This discussion paper aims to set out the key challenges and opportunities emerging from distributed manufacturing (DM). We begin by describing the concept, available definitions and consider its ...evolution where recent production technology developments (such as additive and continuous production process technologies), digitisation together with infrastructural developments (in terms of IoT and big data) provide new opportunities. To further explore the evolving nature of DM, the authors, each of whom are involved in specific applications of DM research, examine through an expert panel workshop environment emerging DM applications involving new production and supporting infrastructural technologies. This paper presents these generalisable findings on DM challenges and opportunities in terms of products, enabling production technologies and the impact on the wider production and industrial system. Industry structure and location of activities are examined in terms of the democratising impact on participating network actors. The paper concludes with a discussion on the changing nature of manufacturing as a result of DM, from the traditional centralised, large-scale, long lead-time forecast-driven production operations to a new DM paradigm where manufacturing is a decentralised, autonomous near end user-driven activity. A forward research agenda is proposed that considers the impact of DM on the industrial and urban landscape.
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A promising method of enhancing the circular economy is distributed plastic recycling. In this study plastic waste is upcycled into 3-D printing filament with a recyclebot, which is ...an open source waste plastic extruder. The recyclebot is combined with an open source self-replicating rapid prototyper (RepRap) 3-D printer, to enable post-consumer ABS plastic filament from computer waste to be further upcycled into valuable consumer products pre-designed in the digital commons. The total electrical energy consumption for the combined process is monitored and an economic evaluation is completed. The coupled distributed recycling and manufacturing method for complex products reduces embodied energy by half, while reducing the cost of consumer products to pennies. This economic benefit provides an incentive for consumers to both home recycle and home manufacture, which tightens the loop on the circular economy by eliminating waste associated from transportation and retail. It is clear from the results that waste plastic can be significantly upcycled at the individual level using this commons-based approach. This tightening of the loop of the circular economy benefits the environment and sustainability as well as the economic stability of consumers/prosumers.
Fused deposition modeling (FDM) is the most common additive manufacturing system that is increasingly used for industrial and consumer applications. These systems selectively extrude/deposit polymers ...to manufacture parts directly from computational designs. Therefore, FDM enables conversion of recycled thermoplastic polymers to higher quality products. However, FDM induces porosity, which reduces mechanical performance and causes variations in mechanical properties of fused deposition modeled (FDMed) polymers. A safe and reliable use of FDMed-recycled polymers demands a better understanding of the effect of recycling on the mechanical properties. In this study, we investigated the effect of three rounds of recycling on the stochastic mechanical properties of FDMed ABS. A total of 337 tensile tests were performed on FDMed virgin and recycled ABS. Recycling increased the porosity of FDMed ABS from ∼11 vol% to ∼17 vol %. The tensile and fracture strength decreased by ∼10%. The strain at break decreased by 25% from 5.2% to 3.9%, causing a decrease in toughness by 37%. We observed significant variations in the mechanical properties, which were analyzed using Weibull statistics. An S-type deviation from Weibull distribution was observed for strength variations that was related to porosity. Minimal degradation in ABS molecular structure was observed via gel permeation chromatography, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. X-ray fluorescence spectroscopy revealed an increase in elemental iron with recycling.
•Recycling decreased the mechanical properties of the FDMed ABS due to porosity.•Mechanical properties of FDMed ABS vary significantly even for identical processing.•Weibull analysis was used to quantify the variations in mechanical properties.•Porosity was revealed as the origin of the variations in mechanical properties.•Recycling had minimal effect on ABS chemistry and molecular structure.
The trialing of new products in production typically suffers from quality and productivity problems because of immature manufacturing processes. As an efficient virtual-real interaction technology, ...digital twin technology can optimize the manufacturing process adaptively in a single station. However, existing digital twin systems lack an effective collaboration mechanism between manufacturing units, thus failing to optimize the overall manufacturing processes dynamically. This paper proposes a practical collaboration theory and methodology between digital twin manufacturing units. To overcome the above challenges, this digital thread-driven method models the manufacturing tasks by heterogeneous information network to analyze the product quality information during the manufacturing process, and adjusts the subsequent manufacturing tasks according to the analysis results. The collaboration between manufacturing units forms a stable and reliable operation mode for improving production efficiency during the whole manufacturing process. The graph-based manufacturing task model can help analyze the machining and assembly process based on the digital thread, distinguish the error sources of products, and dynamically reconstruct production tasks. Finally, the feasibility of the proposed method is verified by a case of a crank and connecting rod mechanism in a manufacturing workshop.
