Browsing by Subject "Sustainable Manufacturing"
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Item An Assessment and Simulation Methodology of Sustainability in Manufacturing System(2018-06) Islam, MdThis thesis work presents a new integrated framework to connect the economic, environmental and social factors, and to analyze sustainability performance of the system by balancing these factors. Sustainable manufacturing systems should be profitable and environmentally friendly while being safe both physically and socially for everyone in the system. This thesis work highlights the main aspects and requirements of sustainability, which are related to manufacturing systems, demonstrating that there are other aspects of sustainability in general that are not reflective on manufacturing. This work also highlights many useful assessment indices of manufacturing sustainability, which makes quantification, and then comparison and optimization of system performance possible. A comparative study on the existing sustainability assessment tools is performed to classify these tools based on appropriateness to manufacturing systems and limitations by reviewing the significant research work in system modeling for assessing and optimizing manufacturing sustainability. The review has revealed that the triple bottom line TBL factors, economic, social and environmental, are difficult to evaluate and optimize simultaneously due to the complex nature of manufacturing systems and the wide variety of processes and type of the system. Furthermore, the review has demonstrated that there is significant research gap in considering social sustainability for overall sustainability characterization. The consideration and the integration of social sustainability with other factors make this framework unique and more functional. Three case studies have been conducted to understand the applicability of this novel framework. The first case study reveals the difficulties associated with achieving social sustainability as most of the parameters in social sustainability are intangible in nature that’s why it is difficult to optimize the parameters associated with social sustainability. The last two case studies are analyzed to evaluate the sustainability in oil and gas industry with the help of fuzzy interference modelling. Fuzzy interference modelling is the core unit of decision making and mathematical reasoning of the sustainability assessment simulation, when the outcomes are uncertain. The modelling is built with the help of triangle membership functions to fuzzify the variables. Fuzzy rules like ‘IF THEN’ along with operators “OR” or “AND” then come into play for generating necessary decision rules. In this work, these decision rules aggregately simulate and generate the overall sustainability assessment results for case studies 2 and 3. All case studies strongly demonstrate the pragmatic and facile application of the proposed framework to assess the overall sustainability in continuous manufacturing context. Finally, the scope of future research work is also presented for the proposed novel framework.Item Performance Measures of Direct Metal Laser Sintering Hybrid Milling: Mechanical Properties and Environmental Performance Indicators(2019-07) Ahmad, NabeelApplications of metal additive manufacturing (AM) has increased substantially because it allows cost and resources efficient small-scale production required in industries such as aerospace and mold and die manufacturing. Geometric and dimensional accuracy of parts produced by AM is still subpar compared to conventional subtractive approaches. Recently, hybrid additive-subtractive called direct metal laser sintering hybrid milling (DMLS-HM) technology has been introduced which combines strengths and robustness of both additive and subtractive units. This thesis explores the adoption consequences and impacts of DMLS-HM through relative performance measures of mechanical and metallurgical properties as well as environmental impact assessment. This was achieved by first characterizing mechanical properties of Maraging steel powder and comparing it with conventional DMLS to understand the degree of variability. It was found out that DMLS-HM has superior mechanical properties for impact toughness and surface finish; however, tensile strength and hardness values were similar with DMLS. Environmental performance assessment was achieved by first identifying and finding the energy requirements in subsystems (additive and subtractive) of DMLS-HM and then converting into equivalent carbon emission. Carbon emission results for DMLS-HM printed geometry were compared with two other manufacturing approaches namely electron beam melting and conventional milling which fabricated the same geometry. The DMLS-HM process showed higher energy consumption during the part production stage with an average 84% more than EBM and CM processes. However, the CM was dominant in energy consumption during the procurement stage with an around 70% more energy than DMLS-HM and EBM processes. The outcome of this research project will contribute to the understanding of basic physics of energy consumption in AM and can be used in suitable process selection and setting sustainable manufacturing goals.Item Textile Mechanical Recycling: Design, Improvement, and Analysis of a Carding Wire Drum System(2023-12) Teixeira Franca Alves, Paulo HenriqueTextile manufacturing is responsible for significant environmental impacts such as 35% of primary microplastics production, 20% of global clean water pollution, and 10% of global greenhouse gas emissions. The growing problem of textile waste, further fueled by fast fashion and overconsumption, is set to grow with the rising global population. In 2018, 17 million tons of textile waste was generated in the US of which only 15% was recycled. Furthermore, only 1% of recycling policy research focuses on textile waste, demonstrating the great need for new studies and technologies to mitigate this problem. Additionally, present textile recycling technologies produce downcycled fibers, have high costs, or lack scalability for industrial production volumes. Despite the existence of various shredding machines for recycling textiles, the parameters that can influence this process have not been broadly investigated, decelerating the development of machines that could make fiber-to-fiber recycling a possibility. This study investigates the principles behind carded (toothed) drum textile shredding, to optimize the shredding process to obtain reusable fiber while decreasing the generation of fabric pieces and dust. The mechanics involved in subjecting fabrics to tensile and shear forces in a carding wire drum-operated system were investigated to understand better how the textile material behaves during the shredding process. By focusing on the interaction between the feeding and shredding drums and characterizing the failure mechanics of the drum-textile and tooth-yarn interactions, it was proposed that reducing tooth size and increasing the relative speed between drums will enhance the shear failure ratio, increasing the output of fibers and yarns. Because most existing textile recycling technologies are expensive, yield low-quality outputs, or lack scalability for industrial use, there is an urgent need for adaptable and sustainable textile recycling system designs that account for the dynamic nature of the textile and fashion industry. To ensure sustainability, these designs must be flexible enough to adapt to technological advancements, user needs, societal changes, and environmental conditions. To make this possible, flexible and sustainable principles were evaluated and overlapping principles were combined while missing principles were added, creating the design for sustainability and flexibility method (DfSFlex). The Fiber Shredder, a textile mechanical recycling machine, was developed with a focus on flexibility and sustainability and was evaluated based on how well it addressed the DfSFlex principles. The design and assembly processes of this machine were detailed to illustrate the decision-making involved in developing the technology. Later, a performance evaluation of the Fiber Shredder was performed and indicated that increased speed and processing time led to a higher generation of desired outputs (fibers and yarns) reflecting the principles of Design for Separation and Facilitate Resource Recovery in both design and processing. Furthermore, tests involving different materials and fabric structures demonstrated that material type, fabric thickness, and structure significantly influenced the output of recycled fibers. The Fiber Shredder outperformed an industrial shredding machine by producing outputs with fewer undesirable fabric pieces, more desirable fibers and yarns, and lower process losses. However, while effective for laboratory research purposes, the Fiber Shredder has limited capacity and requires automation and scaling up to meet industrial demands. Nonetheless, the development of this technology utilizing sustainable and flexible design principles shows promise in mechanical fiber-to-fiber recycling, contributing to the repurposing of textiles and reducing the amount of textile waste ending up in landfills.