As three-dimensional printing becomes more common in our world, users express concerns for hazards associated with the practice. With over 7 different types of these additive manufacturing methods, each can come with their own subset of hazards, while also having hazards they may have in common such as VOC emissions while printing, post processing chemicals or machining, and more.
Common types of printing As 3D printing has evolved and progressed over the years, newer and more diverse methods of printing have been employed, depending on the desired final product or materials available. The following are the most common methods that can be found both in the professional field and the public market.
Binder jetting: Consists of two main components, liquid binder and ceramic/metal powder. As the binder agent is sprayed, the powders solidify and are then heated to remove the binder and cement the remaining material. Directed energy deposition (DED): Similar to fused deposition modeling, but uses a metal powder or wire, which melts as the print head deposits it. Fused deposition modeling: Filament is heated up and melted to then be layered by a fine tip nozzle (most common in open markets). Material jetting: Use of small quantities of ink as feed material, which is placed onto a platform. As droplets solidify, the following layer begins to be placed. Powder bed fusion: Materials such as plastic, metal, ceramic, and glass powders are layered by lasers or other high-energy sources to solidify into a structure. Sheet lamination: Cuts and bonds thin materials like paper and aluminum foil by using a laser or a sharp blade. Stereolithography (SLA): A UV laser is used on photopolymer resin to harden and shape the object layer by layer.
Hazards
Emissions As the industry expands and transforms, 3d printing's advancements have been both technical and commercial. Beginning to be adopted around the world inside classrooms, medical institutions, orthodontist offices, and private residences, potential risks are ever more increasing. Emissions from fused filament printers can include a large number of ultrafine particles and volatile organic compounds (VOCs). The toxicity from emissions varies by source material due to differences in size, chemical properties, and quantity of emitted particles. Excessive exposure to VOCs can lead to irritation of the eyes, nose, and throat, headaches, cancer, and damage to the liver, kidneys, and central nervous system, while some of the chemical emissions of fused filament printers have also been linked to asthma. Based on animal studies, carbon nanotubes and carbon nanofibers sometimes used in fused filament printing can cause pulmonary effects, including inflammation, granulomas, and pulmonary fibrosis when at the nanoparticle size. A National Institute for Occupational Safety and Health (NIOSH) study noted particle emissions from a fused filament peaked a few minutes after printing started and returned to baseline levels 100 minutes after printing ended. Workers may also inadvertently transport materials outside the workplace on their shoes, garments, and bodies, potentially posing hazards for other members of the public. Laser sintering and laser beam melting systems for additive manufacturing have become more important recently. The Institute for Occupational Safety and Health (IFA) together with German social accident insurance institutions conducted a measurement program on inhalation exposure to hazardous substances during laser deposition welding and laser beam melting with alloyed steels and nickel-, aluminium- and titanium-based alloys. No chromium(VI) compounds were detected in the workplace air during the process when materials containing chromium were processed, and the assessment criteria were complied with during processes with the other metal powders. One reason for this is that the machines are usually operated with encapsulation or dust extraction in order to achieve the required product quality. Since many work steps before and after the process (including the handling of powder itself or powdered parts) are performed manually or semi-automatically, there are huge effects on the degree of inhalation exposure and the measured values vary broadly. It is therefore difficult to derive tailored measures for these processes. Carbon nanoparticle emissions and processes using powder metals are highly combustible and raise the risk of dust explosions. Two especially hazardous nanometals are aluminum an titanium, both of which are widely used in metal powder 3D printing processes. At least one case of severe injury was noted from an explosion involving metal powders used for fused filament printing.
Post-Processing Hazards to health and safety also exist from post-processing activities done to finish parts after they have been printed. These post-processing activities can include chemical baths, sanding, polishing, or exposing parts to a vapor bath to refine surface finish through smoothing/polishing using solvent chemicals. Other post-processing can also include general subtractive manufacturing techniques such as drilling, milling, or turning to modify the printed geometry. Any technique that removes material from the printed part has the potential to generate particles that can be inhaled or cause eye injury if proper personal protective equipment is not used, such as respirators or safety glasses. Caustic baths are often used to dissolve support material used by some 3D printers, which allows more complex shapes to be made. These baths require personal protective equipment to prevent injury to exposed skin.
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