Environmental Impacts of Distributed Manufacturing from 3-D Printing of Polymer Components and Products

Abstract

Although additive layer manufacturing is well established for rapid prototyping the low throughput and historic costs have prevented mass-scale adoption. The recent development of the RepRap, an open source self-replicating rapid prototyper, has made low-cost 3-D printers readily available to the public at reasonable prices (<$1,000). The RepRap (Prusa Mendell variant) currently prints 3-D objects in a 200x200x140 square millimeters build envelope from acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA). ABS and PLA are both thermoplastics that can be injection-molded, each with their own benefits, as ABS is rigid and durable, while PLA is plant-based and can be recycled and composted. The melting temperature of ABS and PLA enable use in low-cost 3-D printers, as these temperature are low enough to use in melt extrusion in the home, while high enough for prints to retain their shape at average use temperatures. Using 3-D printers to manufacture provides the ability to both change the fill composition by printing voids and fabricate shapes that are impossible to make using tradition methods like injection molding. This allows more complicated shapes to be created while using less material, which could reduce environmental impact.As the open source 3-D printers continue to evolve and improve in both cost and performance, the potential for economically-viable distributed manufacturing of products increases. Thus, products and components could be customized and printed on-site by individual consumers as needed, reversing the historical trend towards centrally mass-manufactured and shipped products. Distributed manufacturing reduces embodied transportation energy from the distribution of conventional centralized manufacturing, but questions remain concerning the potential for increases in the overall embodied energy of the manufacturing due to reduction in scale. In order to quantify the environmental impact of distributed manufacturing using 3-D printers, a life cycle analysis was performed on a plastic juicer. The energy consumed and emissions produced from conventional large-scale production overseas are compared to experimental measurements on a RepRap producing identical products with ABS and PLA. The results of this LCA are discussed in relation to the environmental impact of distributed manufacturing with 3-D printers and polymer selection for 3-D printing to reduce this impact. The results of this study show that distributed manufacturing uses less energy than conventional manufacturing due to the RepRap's unique ability to reduce fill composition. Distributed manufacturing also has less emissions than conventional manufacturing when using PLA and when using ABS with solar photovoltaic power. The results of this study indicate that open-source additive layer distributed manufacturing is both technically viable and beneficial from an ecological perspective.

Distributed Manufacturing of Flexible Products: Technical Feasibility and Economic Viability

“…Distributed manufacturing is the term used here to describe decentralized fabrication of parts in smaller factories or homes that are local to end-users [12,13,69,[79][80][81][82][83]. This concept is ideal for additive manufacturing as 3-D printers located around the globe could be utilized to make a variety of parts for people that are geographically close to consumers.…”

“…This concept is ideal for additive manufacturing as 3-D printers located around the globe could be utilized to make a variety of parts for people that are geographically close to consumers. This reduces shipping time, packaging materials and emissions from the embodied energy of transportation as well as material savings [79,80]. If someone wanted to start up their own micro-factory at home as a source of income they could do so for a very low up-front investment in machinery [17].…”

Open Source Multi-Head 3D Printer for Polymer-Metal Composite Component Manufacturing

“…This improved product manufacturing time is an advantage for small lots as could be used in a 3D print shop or part to order factory for small business manufacturing [61]. In addition, this improved embodied energy of manufacturing [62,63] if dispersed would provide an advantage over conventional manufacturing and home-based manufacturing [60,64,65]. At the same time, this methodology points the way toward potential 3D printing-based mass production [66] by ganging many print heads to manufacture identical bespoke products simultaneously [67][68][69][70].…”

Applications of Open Source 3-D Printing on Small Farms

“…The environmental benefits of organic farming and food systems are well established [96]: they contribute to climate change mitigation [97] because of improved energy efficiency and biodiversity conservation [98][99][100]. In order to improve the environmental benefits of organic hydroponics even further, distributed manufacturing with open-source 3-D printers can be used as there is already evidence that it has a lower environmental impact than conventional manufacturing [101,102].…”