The Additive Manufacturing section of this blog is for PADT customers in particular, and users of 3D Printing in general. We hope you find it useful and entertaining.
Over time we will post information below. Feel free to use the search to find specific information. We also have some non-changing information on our resource page.
Posted on July 20, 2017, by: Dhruv Bhate, PhDWhat waste streams are generated in powder-based metal 3D printing? Are they hazardous? How should they be disposed responsibly? This is the fourth part of a 5-part series discussing things we learned installing a metal 3D printer (specifically, a laser powder bed fusion machine). If you haven't already done so, please read the previous parts using the links below.
- Part 1: Equipment
- Part 2: Facilities
- Part 3A: Safety Risks
- Part 3B: Safety Risks - Prevention & Mitigation
1. Sources of WasteAs shown in Figure 1 below, metal powder used in this process ends up in dry and wet waste. The dry waste can be composed of wipes and gloves with powder and soot, and the wet waste is mostly composed of water and suspended metal particles (from the wet separator and ultrasonic cleaner), and for reactive alloys, can also consist of filter cartridges that need to be suspended in water throughout. Because the wastes contain metal powders, we must stop and ask if this is safe for sending to our landfills and into our sewers where there is a risk of contaminating groundwater and creating other long term environmental havoc. Thus, the first question is: are these wastes hazardous?
2. Is this Waste Hazardous?There are two sources for this information: the EPA (in the US) and the powder supplier's data sheets. It helps to begin by understanding some definitions - statements in italics are quoted from the EPA, the rest of the text is mine.
- Waste: "A waste is any solid, liquid, or contained gaseous material that is discarded by being disposed of, burned or incinerated, or recycled"
- Hazardous Waste: There are several types of hazardous waste and associated definitions of each. The two main categories are:
- Listed Waste: "Your waste is considered hazardous if it appears on one of four lists published in the Code of Federal Regulations (40 CFR Part 261)." I have looked at this list and to the best of my knowledge, no metal powders of concern to the metal 3D printing process appear on this list (as of July 10, 2017). The metal powders currently used are also not considered acute hazards.
- Characteristic Waste: In addition to listed wastes, the EPA specifies certain characteristics that a waste may possess (even if not listed) that would make it hazardous. In the context of metal powders, the potentially relevant categories are:
- "It catches fire under certain conditions. This is known as an ignitable waste".
- "It is harmful or fatal when ingested or absorbed, or it leaches toxic chemicals into the soil or ground water when disposed of on land. This is known as a toxic waste."
- Dry Waste: We know that given the right conditions and an ignition source, that these powders, especially reactive alloys and combustion products, can ignite.
- Wet Waste: We also know that while water serves as a passivation for powders, we cannot guarantee that the powder will always stay in wet state if it is not disposed as such. Evaporation, for example, can leave behind combustible powder.
3. What Regulations do I need to be aware of?The EPA established three categories of waste generators in their regulations, listed below along with the relevant quantity of waste generated and stored, for our purposes (visit EPA's site for the full list, this is not comprehensive) - EPA cites these numbers in hundreds and thousands of kilograms, hence the strange numbers below (in lbs): Note this is the sum total of all hazardous wastes your site is generating (in our case, dry and wet wastes combined), not a limit per category. Depending on what category you fall in, you will need to follow EPA's regulations, available here. Additionally, some states may have additional regulations and this is where I only have studied this problem for my home state of Arizona, which is in line with the EPA's federal guidelines and does not, to the best of my knowledge, impose additional restrictions. The full list by state is here. If you are a "Very Small Quantity Generator" as we are at PADT, the regulations are fairly straightforward and involve three items (quoted from the EPA's site) - the requirements are more stringent for larger quantities.
- VSQGs must identify all the hazardous waste generated.
- VSQGs may not accumulate more than 1,000 kilograms of hazardous waste at any time.
- VSQGs must ensure that hazardous waste is delivered to a person or facility who is authorized to manage it.
4. OpinionAs with all regulations, one can approach them by focusing on the specificity of the language. While this is important, it is also useful to seek to understand the intent of the regulation. When it comes to these wastes, I ask if I would be comfortable carrying it in my car and disposing it in my hypothetical backyard landfill (dry waste) or my local water body (wet waste) - and the answer to both, for me, is a NO. So why should I ask my city to do this? This is understandably an exaggerated way of looking at the problem, but I believe at a minimum, serves as a risk-conservative upper-bound that is useful when addressing uncertainty in these matters.
