Rapid Prototyping Journal, Volume 21, Issue 1, January 2015.
Purpose The environmental impacts of two additive manufacturing machines were compared to a traditional CNC milling machine to determine which method is the most sustainable. Design/methodology/approach A life-cycle assessment was performed, comparing a Haas VF0 CNC mill to two methods of additive manufacturing: a Dimension 1200BST FDM and an Objet Connex 350 “inkjet” / “polyjet”. The LCA's functional unit was the manufacture of two specific parts in ABS plastic or similar polymer as required by the machines. The scope was cradle-to-grave, including embodied impacts, transportation, energy use during manufacture, energy use while idling and in standby, material use in final parts, waste material generated, cutting fluid for CNC, and disposal. Several scenarios were considered, all scored using the ReCiPe Endpoint H and IMPACT 2002+ methodologies. Findings Results showed the sustainability of additive manufacturing vs CNC machining depends primarily on the percent utilization of each machine. Higher utilization both reduces idling energy use and amortizes the embodied impacts of each machine. For both 3D printers, electricity use is always the dominant impact, but for CNC at maximum utilization, material waste became dominant and cutting fluid was roughly on par with electricity use. At both high and low utilization, the FDM machine had the lowest ecological impacts per part. The inkjet machine sometimes performed better and sometimes worse than CNC, depending on idle time/energy and on process parameters. Research limitations/implications The study only compared additive manufacturing in plastic, and did not include other additive manufacturing technologies, such as selective laser sintering or stereolithography. It also does not include post-processing that might bring the surface finish of FDM parts up to the quality of inkjet or CNC parts. Practical implications Designers and engineers seeking to minimize the environmental impacts of their prototypes should share high-utilization machines, and are advised to use FDM machines over CNC mills or polyjet machines if they provide sufficient quality of surface finish. Originality/value This is the first paper quantitatively comparing the environmental impacts of additive manufacturing with traditional machining. It also provides a more comprehensive measurement of environmental impacts than most studies of either milling or additive manufacturing alone--it includes not merely CO2 emissions or waste but also acidification, eutrophication, human toxicity, ecotoxicity, and other impact categories. Designers, engineers, and job shop managers may use the results to guide sourcing or purchasing decisions related to rapid prototyping.
Purpose The environmental impacts of two additive manufacturing machines were compared to a traditional CNC milling machine to determine which method is the most sustainable. Design/methodology/approach A life-cycle assessment was performed, comparing a Haas VF0 CNC mill to two methods of additive manufacturing: a Dimension 1200BST FDM and an Objet Connex 350 “inkjet” / “polyjet”. The LCA's functional unit was the manufacture of two specific parts in ABS plastic or similar polymer as required by the machines. The scope was cradle-to-grave, including embodied impacts, transportation, energy use during manufacture, energy use while idling and in standby, material use in final parts, waste material generated, cutting fluid for CNC, and disposal. Several scenarios were considered, all scored using the ReCiPe Endpoint H and IMPACT 2002+ methodologies. Findings Results showed the sustainability of additive manufacturing vs CNC machining depends primarily on the percent utilization of each machine. Higher utilization both reduces idling energy use and amortizes the embodied impacts of each machine. For both 3D printers, electricity use is always the dominant impact, but for CNC at maximum utilization, material waste became dominant and cutting fluid was roughly on par with electricity use. At both high and low utilization, the FDM machine had the lowest ecological impacts per part. The inkjet machine sometimes performed better and sometimes worse than CNC, depending on idle time/energy and on process parameters. Research limitations/implications The study only compared additive manufacturing in plastic, and did not include other additive manufacturing technologies, such as selective laser sintering or stereolithography. It also does not include post-processing that might bring the surface finish of FDM parts up to the quality of inkjet or CNC parts. Practical implications Designers and engineers seeking to minimize the environmental impacts of their prototypes should share high-utilization machines, and are advised to use FDM machines over CNC mills or polyjet machines if they provide sufficient quality of surface finish. Originality/value This is the first paper quantitatively comparing the environmental impacts of additive manufacturing with traditional machining. It also provides a more comprehensive measurement of environmental impacts than most studies of either milling or additive manufacturing alone--it includes not merely CO2 emissions or waste but also acidification, eutrophication, human toxicity, ecotoxicity, and other impact categories. Designers, engineers, and job shop managers may use the results to guide sourcing or purchasing decisions related to rapid prototyping.