•The framework of DDTMS is proposed to form a unified management system among DTMU.•The quality problems of each stage can be obtained by the digital thread-driven analysis method of the product manufacturing status.•A distributed collaborative manufacturing method is proposed to analyze and reconstruct collaborative tasks quickly.
•The potential for distributed manufacturing to enhance the resilience of sustainable energy systems is discussed.•Methods for assessing resilience and economic performance in the design of energy ...systems are proposed.•A multi-scale framework for energy system resilience that integrates supply chain management strategies is proposed.
The projected increase in global energy consumption, along with recent upheavals such as extreme weather events due to climate change and geopolitical turmoil, motivates the development of sustainable energy supply chains that have the capability to withstand internal and external threats to the system. However, one major challenge is a lack of understanding on the contributing factors to energy supply chain resilience at various spatial and temporal scales. To this end, we argue for the use of a multi-scale approach in studying the resilience of energy supply chains to take advantage of physical and chemical synergies at various scales of operation as well as incorporate risk mitigation techniques drawn from general supply chain literature and practice. We present an initial effort towards a framework for energy supply chain resilience at four scales of operation: molecular, unit, process, and supply chain.
The operation of production facilities is shifting from centralized organizations towards decentralized networks. The paper investigates and compares alternative mechanisms for resource sharing in ...distributed manufacturing. Specifically, with the same underlying assumptions, a platform and a direct exchange-based model are presented and examined. The models have in common that resource assignment decisions are made ultimately by the autonomous facilities, also based on trust they maintain towards each other. Agent-based simulation is used to compare the two mechanisms with respect to utilization rate, service level and communication load. The findings can be applied in the design of crowdsourced manufacturing platforms.
The purpose of this paper is to verify the conceptual benefits of the implementation of additive manufacturing (AM) in spare part supply chains from the point of view of industry. Focus group ...interviews consisting of five sessions and 46 experts in manufacturing were conducted for this study. The focus group interviews served to identify the issues in the adoption of digital spare parts (DSP) and to expand on the available literature. The benefits found in the reviewed literature were partially verified by the participants but certain limitations, such as the excessive need of post processing, supplier quality parity, and ICT inadequacies, were presented that were absent or not highlighted in literature. The information gathered from the participants made it possible to create a realistic model of a digital spare part distribution network. According to the focus group interviews, digital spare parts could be deployed immediately for a specific type of product in the long tails of company spare part catalogues. However, improvements in AM, company ICT infrastructure, and 3D model file formats need to be achieved for a larger deployment of DSP.
Fused particle fabrication (FPF) (or fused granular fabrication (FGF)) has potential for increasing recycled polymers in 3-D printing. Here, the open source Gigabot X is used to develop a new method ...to optimize FPF/FGF for recycled materials. Virgin polylactic acid (PLA) pellets and prints were analyzed and were then compared to four recycled polymers including the two most popular printing materials (PLA and acrylonitrile butadiene styrene (ABS)) as well as the two most common waste plastics (polyethylene terephthalate (PET) and polypropylene (PP)). The size characteristics of the various materials were quantified using digital image processing. Then, power and nozzle velocity matrices were used to optimize the print speed, and a print test was used to maximize the output for a two-temperature stage extruder for a given polymer feedstock. ASTM type 4 tensile tests were used to determine the mechanical properties of each plastic when they were printed with a particle drive extruder system and were compared with filament printing. The results showed that the Gigabot X can print materials 6.5× to 13× faster than conventional printers depending on the material, with no significant reduction in the mechanical properties. It was concluded that the Gigabot X and similar FPF/FGF printers can utilize a wide range of recycled polymer materials with minimal post processing.
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