Additive manufacturing processes are distinguished by the type of raw material they require. The most widespread processes, such as FDM and SLA, use filaments and resins, respectively, as raw materials. These raw materials have their challenges when handled to avoid health hazards. But their risks are miniscule when compared to another type of raw material, powders. Metal powders, plastic powders and composite powders are available. Dusts are used as raw materials in SLS, DMLS, MJF and other processes. The following will outline the risks involved in handling powders as well as strategies to minimize them as much as possible.
Potential health hazards
What are the potential hazards associated with dusts in additive manufacturing?
Breathing and being in contact with dusts (especially metallic)
Skin contact may lead to irritation or allergic reactions (e.g. dermatitis)
Eye contact may result in mechanical irritation and cause damage
Inhalation of dusts may result in respiratory problems
Risk of fire, explosions, implosions due to static electricity
The location of the printer, the use of dielectric protective equipment and the procedures for the reception and disposal of dusts must be taken into account.
Exposure during work activities
In order to correctly determine the risk to which the operators are exposed it is necessary to ask the following questions: Are the work activities likely to generate exposure to dusts, how are these dusts handled, how likely is exposure, can the way the activity is carried out be changed to reduce exposure (from high exposure to low exposure), and finally, be aware of other printing activities in the vicinity. To facilitate these questions, we have provided a table showing the activities involved in the various stages of printing and the exposure risk associated with them.
In general, the following is recommended:
Print in an enclosure with negative pressure and a dedicated ventilation system, in an area away from other work
An adequate fire protection system
It is necessary to consider the current policies, as it is important to be prepared for the management of waste generated by 3D printing processes that use powders as raw material, as well as to have a plan for dust spill situations in the workplace, the following recommendations are offered, applicable to all stages of printing:
Incorporate additive manufacturing powders into workplace safety programs
Develop standardized operating procedures
Avoid consuming beverages and food in the work area
Restrict access to the work area to essential personnel only
Properly handles filters during replacement, removal and disposal, and checks and replaces seals when necessary
Use signs to warn workers of hazards and the actions they should take to protect themselves
Consider the reactivity of your raw material when choosing cleaning agents, equipment and methods
Clean work areas frequently, between printouts and at least once a day
Use wet cleaning methods (avoid using dry cloths or compressed air)
Ensure the handling and disposal of all materials (including PPE and cleaning materials) according to applicable regulations
Personal protective equipment
If all the above points are not sufficient to mitigate the risk of exposure, then what protective equipment to use, have you taken into account other risks, such as fire, static, explosions and lasers?
Always wear the appropriate PPE for the activities around you (e.g., if a dust change is taking place next to your workstation, you should wear the same level of PPE protection). While dust exposure levels during the printing stage are the lowest, work surfaces can become contaminated with dust. If printing is interrupted, it is necessary to wear appropriate protective equipment while the printer is open.
It is advisable to follow PPE replacement practices and not to use PPE outside the work area, the following PPE recommendations are applicable for all stages of printing:
Nitrile or chemically resistant gloves
Lab coats or coveralls
Safety goggles or face shields
Respirators for exposure mitigation
Safety Data Sheets
As a last point to discuss, as there are a variety of raw materials it is not possible to discuss them in this article, but as it is vitally important to know, we will explain below, all materials have a Safety Data Sheet (SDS). Broadly speaking, these sheets are documents that indicate the particularities and properties of each substance for its most appropriate use. Their purpose, therefore, is to protect the integrity of the person handling a particular material. That is why, before applying any of the points exposed in the article, you should search for all the data sheets of the materials involved in your additive manufacturing processes with powders.
As you can see, there are a multitude of measures that can be taken to protect operators from the hazards of working with powders, especially when it comes to additive manufacturing. Hopefully, you will be able to implement most of these measures and thus achieve a safe and efficient working environment.