In recent years the area of additive manufacturing (AM) has seen significant growth and development. The AM machines are widely used in industrial applications and education institutions to produce finished products directly from a digital model. But, the health and safety hazards are often neglected and not considered in the majority of areas of application.
Recent studies have shown that AM machines can cause health and safety issues ranging from minor risks to life-threatening. This article by AM Chronicle explains the various health and safety risk associated with AM. Additionally, it also elaborates on the industrial safety measures that should be taken to overcome the potential risk.
AM Process and Risk
- Fused Deposition Modelling
In fused deposition modeling, the filament is heated through a nozzle and deposited on the print bed. The popular materials used in fused deposition modeling are PLA, ABS, and nylon. Recently, composite materials, ceramics, and metal powders are also used as additional materials in PLA, ABS, and nylon. The main risk developed while using fused deposition modeling is the formation of volatile organic compounds when the polymer material is melted through the nozzle. Additionally, the use of acetone and other chemicals during the post-processing process can also develop risks for human health. Some studies also suggest that the development of microparticles of polymer and add-ons such as ceramic, composite, and metal can also be inhaled during the printing process, which can develop respiratory issues. Accidents may also occur due to direct human contact with the hotbed or nozzle during or after printing. The use of safety chambers is recommended during the fused deposition modeling process.
Source: Hasanov et al. (2021)
- Stereolithography
During stereolithography, a photopolymer material is selectively solidified using UV light. The photopolymer material, UV light, and post-processing method develop health risks while using this method. Some of the photopolymer materials are toxic, which may cause poisoning if consumed indirectly. Additionally, during the post-processing and curing stages, chemicals such as antimony, acrylates, and epoxies are released, which cause risks to human health. Direct contact with the UV light may result in skin cancer, eye damage, and skin damage. The use of personal protection equipment is recommended to reduce the health risk with stereolithography.
- Powder Bed Fusion
In powder bed fusion, an electron beam or laser is directed on metal powder to produce finished parts. The health risk in the case of powder bed fusion is developed due to the use of laser or electron beam, metal powder, and ionizing radiations. The metal powder used may range from the nanoscale to micro-scale, and indirect inhalation may cause serious respiratory issues for the user. Besides this, regular direct contact with ionizing radiation is a serious threat to the eyes and skin. The safety risk is developed if direct human contact has occurred during the printing process with the lasers or the electron beam. It may cause severe burns and damage. It is highly recommended that the printing process is done in a safe area with the powder bed fusion printing.
- Direct Energy Deposition
The direct energy deposition method uses the characteristics of both fused deposition modeling and powder bed fusion to produce the finished parts. In direct energy deposition, a laser beam/electron beam is used to melt the material, which is deposited using powder or filament. The potential risk of direct energy deposition occurs due to ionization radiation and post-processing of the finished part. It is recommended to use safety chambers with personal protection gears for improved safety.
- Binder Jetting
In binder jetting, a liquid material and powder materials are used to print the finished part. During the printing process, the liquid material acts as an adhesive that helps to develop the finished product. The formation of volatile organic compounds causes the health risk in binder jetting during the printing and post-processing. Additionally, in some cases, during the post-processing process, annealing is required to develop a high-quality product, which may result in an accident due to high temperature. The main risk is caused by direct inhalation of the liquid material or the powder materials used during the printing process. It is recommended that the process be performed according to safety standards and wear safety kits.
Source: Nozar et al. (2019)
- Material Jetting
Material jetting is a process in which material is sprayed onto a build platform and solidified under UV light. The health risk in the case of material jetting is caused by the use of UV lights, powder material, and the post-processing of the printed products. The risk is similar to the risk caused by UV light, powder materials, and the post-processing step.
- Sheet Lamination
In sheet lamination printing, the sheet is used as a feedstock rather than powder, photopolymer, or filament material. Using lasers or other thermal sources to cut the sheet may cause a risk of injuries due to thermal sources and lasers. Other than this, the formation of micro powders during the printing process may also cause respiratory risk.
Source: Hasanov et al. (2021)
General Health and Safety Risk
Industrial-scale additive manufacturing machines are also associated with some general health and safety risks. They mainly include electric shocks, mechanical injuries, and thermal/heat injuries.
Electric Shocks
Electric shocks may occur due to loose wiring and the loose electrical fitting in the industrial machines. In the case of machines that use lasers or electron beams, electrical shocks are considered a life-threatening risk.
Mechanical Injuries
In the case of heavy additive manufacturing machines or machines that produce large volume parts, mechanical injuries can occur due to improper loading and unloading. The method of preventing mechanical injuries is proper training for the working staff.
Thermal/Heat Injuries
All the additive manufacturing processes are associated with thermal energy use, which causes a risk of thermal/heat injuries to the services. They can be protected by proper knowledge of the heating areas and training to the staff. The heated areas must also be insulated from the external source so that direct touching is prevented.
Conclusions
Additive manufacturing is a promising technology, but the discussion on health and safety for additive manufacturing is limited. Industrial accidents can be prevented by proper training, personal protection equipment, and safety kits. The manufacturers must also consider health and safety while designing the machines.
Sources :
Hasanov, Seymur & Gupta, Ankit & Alifui-Segbaya, Frank. (2021). Environmental health and safety – Additive Manufacturing. 10.13140/RG.2.2.11267.22564.
Nozar, M., Pokorna, V. and Zetkova, I., 2019. Potential health hazards of additive manufacturing.
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