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Characterization of Particulate Matters and Total VOC Emissions from a Binder Jetting 3D Printer
... Additive manufacturing (AM) introduces tremendous advantages over the traditional manufacturing approaches and has gained unprecedented industrial and academic attentions [1][2][3]. Alongside to industrial improvements and academic achievements, the environmental sustainability in AM is also crucial and involves various environmental impacts [3][4][5][6]. AM sustainability assessment covers energy and material consumption, end-of-life and waste management, gas, liquid, 1 Contact author: chx@uw.edu ...
... Since emissions in AM are harmful for human health, the evaluation and characterization appear to be critical. Researchers have reported the emissions of volatile organic compounds (VOCs) [2,3,10], particulate matter [2,11], ultrafine particles [12,13], carbon dioxide [14,15], and aerosol [16][17][18] from 3D printers. Particularly, VOCs are a mixture of hydrocarbons, oxygenates, halogenates, released from material phase transition [19]. ...
... Since emissions in AM are harmful for human health, the evaluation and characterization appear to be critical. Researchers have reported the emissions of volatile organic compounds (VOCs) [2,3,10], particulate matter [2,11], ultrafine particles [12,13], carbon dioxide [14,15], and aerosol [16][17][18] from 3D printers. Particularly, VOCs are a mixture of hydrocarbons, oxygenates, halogenates, released from material phase transition [19]. ...
Released during 3-dimensional (3D) printing polymeric parts and many other industrial processes, the volatile organic compounds (VOCs) are mixtures that can pollute air quality and harm human health. Particularly, VOCs dominate in causing sick-building syndrome symptoms. Selective laser sintering (SLS) is a popular 3D technique, where the elevated temperature and high-energy laser beam tend to cause more detrimental VOC emission than other 3D printing processes. Though previous work reported to model emission in some 3D printing processes, the emission modelling and prediction in SLS has remained largely unexploited. This work proposes a mass-transfer and experiment-data based approach to model and predict VOC emission in SLS. We monitored the VOC emissions from polyamide 12 in 6 cases with varying printing parameters. With emission curve segmentation based on the physical printing process, we applied the mass-transfer single- and multiple-layer model to simulate the VOC emission. Model matching subsequently yields the suitable model type and node number in each printing stage. Results showed the proposed method has an average accuracy of 85.32% matching to the experiment results.
... Graff et al. (2017) used IN939 as feedstock for their experiment on SLM. Afshar-Mohajer et al. (2015) used zp150 with zbond90 as feedstock for their study on the BJ process. used a gray liquid feedstock for their study on the VATP process. ...
... In addition, it is important to capture most particulates or representative sample size, depending on the goal of the experiment (Mendes et al. 2017). Other aspects of environmental control are controlling the external parameters including temperature and humidity (Afshar-Mohajer et al. 2015;. Table 2 Figure 1. ...
... To the best of our knowledge, only three published papers (Stephens et al. 2013;Afshar-Mohajer et al. 2015;Mendes et al. 2017) provided the location of the instruments utilized in their studies. In Afshar-Mohajer et al. 's work (2015), the instruments were positioned on a two-story tower exactly one meter away from the epicenter of the printer. ...
As additive manufacturing (AM) has become an evolving discipline in many industries, including manufacturing, medical, and aerospace, it becomes important to identify the risk coming from human exposure to particulates and Volatile Organic Compounds (VOCs) in AM which can lead to serious and chronic health issues. To address this issue, this article first provides a summary of previously reported particulate and VOCs characterization studies during AM processes, including equipment, environmental setups, variables studied, and instrumentation reported in the literature. We then reported a synopsis of the nature of the exposure, characteristics of the emitted particulates and VOCs, and associated health risks for different AM settings in a systematic manner. The key factors contributing to the harmful emissions include the use of toxic material compounds, high operating temperature, manual handling of hazardous materials, and limitations of the underlying printing technology among others. For that matter, we have outlined potential pathways to control hazardous exposure. Our recommendations include adopting safer operational practices, developing regulatory frameworks for facilities and equipment manufacturers, and seeking better technologies that minimize harmful emissions. Our aim is to benefit early-stage researchers, regulators, and industry practitioners in understanding and advancing knowledge of health hazards, safer practices, and technologies in AM.
... 9,12 Additionally, the continuous movement of dry powders inside printing chambers and injection of binder fluids in the binder jetting technique may cause emission of particles and VOCs during the printing process. 6 These findings suggest that 3D printingemitted hazards may be significant indoor air pollutants that threaten human health. 15,16 Several cases of occupational diseases associated with 3D printing have been reported, including a case report of workrelated asthma associated with 3D printing 15 and cases of contact dermatitis. ...
... The energy dispersive spectroscopy (EDS) results implied that the composition of the deposited particles was close to calcium sulfate (gypsum). 6 Unlike those from the binder jetting process, particles emitted from vat photopolymerization 3D printers were qualitatively identified as potential occupational carcinogens (Cr and Ni) and reactive metals (Fe and Zn) using EDS analysis. 12 Most particles emitted during the material extrusion process (FDM/FFF) were agglomerated near-spherical particles and clusters of nanoscale particles. ...
... 68 Afsharmohajer et al. measured the total volatile organic compound (TVOC) concentration from a binder jetting 3D printer and showed a maximum value of 1725 μg m −3 that exceeded the upper limit indoor concentration recommended by the Environment Institute of European Commission. 6 Overall, evidence mentioned above has indicated the possible release of large quantities of toxic and carcinogenic VOCs during 3D printing processes; some of them exceeded the recommended indoor levels linked to adverse health effects. ...
... From Figure 1(a), the basic operating principle of a binder jetting machine is as follows: 1) a blade spreads a thin layer of powder over the build platform, 2) a carriage with nozzles selectively deposits droplets of a binder in a pattern onto the powder to bond the particles together via a chemical reaction, 3) the powder bed is lowered incrementally and the blade spreads a fresh layer of powder on top of the hardened powder, 4) binder is again selectively deposited onto the powder bed and hardens the next layer of particles, and 5) the process is repeated until the final build cycle is built (Afshar-Mohajer et al. 2015). The final part is submerged in a powder "cake" and is recovered manually. ...
... No personal exposure monitoring data were reported in the literature for BJ processes. Overall, particle number concentrations measured with a mobility sizer during printing were 1 × 10 4 to 3 × 10 4 #/cm 3 and total volatile organic compound (TVOC) concentrations reached 1725 µg/m 3 for the gypsum process and average particle number concentration was 7000 #/cm 3 for the stainless steel process (Afshar-Mohajer et al. 2015;Lewinski, Secondo, and Ferri 2019). Afshar-Mohajer et al. (2015) performed realtime monitoring of airborne particles and TVOC concentrations for three different periods (before, during, and after printing with gypsum) and investigated the effect of opening the machine lid on workplace contaminant concentrations. ...
... Overall, particle number concentrations measured with a mobility sizer during printing were 1 × 10 4 to 3 × 10 4 #/cm 3 and total volatile organic compound (TVOC) concentrations reached 1725 µg/m 3 for the gypsum process and average particle number concentration was 7000 #/cm 3 for the stainless steel process (Afshar-Mohajer et al. 2015;Lewinski, Secondo, and Ferri 2019). Afshar-Mohajer et al. (2015) performed realtime monitoring of airborne particles and TVOC concentrations for three different periods (before, during, and after printing with gypsum) and investigated the effect of opening the machine lid on workplace contaminant concentrations. From Table 2, during printing, particle number concentrations peaked at 0.9 to 1.2 × 10 4 #/cm 3 for the 205 to 255 nm size fraction; however, 54.3 nm sized particles were most evident at the beginning of printing. ...
This comprehensive review introduces occupational (industrial) hygienists and toxicologists to the seven basic additive manufacturing (AM) process categories. Forty-six articles were identified that reported real-world measurements for all AM processes, except sheet lamination. Particles released from powder bed fusion (PBF), material jetting (MJ), material extrusion (ME), and directed energy deposition (DED) processes exhibited nanoscale to submicron scale; real-time particle number (mobility sizers, condensation nuclei counters, miniDiSC, electrical diffusion batteries) and surface area monitors (diffusion chargers) were generally sufficient for these processes. Binder jetting (BJ) machines released particles up to 8.5 µm; optical particle sizers (number) and laser scattering photometers (mass) were sufficient for this process. PBF and DED processes (powdered metallic feedstocks) released particles that contained respiratory irritants (chromium, molybdenum), central nervous system toxicants (manganese), and carcinogens (nickel). All process categories, except those that use metallic feedstocks, released organic gases, including (but not limited to), respiratory irritants (toluene, xylenes), asthmagens (methyl methacrylate, styrene), and carcinogens (benzene, formaldehyde, acetaldehyde). Real-time photoionization detectors for total volatile organics provided useful information for processes that utilize polymer feedstock materials. More research is needed to understand 1) facility-, machine-, and feedstock-related factors that influence emissions and exposures, 2) dermal exposure and biological burden, and 3) task-based exposures. Harmonized emissions monitoring and exposure assessment approaches are needed to facilitate inter-comparison of study results. Improved understanding of AM process emissions and exposures is needed for hygienists to ensure appropriate health and safety conditions for workers and for toxicologists to design experimental protocols that accurately mimic real-world exposure conditions.
ABBREVIATIONS ABS : acrylonitrile butadiene styrene; ACGIH® TLV® : American Conference of Governmental Industrial Hygienists Threshold Limit Value; ACH : air change per hour; AM : additive manufacturing; ASA : acrylonitrile styrene acrylate; AVP : acetone vapor polishing; BJ : binder jetting; CAM-LEM : computer-aided manufacturing of laminated engineering materials; CNF : carbon nanofiber; CNT : carbon nanotube; CP : co-polyester; CNC : condensation nuclei counter; CVP : chloroform vapor polishing; DED : directed energy deposition; DLP : digital light processing; EBM : electron beam melting; EELS : electron energy loss spectrometry; EDB : electrical diffusion batteries; EDX : energy dispersive x-ray analyzer; ER : emission rate; FDM™ : fused deposition modeling; FFF : fused filament fabrication; IAQ : indoor air quality; LSP : laser scattering photometer; LCD : liquid crystal display; LDSA : lung deposited particle surface area; LOD : limit of detection; LOM : laminated object manufacturing; LOQ : limit of quantitation; MCE : mixed cellulose ester filter; ME : material extrusion; MJ : material jetting; OEL : occupational exposure limit; OPS : optical particle sizer; PBF : powder bed fusion; PBZ : personal breathing zone; PC : polycarbonate; PEEK : poly ether ether ketone; PET : polyethylene terephthalate; PETG : Polyethylene terephthalate glycol; PID : photoionization detector; PLA : polylactic acid; PM1 : particulate matter with aerodynamic diameter less than 1 µm; PM2.5 : particulate matter with aerodynamic diameter less than 2.5 µm; PM10 : particulate matter with aerodynamic diameter less than 10 µm; PSL : plastic sheet lamination; PVA : polyvinyl alcohol; REL : recommended exposure limit; SDL : selective deposition lamination; SDS : safety data sheet; SEM : scanning electron microscopy; SL : sheet lamination; SLA : stereolithography; SLM : selective laser melting; SMPS : scanning mobility particle sizer; SVOC : semi-volatile organic compound; TEM : transmission electron microscopy; TGA : thermal gravimetric analysis; TPU : thermo polyurethane; UAM : ultrasonic additive manufacturing; UC : ultrasonic consolidation; TVOC : total volatile organic compounds; TWA : time-weighted average; VOC : volatile organic compound; VP : vat photopolymerization
... ABS is non-biodegradable and typically printed at 240-260 • C. PLA is a biodegradable plastic derived mostly from natural sources and printed at lower temperatures, typically 200 to 220 • C. ABS is known to have better mechanical strength and higher impact resistance compared to PLA and therefore tends to be better suited to printing goods that require resistance to pressure [15]. Evidence from published research has demonstrated that the thermal degradation of filaments in FDM printing releases submicron as well as ultrafine particles [16,17]. The filament type used is known to primarily influence PM emissions from 3D printing [18,19]. ...
... These differences in PM emissions stem from different additives and pigments in the different colored materials. The observations here are consistent with previous studies performed in closed chamber settings [17,21,30]. For example, Stefaniak et al. [31] reported that the number-based emission rates varied by a factor of up to nine when comparing printing of black and white PLA filament materials. ...
... For example, Stefaniak et al. [31] reported that the number-based emission rates varied by a factor of up to nine when comparing printing of black and white PLA filament materials. Although it is acknowledged that filament color significantly affects PM emissions, the mean particle size for both PLA and ABS has been reported to be equivalent [17,22]. ...