- EPA, Hazardous Waste Generators Home Page
- EPA, Categories of Waste Generators
- EPA e-CFR, Title 40, Part 261
- US Environmental Agencies by state
- This is intended to supplement the supplier training you must receive before using the equipment and not meant to replace it – in case of conflicting information, your supplier’s training and equipment requirements override any discussion here.
- Local, state and federal regulations vary, and are important – partner with your local environmental authorities when making decisions
- My personal experience derives specifically from the use of Laser-based metal 3D printing tools, specifically Concept Laser’s MLab Cusing R equipment. I expect majority of this information to be of use to users of other laser based powder bed fusion metal systems and to a lesser extent to Electron Beam systems, but have no personal experience to vouch for this.
- PADT and the author assume no legal responsibilities for any decisions or actions taken by the readers of this document or of subsequent information generated from it.
Posted on July 18, 2017, by: Dhruv Bhate, PhDHow can you minimize safety risks in powder-based metal 3D printing? This is my fourth post discussing things we learned installing a metal 3D printer (specifically, a laser powder bed fusion machine). If you haven't already done so, please read the previous posts using the links below, in particular part 3A which is a prequel to this post. I also recommend reading my post on the difference between reactive and non-reactive alloys in the context of this process.
- Part 1: Equipment
- Part 2: Facilities
- Part 3A: Safety Risks
- Reactive & Non-Reactive Metal Alloys in Laser Powder Bed Fusion
Risk 1: Fire and Explosion
1.1 Prevention:The key to preventing a fire is to remember that it needs three things ("the fire triangle"): fuel (metal powder or soot), an ignition source (laser or spark) and oxygen. While certified equipment is designed to operate in a safe manner when bringing the laser and the metal powder in contact by doing so in an inert gas environment, you as the operator, are responsible for avoiding any ignition sources when handling powder or soot outside of the inert environment. This is because two of the three aspects have been met: fuel (powder or soot) and oxygen (in the ambient). As long as basic risks are eliminated (sparking equipment, smoking etc.), the primary risk that remains is Electro Static Discharge (ESD) and thus the main piece of preventive equipment is an ESD wrist-strap, as shown in Figure 1, or equivalent ESD management methods. It helps to appreciate the life cycle of the powder, as it goes from purchased jar to ending up returned as recycled powder (the majority of the powder), or in the wet or dry waste streams. This is shown in Figure 2. While this looks quite complex, coming out of the machine, the powder and soot only have 4 streams that you have to follow: the powder trapped in the part, the powder that you will recycle, the soot and powder trapped in the filter and finally, what will be cleaned with wipes and accumulate on gloves. While this is not comprehensive (internal hoses and shafts can also accumulate powder), these are the ones operators will deal with on a regular basis.
1.2 Mitigation:In addition to doing everything we can to prevent fire, we also need to be prepared in case it does happen. There are (at least) four aspects that need to be considered, dealt with in turn below: 1.2.1 Personal Protective Equipment (PPE) PPE is your self-defense in case of a fire and it is thus a critical element of the safety procedures you need to pay attention to and remember. Tasks are of varying risks, and our supplier recommends PPE for this process in three categories:
- Protective Clothing: A lab-coat that covers your arms, protective gloves, ESD strap if working with reactive metals
- Standard PPE: Respirator, nitrile gloves, face mask (if not integrated with respirator), ESD strap
- Extended PPE: Standard PPE PLUS fire-rated bunny suit, fire-rated gloves (see Figure 3)
- Always wear gloves, goggles and protective clothing (lab-coat) when you work with the machine - make this a rule even for the simplest of tasks like using the keyboard and mouse
- If you are directly handling (i.e. not through a glove box) virgin or recycled non-reactive metal alloy powder (i.e. no reactive powders or combustion products), standard PPE is adequate
- For everything else, you need extended PPE
Risk 2: Powder Inhalation and Contact
2.1 PreventionThe main method of minimizing risk of powder inhalation is through the use of a respirator. These come in many forms, but the two most recommended ones for this process are respirators with built-in face-masks (as shown in Figure 3), and more preferable, the PAPR respirator, which delivers a positive pressure of air (for more information, read OSHA's guide on respirators). N95 and higher respirator filters are recommended, though N100 are ideal. Contact with powder is avoided by wearing gloves at all times when handling the machine. It is also useful to minimize risk of carrying powder outside the metal 3D printer area:
- Before starting work, put away watches, wrist jewelry and cell phones.
