NIOSH Field Efforts in Additive ManufacturingNIOSH Field Efforts in Additive Manufacturing Kevin L...

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

Presenter

Presentation Notes

Before we dive into it, here is what I hope you will come away with today by the end of the presentation. What are some exposure assessment techniques that you can use when evaluating processes in your workplace, and what are some of the potential hazards that you need to be aware of that are associated with additive manufacturing.

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

Presenter

Presentation Notes

FFF mention possibility of ENM infused filaments

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

Presenter

Presentation Notes

Our exposure process is based on the NEAT 2.0 method. Original NEAT was focused more on emissions of nanomaterial. Since it came out we wanted a more robust sampling strategy with a stronger emphasis on worker exposure to develop a more accurate picture of exposure. NEAT 2.0 combines traditional industrial hygiene methods and new sampling techniques. I do want to point out that this really is a guideline, and not a prescriptive thing like a NIOSH numbered method. We may go to a site and not perform EM. NEAT 2.0 is a comprehensive assessment of emission and exposure, and I’ll briefly go through some of the process, with more time spent on implementing the sampling plan. But in general it an evaluation of worker exposures, combined with worker practices, ventilation efficacy, and other engineering exposure control systems and risk management strategies serve to allow for a comprehensive exposure assessment. The first part is collecting basic workplace information. This would include looking at SDS for print materials, looking at how many workers involved in processes, what is the ventilation setup and engineering controls, frequency, duration of printing, etc. Then we design and implement a sampling strategy based on that info.

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

Presenter

Presentation Notes

Also non-process areas for process migration Transmission electron microscopy (TEM) / scanning electron microscopy (SEM) sampling for identification, sizing and morphology (if engineered nanomaterials involved) identification, sizing and morphology

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

Presenter

Presentation Notes

Mention VOCs too

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

Presenter

Presentation Notes

AMMFT typically uses a CPC and aerosol photometer for most evaluations. These two instruments can cover a wide range of particle sizes but do not provide particle sizing specifically.

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

Presenter

Presentation Notes

No material identification, can’t tell if it is a plastic particulate or piece of dust. It’s not just ultrafine particles, wide size range of particles measured 0.01 – 10 µm Designed to measure particles not fibers Use data with caution since there are many interfering incidental fine particles – take good notes with time stamps No OELs like “this many particles per cubic centimeter”

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 -

http://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)

Presenter

Presentation Notes

Also point out to look at where ventilation goes – is it connected to office lab next door? Or goes out the top of the roof

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

Presenter

Presentation Notes

Good to observe workplace environment, and how much/often/volume of printing performed. They may say it is 24/7 printing, but are 5 printers running all the time? Is it actually a 6 hour build, with two hours of prep? Good to note these things. Housekeeping – is it performed at end of day? End of week? As needed? How is it performed? Wet wiping or sweeping up with broom? Look at training and programs that may be in place. Are 3D printing activities incorporated into SOPs? Workers know about SDS for filament or metal powders? Incorporated into respiratory protection program if wearing respirators?

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

Presenter

Presentation Notes

Field team has conducted 13 site visits covering FFF with thermoplastics (with and without nanomaterials), SLA, Polyjet, and direct metal melting or sintering. We bring the LAB to the field to collect actual workplace exposure data in an attempt to better understand the laboratory studies and relate real world exposure levels to the Toxicological studies. Most common findings are that while we do not yet know the “safe” or target level of exposure for most of these materials and processes, traditional IH safety, control and work practice guidance is effective in reducing or eliminating exposures. Reduced/restricted access, LEV and other engineering controls as well as focus good work practices such as proper powder handling and PPE use and disposal, and good housekeeping all are effective. 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 among the interested partners.


• 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.


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.

Presenter

Presentation Notes

Published the Blog and Poster- another study of multi printer working environment in review. Lab based studies/ Pubs- info from Stefaniak •Emission rate characterization •Emission toxicology oPub with WVU- demonstrated acute CV effects from single inhalation exposure of 3D printer emissions from ABS polymer in rats oOngoing studies by Yong Qian’s group to investigate in vitro toxicity to lung cells oPreliminary data suggest differential cytotoxicity between ABS and PC oAdditionally, Yong Qian is leading a collaborative effort with CPSC to fund larger scale more in depth animal toxicology studies in vitro and in vivo for a number of pulmonary and cardiovascular endpoints

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

Presenter

Presentation Notes

Currently Testing a NIOSH developed control for FFF printers that can be assembled for <$75and greater than 98% capture efficiency - you Chart one shows the particle size distribution of four different filaments, with the majority of the particulate being <100nm. Chart two demonstrates how much the emission rate can change dependent on the filament. PLA 1 emitted particles at the highest rate for the four we were able to test, so we used it in our LEV tests to provide the greatest challenge to our device. Charts three and four show the effectiveness of our control and calculations determined a >98% reduction in particulate emission release in the chamber, reducing emissions to levels very near those of the lowest emitting feedstock in the initial tests. Cost of the device > $75

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

Presenter

Presentation Notes

As its prevalence in industry has increased, so has its popularity in makerspaces. A makerspace is a place in which people with shared interests, especially in computing or technology, can gather to work on projects while sharing ideas, equipment, and knowledge. The rapidly evolving printing process has resulted in work practices, potential employee exposures, and engineering controls that have not yet been fully evaluated

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

http://www.cdc.gov/niosh/topics/nanotech/

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