Consumer-level 3D printers are becoming increasingly prevalent in home settings. However, research shows that printing with these desktop 3D printers can impact indoor air quality (IAQ). This study examined particulate matter (PM) emissions generated by 3D printers in an indoor domestic setting. Print filament type, brand, and color were investigated and shown to all have significant impacts on the PM emission profiles over time. For example, emission rates were observed to vary by up to 150-fold, depending on the brand of a specific filament being used. Various printer settings (e.g., fan speed, infill density, extruder temperature) were also investigated. This study identifies that high levels of PM are triggered by the filament heating process and that accessible, user-controlled print settings can be used to modulate the PM emission from the 3D printing process. Considering these findings, a low-cost home IAQ sensor was evaluated as a potential means to enable a home user to monitor PM emissions from their 3D printing activities. This sensing approach was demonstrated to detect the timepoint where the onset of PM emission from a 3D print occurs. Therefore, these low-cost sensors could serve to inform the user when PM levels in the home become elevated significantly on account of this activity and furthermore, can indicate the time at which PM levels return to baseline after the printing process and/or after adding ventilation. By deploying such sensors at home, domestic users of 3D printers can assess the impact of filament type, color, and brand that they utilize on PM emissions, as well as be informed of how their selected print settings can impact their PM exposure levels.
... Another study confirmed higher particle concentrations emitted when using PLA compared to ABS (Kim et al., 2015). A type of 3D printing called binder jetting printing builds a 3D design at a rate of 25 mm/hour; therefore, total exposure time to emitted particles may be over the course of hours (Afshar-Mohajer et al., 2015). Binder jetting printing exceeded U.S. EPA ambient air quality standards with the use of a central ventilation hood in the space (Afshar-Mohajer et al., 2015). ...
... A type of 3D printing called binder jetting printing builds a 3D design at a rate of 25 mm/hour; therefore, total exposure time to emitted particles may be over the course of hours (Afshar-Mohajer et al., 2015). Binder jetting printing exceeded U.S. EPA ambient air quality standards with the use of a central ventilation hood in the space (Afshar-Mohajer et al., 2015). This was based on using exposure measured as a time weighted average (TWA) over a 24-h period for particlulate matter with a 2.5-µm size (PM 2.5 ) and particulate matter with a 10-µm size (PM 10 ) (Afshar-Mohajer et al., 2015). ...
... Binder jetting printing exceeded U.S. EPA ambient air quality standards with the use of a central ventilation hood in the space (Afshar-Mohajer et al., 2015). This was based on using exposure measured as a time weighted average (TWA) over a 24-h period for particlulate matter with a 2.5-µm size (PM 2.5 ) and particulate matter with a 10-µm size (PM 10 ) (Afshar-Mohajer et al., 2015). Continuous operation exceeded standards by 10 times for PM 2.5 and 3 times for PM 10 (Afshar- Mohajer et al., 2015). ...
Nanotechnology has increasing applications in numerous markets, particularly in additive processing (3D printing) and manufacturing, which is important for consumer products, medical devices, construction, and general research and development across many other industries. Nanomaterials are desirable in many products due to their unique properties, but those same properties have made evaluating the risk and regulation of these materials challenging. For risk-based regulations, new applications and nanomaterials should be assessed for both human and environmental hazards and exposure to ensure protection. In general, many risk assessments to date have focused on the non-nano versions of chemicals. The lack of guidance on assessing the hazard and exposure of nanomaterials in 3D printing is apparent, and these areas of assessment are actively being evaluated. Industry in most cases will now need to provide specific additional information for assessing the risk of nanomaterials in 3D printing. This review paper focuses on the use of nanomaterials in 3D printing for industrial and manufacturing applications, summarizes the current literature on human health and safety related to 3D printing and inhalation exposure, and the regulations relating to 3D printing in the U.S., Canada, and Europe for this industry.
... Precise information about emissions would be useful to prevent potential damage to users' health. Several studies conducted both in isolated test chambers and conventional office buildings have identified that 3D printers emit UltraFine Particles (UFPs: Particulate Matter (PM) of nanometer scale size, <100 nm), as well as a mixture of potentially dangerous Volatile Organic Compounds (VOCs) such as styrene, butanol, ethylbenzene and xylene [9][10][11][12][13]. ...
... Made up of a combination of solid volumes, thin protrusions and holes [29], the part can influence dynamic printer emissions. Indeed, this model has been used in several previous studies with printing times varying from 2.5 to 4 h [9,17]. In the research reported here, short-term sampling was conducted with the printing time reduced to approximately 60 min. ...
The emergence of additive manufacturing (AM) technologies, such as 3D printing and laser cutting, has created opportunities for new design practices covering a wide range of fields and a diversity of learning and teaching settings. The potential health impact of particulate matter and volatile organic compounds (VOCs) emitted from AM technologies is, therefore, a growing concern for makers. The research behind this paper addresses this issue by applying an indoor air quality assessment protocol in an educational fabrication laboratory. The paper presents the evaluation of the particle emission rate of different AM technologies. Real-time monitoring of multiple three-dimensional Polylactic Acid (PLA), Acrylonitrile Butadiene Styrene (ABS) and Thermoplastic Elastomers (TPE) printers and Polymethyl methacrylate (PMMA) laser cutters was performed in different usage scenarios. Non-contact electrical detectors and off-line gas chromatography–mass spectrometry (GC-MS) were used to detect VOCs. The results show that the emitted particle surface area concentrations vary between 294 and 406.2 μm2/cm3 for three-dimensional printers, and between 55.06 and 92.3 μm2/cm3 for laser cutters. The experiments demonstrate that the emission concentrations were highly dependent on the filtration systems in place. The highest quantities of VOCs emitted included Cyclohexene and Benzyl Alcohol for PLA, ABS and TPE 3D printers, and formic acid and Xylene for PMMA laser cutters. The experiment concludes that signature emissions are detectable for a given material type and an AM technology pair. A suitable mitigation strategy can be specified for each signature detected. Finally, this paper outlines some guidelines for improving indoor air quality in such specific environments. The data provided, as well as the proposed indoor air quality protocol, can be used as a baseline for future studies, and thus help to determine whether the proposed strategies can enhance operator and bystander safety.
... While there are no occupational exposure limits (OELs) for emissions from 3D printing and information on toxicological effects from 3D printer emissions are not completely understood, it asks for further studies to develop a system for identifying the health risks and categorizing emission rates from 3D printing processes. In addition, the increasing number of hours of 3D printing in household living areas raises the issue of possible emissions of UFPs and VOCs from printers that use polymeric materials into indoor air [10], [13], [14]. ...
... No studies were found reporting the release of UFPs and VOCs during printing with printers using nGEN filament. Moreover, UFPs may be of particular importance for the toxicity of fumes emitted from the melting of some thermoplastics [9], [13]. ...
While many people work remotely during the pandemic, three-dimensional (3D) printers are working to ensure the medical personnel and general public with the necessary specific materials. Ease of use, low cost, fast prototyping, and a wide range of materials are the advantages of 3D technology that can quickly adapt to specific needs in different application areas and result in increased popularity. The aim was to analyse the concentrations of particulate matter (PM) and volatile organic compounds (VOCs) emitted in 3D printing zone where printers are located throughout the room around the perimeter and where orthopaedics and designers develop models during their full shift. The average ultrafine particles (UFP) concentration level fluctuates from 4×10 ³ to 26×10 ³ particles/cm ³ that exceed the background level (<3×10 ³ particles/cm ³ ) during 8 h-shift. Microclimate was evaluated as unsatisfied regarding permissible values for air quality at workplaces: air temperature exceeds permissible upper level +25 °C, relative humidity was 21.5 % and air velocity ≤0.05 m/s. The highest particles’ number concentrations in the nano-scale range (<0.1 μm) and significantly higher mass concentrations in the coarse particle range (>2.5 μm) were detected. The median diameters of particle number (0.019, 0.014, 0.015 μm) and mass concentrations (4.394, 4.433, and 4.677 μm) were similar in all observed premises. Total VOC concentration was increased and specific substances such as toluene and formaldehyde (0.56±0.1 and 0.23±0.034 mg/m ³ ) were found at high concentration in comparison with indoor air quality recommendations.
... ASTM (American Society of Testing and Materials) generically defines seven classifications for additive manufacturing, namely [26,27] (1) Binder Jetting (BJ) [28][29][30][31], (2) Directed Energy Deposition (DED) [32][33][34][35], (3) Material Extrusion (ME) [36][37][38][39], (4) Material Jetting (MJ) [40][41][42][43], (5) Powder Bed Fusion (PBF) [44][45][46][47], (6) Sheet Lamination (SL) [48][49][50][51], and (7) Vat Photopolymerization (VP) [52][53][54][55]. Among these, the authors of this paper select ME types, called 3D printing, and we introduce nine different and popularly adapted methods in thermoplastics and photopolymer desktop 3D printing processes. ...
... However, metal parts produced by Binder Jetting have inferior mechanical properties than DMLS/SLM parts. Additionally, the choice of materials used in Binder Jetting is limited [28][29][30][31]70,71] • Material Jetting Polyjet (MJ): The MJ method uses molten wax as the material to make molds and casts. A UV light helps the layers to cure, and a gel-like material is used for supports. ...
With the advancement of additive manufacturing technologies in their material processing methodologies and variety of material selection, 3D printers are widely used in both academics and industries for various applications. It is no longer rare to have a portable and small desktop 3D printer and manufacture your own designs in a few hours. Desktop 3D printers vary in their functions, prices, materials used, and applications. Among many desktop 3D printers with various features, it is often challenging to select the best one for target applications and usages. In this paper, commercially available and carefully selected thermoplastic and photopolymer desktop 3D printers are introduced, and some representative models’ specifications and performances are compared with
each other for user selection with respect to instructional applications. This paper aims to provide beginner-level or advanced-level end-users of desktop 3D printers with basic knowledge, selection criteria, a comprehensive overview of 3D printing technologies, and their technical features, helping them to evaluate and select the right 3D printers for a wide range of applications. URL: https://www.mdpi.com/2227-7080/9/4/91
... The principle of 3D printers' operation depends on the technology of application and curing the material from which three-dimensional elements are being made. 18 The process seven categories defined by ISO/ASTM 52900 17 11,19,20 Their classification is presented in Figure 1, and the technologies are briefly described below to introduce to the issue of printing. ...
... 132,134,156 Afshar-Mohajer and col. 19 stated that the quantity of ultrafine particles released from a binder jetting 3D printer was 104-105 times lower than from common FDM ® 3D printers using PLA and 105-106 times lower than from a printer using ABS. At the same time, the emission of particles larger than 200 nm was noticeably higher. ...
Additive manufacturing, enabling rapid prototyping and so-called on-demand production, has become a common method of creating parts or whole devices. On a 3D printer, real objects are produced layer by layer, thus creating extraordinary possibilities as to the number of applications for this type of devices. The opportunities offered by this technique seem to be pushing new boundaries when it comes to both the use of 3D printing in practice and new materials from which the 3D objects can be printed. However, the question arises whether, at the same time, this solution is safe enough to be used without limitations, wherever and by everyone. According to the scientific reports, three-dimensional printing can pose a threat to the user, not only in terms of physical or mechanical hazards, but also through the potential emissions of chemical substances and fine particles. Thus, the presented publication collects information on the additive manufacturing, different techniques, and ways of printing with application of diverse raw materials. It presents an overview of the last 5 years’ publications focusing on 3D printing, especially regarding the potential chemical and particle emission resulting from the use of such printers in both the working environment and private spaces.
... However, exposure to gaseous and particulate contaminants in other AM methods has gained less attention (Runström Eden et al., 2022;Stefaniak et al., 2021). Exposure to particles and volatile organic compounds (VOCs) has been studied during PBF and BJT (Afshar-Mohajer et al., 2015;Graff et al., 2016;Mellin et al., 2016;Ljunggren et al., 2019;Väisänen et al., 2019;Zisook et al., 2020;Runström Eden et al., 2022). These studies showed that there exists notable exposure to contaminants not only during the 3D printing but especially during pre-and post-processing phases. ...
Particle and gaseous contaminants from industrial scale additive manufacturing (AM) machines were studied in three different work environments. Workplaces utilized powder bed fusion, material extrusion, and binder jetting techniques with metal and polymer powders, polymer filaments, and gypsum powder, respectively. The AM processes were studied from operator’s point of view to identify exposure events and possible safety risks. Total number of particle concentrations were measured in the range of 10 nm to 300 nm from operator’s breathing zone using portable devices and in the range of 2.5 nm to 10 µm from close vicinity of the AM machines using stationary measurement devices. Gas-phase compounds were measured with photoionization, electrochemical sensors, and an active air sampling method which were eventually followed by laboratory analyses. The duration of the measurements varied from 3 to 5 days during which the manufacturing processes were practically continuous. We identified several work phases in which an operator can potentially be exposed by inhalation (pulmonary exposure) to airborne emissions. A skin exposure was also identified as a potential risk factor based on the observations made on work tasks related to the AM process. The results confirmed that nanosized particles were present in the breathing air of the workspace when the ventilation of the AM machine was inadequate. Metal powders were not measured from the workstation air thanks to the closed system and suitable risk control procedures. Still, handling of metal powders and AM materials that can act as skin irritants such as epoxy resins were found to pose a potential risk for workers. This emphasizes the importance of appropriate control measures for ventilation and material handling that should be addressed in AM operations and environment.