- Once done with the work, take off your protective coat and wash your hands and arms up to elbows before handling anything else.
- Consider installing an adhesive floor mat for you to step on as you walk out of the room.
2.2 MitigationWhat to do in case of exposure is typically documented in the SDS (Safety Data Sheets), which is specific to the material in question, as shown in Figure 6 below. Ensure you have an SDS from your powder supplier for all powders you order, and collect them in a folder that is stored close to the entrance for easy retrieval, as shown in Figure 7.
Risk 3: Inert Gas Asphyxiation
3.1 PreventionInert gas (Nitrogen or Argon) is used for every build and is either stored in cylinders (argon) or piped from a generator (Nitrogen). Proper, leak-free facilities setup and equipment performance is essential, as is following recommended supplier maintenance on the equipment itself. An inability to drop to required oxygen PPM levels in the build chamber, or large fluctuations in maintaining them may be associated with a leak and should be addressed with the supplier before proceeding. Users of the equipment must know where the shut-off valves for the gases are, in case they need to turn it off for any reason.
3.2 MitigationThe main mitigation device is an Oxygen sensor such as the one in Figure 7. This is an important sensor to have especially in confined spaces around any equipment that relies on inert gases, including the 3D printer and furnace. If oxygen levels fall below safe values, an alarm is triggered and immediate evacuation is required.
- National Fire Protection Association’s standard for combustible metals, NFPA 484
- OSHA on Oxygen Deficiency
- OSHA’s Guidance on Dust Explosions
- OSHA Respirator guide
- J.M. Benson, “Safety considerations when handling metal powders,” Southern African Institute of Mining and Metallurgy, 2012
- R. G. Goldich, “Fundamentals of Particle Technology,” Chapter 15, Midland IT and Publishing, UK, 2002
- This is intended to supplement the supplier training you must receive before using the equipment and not meant to replace it – in case of conflicting information, your supplier’s training and equipment requirements override any discussion here. PADT and the author assume no legal responsibilities for any decisions or actions taken by the readers of this document.
- My personal experience derives specifically from the use of Laser-based metal 3D printing tools, specifically Concept Laser’s MLab Cusing R equipment. I expect majority of this information to be of use to users of other laser based powder bed fusion metal systems and to a lesser extent to Electron Beam systems, but have no personal experience to vouch for this.
- Local, state and federal regulations vary, and are important – partner with your local fire marshal (or equivalent authority) as a starting point and take them along with you every step of the way. If in the US, familiarize yourself in particular with OSHA’s guidance on dust explosions and NFPA 484, the National Fire Protection Association’s standard for combustible metals (links above).
Posted on July 12, 2017, by: Jeannie Kozicki
1. Background:When it comes to Additive Manufacturing (AM), there is a lot to consider before hitting the print button. One of the biggest constraints in most AM processes is the need for supports for overhangs, which are aspects of the design that will not print properly without supports either due to the force of gravity acting on the material (natural free-falling state of the material with no support forcing it into position), or the thermomechanical effects associated with printing with no underlying thermally conductive and warpage-constraining material. The solution is to either redesign any of the problem areas or reorient the whole piece to avoid any overhangs that need these supports. During my internship at PADT Inc., I will be focusing on strategies to minimize the need for supports, towards the ideal goal of manufacturing only self-supporting structures, because it’s never a bad idea to decrease waste, both in terms of additional material used and the labor involved in removing the support materials after the print. This post (part 1) of this blog series is going to be about evaluating the most basic guidelines of printing a self-supporting structure to extract some insight.
2. Methodology:Using inspiration from some machine accuracy tests found online, I designed my own prints to evaluate the Makerbot Replicator 5th generation’s ability to print overhangs using angles, upright holes, bridges, arched bridges, and 90 degree overhangs—and I present each one of these standard guidelines below. My process parameters for almost all of the tests with, of course, supports OFF were as follows:
- Extruder Temp: 212 C
- Travel Speed: 70 mm/s
- Infill Density: 10%
- Layer Height: 0.20 mm
- Number of Shells: 2
3. Observations:3.1 Angles For testing overhangs with angles, I printed out two different sets of trapezoids. The first was a set of six ranging from 25-75 degrees (or 65-15 degrees from the leveled plane).
