niosh field efforts in additive manufacturingniosh field efforts in additive manufacturing kevin l...
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NIOSH Field Efforts in Additive Manufacturing
Kevin L Dunn, MS, CIH
Advanced Materials and Manufacturing Field Studies Team LeadDivision of Surveillance, Hazard Evaluations and Field StudiesNational Institute for Occupational Safety and Health (NIOSH)
DOE Office of Worker Safety and Health Policy, and IH/OS SIG WebinarFebruary 12, 2018
Goals of field team assessments
• Increase awareness and understanding of the potential hazards associated with additive manufacturing
• Identify risk assessment considerations when evaluating additive manufacturing activities
• Identify exposure assessment techniques for evaluating additive manufacturing processes in your workplace
Potential printing hazards by type
Fused Filament Fabrication (FFF)
• Particulate emissions• Volatile organic compound (VOCs) emissions• Thermal hazards such as burns
Direct Metal Laser Melting (DMLM)
• Inhalation and dermal contact of metals• Explosion and fire• High powered lasers• Exposure potential over multiple activities – post processing,
maintenance
Stereolithography(SLA)
• Dermal contact with photopolymer resins• VOC emissions• Ultraviolet light
Exposure assessment process
Based on Nanomaterial Exposure Assessment Technique (NEAT) 2.0
Collect Basic Workplace Information
Design and Implement the Sampling Plan
Exposure Assessment
Risk Management
Integrated air sampling
Note: transmission electron microscopy (TEM) / scanning electron microscopy (SEM) sampling for identification, sizing and morphology if engineered nanomaterials involved
Personal and area air sampling
• Full-shift• Task-based• Include non-process areas to
check for process migration
Chemical and/or gravimetric analysis
• Metals – NIOSH Method of Analytical Methods (NMAM) 7300
• VOCs – NMAM 1500, NMAM 2549• Total and/or respirable
particulates – NMAM 0500/0600
Direct-reading instruments (DRIs)
• Co-located with area air samples• Typically sample for particulates• Particle counting and sizing instruments can include:
– Condensation Particle Counters (CPC)– Optical Particle Sizers– Optical Particle Counters– Aerosol photometers such as TSI SidePak or DustTrak– Nano Scan– Fast Mobility Particle Sizer
1nm 10 nm 100 nm 1 um 10 um
PhotometerCPC
Condensation Particle Counter (CPC)• particle size range 10 nanometers (nm) to >1.0 micrometer (µm)• concentration range 0 to 100,000 particles per cubic centimeter
Aerosol Photometer • particle size range 0.1 to 15 µm• mass concentration range 0.001 to 150 milligrams per
cubic meter, depending on instrument• size selectable fractions - thoracic, respirable, PM1,
PM2.5, PM4, PM10
Limitations of DRIs• No material identification• Wide size range of particles• Professional judgement on data interpretation
– remember to take excellent notes
• Upper dynamic range can be exceeded – may not be great for really dusty environments
• No occupational exposure limits
Other sampling options• Thermophoretic sampler
– Designed by RJ Lee and Colorado State University – Particle deposition based on heat differential– Sampling directly onto an electron microscopy grid
• Real-time Aerosol MultiElemental Spectrometer (in development)– Direct-reading - near real time– Low detection limits,0.01 to 1 micrograms per cubic meter for a 5 minute collection– Can also analyze wipe samples on site
• Surface Wipe Sampling– Can be used to assess work practices and/or work procedures– Qualitative (yes/no) or quantitative, or both– How clean is clean enough?– Brookhaven National Laboratory www.bnl.gov -
Evaluate ventilation and engineering controls
• Measuring general and local exhaust ventilation– Thermal (“hot-wire”) anemometer– Balometer (flow hood)– Ventilation “smoke” tubes (qualitative)
• Maintaining the desired air pressure differentials between process and non-process areas– Keeping the process area under negative air pressure relative to
adjacent areas (meaning that air flows into the process area)
Evaluate work practices and workplace conditions
• Frequency, duration, and volume of printing• Housekeeping frequency and method• Health and safety training and program reviews• Work practices
– Use of personal protective equipment (PPE)– Consumption of food/drink in process areas– Hand-washing
Advanced Materials and Manufacturing (AMM) Field Studies
• Field team has conducted 13 site visits for AMM, and have six more scheduled for 2019. (Fused filament Fabrication (FFF), Stereolithography (SLA), Metal Powder Melting, Polymer Powder Melting)– Printer manufacturers– Polymer feedstock manufacturers (filament, resin, and polymer powder)– Research and Development– Aerospace– Academia– Manufacturing
Survey Sites
Advanced Materials and Manufacturing (AMM) Field Studies
• Thermoplastics (FFF,SLA)– Field chamber emission rates similar to other published results– VOCs present but well below any applicable OELs
• Metal powders– Print process enclosed and emissions likely contained if sealed properly– Greatest potential exposure during powder handling, loading, unloading, and post processing– Work practice and housekeeping very important.