... UFPs may be of particular importance for the toxicity of fumes emitted from the melting of some thermoplastics [31,33], although the latest literature reports show the release of UFPs and VOCs during printing with printers using nGEN (made by ColorFabb from Eastman Amphora™ AM3300 polymer) filament as well [31]. ...
3D (three-dimensional) printing technologies are widespread and rapidly evolving, creating new specific working conditions, and their importance has been highlighted by increasing publications in recent years. The report provides a compilation of current information on 3D technologies, materials, and measurements, considering the determination of the potential actual exposure dose of chemicals through airborne inhalation and dermal exposure, including workers’ exhaled breath condensate and urine data. Noninvasive assessment methods are becoming increasingly popular, as they are painless, easy to perform, and inexpensive. Investigation of biomarkers reflecting pulmonary inflammation and local and systemic oxidative stress in exhaled breath, exhaled breath condensate, and urine are among them. It is also important to consider the occupational health and safety risks associated with the use of various new materials in 3D printing, which are associated with skin irritation and sensitivity risks. Therefore, EDI (estimated daily intake) calculations for assessment of the potential occupational health risk purposes via inhalation and dermal exposure are critical in future. The assessment of occupational exposure and health risks of 3D printing processes is essential for the proper identification, control, and prevention of working conditions, also for the diagnosis and monitoring of occupational diseases among workers to improve public health and well-being in general.
... Metal Ceramic compatible liquid binder 50-400 μm [22] 25 mm/h [23] Jets tiny droplets of binder onto a polymer, metal, or ceramic powder using an inkjet printhead Fused deposition modeling (FDM) ...
3D printing is a manufacturing technique in constant evolution. Day by day, new materials and methods are discovered, making 3D printing continually develop. 3D printers are also evolving , giving us objects with better resolution, faster, and in mass production. One of the areas in 3D printing that has excellent potential is 4D printing. It is a technique involving materials that can react to an environmental stimulus (pH, heat, magnetism, humidity, electricity, and light), causing an alteration in their physical or chemical state and performing another function. Lately, 3D/4D printing has been increasingly used for fabricating materials aiming at drug delivery, scaffolds, bi-oinks, tissue engineering (soft and hard), synthetic organs, and even printed cells. The majority of the materials used in 3D printing are polymeric. These materials can be of natural origin or synthetic ones of different architectures and combinations. The use of block copolymers can combine the exemplary properties of both blocks to have better mechanics, processability, biocompatibility, and possible stimulus behavior via tunable structures. This review has gathered fundamental aspects of 3D/4D printing for biomaterials, and it shows the advances and applications of block copolymers in the field of biomaterials over the last years.
... Several primary, natural, and man-made sources of PM 2.5 are volcanic gases, sand, rock erosion, forest res, pollens, lichen propagules, incinerators, cement plants, industrial gases, household heating, manufacturing facilities, steel plants, and coal or heavy crude power plants, as examples of facilities that rely on fossil fuels for energy. [69][70][71] Many virologists have recently raised concerns about particulate-assisted viral transmission, which is unsurprising. 38,72 Likewise, virus durability with the PM 2.5 in the atmosphere (airborne transmission) is high, as compared to the direct (sneezing, coughing) and indirect (infected surfaces) transmission modes. ...
The rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the resulting
worldwide death toll have prompted worries regarding its transmission mechanisms. Direct, indirect, and
droplet modes are the basic mechanisms of transmission. SARS-CoV-2 spreads by respiratory droplets
(size range >10 mm size ranges), aerosols (5 mm), airborne, and particulate matter. The rapid transmission
of SARS-CoV-2 is due to the involvement of tiny indoor air particulate matter (PM2.5), which functions as
a vector. SARS-CoV-2 is more contagious in the indoor environment where particulate matter floats for
a longer period and greater distances. Extended residence time in the environment raises the risk of
SARS-CoV-2 entering the lower respiratory tract, which may cause serious infection and possibly death.
To decrease viral transmission in the indoor environment, it is essential to catch and kill the SARS-CoV-2
virus and maintain virus-free air, which will significantly reduce viral exposure concerns. Therefore,
effective air filters with anti-viral, anti-bacterial, and anti-air-pollutant characteristics are gaining
popularity recently. It is essential to develop cost-effective materials based on nanoparticles and metal–
organic frameworks in order to lower the risk of airborne transmission in developing countries. A diverse
range of materials play an important role in the manufacturing of effective air filters. We have
summarized in this review article the basic concepts of the transmission routes of SARS-CoV-2 virus and
precautionary measures using air purifiers with efficient materials-based air filters for the indoor
environment. The performance of air-filter materials, challenges and alternative approaches, and future
perspectives are also presented. We believe that air purifiers fabricated with highly efficient materials can
control various air pollutants and prevent upcoming pandemics
... The development of mechanical metamaterials favored by advances in the incremental method, in other words 3D printing with high resolution [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. ...
The emerging concept of mechanical meta-materials has gained increasing attention in recent years, partly due to advances in additive manufacturing techniques (additive manufacturing, 3D printing) that have allowed the fabrication of materials with arbitrarily complex micro / nanostructures. The designed geometry of these structures gives rise to unprecedented or rare mechanical properties that can used to create advanced elements with new, unprecedented functions. This paper presents the method of prototyping a vibro-isolator made of a material that has the properties of storing and disposing of mechanical vibration energy and that can freely be shaped by modern manufacturing techniques. An example of a vibration isolator of the proprietary concept analyzed, using the concept of stepped and adding elements. The method is based on the use of two main tools. Mechanical properties verified by analyzing the frequency and mode of free vibrations of the prototype using the finite element method. The same CAD model of the vibro-isolator prototype produced by 3D printing. The paper presents one of the production techniques, which is 3D printing in SLS (Selective Laser Sintering) technology, and the SolidWorks and Comsol Multhiphysics software used in the CAD / CAE prototyping method.
... e 3D slice model is traversed and searched according to the matrix relationship, and the cylindrical coordinates obtained by intersecting the same section are stored in the same group. Each layer generates a set of intersecting surfaces with layer number as the search criterion [11,12]. ...
In view of the problems of low printing efficiency and low accuracy of 3D printers currently developed in the domestic market, based on fused deposition modeling technology, this paper constructs a processing data model with a cylindrical coordinate data structure by 3D printing and processing models according to the cylindrical coordinate slicing rules. The data model can be used to search in adjacent cylinders to obtain the cylindrical coordinate information of the printing model and use the depth-first traversal method of the slicing model to establish a cylindrical coordinate slicing function. Aiming at the problem of “pointcut” of the model cylinder in cylindrical coordinate slice, a high-performance calculation method of machining accuracy based on the cylindrical coordinate slice algorithm is proposed. This algorithm is used to perform 3D printing processing through high-performance computing of cylindrical coordinate slices. After obtaining the intersection points obtained according to the order of the cylindrical coordinate slices of the model, through the automatic generation of the section profile corresponding to the printed model in OpenGL software, the profile direction of the model section can be determined according to the first cylindrical coordinate slice data generated by cutting each contour. The software and hardware of the 3D printer control system are designed, and the actual model printing test is conducted at the same time. By debugging and testing each module of software and hardware, the system is guaranteed to run stably under scientific and reasonable design. Finally, the experimental analysis results show that the algorithm proposed in this paper can effectively reduce the topology time required for cylindrical coordinate slicing, and the operation is simple, stable, and reliable.
... × 106 particles/cc depending on the 3-D printing process. Our UFP concentration of 16,000 particles/cc during printer operations was similar to the range reported by other studies (Stephens et al., 2013;Afshar-Mohajer et al., 2015;Deng et al., 2016;Steinle, 2016;Mendes et al., 2017;Vance et al., 2017). Total VOC (TVOC) concentrations from 3-D printing emission reported in another paper (Kim et al., 2021 submitted) were also similar to concentrations of 102-103 μg/m 3 reported previously (Azimi et al., 2016;Steinle, 2016;Floyd et al., 2017;Mendes et al., 2017). ...
Biomonitoring of workers is an approach of evaluating workers' exposure to chemicals and particulate matter by measuring biomarkers of parent chemicals, their metabolites, and reaction products in workers' biospecimens. Prerequisites for biological monitoring in the workplace include permission to enter the workplace, approval of the study plan from the IRB (Institutional Review Board), and obtaining consent from workers. Because of the complex legal process involved in biomonitoring, few studies have been conducted so far on biomonitoring of workers' exposures to nanoparticles and other hazards from emerging materials and advanced nanotechnologies. We have developed a cell-based biomonitoring device that can evaluate acute cytotoxicity and various other effect biomakers, such as inflammation, at realistic workplace exposure. This device is based on air-liquid interphase (ALI) and can be used to evaluate cell toxicity and early effect biomarkers along adverse outcome pathways. Following exposure of A549 lung epithelial cells in ALI to workplace air for 1-2 h, the cells were processed to assess the induction of inflammatory and cell damage biomarkers. Initially, we estimated the deposition rate of nanoparticles in the transwell by exposing the cell-free ALI device to silver nanoparticle aerosols (AgNP 20-30 nm) for 2 h in the laboratory. Then A549 lung epithelial cells cultured on the transwell in the ALI device were exposed to AgNP nanoaerosols for 2 h and evaluated for cytotoxicity and induction of mRNAs of pro-inflammatory cytokines IL-1b, IL-6, and TNF-α. Then the cells in the ALI device were exposed to 3-D printer emissions at the workplace and evaluated for the same matched endpoints. The mRNA levels for IL-1b, IL-6, and TNF-α increased significantly at the end of 2-h exposure of A549 cells to the positive control AgNP aerosols. These mRNAs, as well as LDH and microprotein concentrations, increased even more after 24-h post-exposure incubation (p < 0.05). Cytotoxicity evaluation of 3-D printer emissions at 810 and 957 μg/m 3 , which was more than 80 times higher than the airborne total suspended particulate concentrations in the workplace air (9-12.5 μg/m3), suggested no significant acute cytotoxicity at the end of 2-h exposure to 3-D-printing emission, as well as at 24-h post-exposure incubation. Hyperspectral microscopic observation showed that 3-D printers emitted particles to be attached to A549 cells after 2-h exposure, and many particles were internalized by A549 cells after 24 h of post-exposure incubation. The mRNA expression of pro-inflammatory cytokine IL-1b and IL-6 increased significantly after 2-h exposure to 3-D printer emissions and after 24-h incubation (only IL-6). In contrast, the expression of TNF-α mRNA decreased significantly after 2 h of exposure to 3-D printers and decreased even more after 24-h post-exposure incubation. These results support the use of cell-based ALI devices for direct assessment of airborne hazards in the workplace, for probing toxicological properties of airborne contaminants using adverse molecular pathways, and for guiding study design for workplace biomonitoring. ALI devices can bridge conventional exposure assessment with cellular toxicity testing platforms for hazard and risk assessment.
... However, only a few candidates for metal BJ3DP have been explored so far, and the reported characteristics of printed objects such as the porosity and mechanical strengths are far below the ones based on the aforementioned common binder materials 38 . Therefore, it is now imperative to broaden the technological horizon thorough developing new green binding agents for metals that can be ecofriendly as well as non-hazardous 24,[39][40][41] , with prospects of simultaneously achieving the desired properties of printed objects. ...
Recent advances in metal additive manufacturing (AM) have provided new opportunities for prompt designs of prototypes and facile personalization of products befitting the fourth industrial revolution. In this regard, its feasibility of becoming a green technology, which is not an inherent aspect of AM, is gaining more interests. A particular interest in adapting and understanding of eco-friendly ingredients can set its important groundworks. Here, we demonstrate a water-based solid-phase binding agent suitable for binder jetting 3D printing of metals. Sodium salts of common fruit acid chelators form stable metal-chelate bridges between metal particles, enabling elaborate 3D printing of metals with improved strengths. Even further reductions in the porosity between the metal particles are possible through post-treatments. A compatibility of this chelation chemistry with variety of metals is also demonstrated. The proposed mechanism for metal 3D printing can open up new avenues for consumer-level personalized 3D printing of metals. Additive manufacturing of metals has revolutionized production and personalization of commodities. Here, authors demonstrate its feasibility of becoming a green technology, by developing an eco-friendly fruit-acid-based chelation approach.
... × 106 particle/cc depending on the 3-D printing process. Our UFP concentration of 16,000 particle/ cc during printer operations was similar to the range reported by other studies (Stephens et al., 2013;Afshar-Mohajer et al., 2015;Deng et al., 2016;Steinle, 2016;Mendes et al., 2017;Vance et al., 2017). Total VOC (TVOCs) concentrations from 3-D printing emission were also similar to concentrations of 102-103 μg/m 3 reported previously (Azimi et al., 2016;Steinle, 2016;Floyd et al., 2017;Mendes et al., 2017). ...
