluminum powder impacts were computed using life cycle inventories of materials and processes; electricity usage was monitored using an in-line power meter, and transport and disposal were also evaluated. Energy consumption was used to calculate the impacts. A study was conducted and reported in
[89] in which the part was manufactured and studied its construction orientation and interior filling, production time, energy consumption, and the product’s end-of-life. The study was further intended to assess the environmental implications of traditional manufacturing processes against AM for a real-world industrial application. The repair procedure of a burner was utilized in Siemens industrial gas turbine, and the results indicated that the AM-based repair procedure significantly reduces material footprint and primary energy use
[90].
A mathematical model for energy consumption of stereolithography apparatus (SLA)-based procedures was also proposed
[91], and experiments were conducted to assess the actual energy usage from an SLA-based AM machine. The comparative study results demonstrated that the overall energy consumption of SLA-based AM processes might be significantly lowered to optimize parameter settings without visible product quality degradation. According to
[92], who created a system modeling framework using life cycle inventory analysis and results, the AM has the potential to save 3 to 5% primary energy, 4 to 7% GHG emissions, 12 to 60% lead time, and 15 to 35% cost over 1 million injection molding production cycles.
Nagarajan and Haapala
[93] conducted a study to uncover the systemic contributions to environmental effects in AM by exergy analysis and life cycle impact assessment. These methodologies were used to assess the environmental performance of conventional and non-conventional manufacturing processes. Yang and Li
[94] studied how to enhance the state-of-the-art sustainable environmental assessment for AM batch processes by comparing key environmental sustainability characteristics (i.e., energy consumption, emission, and material waste) with batch production processes of varied batch sizes. Their study covers the critical sustainability challenges in AM manufacturing technologies.