Findings
We do not yet know the “safe” or target exposure level for most of these materials. However, traditional IH safety, control, and work practice
guidance are effective in reducing or eliminating exposures.
• Have a focused study starting in 2019 addressing the use of 3D printing in nontraditional areas, such as:– Schools– Libraries– State of Washington Department of Health
• We currently have three universities, one high school, and one grade school confirmed for participation.
Advanced Materials and Manufacturing (AMM) Field Studies
Communication products• Published the NIOSH Science Blog with MakerBot, study of multi printer working environment. Three
other publications in process– Field measurements of chamber and production area using multiple FFF 3D printers with CNT infused and unfilled PEEK
polymer. JOEH article accepted/in review– Field measurement of FFF emissions in chamber and multiple printer environments with and without NOISH designed
LEV.– Summary of 11 worksite evaluations during the production and use of nanomaterials with wet process practices.– Questions to ask before you start posters; Nano poster, Metals 3D printing poster, Thermoplastics/SLA poster.– Emerging Technologies Webinar series
• NIOSH also working on lab based studies for emission rate characterization, emission toxicology, and further testing of a NIOSH designed LEV control for FFF printing applications.
Local Exhaust Ventilation Tests
0
5000
10000
15000
20000
25000
30000
11.5 15.4 20.5 27.4 36.5 48.7 64.9 86.6 115.5 154 205.4 273.8 365.2
dN (#
/cm
3 )
Particle size (nm)Nanoparticle size distribution from chamber tests using the
TSI Nanoscan.
Table 2. Nanoparticle emission rates in isolation chamber from 3D printing
Year Filament typeLocal exhaust
VentilationEmission rate,
#/s*
2017
PLA 1 No 2000 x 105
PLA 1No 1400 x 105
ABSNo 470 x 105
PLA 2 No 1.20 x 105
2018 PLA 1
No 500 x 105
No 200 x 105
No 200 x 105
No 200 x 105
Yes 6.50 x 105
Yes 4.80 x 105
Yes 4.60 x 105
* #/s = Number of particles per second.
Total number concentration of particles in the conference room
Total number concentration of particles in the chamber
Nano Risk AssessmentTool• Poses questions that employers
and workers should consider before starting work with a nanomaterial
• For each question, the poster provides options to reduce exposures to nanomaterials based on the physical form
• Can be displayed in a lab or work environment
• Reminder of the important health and safety considerations for working with nanomaterials
Controlling Health Hazards When Working with Metal Powders for Additive Manufacturing: Questions to Ask Before You Start
Questions Here are some options you can use to reduce exposures to metal powders in your workplace. These options correspond with the questions on the left.
Pre-printing Printing Post-printing Maintenance, machine cleaning, and housekeeping
Characterization and Potential Hazards - What are potential hazards associated with metal powder additive manufacturing? Have you done a job hazard analysis? What metals are in the powder? Are there known health effects from the metals? What is the work environment like (for example, open area or segregated)?
Potential hazards may include: Inhalation and dermal exposures to metals; fire and explosion from finely divided powders and reactive metals; high powered lasers; Job hazard analysis questions such as: what is the location of printer(s)? Are grounding and bonding straps used when removing filters? Is there a fire suppression system in the
location? Are there written procedures covering receiving and disposal of metal powders, operation and maintenance activities? Consult safety data sheets (SDS) health effects from metal powder exposures, as well as material specific health hazards documentation
Is the printing or work activities performed in a segregated work area or open area? Does the work area have dedicated ventilation system or shared general ventilation system with non-printing or work areas? Is the area negatively pressured compared to surrounding areas?
