Use of 3-Dimensional Printers in Educational Settings: The Need for Awareness of the Effects of Printer Temperature and Filament Type on Contaminant Releases

Abstract

Material extrusion-type fused filament fabrication (FFF) 3-D printing is a valuable tool for education. During FFF 3-D printing, thermal degradation of the polymer releases small particles and chemicals, many of which are hazardous to human health. In this study, particle and chemical emissions from 10 different filaments made from virgin (never printed) and recycled polymers were used to print the same object at the polymer manufacturer’s recommended nozzle temperature (“normal”) and at a temperature higher than recommended (“hot”) to simulate the real-world scenarios of a person intentionally or unknowingly printing on a machine with a changed setting. Emissions were evaluated in a college teaching laboratory using standard sampling and analytical methods. From mobility sizer measurements, particle number-based emission rates were 81 times higher; the proportion of ultrafine particles (diameter <100 nm) were 4% higher, and median particle sizes were a factor of 2 smaller for hot-temperature prints compared with normal-temperature prints (all p-values <0.05). There was no difference in emission characteristics between recycled and virgin acrylonitrile butadiene styrene and polylactic acid polymer filaments. Reducing contaminant release from FFF 3-D printers in educational settings can be achieved using the hierarchy of controls: (1) elimination/substitution (e.g., training students on principles of prevention-through-design, limiting the use of higher emitting polymer when possible); (2) engineering controls (e.g., using local exhaust ventilation to directly remove contaminants at the printer or isolating the printer from students); (3) administrative controls such as password protecting printer settings and establishing and enforcing adherence to a standard operating procedure based on a proper risk assessment for the setup and use (e.g., limiting the use of temperatures higher than those specified for the filaments used); and (4) maintenance of printers.

Metal compositions of particle emissions from material extrusion 3D printing: Emission sources and indoor exposure modeling

“…Other commonly detected metals (in 5 to 6 out of the 8 samples) included Mg, Ca, Mn, Zn, As, Sr, Sn, and Pb ( Table 3 ). Previous studies reported metals commonly detected from PLA emitted particles included Fe, Zn, Si, K, Cu, Al, Na, Mg ( Steinle, 2016 ; Zontek et al, 2017 ; Stefaniak et al, 2017a; Youn et al, 2019 ; Stefaniak et al, 2021 ; Yi et al, 2019 ), which were also detected in this study, except for Fe. In addition, Na, Al and K were only detected in particles emitted from the two green PLA filaments ( Table 3 ).…”

“…Of these, the extruder nozzle had the highest temperature ( Table 1 ). However, the extruder nozzle made of brass (printer D1 ) was unlikely to be a source of Cu and Zn in emitted particles due to the inconsistency of detection frequencies of these elements in the particles, i.e., neither Cu nor Zn was consistently detected from all particle samples emitted from printer D1 ; this was also suggested in a previous study ( Stefaniak et al, 2021 ). In addition, the build plate was heated for printer D1 (50 °C); the print chamber (i.e., where the printing process happened) was heated for printer E2 (80 °C); even without additional heating for printer E1 , the temperature inside the print chamber was also elevated since the printer is enclosed.…”

“…The most commonly detected metal from particles was silicon, which was detected from all samples. The second one was boron that was found in seven samples except Metal filament, which has not been previously reported in emitted particles ( Zontek et al, 2017 ; Stefaniak et al, 2017a; Youn et al, 2019 ; Stefaniak et al, 2021 ; Yi et al, 2019 ). Other commonly detected metals (in 5 to 6 out of the 8 samples) included Mg, Ca, Mn, Zn, As, Sr, Sn, and Pb ( Table 3 ).…”

“…Elemental analysis of emitted particles showed the predominant elements were carbon and oxygen ( Kwon et al, 2017 ; Zisook et al, 2020 ; Steinle, 2016 ; Zontek et al, 2017 ; Zhu et al, 2020 ; Rao et al, 2017 ), which were associated with the polymer materials; other non-metal elements included sulfur and chlorine ( Zisook et al, 2020 ; Zontek et al, 2017 ; Rao et al, 2017 ; Stefaniak et al, 2017a; Youn et al, 2019 ). Trace amount of metals and metalloids, refer to as metals hereafter, have also been detected; common ones included aluminum (Al), iron (Fe), zinc (Zn), chromium (Cr), copper (Cu), sodium (Na), calcium (Ca), magnesium (Mg), and manganese (Mn) ( Zontek et al, 2017 ; Stefaniak et al, 2017a; Stefaniak et al, 2021 ). Metals detected from the emitted particles could be associated with bulk filament materials and additives ( Zontek et al, 2017 ; Stefaniak et al, 2021 ), from the printer itself, contamination from sampling sites ( Zontek et al, 2017 ) or sample preparation processes ( Zhu et al, 2020 ), therefore, more studies are needed to identify the exact sources.…”

“…Trace amount of metals and metalloids, refer to as metals hereafter, have also been detected; common ones included aluminum (Al), iron (Fe), zinc (Zn), chromium (Cr), copper (Cu), sodium (Na), calcium (Ca), magnesium (Mg), and manganese (Mn) ( Zontek et al, 2017 ; Stefaniak et al, 2017a; Stefaniak et al, 2021 ). Metals detected from the emitted particles could be associated with bulk filament materials and additives ( Zontek et al, 2017 ; Stefaniak et al, 2021 ), from the printer itself, contamination from sampling sites ( Zontek et al, 2017 ) or sample preparation processes ( Zhu et al, 2020 ), therefore, more studies are needed to identify the exact sources.…”