This study monitored particulates, and volatile organic compounds (VOCs) emitted from 3-D printers using acrylonitrile-butadiene-styrene copolymer (ABS) filaments at a workplace to assess exposure before and after introducing exposure mitigation measures. Air samples were collected in the printing room and adjacent corridor, and real-time measurements of ultrafine and fine particle were also conducted. Extensive physicochemical characterizations of 3-D printer emissions were performed, including real-time (size distribution, number concentration) nanoparticle characterization, size-fractionated mass distribution and concentration, as well as chemical composition for metals by ICP-MS and VOCs by GC-FID, real-time VOC monitors, and proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS). Air sampling showed low levels of total suspended particulates (TSP, 9–12.5/m ³ ), minimal levels (1.93–4 ppm) of total volatile organic chemicals (TVOC), and formaldehyde (2.5–21.7 ppb). Various harmful gases, such as formaldehyde, acrolein, acetone, hexane, styrene, toluene, and trimethylamine, were detected at concentrations in the 1–100 ppb by PTR-TOF-MS when air sample was collected into the Tedlar bag from the front of the 3-D printer. Ultrafine particles having an average particle size (30 nm count median diameter and 71 nm mass median diameter) increased during the 3-D printing operation. They decreased to the background level after the 3-D printing operation, while fine particles continually increased after the termination of 3-D printing to the next day morning. The exposure to 3-D printer emissions was greatly reduced after isolating 3-D printers in the enclosed space. Particle number concentration measured by real-time particle counters (DMAS and OPC) were greatly reduced after isolating 3-D printers to the isolated place.
... As stated by ISO standard ASTM 52900:2019 2) , AM technologies allow the production of complex objects through the addition of subsequent layers of material according to digital control based on 3D models. There are several studies that evaluate the occupational health risks of AM processes with thermoplastics, particularly due to the associated emissions of Volatile Organic Compounds (VOCs) [3][4][5][6][7][8] . Another important branch of AM deals with the use of metals and metal alloys in production processes, mainly adopted by biomedical, aerospace, energy, tool, and mould sectors. ...
Introduction. The high energy and temperature used for melting metals during additive manufacturing generate high numbers of fine (FP) and nanoparticles (NP), with significant time-dependent variations. To evaluate possible health risk, we investigated the time course of airborne FP and NP released during different phases of two selective laser melting processes as well as their environment boundaries (temperature t, humidity UR, mechanical ventilation MV).
Materials and methods. FP were monitored by the aerosol particle counter LasairIII (Particle Measuring System, 0.3-25 μm). DiSCmini (Testo), was used for measuring number (n) and average diameter (δ) of NP (10-300 nm). t and UR were monitored through data logger 174-H (Testo).
Results. The core of the printing phase entailed a slight but continuous increase of n and δ, and almost constant FP number, whereas the warm-up and cleaning without MV increased the n of released NP by +26% and +37%, respectively. Turning-on MV during cleaning and warm-up limited the increase of n (respectively -50% and +1% as compared to printing). At the end of printing, with no MV and no operating activities, there was a constant increase of n and decrease of δ (respectively +48% and –22% in 14 hours), suggesting the low deposition rate of generated NP, with a positive relationship between the n and UR.
Conclusions. The phases and operators’ tasks as well as the environment boundaries have impact on the NP release and size. Analysing a wider spectrum of conditions and processes is necessary to characterize potential exposures and to suggest effective mitigation measures.
... Afshar-Mohajer et al. [99] stated that the operation of printing will depend on the size of the printed specimens, therefore, the curing process might need further investigation whether the post-processing would need more time for the larger size. ...
Binder jetting (inkjet), featured by the dripping of liquid on the powder-based layer for solidification and bonding, is the second most popular 3D printing (3DP) technology for the construction industry. Therefore, an overview of this technology is necessary for both industry and academia. The paper discussed the most suitable materials for the construction industry which can be used in binder jetting 3DP. Attention was given not only to the selection of the materials but also the printing process and challenges that might face the printing process and post-processing stages, with an emphasis on sustainability and suitability. The whole process of printing gypsum, cement and geopolymer mortar, clay, chipped wood and sand materials through the binder jetting technique has been summarized, followed by curing and post-processing to achieve desirable mechanical properties. Finally, an informative approach was introduced for the scale-up of binder jetting 3DP in the construction industry.
... Third, calibrations based on short-term field colocations with reference instruments are often limited by the range of particle properties, concentrations, and environmental conditions and thus cannot be generalized to other studies. This is a concern because with improving air quality in the developed nations, the typical PM 2.5 levels are relatively low (<20 μg/m 3 ); however, PM concentration during wildfires [31] and in occupational settings [32,33] often exceeds regulatory limits for short periods. In developing countries with less strict regulations, the PM level associated with, e.g., traffic emissions [34], agricultural waste burning [35], indoor cooking [36] is significantly higher. ...
Low-cost optical scattering particulate matter (PM) sensors report total or size-specific particle counts and mass concentrations. The PM concentration and size are estimated by the original equipment manufacturer (OEM) proprietary algorithms, which have inherent limitations since particle scattering depends on particles' properties such as size, shape, and complex index of refraction (CRI) as well as environmental parameters such as temperature and relative humidity (RH). As low-cost PM sensors are not able to resolve individual particles , there is a need to characterize and calibrate sensors' performance under a controlled environment. Here, we present improved calibration algorithms for Plantower PMS A003 sensor for mass indices and size-resolved number concentration. An aerosol chamber experimental protocol was used to evaluate sensor-to-sensor data reproducibility. The calibration was performed using four polydisperse test aerosols. The particle size distribution OEM calibration for PMS A003 sensor did not agree with the reference single particle sizer measurements. For the number concentration calibration, the linear model without adjusting for the aerosol properties and environmental conditions yields an absolute error (NMAE) of 4.0% compared to the reference instrument. The calibration models adjusted for particle CRI and density account for non-linearity in the OEM's mass concentrations estimates with NMAE within 5.0%. The calibration algorithms developed in this study can be used in indoor air quality monitoring, occupational/industrial exposure assessments, or near-source monitoring scenarios where field calibration might be challenging.
... As stated by ISO standard ASTM 52900:2019 2) , AM technologies allow the production of complex objects through the addition of subsequent layers of material according to digital control based on 3D models. There are several studies that evaluate the occupational health risks of AM processes with thermoplastics, particularly due to the associated emissions of Volatile Organic Compounds (VOCs) [3][4][5][6][7][8] . Another important branch of AM deals with the use of metals and metal alloys in production processes, mainly adopted by biomedical, aerospace, energy, tool, and mould sectors. ...
This paper presents the results of a measurement campaign for assessing the release of particles and the potential exposure of workers in metal additive manufacturing. The monitoring deals with three environments, i.e., two academic laboratories and one production site, while printing different metallic alloys for chemical composition and size. The monitored devices implement different metal 3D printing processes, named Selective Laser Melting, Laser Metal Deposition and Hybrid Laser Metal Deposition, providing a wide overview of the current laser-based Additive Manufacturing technologies. Despite showing the generation of metal powders during the printing processes, the usual measurements based on gravimetric analysis did not highlight concentrations higher than the international exposure limits for the selected metals (i.e., chromium, cobalt, iron, nickel, and copper). Additional data, collected through a cascade impactor and particle counter coupled with the achievements from previous measurements reported in literature, indicate that during the printing operations, fine and ultrafine metal particles might be generated. Finally, the authors introduced a preliminary characterisation of the particles released during the different phases of the investigated AM processes (powder charging, printing, part cleaning and support removal), highlighting how the different operations may affect the particle size and concentration.
... This resulted in 36 out of 56 sites (~64%) TVOC concentration higher than WHO safe limit. Literature studies have reported the TVOC values in the non-industrial indoor workplaces in the range of <1-10 mg/m 3 [18,26,35,36]. ...
Volatile organic compounds (VOCs) are one of the major contributors to poor indoor air quality. Due to advancements in sensor technologies, continuous if not regular monitoring total VOC (TVOC) and or some specific VOC in potential high risk workplaces is possible even in resource limited settings. In this study, we implemented a portable VOC sensor to measure concentration of TVOC and formaldehyde (HCHO) in six types of potential high risk workplaces (n= 56 sites) of Katmandu Valley. For comparison, concentration was also measured in immediate surroundings (n=56) of all the sites. To get preliminary information on safety practices, a survey study was also conducted. The mean TVOC and HCHO concentration in the sites ranged from 1.5‒8 mg/m³ and <0.01 to 5.5 mg/m³, respectively. The indoor: outdoor TVOC and HCHO ratio (I/O) was found to be significantly higher (I/O>1.5 and p<0.05) in 26 (∼46%) and 47 sites (∼84%), respectively. A strong positive correlation between HCHO and TVOC concentration was observed in furniture industry (R =0.91) and metal workshops (R =0.98). Interestingly, we found TVOC and HCHO concentration higher than WHO safe limit in ∼70% and ∼32% sites, respectively. A rough estimate of chronic daily intake (CDI) of formaldehyde showed that CDI is higher than WHO limit in four sites. These findings suggested that indoor air quality in the significant number of the workplaces is poor and possible measures should be taken to minimize the exposure.
... The release of airborne particulates and volatile organic compounds during the 3D production process has been reported. [62][63][64] In the studies reviewed there seems to be little to no consideration of potential harm to the user during subtractive machining. In simulation of procedures such as temporal bone drilling, this factor is of particular importance. ...
Background:
Intracranial surgery can be complex and high risk. Safety, ethical and financial factors make training in the area challenging. Head model 3-dimensional (3D) printing is a realistic training alternative to patient and traditional means of cadaver and animal model simulation.
Objective:
To describe important factors relating to the 3D printing of human head models and how such models perform as simulators.
Methods:
Searches were performed in PubMed, The Cochrane Library, Scopus and Web of Science. Article screening was conducted independently by three reviewers using Covidence software. Data items were collected under five categories: 'Study information', 'Printers and processes' 'Head model specifics,' 'Simulation and evaluations' and 'Costs and production times'.
Results:
Forty articles published over the last 10 years were included in the review. A range of printers, printing methods and substrates were used to create head models and tissue types. Complexity of the models ranged from sections of single tissue type (e.g., bone) to high-fidelity integration of multiple tissue types. Some models incorporated pathology (e.g., tumours, aneurysms) and artificial physiology (e.g., pulsatile circulation). Aneurysm clipping, bone drilling, craniotomy, endonasal surgery and tumour resection were the most commonly practiced procedures. Evaluations completed by those using the models were generally favourable.
Conclusions:
This review's findings indicate that those who practice surgery and surgical techniques on 3D printed head models deem them to be valuable assets in cranial surgery training. Understanding how surgical simulation on such models impacts on surgical performance and patient outcomes, whilst considering cost-effectiveness, are important future research endeavours.
... The formula composition of RC-MET-3, which has API , Lactose Super Tab 21 AN , Silicified Microcrystalline Cellulose PROSOLV® SMCC HD 90 and 2% w/w of dry binder hydroxy propyl cellulose shows highest retention of granules up to 84% w/w above mesh no # 60 ASTM . Highest particle size can be observed in the formula composition with binders and the percentage of retention particle is more at 75 bar roller pressure [23] . ...
Dry granulation is defined as a process whereby powders of different physical properties are combined to form denser, bigger, permanent masses with the aid of some tangible or intangible external agents. In dry-granulation, roller pressure is the driving force. Careful selection of the quantitative composition of functional ingredients has a big role to play in the scalability of the manufacturing process when drug load is as high as 66.67%w/w. Metformin hydrochloride has an inherent issue of flowability and compressibility. A high drug load gives little space for other functional inactive ingredients; hence it becomes more critical to choose efficient highly compressible diluent at an equal quantitative ratio with a dry binder. Better compressible diluents along with dry binder also add flexibility and help the recycling granules for better results. A physical property of selected individual ingredients and a mixture of ingredients has a direct impaction on the compressibility of granules, solid fraction, density, and particle size distribution of compressed granules. Current dry granulation study with a composition of Lactose anhydrous and Silicified Microcrystalline Cellulose along with 2% w/w hydroxypropyl cellulose gives the flexibility of recycling to high drug load Metformin hydrochloride granules, this helps to improve its tablet ability.
... The presented research focussed on printing with polymers, which is the most commonly used printing material (Statista, 2020). Printing emissions from polymeric materials have been examined in a number of studies focussing on mainly ME, but also binder jetting, VP, and PBF (Stephens et al., 2013;Afshar-Mohajer et al., 2015;Kim et al., 2015;Stefaniak et al., 2017bStefaniak et al., , 2019aDamanhuri et al., 2019;Jeon et al., 2020). Research that includes measurements of personal exposures in real industrial occupational settings is limited. ...
3D printing, a type of additive manufacturing (AM), is a rapidly expanding field. Some adverse health effects have been associated with exposure to printing emissions, which makes occupational exposure studies important. There is a lack of exposure studies, particularly from printing methods other than material extrusion (ME). The presented study aimed to evaluate measurement methods for exposure assessment in AM environments and to measure exposure and emissions from four different printing methods [powder bed fusion (PBF), material extrusion (ME), material jetting (MJ), and vat photopolymerization] in industry. Structured exposure diaries and volatile organic compound (VOC) sensors were used over a 5-day working week. Personal and stationary VOC samples and real-time particle measurements were taken for 1 day per facility. Personal inhalable and respirable dust samples were taken during PBF and MJ AM. The use of structured exposure diaries in combination with measurement data revealed that comparatively little time is spent on actual printing and the main exposure comes from post-processing tasks. VOC and particle instruments that log for a longer period are a useful tool as they facilitate the identification of work tasks with high emissions, highlight the importance of ventilation and give a more gathered view of variations in exposure. No alarming levels of VOCs or dust were detected during print nor post-processing in these facilities as adequate preventive measures were installed. As there are a few studies reporting negative health effects, it is still important to keep the exposure as low as reasonable.