Work activities - How are you handling the metal powders? Could the work activity cause exposures? Is the likelihood of exposure low or high? Can you change the way you do the activity to reduce exposures (high potential to low)?
Higher potential - manual loading of powders into machines;
powder sieving performed outside of machines
Lower potential - enclosed powder loading;enclosed powder sieving
monitoring printing progress;
closed process with minimal potential for
exposure
Higher potential: removing powder from printer; removing printed object; transfer of powder/printed object around
work area; sieving powder outside machine;
Lower potential: cleaning and finishing of object inside containment system; post-process machining of object
(finishing); enclosed powder sieving and powder removal
Higher potential: performing preventative maintenance on printer; removing/installing high
efficiency particulate air (HEPA) filters;
Lower potential: cleaning printer equipment and tools; housekeeping
Engineering Controls - Based on the work activity or step in printing process, what engineering controls will be effective? What are the key design and operational requirements for the control? Remember to consider fire and explosion hazard of metal powder when selecting controls.
HEPA-filtered local exhaust ventilation placed in close proximity to powder handling; ergonomic assist for handling powder
containers and transfers
Closed process with minimal potential for
exposures
HEPA-filtered local exhaust ventilation placed in close proximity to powder handling; ergonomic assist for powder
container and printed object transfers; ventilated glove box or containment system (for example during cleaning and finishing activities); ventilated bagging or dumping
stations
HEPA-filtered local exhaust ventilation placed in close proximity to powder handling; HEPA-filtered and fire/explosion-appropriate waste vacuum; bag
in/bag out filter removal techniques; grounding and bonding of equipment; sticky mats on floors at
processing area exits/entrances
Administrative Controls - Have you considered the role of administrative controls? Have you set up a plan for waste management? Have you considered what to do in case of a spill?
Incorporate metal powder additive manufacturing into existing programs like hazard communication; train workers; use signs and labels; control access to essential personnel only; use wet methods or HEPA-filtered vacuum with appropriate fire and explosion controls for housekeeping measures; Do not dry sweep or used compressed air during
housekeeping; use appropriate work practices such as proper personal protective equipment replacement and donning/doffing; do not wear contaminated personal protective equipment outside of work areas such as offices; do not consume food or drinks in work areas; handle and dispose of all waste materials (including cleaning materials/gloves) in
compliance with all applicable federal, state, and local regulations
Personal Protective Equipment - If the measures above do not effectively control the hazard, what personal protective equipment can be used? Have you considered personal protective equipment for other safety hazards (for example fire and explosion potential from certain metals and finely divided powders).
Nitrile or chemical resistant gloves; Lab coat or coveralls;
Safety glasses, goggles, or face shields; Respiratory protection when indicated and engineering controls cannot control exposures, and in accordance with federal regulations (29 CFR 1910.134);
NIOSH guidance on respirators can be found at www.cdc.gov/niosh/topics/respirators/;
While potential exposures are typical lowest during the Printing stage be aware of metal powder surface contamination. If printing is interrupted, revert to previous levels of controls and personal protective equipment for other stages and work activities. If working in an area with multiple printers, be aware of the activities occurring on other
machines and wear appropriate PPE. ( powder change out on the machine next to your work station may require you to wear the same level of PPE.)
Controlling Health Hazards When Performing Additive Manufacturing with Thermoplastics: Questions to Ask Before You Start
Questions Here are some options you can use to reduce exposures to thermoplastics in your workplace. These options correspond with the questions on the left. Pre-printing Printing Post-printing Maintenance and housekeeping
Characterization and Potential Hazards - What are potential hazards associated with thermoplastic additive manufacturing? Have you done a job hazard analysis? What is the work environment like (for example, open area or segregated)?
Potential hazards may include: Inhalation and dermal exposures to volatile organic compounds, resins, and particulates, ultraviolet light, hot surfaces and parts; Job hazard analysis questions such as: what type of printing is being performed such as fused-filament fabrication (FFF) and stereolithography (SLA), what is the printing
material being used, location of printer(s), frequency and duration printing performed? Is the printing or work activities performed in a segregated work area or open area? Does the work area have dedicated ventilation system or shared general ventilation
system with non-printing or work areas? Is the work area under negative pressure relative to adjoining areas?
Work activities - Could the work activity cause exposures? Is the likelihood of exposure low or high? Can you change the way you do the activity to reduce exposures (high potential to low)?