As shown by the photos above, the prints were of good quality and only started to show visibly poor quality on the 65 and 75 degree samples. The thinnest edge on the 65 degree sample curled up due to the heat of the extruder. The same issues were present on the 75 degree piece, but this is more exaggerated because of how harsh the angle is.
My hope of printing self-supporting pieces was shattered when I printed out an 85 degree trapezoid. To save material, I only printed out a section of the trapezoid, but the angled edge did not print smoothly at all. Not only that, but it did not print at a true 85 degree angle. With these tests, it is safe to say that a machine can handle up to a 65 degree angle with light finishing needed, but further experimentation can be done to see if these angles can be improved.3.2 Upright Holes
For these, I did 2 quick tests. The first was printed with the settings listed above, and the second was printed with only one shell (contour). The numbers next to the circles (1, 2, 4, 6, 8, 10) represent the radii in millimeters. The double-shelled print came out a lot better than the single-shell replica on the edges of the piece, but the single-shelled piece had slightly cleaner holes due to less weight on the overhang. However, both pieces had defects that can easily be sanded down. 3.3 “H” Overhangs/Bridges
Bridges are sometimes referred to as an “H” overhang due to the overhang having two sides to support it. When testing bridges with 90 degree overhangs of 0.25, 0.75, 1.25, 1.75, and 2.25 inches, the results showed increasing stringing with length for all but the 0.25 inch sample.3.4 Arched Bridges
The inspiration for these came from the shape of an egg. That’s because I learned during an egg drop lab that an egg is stronger when weight is being put on it length-wise than if the sides are pinched. As expected, the pieces where the curves are less steep (like an egg laying so the shorter distance is perpendicular to the ground) have more defects, and the steepest curve (as if the top of an egg was the mold for this piece) was almost perfect. The wider the curve becomes, the less it can support itself and the more the piece is unrecoverable. 3.5 “T” Overhangs/Cantilevers
The final test for this section is the “T” overhang, which only has a support on one side. This happened to be the only test that completely failed, as none of these pieces are usable - it’s safe to say that pieces should not be made without supports on both side of the overhang.
4. InsightA rule-of-thumb “overhang rule” used in the industry is that a piece can be self-supporting as long as the overhang does not exceed the angle to the horizontal by more than 45 degrees. A back-of-the-envelope (literally) calculation shows that if we approximate an angular edge with stair-steps of thickness t, the overhang length l equals t/tan(Θ). According to this equation, this means that to increase the allowable angle, the layer thickness can be increased or the unsupported length should be reduced. This observation is confirmed by a previous investigation into the angles of self-support for ULTEM-9085 on Stratasys Fortus systems showed how the maximum angle that can be self-supported is indeed a function of layer thickness, but also a function of the contour width (see graph below). In the graph, the lower the angle, the lesser the support needed, since everything above that angle will need to be supported. Thus, thicker layers result in lesser support. Due to the nature of contouring in the FDM processes, a thin contour that forms the edge of the overhang is likely to droop off. But as it gets thicker, it maintains greater contact with the supported portion. The fact that thicker layers and contour widths may yield larger support angles is counter intuitive since we generally assume thinner layers improve print quality - and this is in general true. But if the aim is to design parts without supports, both these variables can push the limits of the process.
5. ConclusionsBasic design guidelines for overhangs can be, to a first order, simplified to one design rule: the angle below which material needs to be supported. This angle in turn, for the Fused Deposition Modeling process on a given machine and material, can be optimized by manipulating layer thickness and contour width. In my next post, I will look for inspiration for self-supporting strategies from other disciplines. Stay tuned.
Posted on July 6, 2017, by: Eric MillerThe world of 3-D printing is changing fast. New materials are announced and new systems are proposed almost every month. And as with any fast-growing technology, there is a lot of hype. When something is announced it will get a lot of press and attention, but what do you really need to know to follow the industry? In "Five 3-D printing breakthroughs everyone needs to know about" I take a look at the changes that should have the most impact on product development.