... Third, calibrations based on short-term field colocations with reference instruments typically cannot be used to generalize wide-ranging concentrations and the effect of varying particle sources. This is a concern because with improving air quality in the developed nations, where typical PM2.5 levels are relatively low (<20 μg/m 3 ); however, PM concentration during wildfires [31] and in occupational settings [32,33] often exceeds regulatory limits for short periods. Also, in developing countries with less strict regulations, the PM level associated with, e.g., traffic emissions [34], agricultural waste burning [35], indoor cooking [36] is significantly higher, but where field colocations for calibration studies can be conducted. ...
Commercially available low-cost particulate matter (PM) sensors provide output as total or size-specific particle counts and mass concentrations. These quantities are not measured directly but are estimated by the original equipment manufacturers' (OEM) proprietary algorithms and have inherent limitations since particle scattering depends on their composition, size, shape, and complex index of refraction (CRI). Hence, there is a need to characterize and calibrate their performance under a controlled environment. We present calibration algorithms for Plantower PMS A003 sensor as a function of particle size and concentration. A standardized experimental protocol was used to control the PM level, environmental conditions and to evaluate sensor-to-sensor reproducibility. The calibration was based on tests when PMS A003 were exposed to different polydisperse standardized testing aerosols. The results suggested particle size distribution from PMS A003 was shifted compared to reference instrument measures. For calibration of number concentration, linear model without adjusting aerosol properties corrects the raw PMS A003 measurement for specific size bins with normalized mean absolute error within 4.0% of the reference instrument. Although the Bayesian Information Criterion suggests that models adjusting for particle optical properties and relative humidity are technically superior, they should be used with caution as the particle properties used in fitting were within a narrow range for challenge aerosols. The calibration models adjusted for particle CRI and density account for non-linearity in the OEM's mass concentrations estimates and demonstrated lower error. These results have significant implications for using PMS A003 in high concentration environments, including indoor air quality and occupational/industrial exposure assessments, wildfire smoke, or near-source monitoring scenarios.
... However, emissions of particle and volatile organic compounds (VOCs) from 3D printing were recently reported and the spotlight was on desktop MEX printers (e.g. fused filament fabrication or also known as fused deposition modeling) due to its widespread adoption in product prototyping (Afshar-Mohajer et al., 2015;Azimi et al., 2016;Graff et al., 2017;Du Preez et al., 2018;Ding et al., 2019). While most attention is focused on desktop MEX printers, particle emissions from other kinds of 3D printing techniques are also of concern to occupational health but have since been less explored. ...
Purpose
This study aims to examine on-site particle concentration levels due to emissions from a wide spectrum of additive manufacturing techniques, including polymer-based material extrusion, metal and polymer-based powder bed fusion, directed energy deposition and ink-based material jetting.
Design/methodology/approach
Particle concentrations in the operating environments of users were measured using a combination of particle sizers including the TSI 3910 Nano SMPS (10–420 nm) and the TSI 3330 optical particle sizer (0.3–10 µm). Also, fumes from a MEX printer during printing were directly captured using laser imaging method.
Findings
The number and mass concentration of submicron particles emitted from a desktop open-type MEX printer for acrylonitrile-butadiene-styrene and polyvinyl alcohol approached and significantly exceeded the nanoparticle reference limits, respectively. Through laser imaging, fumes were observed to originate from the printer nozzle and from newly deposited layers of the desktop MEX printer. On the other hand, caution should be taken in the pre-processing of metal and polymer powder. Specifically, one to ten micrometers of particles were observed during the sieving, loading and cleaning of powder, with transient mass concentrations ranging between 150 and 9,000 µg/m ³ that significantly exceeded the threshold level suggested for indoor air quality.
Originality/value
Preliminary investigation into possible exposures to particle emissions from different 3D printing processes was done, which is useful for the sustainable development of the 3D printing industry. In addition, automatic processes that enable “closed powder cycle” or “powder free handling” should be adopted to prevent users from unnecessary particle exposure.
... Additionally, the recently developed metal-organic dispersion ink composed of cupric formate and octylamine has also been found to have an adverse environmental impact 32,33 . Therefore, to enable domestic-scale desktop application of BJM3DP, it is essential to develop a binding agent that is eco-friendly as well as nonhazardous 24,[34][35][36] . ...
Recent advances in metal additive manufacturing (AM) have provided new opportunities for the design of prototypes of metal-based products and personalization of products for the fourth industrial revolution. Although metal AM, which enables fabrication of varied and sophisticated objects, is in the spotlight as a next-generation printing method, environmental issues arising during the printing process need to be addressed before it can be commercialized. Here, we demonstrate a novel mechanism for binder jetting three-dimensional (3D) printing of metals that is based on chelation triggered by an eco-friendly binding agent. Sodium salts of fruit acid chelators are used to form stable metal-chelate bridges between metal particles, which enable elaborate metal 3D printing. The strength of the 3D-printed object is improved by post-treatment, through a reduction in the porosity between the metal particles. Finally, the compatibility of the novel printing mechanism with a variety of metals is demonstrated via successful 3D printing of objects of various shapes using various metal powders. The proposed mechanism for metal 3D printing is expected to open up new avenues for the development of domestic-scale desktop 3D printing of metals.
... There are many different techniques for AM, appropriate for diverse materials, and requiring different types of postprocessing treatments (Ljunggren et al., 2019). Nonexhaustive examples include the material extrusion (ME) technique, in which a solid thermoplastic filament is heated and extruded through a nozzle onto a build plate (Stefaniak et al., 2019a), as well as the vat photopolymerization (VP), and multijet (MJ) modeling technologies where photopolymer resins are selectively jetted layer-by-layer and hardened with UV laser or UV light, respectively (Afshar-Mohajer et al., 2015). Powder bed fusion (PBF) is a metal-powder feeding system in which thin layers of powder are selectively joined together by laser (King et al., 2015), while, in the binder jetting (BJ) technology, a liquid agent is selectively deposited to bond powder particles, layer-by-layer, into a solid object (Lewinski et al., 2019). ...
The widespread application of additive manufacturing (AM) technologies, commonly known as three-dimensional (3D) printing, in industrial and home-business sectors, and the expected increase in the number of workers and consumers that use these devices, have raised concerns regarding the possible health implications of 3D printing emissions. To inform the risk assessment and management processes, this review evaluates available data concerning exposure assessment in AM workplaces and possible effects of 3D printing emissions on humans identified through in vivo and in vitro models in order to inform risk assessment and management processes. Peer-reviewed literature was identified in Pubmed, Scopus, and ISI Web of Science databases. The literature demonstrated that a significant fraction of the particles released during 3D printing could be in the ultrafine size range. Depending upon the additive material composition, increased levels of metals and volatile organic compounds could be detected during AM operations, compared with background levels. AM phases, specific job tasks performed, and preventive measures adopted may all affect exposure levels. Regarding possible health effects, printer emissions were preliminary reported to affect the respiratory system of involved workers. The limited number of workplace studies, together with the great variety of AM techniques and additive materials employed, limit generalizability of exposure features. Therefore, greater scientific efforts should be focused at understanding sources, magnitudes, and possible health effects of exposures to develop suitable processes for occupational risk assessment and management of AM technologies.
... The increasing number of hours of 3D printing in household living areas raises the issue of possible emissions of UFPs and VOCs from printers that use polymeric materials. To pay attention to emissions from 3D printers is important based on past experiences with office equipment as a possible source of air pollution [3,4,16] and the potential negative impacts on human health. Emerging evidence has suggested that inhalation of emissions from material extrusion is associated with adverse effects on the cardiovascular system and respiratory tract [17,18]. ...
Currently, widely available three-dimensional (3D) printers are very popular with the public. Previous research has shown that these printers can emit ultrafine particles (UFPs) and volatile organic compounds (VOCs). Several studies have examined the emissivity of filaments from 3D printing, except glycol modified polyethylene terephthalate (PETG) and styrene free co-polyester (NGEN) filaments. The aim of this study was to evaluate UFP and VOC emissions when printing using a commonly available 3D printer (ORIGINAL PRUSA i3 MK2 printer) using PETG and NGEN. The concentrations of UFPs were determined via measurements of particle number concentration and size distribution. A thermal analysis was carried out to ascertain whether signs of fiber decomposition would occur at printing temperatures. The total amount of VOCs was determined using a photoionization detector, and qualitatively analyzed via gas chromatography-mass spectrometry. The total particle concentrations were 3.88 × 1010 particles for PETG and 6.01 × 109 particles for NGEN. VOCs at very low concentrations were detected in both filaments, namely ethylbenzene, toluene, and xylene. In addition, styrene was identified in PETG. On the basis of our results, we recommend conducting additional measurements, to more accurately quantify personal exposure to both UFPs and VOCs, focusing on longer exposure as it can be a source of potential cancer risk.
In this study, we have developed a cure for indoor air pollution. Herein, we have fabricated CuBTC metal-organic framework MOF combined with TiO2 nanoparticle hybrid material by solvothermal method and obtained it in powder form. The CuBTC/TiO2 hybrid material absorbed toluene higher than TiO2 and CuBTC. CuBTC/TiO2 powder hinders its practical application, however, for the first time, CuBTC/TiO2/PS-based nanofibers were electrospun on a commercial HEPA filter using the electrospinning process in order to examine their air-filtering capabilities. This air filter exhibited 98.6% adsorption efficiency and 129.45 mg g-1 toluene gas adsorption capacity, although pristine HEPA was incapable of absorbing toluene. After the saturated point, a self-cleaning strategy was employed under UV light for regeneration purposes. In addition, the CuBTC/TiO2/PS nanofiber demonstrated superior PM2.5 removal performance, with a 99.82% filtration rate. Compared to a pure HEPA filter, the CuBTC/TiO2/PS-C nanofiber-based HEPA filter has a very high filtration rate and negligible pressure drop when evaluated at various airflow velocities. This study gives significant insight into the design of a self-cleaning nanofiber air filter to protect public health from indoor air pollution and save lives in the near future.
Recently, the development of 3D printing (3DP) technology and its application in various fields have improved our quality of life. However, hazardous materials that affect the human body, such as formaldehyde and particulate matter (PM), are emitted into the air during 3DP. This study measured the formaldehyde, PM10, and PM2.5 emitted by 3DP with the ventilation operation using six materials in material extrusion (ME) and vat photopolymerization (VP) and compared them between the 3DP workspace and the control setting with test–retest validation by two researchers. The experiments were divided into four stages based on the 3DP and ventilation operation. A linear mixed model was used to analyze the mean differences and tendencies between the 3DP workspace and the control setting. The change as ventilation was switched from off to on was evaluated by calculating the area. The differences and tendencies were shown in the statistically significant differences from a post-hoc test (α = 0.0125) except for some cases. There was a significant difference in formaldehyde depending on the ventilation operation; however, only a minor difference in PM10, and PM2.5 was confirmed. The amount of formaldehyde exceeding the standard was measured in all materials during 3DP without ventilation. Therefore, it is recommended to operate ventilation systems.
Background
During industrial scale binder jetting utilising poly methyl methacrylate (PMMA) hazardous chemical substances (HCSs) such as PMMA powder particles, methyl methacrylate (MMA) and acetone may be emitted and potentially inhaled by Additive Manufacturing (AM) operators.
Methods
Physical and chemical characterisation of virgin and used PMMA powder samples were characterised in terms of their size, shape and chemical composition. Direct reading particle counting instruments were used to determine particle emissions and emission rates (ER). Internationally recognised methods were used to monitor HCSs in the ambient workplace environment and personal respiratory exposure of the AM operators.
Results
There were no differences between the median powder size distributions of virgin and used PMMA powders. Scanning Electron Microscopy images indicated the presence of <10 µm and <4 µm sized particles in virgin and used powders. Particle ERs as high as 3.33 × 10⁶ particles/min for 0.01 - ∼1.00 µm sized particles were measured during the post-processing phase. Inhalable and respirable particles, acetone, pentane and toluene were detected in ambient air and AM operators were exposed to quantifiable concentrations of these HCSs.
Conclusions
Particles sized 0.01 - ∼1.00 µm were the most prevalent particles emitted, with a maximum ER of 3.33×10⁶ particles/min. Eight-hour Time Weighted Average personal exposures were below their respective Occupational Exposure Limit (OELs), with the exception of inhalable particles (mean >50% of the South African OEL). Recommendations were made to reduce exposure to inhalable particles, which could be applied to other AM facilities.