Higher Potential: pouring resins into printer
Lower Potential: loading filament into printer; cleaning or changing printer heads/nozzles; prepping
build plate
Higher Potential: working near printer during operation, near printer during print
failures
Lower Potential: not approaching printer during failures; waiting several minutes
after print job has ended to collect object
Higher Potential: removing part after SLA printing; using solvents and other chemicals to remove
support structures; cleaning printer head/build plate with solvents; adding additional resin to printer
Lower Potential: removing part after FFF printing; scraping build plate with tools; post-processing
activities such as machining, washing, oven curing; change out of filaments
Higher Potential: Changing of resin, calibration of machines (UV Light)
Lower Potential: Changing of filament, waste collection, housekeeping
Engineering Controls - Based on the work activity or step in printing process, what engineering controls will be effective? What are the key design and operational requirements for the control?
Splash guards when pouring resin material; Use pumps rather
than manual pouring
HEPA-filtered local exhaust ventilation placed in close proximity to printing; ventilated enclosure or containment,
local exhaust ventilation or canopy-style hoods with enclosures for solvent tanks
Splash guards when pouring resin material; Use pumps rather than manual
pouring
Administrative Controls - Have you considered the role of administrative controls? Have you set up a plan for waste management? Have you considered what to do in case of a spill?
Incorporate thermoplastic additive manufacturing into existing programs like hazard communication; train workers; use signs and labels; control access to essential personnel only or use remote monitoring if available and appropriate; select the lowest printing temperature that achieves the desired product; choose a filament or resin with lower known emission rates that achieve the desired product such as using polylactic acid (PLA) filament rather than acrylonitrile butadiene styrene (ABS); handle and
dispose of all waste materials (including cleaning materials/gloves) in compliance with all applicable federal, state, and local regulations
Personal Protective Equipment - If the measures above do not effectively control the hazard, what personal protective equipment can be used? Have you considered personal protective equipment for other safety hazards (for example ultraviolet light or burns from hot printer heads).
Nitrile or chemical resistant gloves for chemical handling (such as resins and solvents);Thermal gloves for thermal hazards
Lab coat or coveralls; Safety glasses, goggles, or face shields;
Eye and protection for ultraviolet light hazards;Respiratory protection when indicated and engineering controls cannot control exposures, and in accordance with federal regulations (29 CFR 1910.134);
NIOSH guidance on respirators can be found at www.cdc.gov/niosh/topics/respirators/;
NIOSH research effortsAMMFT Field
Studies• Interested in evaluating all types of 3D printing• Free evaluation – protect proprietary processes and information• Goal is to put out guidance for industry as a whole• Portable chamber to place over printers, allows individual verses work environment comparisons• Published the NIOSH Science Blog with MakerBot, working on publishing study of multi-printer
environment
Emissions and controls
• Engineering Control Technology group – Evaluating emissions and controls from BOT farms; evaluating manufacturer-designed controls
Acknowledgements
• NIOSH NTRC• Kevin L. Dunn• Charles Geraci• Kevin H. Dunn• Duane Hammond• Gary Roth• Laura Hodson• Aleks Stefaniak• Jennifer Tyrawski
Thank YouEric Glassford, MS, CIHHazard Evaluations & Technical Assistance Branch (HETAB)Division of Surveillance, Hazard Evaluations, and Field Studies (DSHEFS)National Institute for Occupational Safety and Health (NIOSH)Centers for Disease Control and Prevention (CDC)
1090 Tusculum Ave, Mailstop R-9Cincinnati, Ohio 45226Office: 513.841.4473Email: [email protected]
The findings and conclusions in this presentation are those of the author and do not necessarily represent the view of the National Institute for Occupational Safety and Health (NIOSH).
Kevin L. Dunn, MS, CIHHazard Evaluations & Technical Assistance Branch (HETAB)Division of Surveillance, Hazard Evaluations, and Field Studies (DSHEFS)National Institute for Occupational Safety and Health (NIOSH)Centers for Disease Control and Prevention (CDC)
1090 Tusculum Ave, Mailstop R-9Cincinnati, Ohio 45226Office: 513.841.4571Email: [email protected]
www.cdc.gov/niosh/topics/nanotech/
For more information, contact CDC1-800-CDC-INFO (232-4636)TTY: 1-888-232-6348 www.cdc.gov