Abstract

In this pilot-scale study, a wide range of potential emissions were evaluated for four types of additive manufacturing (AM) machines. These included material extrusion (using acrylonitrile-butadiene-styrene [ABS]); material jetting (using liquid photopolymer); powder bed fusion (using nylon); and vat photopolymerization (using liquid photopolymer) in an industrial laboratory setting. During isolated operation of AM machines, adjacent area samples were collected for compounds of potential concern (COPCs), including total and individual volatile organic compounds (VOCs), nano- and micron-sized particulate matter, and inorganic gases. A total of 61 compounds were also sampled using a canister followed by gas chromatography and mass spectrometry analysis. Most COPCs were not detected or were measured at concentrations far below relevant occupational exposure limits (OELs) during AM machine operations. Submicron particles, predominantly nanoparticles, were produced during material extrusion printing using ABS at approximately 12,000 particles per cubic centimeter (p cm⁻³) above background. After subtracting the mean background concentration, the mean concentration for material extrusion printing operations correlated with a calculated emission rate of 2.8 × 10¹⁰ p min⁻¹ under the conditions tested. During processing of parts produced using material jetting or powder bed fusion, emissions were generally negligible, although concentrations above background of respirable and total dust were measured during processing of powder bed fusion parts. Results of this pilot-scale study indicate that airborne emissions associated with AM operations are variable, depending on printing and parts handling processes, raw materials, and ventilation characteristics. Although personal samples were not collected in this pilot-scale study, the results can be used to inform future exposure assessments. Based on the results of this evaluation, measurement of submicron particles emitted during material extrusion printing operations and dust associated with handling parts manufactured using powder bed fusion processes should be included in exposure assessments.

摘要

在这项中试规模研究中，评估了四种类型的增材制造（AM）机器的各种潜在排放。这些包括材料挤压（使用丙烯腈-丁二烯-苯乙烯[ABS]）；材料喷射（使用液态光敏聚合物）；粉末床融合（使用尼龙）；在工业实验室中进行桶式光聚合（使用液态光聚合物）。在AM机隔离运行期间，会收集相邻区域的样本，以查找潜在关注的化合物（COPC），包括总和单独的挥发性有机化合物（VOC），纳米和微米大小的颗粒物以及无机气体。还使用罐采样了总共61种化合物，然后进行了气相色谱和质谱分析。在AM机器操作过程中，大多数COPC未被检测到或以远低于相关职业接触限值（OEL）的浓度进行测量。亚微米颗粒，主要是纳米颗粒，是在使用ABS的材料挤压印刷过程中产生的，约每立方厘米12,000个颗粒（p cm⁻³）高于背景。减去平均背景浓度后，材料挤压印刷操作的平均浓度与计算的2.8×10 ¹⁰ p min ^-1的发射率相关在测试条件下。在使用材料喷射或粉末床熔接生产的零件加工过程中，尽管在粉末床熔接零件的加工过程中测得的浓度高于可吸入和总粉尘的背景，但排放通常可以忽略不计。这项中试研究的结果表明，与增材制造操作相关的空气散发是可变的，取决于印刷和零件处理过程，原材料和通风特性。尽管在该中试规模研究中未收集个人样品，但结果可用于将来的暴露评估。根据评估结果，