Volume 23A provides a comprehensive review of established and emerging 3D printing and bioprinting approaches for biomedical applications, and expansive coverage of various feedstock materials for 3D printing. The Volume includes articles on 3D printing and bioprinting of surgical models, surgical implants, and other medical devices. The introductory section considers developments and trends in additively manufactured medical devices and material aspects of additively manufactured medical devices. The polymer section considers vat polymerization and powder-bed fusion of polymers. The ceramics section contains articles on binder jet additive manufacturing and selective laser sintering of ceramics for medical applications. The metals section includes articles on additive manufacturing of stainless steel, titanium alloy, and cobalt-chromium alloy biomedical devices. The bioprinting section considers laser-induced forward transfer, piezoelectric jetting, microvalve jetting, plotting, pneumatic extrusion, and electrospinning of biomaterials. Finally, the applications section includes articles on additive manufacturing of personalized surgical instruments, orthotics, dentures, crowns and bridges, implantable energy harvesting devices, and pharmaceuticals. For information on the print version of Volume 23A, ISBN: 978-1-62708-390-4, follow this link.
Background
TVOC (total volatile organic compounds) has been used as a sum parameter in indoor air sciences for over 40 years. In the beginning, individual VOC concentrations determined by gas chromatography were simply added together. However, several methods for calculating TVOC have become established over time.
Methods
To understand the manifold definitions of TVOC, one must trace the history of indoor air sciences and analytical chemistry. Therefore, in this work, the original approaches of TVOC are searched and explained. A detailed description of the measurement methods is followed by a critical evaluation of the various TVOC values and their possible applications. The aim is to give the reader a deeper understanding of TVOC in order to use this parameter correctly and to be able to better assess published results. In addition, related sum values such as TSVOC and TVVOC are also addressed.
Results
A milestone was the analytical definition of VOCs and TVOC in 1997. A list of VOCs that should at least be considered when calculating TVOC was also provided. This list represented the status at that time, is no longer up-to-date and is being updated by a European working group as part of a harmonization process. However, there is still confusion about the exact definition and reasonable application of TVOC. The signals of other sum parameters, measured with photoacoustics, flame ionization, photoionization or electrochemical sensors, are also often given under the term TVOC.
Conclusions
It was recognized early that TVOC is not a toxicologically based parameter and is therefore only suitable for a limited number of screening purposes. Consequently, TVOC cannot be used in connection with health-related and odor-related issues. Nevertheless, such references are repeatedly made, which has led to controversial scientific discussions and even court decisions in Germany about the correct and improper use of TVOC.
Particles and volatile organic compounds (VOCs) have been detected emitting from material extrusion 3D printing, which is widely used in nonindustrial environments. However, vat polymerization 3D printing that is also commonly used has yet to be well-characterized for its emissions. In this study, we measured particle and VOC emission rates from stereolithography (SLA) 3D printing during print and post-processing wash and cure processes individually using a standardized testing method for 3D printer emissions in an exposure chamber. We observed minimal particle emissions and identified 30 to over 100 individual VOCs emitted from each operating phase, some of which accumulated after the printing ended. The total VOC emissions from SLA processes were higher than typical levels from material extrusion 3D printing, and the emission rate could be over 4 mg/h. Major VOCs emitted were associated with the resin and chemicals used in print and post-processing procedures, which included esters, alcohols, aldehydes, ketones, aromatics, and hydrocarbons. Emissions from post-processing units were lower than those from printing but also included chemicals with health concerns. The emitted mixture of sensitizers, carcinogens, irritants, and flammable chemicals may present a hazard for indoor air quality and human health. The estimated personal exposure to total VOC and some specific VOCs of concern to human health, like formaldehyde and naphthalene, exceeded the recommended indoor levels (e.g., California Office of Environmental Health Hazard Assessment), potentially causing irritation and other health impacts for 3D printer users.
Medical shortages during the COVID-19 pandemic saw numerous efforts to 3D print personal protective equipment and treatment supplies. There is, however, little research on the potential biocompatibility of 3D-printed parts using typical polymeric resins as pertaining to volatile organic compounds (VOCs), which have specific relevance for respiratory circuit equipment. Here, we measured VOCs emitted from freshly printed stereolithography (SLA) replacement medical parts using proton transfer reaction mass spectrometry and infrared differential absorption spectroscopy, and particulates using a scanning mobility particle sizer. We observed emission factors for individual VOCs ranging from ∼0.001 to ∼10 ng cm–3 min–1. Emissions were heavily dependent on postprint curing and mildly dependent on the type of SLA resin. Curing reduced the emission of all observed chemicals, and no compounds exceeded the recommended dose of 360 μg/d. VOC emissions steadily decreased for all parts over time, with an average e-folding time scale (time to decrease to 1/e of the starting value) of 2.6 ± 0.9 h.
Volatile organic compounds (VOCs) emitted from electronic industry may pose severe problems to human health and the environment. In the present study, the VOCs adsorption on commercial activated carbon fibers (ACFs) in a fixed-bed column was investigated by continuous mode as a function of inlet flow rate (100–500 L/h), inlet VOCs concentration (200–400 mg/m³), adsorption temperature (15–35 °C) and bed height (120–240 mm). Afterwards, the adsorption behavior and mechanism of VOCs on ACFs were quantified by the adsorption kinetic, equilibrium, thermodynamic models. To further quantify the adsorption performance in the fixed bed column, an axial dispersion model was proposed to model the breakthrough curves. The results indicated that the adsorption process conformed to the Langmuir isotherm and pseudo-first-order kinetic equation, indicative of physical adsorption. Moreover, the adsorption capacity increased with the increase of VOCs concentration and bed height, but decreased with the increase of inlet flow rate and adsorption temperature. Interestingly, the axial dispersion model can well predict the breakthrough curve and visualize the temporal and axial distribution of VOCs adsorption in the fixed-bed column by integrating Matlab ode15s solver with lsqcurvefit function, from which both the overall mass transfer and axial dispersion coefficient were also derived. The model herein may facilitate the process design of VOCs adsorption and precisely predict the adsorption performance of a scaled-up adsorption fixed bed.
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.
As additive manufacturing becomes more prevalent in industrial manufacturing facilities, so does human interaction with these machines. In this study, we characterized the size-resolved concentrations of particulate matter (PM, from ≈ 11 to 20,000 nm in size) and volatile organic compounds (VOC) resulting from a material-jetting (Projet 5500X), multi jet fusion (HP MJF 4200), and photopolymerization (Carbon 3D continuous liquid interface production). During all processes, PM concentrations were below the OSHA limits and ultrafine PM (PM0.1) concentrations were well below levels commonly observed for fused deposition modeling printers. PM and total volatile organic compound (VOC) concentrations during printing were close to background levels for the HP MJF printer and HP MJF post processing station. However, the mean particle size of the powder used (PA 12) was above the upper detection limit of the instrument (20 μm). Carbon 3D total VOC levels were highest during part post processing. Cyclic PM emissions from the Projet 5500X printer suggested higher PM emissions during cooling fan activity. VOC analysis revealed high concentrations of HP ink solvents (2-Pyrrolidinone and Triethylene glycol), potential exposure to fluorinated compounds and photoresin VOCs during Carbon 3D post-processing, and exposure to photo-resin compounds during Projet 5500X printing. This study indicates that proper exhaust and facility air exchange can limit concentrations of PM and VOCs and therefore particular attention to the building design and ventilation system should be taken into consideration for additive manufacturing facilities to mitigate potential human exposure and associated health risks.
Emissions of volatile organic compounds (VOCs) are known to be significant human health and ecological risks. Absorption is classical process applied to eliminate air pollutants, yet the removal efficiency of gaseous contaminants is often curbed by the mass transfer resistance between absorption liquids and hydrophobic VOCs (e.g., toluene). This work aims to evaluate the feasibility of capturing VOCs from exhaust through the use of hydrophobic deep eutectic solvents (DESs). Among the examined DESs, hydrophobic DESs whose hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) are both fatty acids with long alkyl chains (i.e., decanoic acid [DecA] and lauric acid [LauA]) achieve the highest absorption capacity of toluene at 9.94 mg toluene per g DES at 30°C and 800 ppm toluene with an HBA:HBD molar ratio of 1:3. Hydrophobic interactions between the fatty acids and toluene are critical for improving the VOC absorption ability of DESs, as the toluene solubility increases with an increase in the alkyl chain length of the fatty acid eutectics. The compiled results suggest that effective hydrophobic VOC removal can be realized by the proposed hydrophobic fatty acid eutectics, [LauA][DecA], and the physical absorption nature of toluene in fatty acid eutectics benefits facile recovery and recycling.
Industry 4.0 presents new challenges for traditional sectors of the economy, for example, the production of ceramic products. This chapter reveals how traditional ceramic industries can (1) assess, (2) plan, and (3) execute Industry 4.0 adoption. The findings are based on the Portuguese ceramic sector. Three interrelated dimensions of the fourth industrial revolution are studied, namely, (1) digital ecosystems, (2) security and safety, and (3) digital sustainability. Industry 4.0 is not restricted to high-tech products and cannot be addressed by one-size-fits-all solutions. Moreover, it requires cooperation within business ecosystems. The authors propose a model for Ceramic Industry 4.0 and accessible guidelines for managers involved in global supply chains. This chapter suggests emergent research opportunities for (1) sectorial maturity models, (2) data quality and regulatory compliance, (3) cyber-security and risk management, and (4) an integrated vision of sustainability in the digital era.
The literature on emissions during material extrusion additive manufacturing with 3-D printers is expanding; however, there is a paucity of data for large-format additive manufacturing (LFAM) machines that can extrude high-melt-temperature polymers. Emissions from two LFAM machines were monitored during extrusion of six polymers: acrylonitrile butadiene styrene (ABS), polycarbonate (PC), high-melt-temperature polysulfone (PSU), poly(ether sulfone) (PESU), polyphenylene sulfide (PPS), and Ultem (poly(ether imide)). Particle number, total volatile organic compound (TVOC), carbon monoxide (CO), and carbon dioxide (CO2) concentrations were monitored in real-time. Particle emission rate values (no./min) were as follows: ABS (1.7 × 10¹¹ to 7.7 × 10¹³), PC (5.2 × 10¹¹ to 3.6 × 10¹³), Ultem (5.7 × 10¹² to 3.1 × 10¹³), PPS (4.6 × 10¹¹ to 6.2 × 10¹²), PSU (1.5 × 10¹² to 3.4 × 10¹³), and PESU (2.0 to 5.0 × 10¹³). For print jobs where the mass of extruded polymer was known, particle yield values (g–1 extruded) were as follows: ABS (4.5 × 10⁸ to 2.9 × 10¹¹), PC (1.0 × 10⁹ to 1.7 × 10¹¹), PSU (5.1 × 10⁹ to 1.2 × 10¹¹), and PESU (0.8 × 10¹¹ to 1.7 × 10¹¹). TVOC emission yields ranged from 0.005 mg/g extruded (PESU) to 0.7 mg/g extruded (ABS). The use of wall-mounted exhaust ventilation fans was insufficient to completely remove airborne particulate and TVOC from the print room. Real-time CO monitoring was not a useful marker of particulate and TVOC emission profiles for Ultem, PPS, or PSU. Average CO2 and particle concentrations were moderately correlated (rs = 0.76) for PC polymer. Extrusion of ABS, PC, and four high-melt-temperature polymers by LFAM machines released particulate and TVOC at levels that could warrant consideration of engineering controls. LFAM particle emission yields for some polymers were similar to those of common desktop-scale 3-D printers.
Mobility particle size spectrometers often referred to as DMPS (Differential Mobility Particle Sizers) or SMPS (Scanning Mobility Particle Sizers) have found a wide range of applications in atmospheric aerosol research. However, comparability of measurements conducted world-wide is hampered by lack of generally accepted technical standards and guidelines with respect to the instrumental set-up, measurement mode, data evaluation as well as quality control. Technical standards were developed for a minimum requirement of mobility size spectrometry to perform long-term atmospheric aerosol measurements. Technical recommendations include continuous monitoring of flow rates, temperature, pressure, and relative humidity for the sheath and sample air in the differential mobility analyzer.
We compared commercial and custom-made inversion routines to calculate the particle number size distributions from the measured electrical mobility distribution. All inversion routines are comparable within few per cent uncertainty for a given set of raw data.
Furthermore, this work summarizes the results from several instrument intercomparison workshops conducted within the European infrastructure project EUSAAR (European Supersites for Atmospheric Aerosol Research) and ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) to determine present uncertainties especially of custom-built mobility particle size spectrometers. Under controlled laboratory conditions, the particle number size distributions from 20 to 200 nm determined by mobility particle size spectrometers of different design are within an uncertainty range of around ±10% after correcting internal particle losses, while below and above this size range the discrepancies increased. For particles larger than 200 nm, the uncertainty range increased to 30%, which could not be explained. The network reference mobility spectrometers with identical design agreed within ±4% in the peak particle number concentration when all settings were done carefully. The consistency of these reference instruments to the total particle number concentration was demonstrated to be less than 5%.
