Characterization of Particulate Matter and Gaseous Material Emission at 3D Printer Operation

Abstract

Objective Three-dimensional (3D) printers are used for various purposes, including education, production of vehicle and aircraft parts, and in medical science. The most popular 3D printers use the fused deposition modeling (FDM) printing method. FDM printing uses a plastic filament cartridge that contains acrylonitrile-butadiene-styrene (ABS) or polylactic acid (PLA). The objective of this study was to evaluate the emission characteristics of the particulate matter and gaseous material released during 3D printing.

Methods Particulate and gaseous materials were measured before, during, and after FDM 3D printing in a test chamber. One ABS and two PLA (PLA1 and 2

i.e., different brands) printer cartridges were tested three times. Both on-line (real time) and off-line monitoring was conducted. For particulate on-line monitoring, a scanning mobility particle sizer (SMPS), condensation particle counter (CPC) and DustTrak with a polyvinyl chloride (PVC) filter (for the mass correction factor) was used. For total volatile organic compounds (TVOC), a ppbRAE monitor was used. For off-line monitoring of the particulate mass concentration, a polycarbonate (PC) filter was placed in an open-faced three-piece cassette. For phthalates, aldehydes, and VOCs, XAD-2 tubes, 2,4-dinitrophenylhydrazine (2,4-DNPH) cartridges, and charcoal tubes, respectively, were connected to low flow rate sampling pumps. Outdoor air was also measured during the testing period.

Results The particle concentration during 3D printing was much higher than before and after the printing period and the ABS cartridge emitted more particles than the PLA cartridges. The number concentration measured with the SMPS during ABS cartridge printing (1,731,578 #/cm3) was 345 times higher than before printing (5,021 #/cm3) and 272 times higher than after printing (6,373 #/cm3). Three-dimensional printing using ABS material was found to emit 33 – 38 times more particles than when PLA materials were used (1,731,578 #/cm3 vs. 52,252 #/cm3 (PLA1) or 45,690 #/cm3 (PLA2)). Most particles were nanosize (<100 nm) during ABS cartridge use (96%), but particle size varied widely when PLA was used (98% were nanosize for PLA1, but only 12% were nanosize for PLA2). Aldehydes including formaldehyde, acetaldehyde, and isovalderaldehyde were emitted when both ABS and PLA cartridges were used. Formaldehyde, a suspected human carcinogen, was measured at concentrations of 80 µg/m3, 72 µg/m3, 203 µg/m3 when using ABS, PLA1 and PLA2 cartridges, respectively. TVOC was also emitted when the ABS cartridge was used (GM

155 ppb, GSD

3.4), but not when the PLA cartridge was used. Benzene was not detected but toluene, ethyl benzene, and xylene were detected at ppb levels.

Conclusions In this study, we found that hazardous agents including nanoparticles, VOCs, and aldehydes were emitted during 3D printing, depending on the filler material used. More particles were emitted when the ABS cartridge was used compared to the PLA cartridges, and aldehydes and VOCs were emitted by both the ABS and PLA cartridges. These results suggest that caution should be implemented during FDM 3D printer use and emission control measures may be required.