Potential Hazards of Additive ManufacturingPosted on by
Additive manufacturing (AM), commonly referred to as 3-D printing, is becoming more prevalent in industry. AM is a set of processes for making products by selectively joining small amounts of material, using a computer-aided design file. [1,2] The advantages for industry include: shortened production cycles, reduced tooling costs, reduced waste material, easier product customization, novel design options, and new possibilities in distribution and fulfilment. [2–6] The automotive, aerospace, medical device, and electronics manufacturing industries are already using AM, and biomedical applications are expected to grow. Additionally, AM is found in construction, offices, and libraries. It is also important to note the rapid rise of AM in schools, including K–12, as a teaching tool for advanced design and manufacturing technologies.
Though progress has been made in understanding exposures and risks in this field, there is still a need for research on the potential health and safety implications for workers. A new paper from NIOSH researchers, “Potential Occupational Hazards of Additive Manufacturing” published in the Journal of Occupational and Environmental Hygiene highlights AM processes, identifies potential hazards, and discusses research needs for protecting workers.
While there may be similarities between AM and existing technologies, changes in materials, instrumentation, applications, and work organization can create potential hazards that are entirely new, or are distinct enough to warrant renewed consideration. Addressing potential hazards of AM will require the development of a framework for hazard identification.  Such a framework may be provided by AM process categories. Based on international agreement, most methods fall into the following seven categories defined by feedstock materials, feedstock form (phase or state, such as liquid, solid, or powder), processes (the mechanical forces and energies used to bind the materials), and machine architecture. A summary of these process categories and a list of potentially emergent hazards is provided in the table below.
|Category||Feedstock Materials||Feedstock Form||Binding/Fusing||Most Prominent Potential Hazards|
|Material extrusion||Thermoplastics (may include additives)||Spooled filament, pellet, or granulate||Electrical heating element-induced melting/cooling||Inhalation exposure to VOCs, particulate, additives; burns|
|Powder bed fusion||Metal, ceramic, or plastic||Powder||High-powered laser or electron beam heating||Inhalation/dermal exposure to powder, fume; explosion; laser/radiation exposure|
|Vat photopolymerization||Photopolymer||Liquid resin||Ultraviolet-laser induced curing||Inhalation of VOCs; dermal exposure to resins and solvents, ultraviolet exposure|
|Material jetting||Material jetting Photopolymer or wax||Liquid ink||Ultraviolet-light induced curing||Inhalation of VOCs; dermal exposure to resins and solvents, ultraviolet exposure|
|Binder jetting||Metal, ceramic, plastic, or sand||Powder||Adhesive||Inhalation/dermal exposure to powder; explosion; inhalation of VOCs, dermal exposure to binders|
|Sheet lamination||Metal, ceramic, or plastic||Rolled film or sheet||Adhesive or ultrasonic welding||Inhalation of fumes, VOCs; shock, laser/radiation exposure|
|Directed energy deposition||Metal||Powder or wire||Laser/electron beam heating||Inhalation/dermal exposure to powder, fume; explosion; laser/radiation exposure|
In addition to the hazards listed in the table above, other potential AM hazards may come from the use of electrical machinery itself, such as shock or mechanical injury during maintenance and malfunction. Noise and ergonomic hazards are also possible. AM tools may place constraints on their operating environment, and may generate heat, fumes, or airborne particulate. Workers may inadvertently transport materials beyond the workplace on their shoes, garments, and body creating a secondary risk for the general public, including family members. Autonomous systems used with AM may create hazards (such as impact, or crushing injury) while mitigating others (such as ergonomic stresses or inhalation of powder or VOCs). AM instrument malfunctions often require immediate action from a small group of workers; resulting in scheduling late, irregular, or long shifts, or on-call hours; in turn causing stress and fatigue. Bioprinting, which deposits biological molecules, materials, and cells, can use processes similar to AM. Bioprinting may present some potential hazards that resemble those of non-biological AM, while others may relate to the biological nature of these processes.
Risk Management Considerations
The potential hazards of AM include some that are well understood, and others that are partially or completely new. For many potential hazards of AM, appropriate and generally accepted practices and engineering controls already exist. For instance, general ventilation (HVAC) has been shown useful for VOC and particulate control, and LEV with HEPA is most effective for particulate emissions. Research into toxicology, exposure assessment methods, and the creation of standards will be necessary to address those hazards which are less well-understood. Certain trends in AM may contribute to increasing or unique challenges for the IH professional. The accelerated development cycle may make it more difficult to keep pace with the adoption of materials and processes from a health and safety standpoint. Distributed manufacturing might overstretch the specialized health and safety expertise available at any one point of production, and similar concerns may apply to third-party contractors. Small businesses may be more able to adopt AM, but may lack specialized health and safety resources. These will provide logistics challenges for occupational safety and health in the future. As AM grows in adoption and use, it will be essential that academic, industrial, and occupational safety and health professionals prioritize education and research that will enhance health and safety in this field. Please share with us how you or your company has identified and managed the hazards unique to your use of AM.
Gary A. Roth, PhD, is a Health Scientist in the NIOSH Education and Information Division.
Charles L. Geraci, PhD, is Associate Director for Emerging Technologies in the NIOSH Education and Information Division.
Aleksandr Stefaniak is a Research Industrial Hygienist in the Respiratory Health Division.
Vladimir Murashov, PhD, is a Senior Scientist in the NIOSH Office of the Director.
John Howard, MD, is the Director of the National Institute for Occupational Safety and Health.
1. International Organization for Standardization (ISO): Additive manufacturing — General principles — Terminology. Geneva, Switzerland: ISO/ASTM, 2015.
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