Additionally, a new data structure for particle number size distributions was introduced to store and disseminate the data at EMEP (European Monitoring and Evaluation Program). This structure contains three levels: raw data, processed data, and final particle size distributions. Importantly, we recommend reporting raw measurements including all relevant instrument parameters as well as a complete documentation on all data transformation and correction steps. These technical and data structure standards aim to enhance the quality of long-term size distribution measurements, their comparability between different networks and sites, and their transparency and traceability back to raw data.
Under the umbrella of the generic issue of Rapid X there are some concepts such as: Rapid Prototyping (RP), Rapid Tooling (RT) and Rapid Manufacturing (RM). This paper presents industrial applications of the RP/ RM techniques, developed at the Industrial Innovative Technologies Laboratory, within the Manufacturing Engineering Department from Transilvania University of Braşov. The focus is on the determination of optimal strategies used in polyjet and" inkjet" RP technologies. The optimal strategies affects on the build time, support structure, surface quality as well as the cost of the physical prototype.
Powder-based inkjet 3D printing method is one of the most attractive solid free form techniques. It involves a sequential layering process through which 3D porous scaffolds can be directly produced from computer-generated models. 3D printed products' quality are controlled by the optimal build parameters. In this study, Calcium Sulfate based powders were used for porous scaffolds fabrication. The printed scaffolds of 0.8 mm pore size, with different layer thickness and printing orientation, were subjected to the depowdering step. The effects of four layer thicknesses and printing orientations, (parallel to X, Y and Z), on the physical and mechanical properties of printed scaffolds were investigated. It was observed that the compressive strength, toughness and Young's modulus of samples with 0.1125 and 0.125 mm layer thickness were more than others. Furthermore, the results of SEM and μCT analyses showed that samples with 0.1125 mm layer thickness printed in X direction have more dimensional accuracy and significantly close to CAD software based designs with predefined pore size, porosity and pore interconnectivity.
The development of low-cost desktop versions of three-dimensional (3D)
printers has made these devices widely accessible for rapid prototyping
and small-scale manufacturing in home and office settings. Many desktop
3D printers rely on heated thermoplastic extrusion and deposition, which
is a process that has been shown to have significant aerosol emissions
in industrial environments. However, we are not aware of any data on
particle emissions from commercially available desktop 3D printers.
Therefore, we report on measurements of size-resolved and total
ultrafine particle (UFP) concentrations resulting from the operation of
two types of commercially available desktop 3D printers inside a
commercial office space. We also estimate size-resolved
(11.5 nm-116 nm) and total UFP (<100 nm)
emission rates and compare them to emission rates from other desktop
devices and indoor activities known to emit fine and ultrafine
particles. Estimates of emission rates of total UFPs were large, ranging
from
˜2.0 × 1010 # min-1
for a 3D printer utilizing a polylactic acid (PLA) feedstock to
˜1.9 × 1011 # min-1
for the same type of 3D printer utilizing a higher temperature
acrylonitrile butadiene styrene (ABS) thermoplastic feedstock. Because
most of these devices are currently sold as standalone devices without
any exhaust ventilation or filtration accessories, results herein
suggest caution should be used when operating in inadequately ventilated
or unfiltered indoor environments. Additionally, these results suggest
that more controlled experiments should be conducted to more
fundamentally evaluate particle emissions from a wider arrange of
desktop 3D printers.
The deployment of a distributed point source monitoring system based on wireless sensor networks in an industrial site where dangerous substances are produced, used, and stored is described. Seven essential features, fundamental prerequisites for our estimating emissions method, were identified. The system, consisting of a wireless sensor network (WSN) using photoionisation detectors (PIDs), continuously monitors the volatile organic compound (VOC) concentration at a petrochemical plant on an unprecedented time/space scale. Internet connectivity is provided via TCP/IP over GPRS gateways in real time at a one-minute sampling rate, thus providing plant management and, if necessary, environmental authorities with an unprecedented tool for immediate warning in case critical events happen. The platform is organised into subnetworks, each including a gateway unit wirelessly connected to the WSN nodes. Environmental and process data are forwarded to a remote server and made available to authorized users through a rich user interface that provides data rendering in various formats, in addition to worldwide access to data. Furthermore, this system consists of an easily deployable stand-alone infrastructure with a high degree of scalability and reconfigurability, as well as minimal intrusiveness or obtrusiveness.
Airborne PM1, PM2.5, PM5 and PM10 generated during writing with three types of chalk sticks on a board and particle size distribution of chalk dust fall during writing and dusting of board were studied by portable aerosol spectrometer and particle size analyzer. ‘Local Gypsum’ chalk led to the highest increase in airborne particulate matter while ‘Clean-Write’ the least during writing. About 10% of particles in chalk dust fall during writing were finest from: ‘Clean Write’ (0.5 µm) followed by ‘Abroad Quality’ (0.67 µm) and ‘Local Gypsum’ (1.15 µm), while 50% was finest in abroad quality (5.12 µm) followed by ‘Clean Write’ (6.36 µm) and ‘Local Gypsum’ (77.65 µm). In dusting samples, 10%, 50% and 90% of particles were finest in ‘Clean Write’ followed by ‘Abroad Quality’ and ‘Local Gypsum’ chalks. ‘Clean Write’ chalk produced least total amount of PM1, PM2.4 and PM5 and PM10 per unit time in dust fall during writing. Although short-term exposure to airborne fine chalk particles may be low in classrooms, several years of exposure may be a matter of concern. Purpose of this work was to provide data that would lead to measures for minimization of health risk due to chalk dusts in classrooms
Mobility particle size spectrometers often referred to as DMPS (Differential Mobility Particle Sizers) or SMPS (Scanning Mobility Particle Sizers) have found a wide range of applications in atmospheric aerosol research. However, comparability of measurements conducted world-wide is hampered by lack of generally accepted technical standards and guidelines with respect to the instrumental set-up, measurement mode, data evaluation as well as quality control. Technical standards were developed for a minimum requirement of mobility size spectrometry to perform long-term atmospheric aerosol measurements. Technical recommendations include continuous monitoring of flow rates, temperature, pressure, and relative humidity for the sheath and sample air in the differential mobility analyzer.
We compared commercial and custom-made inversion routines to calculate the particle number size distributions from the measured electrical mobility distribution. All inversion routines are comparable within few per cent uncertainty for a given set of raw data.
Furthermore, this work summarizes the results from several instrument intercomparison workshops conducted within the European infrastructure project EUSAAR (European Supersites for Atmospheric Aerosol Research) and ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) to determine present uncertainties especially of custom-built mobility particle size spectrometers. Under controlled laboratory conditions, the particle number size distributions from 20 to 200 nm determined by mobility particle size spectrometers of different design are within an uncertainty range of around ±10% after correcting internal particle losses, while below and above this size range the discrepancies increased. For particles larger than 200 nm, the uncertainty range increased to 30%, which could not be explained. The network reference mobility spectrometers with identical design agreed within ±4% in the peak particle number concentration when all settings were done carefully. The consistency of these reference instruments to the total particle number concentration was demonstrated to be less than 5%.
Additionally, a new data structure for particle number size distributions was introduced to store and disseminate the data at EMEP (European Monitoring and Evaluation Program). This structure contains three levels: raw data, processed data, and final particle size distributions. Importantly, we recommend reporting raw measurements including all relevant instrument parameters as well as a complete documentation on all data transformation and correction steps. These technical and data structure standards aim to enhance the quality of long-term size distribution measurements, their comparability between different networks and sites, and their transparency and traceability back to raw data.
Indoor air-borne loads of volatile organic compounds (VOCs) are usually significantly higher than those outdoors, and chronic exposures can cause health problems. Our previous laboratory studies have shown that the potted-plant microcosm, induced by an initial dose, can eliminate high air-borne VOC concentrations, the primary removal agents being potting-mix microorganisms, selected and maintained in the plant/root-zone microcosm. Our office field-study, reported in the preceding paper, showed that, when total VOC (TVOC) loads in reference offices (0 plants) rose above about 100 ppb, levels were generally reduced by up to 75% (to < 100 ppb) in offices with any one of three planting regimes. The results indicate the induction of the VOC removal mechanism at TVOC levels above a threshold of about 100 ppb. The aims of this laboratory dose-response study were to explore and analyse this response. Over from 5 to 9 days, doses of 0.2, 1.0, 10 and 100 ppm toluene and m-xylene were applied and replenished, singly and as mixtures, to potted-plants of the same two species used in the office study. The results confirmed the induction of the VOC removal response at the lowest test dosage, i.e in the middle of the TVOC range found in the offices, and showed that, with subsequent dosage increments, further stepwise induction occurred, with rate increases of several orders of magnitude. At each dosage, with induction, VOC concentrations could be reduced to below GC detection limits (< 20 ppb) within 24 h. A synergistic interaction was found with the binary mixtures, toluene accelerating m-xylene removal, at least at lower dosages. The results of these two studies together demonstrate that the potted-plant microcosm can provide an effective, self-regulating, sustainable bioremediation or phytoremediation system for VOC pollution in indoor air.
There are various emission sources of chemical contaminants, such as volatile organic compounds (VOCs) and ozone and particulate matter. This report is a study into the indoor air of a room containing either a laser printer/ink-jet printer, and the air contaminations were monitored for VOCs, ozone and ultrafine particle. The result confirmed an increase in the concentration of ozone and ultrafine particle numbers in the printing processes of the printer. The emission of VOCs and ozone were measured by the use of a test chamber. The chamber concentrations of styrene, xylenes and ozone were increased in printing process of the laser printer, and pentanol was detected from the ink-jet printer. The results suggest that an office or residential printer may be a source of indoor air contamination. It is necessary for emission from printers to monitor not only VOCs and particle but also ultrafine particles and other contaminants in indoor air.
Laser printers are one of the common indoor equipment in schools, offices, and various other places. Laser printers have recently been identified as a potential source of indoor air pollution. This study examines the characteristics of ultrafine particles (UFPs, diameter <100 nm) and volatile organic compounds (VOCs) emitted from laser printers housed in a commercial printing center. The results indicated that apart from the printer type, the age of printers, and the number of pages printed, the characteristics of UFPs emitted from printers also depend on indoor ventilation conditions. It was found that at reduced ventilation rates of indoor air, there was a rise in the number concentration of UFPs in the printing center. Interestingly, the contribution of UFPs to the total number of submicrometer-sized particles was observed to be higher at a sampling point far away from the printer than the one in the immediate vicinity of the printer. Black carbon (BC) measurements showed a good correlation (rs = 0.82) with particles in the size range of 100-560 nm than those with diameters less than 100 nm (rs = 0.33 for 50-100 nm, and rs = -0.19 for 5.6-50 nm particles). Measurements of VOCs in the printing center showed high levels of m-, o-, and p-xylene, styrene, and ethylbenzenes during peak hours of printing. Although toluene was found in higher levels, its concentration decreased during peak hours compared to those during nonoperating hours of the printing center.
The aim of this study was to evaluate the indoor (I) and outdoor (O) levels of NO₂, speciated volatile organic compounds (VOCs) and carbonyls at fourteen primary schools in Lisbon (Portugal) during spring, autumn and winter. Three of these schools were also selected to be monitored for comfort parameters, such as temperature and relative humidity, carbon dioxide (CO₂), carbon monoxide (CO), total VOCs, and both bacterial and fungal colony-forming units per cubic metre. The concentration of CO₂ and bioaerosols greatly exceeded the acceptable maximum values of 1800 mg m⁻³ and 500 CFU m⁻³, respectively, in all seasons. Most of the assessed VOCs and carbonyls occurred at I/O ratios above unity in all seasons, thus showing the importance of indoor sources and building conditions in indoor air quality. However, it has been observed that higher indoor VOC concentrations occurred more often in the colder months, while carbonyl concentrations were higher in the warm months. In general, the I/O NO₂ ratios ranged between 0.35 and 1, never exceeding the unity. Some actions are suggested to improve the indoor air quality in Lisbon primary schools.
This study compared the response of two optical particle counters with that of an aerodynamic particle sizer. The optical particle counters rely on the amount of incident light scattered at 90 degrees by a particle to measure particle number concentration by optical particle size. Two models of optical particle counters from Grimm Technologies were used: the portable aerosol spectrometer (PAS) 1.108 (0.3-20 microm in 15 channels); and the PAS 1.109 (0.2-20 microm in 30 size channels). With a substantially different operating principle from that employed by the optical particle counters, the aerodynamic particle sizer (APS) model 3321 (TSI, Inc., St Paul, MN, USA) sizes particles according to their behavior in an accelerating flow to provide particle number concentration by aerodynamic size over a slightly narrower size range (0.5-20 microm) in 52 channels. The responses of these instruments were compared for three sizes of monodisperse solid aerosols composed of polystyrene latex spheres and a polydisperse aerosol composed of Arizona test dust. The PASs provided similar results to those from the APS. However, there were systematic differences among instruments in number and mass concentration measurement that depended upon particle size.
