Heath and Safety Considerations for 3-D Printers in the Era of Rapid Prototyping. Andrew Kalil CIH,CSP MIT Lincoln Laboratory

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1 Heath and Safety Considerations for 3-D Printers in the Era of Rapid Prototyping Andrew Kalil CIH,CSP MIT Lincoln Laboratory

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6 What is 3-D printing? In contrast to subtractive manufacturing technologies like machining that start with a solid block 3-D printing is an additive process for making threedimensional solid objects layer by layer of virtually any shape from 3-D digital models. Several 3-D printing technologies, large variations within technologies

7 Rapid Prototyping is: Rapid Prototyping The fast manufacture of prototypes for different purposes including ergonomic and visual trials, assessment of functional performance, supporting parts to other processes. New tools and refinements to old technologies have greatly cut lead times for prototyping Instead of months the time between concept and prototype is weeks

8 Rapid Prototyping and 3-D Printers 3-D printing is one of the tools driving rapid prototyping advances. It allows: Quick turnaround and cost reduction by keeping fabrication in-house Additive process allows fabrication of parts that can t be made otherwise. Try several variations on a design o Facilitates exploration of novel designs and allows fine-tuning of concepts.

9 3-D Printing Technologies Material Extrusion [Fused Deposition Modeling (FDM)] o a thermoplastic material is extruded through a temperaturecontrolled print head in a semi-liquid state Vat Polymerization [Stereolithography (SLA)] o a bath of liquid ultraviolet curable photopolymer "resin" and an ultraviolet (UV) laser or digital light processing lamp Material Jetting o For material jetting droplets of the build material are deposited by an array of nozzles like that of a 2D office printer.

10 3-D Printing Technologies (cont) Binder Jetting o Binder jetting works by gluing particles of the build material together. A thin layer of material as spread and then glued at that specific layer into the desired cross section. Powder Bed Fusion [Selective Laser Sintering (SLS)] o Powder bed fusion is very similar to binder jetting except instead of adhering the particles together with a binder they are thermally bonded. A roller spreads a thin layer of heated material, and a laser fuses (sinters) it into a solid form in the desired cross sectional shape. Directed Energy Deposition Focused thermal energy is used to fuse materials (typically metals) as they are deposited. Sheet Lamination o With sheet lamination (also known as Selective Deposition Lamination) material is cut and bonded with an adhesive layer by layer to create the complete object. This can be done with paper

11 Production Systems vs. Personal It can be useful to classify 3-D systems into two categories. o small personal printers usually suitable for prototyping simple objects o large production systems capable of producing precise, complex prototypes, models or tools. Due to increased capabilities, production systems are larger than personal printers and often have machine shop-oriented requirements for power, temperature and humidity control, debris containment, ventilation and parts cleaning. Cubify (desktop size) Fortus 400mc (production system)

12 Stereolithography Stereolithography is an additive manufacturing process which employs a bath of liquid ultraviolet curable photopolymer "resin" and an ultraviolet (UV) laser or digital light processing lamp that traces a cross-section of the part pattern on the surface of the liquid resin. Exposure to the ultraviolet laser light cures and solidifies the pattern traced on the resin and joins it to the layer below.

13 Why do these printers belong?? The xxxxx is designed to be a desktop printer. You can have it in the office without any health worries. You can find our Material Safety Data Sheets on the bottom of this page. If I can answer any other questions let me know. --Manufacturer The ltra is a production printer, no local exhaust ventilation.

14 MSDS for desktop printer (Methacrylate Photopolymer Resin)

15 Switching Resins with the larger printer

16 FDM and FFF FDM builds three-dimensional parts by melting and advancing a fine ribbon of plastic through a computer-controlled extrusion head, producing parts that are ready to use. Fused Filament Fabrication Technology (FFF) is another term for essentially the same process

17 FDM and FFF For most applications two materials: o o ABS(acrylonitrile butadiene styrene) plastic (think Lego) PLA (Polylactic acid), a biodegradable polymer, which is produced from organic material. Different plastics melt at different temperatures -- and in different ways. PLA makes a solid to liquid transition, like that of ice to water, and melts at extrusion temperatures from about 180C up. It also gets shinier and, with translucent colors, clearer when it's extruded at higher temperatures. ABS makes a more gradual transition, and softens enough to be extruded somewhere around 215C.

18 Removing support structures with a caustic solution Sodium Hydroxide Solution o Should it be vented? o Should be it in a lab or machine shop Is the spent solution hazardous waste? o May be close to neutral. Rely on ph? o Lots of solids though. Filter before removal Does this process belong in an office area?

19 Some Measurements of 3-D Printers

20 Some Measurements of 3-D Printers Ambient Location At Start-Up Particles/cc TSI 3007 CPC 2,000(initial) 7,000 (after 10 min) Printer 1 158, , ppm Printer 2 150, , ppm Location After 15 min Particles/cc TSI 3007 CPC Ambient 2,000 - Printer 1 4, ppm Printer 2 3, ppm - TVOC Ion Science Tiger TVOC Ion Science Tiger

21 Measurement of SST Dimension and Photocopier Location Particles/cc TSI 3007 CPC Ambient 1,500 and Printer 3 (enclosed) 1,500 - Photocopier 10,000 - TVOC Ion Science Tiger Photocopier Printer 3

22 Reasons for the observed particle counts? Anecdotally the printer heads run hot until they stabilize when first started. SST Dimension 1200ES is an enclosed system Appears that enclosing systems reduces measured exposures

23 Powder Bed Fusion Selective Laser Sintering (SLS) A roller spreads a thin layer of heated material, and a laser fuses (sinters) it into a solid form in the desired cross sectional shape. Health and safety concerns with this technology vary depending on the type and particle size of the powder being used. These systems may require a separate area with exhaust ventilation and specialized equipment for parts finishing and powder mixing. The 3-D printer may also require exhaust ventilation.

24 Possible Needed Accessories for Plastic Powder SLS processes mixer ventilation Explosion proof vacuum

25 Needed Accessories Breakout Station Parts Cleaning Cabinet

26 Combustible Dust Explosive Concentration Ignition energy will it take just a spark to ignite? Is any dust leaking out of the enclosure. May be a variety of materials Handling methods differ by manufacturer

27 EH&S concerns for DMLS (Direct Metal Laser Sintering) Powder handling procedures o M anufacturers vary in proposed solutions High Powered Laser 400W Maintenance of inert gas (Argon) filter

28 Metal Powder SDS

29 Summary As with any tool or equipment having possible safety concerns, the EHS and Facilities should be consulted when a new 3-D printer is considered for acquisition. Personal printers should be used in areas with adequate ventilation. Prior to the purchase, it is important to consider all facility, site and safety requirements from the manufacturer and EHS. These requirements may be quite extensive depending on the printing technology and model and often include a separate area for finishing.