The purpose of this work is to assess, both experimentally and theoretically the status of air quality in a dentistry clinic of the Athens University Dentistry Faculty with respect to chemical pollutants and identify the indoor sources associated with dental activities. Total VOCs, CO2, PM10, PM2.5, NOx and SO2 were measured over a period of approximately three months in a selected dentistry clinic. High pollution levels during the operation hours regarding CO2, total VOCs and Particulate Matter were found, while in the non-working periods lower levels were recorded. On the contrary, NOx and SO2 remained at low levels for the whole experimental period. These conditions were associated with the number of occupants, the nature of the dental clinical procedures, the materials used and the ventilation schemes, which lead to high concentrations, far above the limits that are set by international organizations and concern human exposure.
Image-guided surgery can be broken down into two broad categories: frame-based guidance and frameless guidance. In order to reduce both the invasive nature of stereotactic guidance and the cost in equipment and time, we have developed a new guidance technique based on rapid prototyping (RP) technology. This new system first builds a computer model of the patient anatomy and then fabricates a physical reference frame that provides a precise and unique fit to the patient anatomy. This frame incorporates a means of guiding the surgeon along a preplanned surgical trajectory. This process involves (1) obtaining a high-resolution CT or MR scan, (2) building a computer model of the region of interest, (3) developing a surgical plan and physical guide, (4) designing a frame with a unique fit to the patient's anatomy with a physical linkage to the surgical guide, and (5) fabricating the frame using an RP unit. Software was developed to support these processes. To test the accuracy of this process, we first scanned and reproduced a plastic phantom fabricated to validate the system's ability to build an accurate virtual model. A target on the phantom was then identified, a surgical approach planned, a surgical guide designed, and the accuracy and precision of guiding a probe to that target were determined. Steps 1 through 5 were also evaluated using a head phantom. The results show that the RP technology can replicate an object from CT scans with submillimeter resolution. The fabricated reference frames, when positioned on the surface of the phantom and used to guide a surgical probe, can position the probe tip with an accuracy of 1.7 mm at the probe tip. These results demonstrate that the RP technology can be used for the fabrication of customized positioning frames for use in image-guided surgery.
Three Dimensional Printing is a process for the manufacture of tooling and functional prototype parts directly from computer models. Three Dimensional Printing functions by the deposition of powdered material in layers and the selective binding of the powder by “link-jet” printing of a binder material. Following the sequential application of layers, the unbound powder is removed, resulting in a complex threedimensional part. The process may be applied to the production of metal, ceramic, and metal-ceramic composite parts. An experiment employing continuous-jet ink-jet printing technology has produced a three-dimensional ceramic part constructed of 50 layers, each 0.005 in. thick. The powder is alumina and the binder is colloidal silica. The minimum feature size is 0.017 in., and features intended to be 0.5000 in. apart average 0.4997 in. apart in the green state and 0.5012 in. apart in the cured state, with standard deviations of 0.0005 in. and 0.0018 in., respectively. Future research will be directed toward the direct fabrication of cores and shells for metal casting, and toward the fabrication of porous ceramic preforms for metal-ceramic composite parts.
When to Screen in Obstetrics and Gynecology 2nd Edition, explains exactly when and how to screen for a wide variety of conditions...addressing the fundamental questions you should consider in order to make informed decisions! Features a standardized format throughout to facilitate quick access to information Makes a clear distinction between the characteristics of screening tests versus diagnostic tests Offers recommendations regarding the usefulness and acceptability of testing and preventative measures for both established and emerging settings Includes expanded coverage of large screening tests for Down Syndrome and cystic fibrosis New screenings for cholesterol levels, thrombophilia, and hypertension as well as new DNA testing methods.
The material removal in ultrasonic machining (USM) is based on brittle fracturing of workpiece materials. The properties and fracture behavior are different for varied materials, and they would have an influence on the machining performance of USM. The smoothed particle hydrodynamics (SPH) method was used to simulate the USM process for different workpiece materials. Three typical hard and brittle materials, i.e. silicon carbide (SiC), alumina (Al2O3), and glass will be used as the workpiece materials. Experiments are also conducted for comparing with the simulation results. Through this study, the material fracturing processes for different work materials are shown visually using the SPH method, which is very useful for USM study.
Most AM processes require post-processing after part building to prepare the part for its intended form, fit and/or function. Depending upon the AM technique, the reason for post-processing varies. For purposes of simplicity, this chapter will focus on post-processing techniques which are used to enhance components or overcome AM limitations. These include:
Additive Manufacturing (AM) technology came about as a result of developments in a variety of different technology sectors. Like with many manufacturing technologies, improvements in computing power and reduction in mass storage costs paved the way for processing the large amounts of data typical of modern 3D Computer-Aided Design (CAD) models within reasonable time frames. Nowadays, we have become quite accustomed to having powerful computers and other complex automated machines around us and sometimes it may be difficult for us to imagine how the pioneers struggled to develop the first AM machines.
This chapter highlights some of the key moments that catalogue the development of Additive Manufacturing technology. It will describe how the different technologies converged to a state where they could be integrated into AM machines. It will also discuss milestone AM technologies. Furthermore, we will discuss how the application of Additive Manufacturing has evolved to include greater functionality and embrace a wider range of applications beyond the initial intention of just prototyping.
Additive manufacturing (AM), the process of joining materials to make objects from three-dimensional (3D) model data, usually layer by layer, is distinctly a different form and has many advantages over traditional manufacturing processes. Commonly known as "3D printing," AM provides a cost-effective and time-efficient way to produce low-volume, customized products with complicated geometries and advanced material properties and functionality. As a result of the 2013 National Science Foundation (NSF) Workshop on Frontiers of Additive Manufacturing Research and Education, this paper summarizes AM's current state, future potential, gaps and needs, as well as recommendations for technology and research, university-industry collaboration and technology transfer, and education and training.
In modern society, people spend more than 90% of their time indoors; good indoor air quality is very important to us. Poor indoor air quality can cause many adverse health effects such as respiratory symptoms, asthma, especially for children. Thus, indoor air quality of schools is important since children are susceptible to indoor pollutants, including airborne particles, volatile organic compounds, etc. Indoor air problems can increase the chance of long-term and short-term health problems for students and teachers in terms of comfort and productivity. One of the strategies to maintain indoor air quality in buildings is to use mechanical ventilation systems. Investigation of indoor air quality in classrooms helps us to characterize pollutant levels and effects of ventilation systems. In this study, three classrooms, two laboratories and one computer classroom at three different schools in Korea were chosen for investigation of indoor air quality with mechanical ventilation systems. Measurements were conducted for particulate matter (PM 10), formaldehyde (HCHO), total volatile organic compounds (TVOC), carbon monoxide (CO), carbon dioxide (CO 2), nitrogen dioxide (NO 2), ozone (O 3), radon, and total bacteria counts. Differences in indoor pollutants concentrations with and without operation of ventilation systems in each classroom were analyzed. Operation of ventilation systems could decrease the levels of indoor pollutants in the classrooms, especially showing the reduction of TVOC concentrations by 26.3–64.4 %.
A scanning mobility particle sizer (SMPS --TSI Model 3936-Series) was evaluated using Duke Scientific NIST-traceable particle size standards and Standard Reference Materials from the National Institute of Standards and Technology (NIST SRM's). The importance of instrument setup, electrospray operation and sample preparation for polystyrene spheres are discussed as well as the results from 14 different size reference standards. Correlations between the SMPS system and established electron microscopy and dynamic light scatting methods are also shown in tabular and graphical forms. Results show that with proper operation, the SMPS results fall within the uncertainty of the NIST traceable diameters in the range that was evaluated — 20 to 100 nanometers.
Introduction:
The first off-Earth fused deposition modeling (FDM) 3D printer will explore thermoplastic manufacturing capabilities in microgravity. This study evaluated the feasibility of FDM 3D printing 10 acrylonitrile butadiene styrene (ABS) thermoplastic surgical instruments on Earth.
Methods:
Three-point bending tests compared stiffness and yield strength between FDM 3D printed and conventionally manufactured ABS thermoplastic. To evaluate the relative speed of using four printed instruments compared to conventional instruments, 13 surgeons completed simulated prepping, draping, incising, and suturing tasks. Each surgeon ranked the performance of six printed instruments using a 5-point Likert scale.
Results:
At a thickness of 5.75 mm or more, the FDM printing process had a less than 10% detrimental effect on the tested yield strength and stiffness of horizontally printed ABS thermoplastic relative to conventional ABS thermoplastic. Significant weakness was observed when a bending load was applied transversely to a 3D printed layer. All timed tasks were successfully performed using a printed sponge stick, towel clamp, scalpel handle, and toothed forceps. There was no substantial difference in time to completion of simulated surgical tasks with control vs. 3D printed instruments. Of the surgeons, 100%, 92%, 85%, 77%, 77%, and 69% agreed that the printed smooth and tissue forceps, curved and straight hemostats, tissue and right angle clamps, respectively, would perform adequately.
Discussion:
It is feasible to 3D print ABS thermoplastic surgical instruments on Earth. Loadbearing structures were designed to be thicker, when possible. Printing orientations were selected so that the printing layering direction of critical structures would not be transverse to bending loads.
The performance of the Scanning Mobility Particle Sizer (SMPS, TSI Model 3934) and the Aerodynamic Particle Sizer (APS, TSI Model 3310A) were evaluated to assess their ability to obtain mass concentrations from near real-time particle number concentration measurements made as a function of particle size. Tests were performed by generating monodisperse (polystyrene latex microspheres, 0.05-9.20 mu m) and polydisperse aerosols (potassium sulfate and ammonium nitrate, mass median aerodynamic diameter (MMAD) U 0.16-0.30 mu m) and comparing mass concentrations determined by the SMPS and APS, with concentrations measured gravimetrically on Teflon filters. Previous performance evaluation tests of these instruments has focused primarily on their ability to measure particle number concentrations (Kinney et al. 1991; Wang and Flagan 1990) or mass concentrations of polydisperse aerosols with mass median aerodynamic diameters (MMAD) of about 0.7-2.5 mu m (Peters et al. 1993). Findings from the monodisperse aerosol tests indicate that the mass concentrations obtained by the APS compared similarly to those obtained using the gravimetric method for particle sizes between 0.5-9.2 mu m. Similarly, SMPS measurements were in good agreement with the gravimetric analysis for particle sizes between 0.3-0.5 mu m. However, for particles less than 0.30 mu m, the SMPS overestimated their mass concentrations by a factor of 1.5-1.6. Tests using polydisperse aerosols showed that at particle size ranges from 0.09-0.18 mu m and from 0.18-0.29 mu m, the SMPS also overestimated mass concentrations.
Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing deals with various aspects of joining materials to form parts. Additive Manufacturing (AM) is an automated technique for direct conversion of 3D CAD data into physical objects using a variety of approaches. Manufacturers have been using these technologies in order to reduce development cycle times and get their products to the market quicker, more cost effectively, and with added value due to the incorporation of customizable features. Realizing the potential of AM applications, a large number of processes have been developed allowing the use of various materials ranging from plastics to metals for product development. Authors Ian Gibson, David W. Rosen and Brent Stucker explain these issues, as well as: Providing a comprehensive overview of AM technologies plus descriptions of support technologies like software systems and post-processing approaches Discussing the wide variety of new and emerging applications like micro-scale AM, medical applications, direct write electronics and Direct Digital Manufacturing of end-use components Introducing systematic solutions for process selection and design for AM Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing is the perfect book for researchers, students, practicing engineers, entrepreneurs, and manufacturing industry professionals interested in additive manufacturing.
Purpose
This paper aims to illustrate a number of instances where RP and associated technology has been successfully used for medical applications.
Design/methodology/approach
A number of medical case studies are presented, illustrating different uses of RP technology. These studies have been analysed in terms of how the technology has been applied in order to solve related medical problems.
Findings
It was found that RP has been helpful in a number of ways to solve medical problems. However, the technology has numerous limitations that have been analysed in order to establish how the technology should develop in the future.
Practical implications
RP can help solve medical problems, but must evolve if it is to be used more widespread in this field.
Originality/value
This paper has shown a number of new applications for RP, providing a holistic understanding how the technology can solve medical problems. It also identifies a number of ways in which the technology can improve in order to better solve such problems.
This paper discusses the current status of layer-based manufacturing rapid prototyping (RP) technology and how it is currently being implemented as a tool for product development (PD). A discussion on RP for PD is given, focusing on the limitations of existing technology. The paper then goes on to discuss the specific application field of medicine, explaining how this application may influence changes in the technology. Future trends for RP development are then discussed with further consideration for software issues in future applications and how the technology is being accepted worldwide.
This article examines the characteristics and applications of 3-D printing and compares it with mass customization and other manufacturing processes. 3-D printing enables small quantities of customized goods to be produced at relatively low costs. While currently used primarily to manufacture prototypes and mockups, a number of promising applications exist in the production of replacement parts, dental crowns, and artificial limbs, as well as in bridge manufacturing. 3-D printing has been compared to such disruptive technologies as digital books and music downloads that enable consumers to order their selections online, allow firms to profitably serve small market segments, and enable companies to operate with little or no unsold finished goods inventory. Some experts have also argued that 3-D printing will significantly reduce the advantages of producing small lot sizes in low-wage countries via reduced need for factory workers.