Aerospace Summit, Additive Manufacturing Peer Group, and Industry-Education Partnership – A Three Event, Three State Hat Trick
Posted on June 23, 2017, by: Eric MillerSometimes everything happens at once. This June 22nd was one of those days. Three key events were scheduled for the same time in three different states and we needed to be at all of them. So everyone stepped up and pulled it off, and hopefully some of you reading this were at one of these fantastic events. Combined they are a great example of PADT's commitment to the local technology ecosystem, showing how we create true win-win partnerships across organizations and geographies. Since the beginning we wanted to be more than just a re-seller or just consultants, and this Thursday was a chance to show our commitment to doing just that.
Albuquerque: New Mexico Technology Council 3D Printing Peer Group KickoffEveryone talks about how they thing we should all work together, but there never seems to be someone who is willing to pull it all together. That is how the additive manufacturing committee in New Mexico was until the New Mexico Technology Council (NMTC) stepped up to host a peer group around 3D Printing. Even though it was a record 103f in Albuquerque, 35 brave 3D Printing enthusiasts ventured out into the heat and joined us at Rio Bravo Brewing to get the ball rolling on creating a cooperative community. We started with an introduction from NMTC, followed by an overview of what we want to achieve with the group. Our goals are:
- Create stronger cooperation between companies, schools, and individuals involved in 3D Printing in New Mexico
- Foster cooperation between organizations to increase the benefits of 3D Printing to New Mexico
- Make a contribution to New Mexico STEM education in the area of 3D Printing
Once that was done PADT's Rey Chu gave a presentation where it went over the most important developments in Additive Manufacturing over the last year or so. He talked about the three new technologies that are making an impact, new materials, and what is happening business wise. Check out his slides to learn more: NMTC-PADT-New-3D-Printing-2017_06_22
After a question and answer period we had some great conversations in small groups, which was the most valuable part. If you want to learn more, please reach out to firstname.lastname@example.org and we will add you to the email list where we will plan and execute future activities. We are also looking for people to be on the steering committee and locations for our next couple of meetings. Share this with as many people as you can in New Mexico so that next event can be even better!
Denver: MSU Advance Manufacturing & Engineering Sciences Building OpeningMeanwhile, in Denver it was raining. In spite of that, supporters of educating the next generation of manufacturers and engineers gathered for the opening of the Advanced Manufacturing and Engineering Sciences Building at Metropolitan State University. This 142,000 sqft multi-disciplinary facility is located in the heart of downtown Denver and will house classes, labs, and local companies. PADT was there to not only celebrate the whole facility, but we were especially excited about the new 3D Printing lab that is being funded by a $1 million gift from Lockheed Martin. A nice new Stratasys Fortus 900 is the centerpiece of the facility. It will be a while before the lab itself is done, so watch for an invite to the grand opening. While we wait we are working with MSU, Lockheed Martin, Stratasys, and others to put a plan together to develop the curriculum for future classes and making sure that the engineers needed for this technology are available for the expected explosion of use of this technology. email@example.com or give us a call. Phoenix: 2017 Aerospace, Aviation, Defense + Manufacturing Conference The 113f high in Phoenix really didn't stop anyone from coming to the AADM conference. This annual event was at ASU SkySong in Phoenix and is sponsored by the AZ Tech Council, AZ Commerce Authority, and RevAZ. PADT was proud to not only be a sponsor, but also have a booth, participate in the advanced manufacturing panel discussion, and do a short partner presentation about what we do for our Aerospace and Defense Customers. PADT-AeroConf-AZTC-2017
We had great conversations at our booth with existing customers, partners, and a few people that were new to us. This is always one of the best events of the summer, and we look forward to next year. If you want to know more about how PADT can help you in your Aerospace, Defense, and Manufacturing efforts, reach out and contact us.
Posted on June 22, 2017, by: Eric MillerOne of the fun things I get to do is design and print cool things to share what you can do with 3D Printing. This has extended to making awards for organizations that PADT supports like the Arizona Technology Council, The Arizona SciTech Festival, and AZBio. Recently our favorite incubator asked us to design a custom award for their first Impact and Innovation Celebration. The request was to incorporate the CEI logo: Taking a 2D image and making it 3D can be a lot of fun, and in this case it showcased some cool things you can do with 3D CAD and then 3D Printing. There were some special steps needed to get this one done so I thought I'd share them. The basic concept was to take the initials, CEI, and create a block that can serve as base. Then extrude the orange line-circle geometry as the key visual object. But the thing that sets the logo apart from most, is the use of the succulent plant, an agave I think, in the logo. So we definitely need a 3D agave on there. The last element needed was the actual award part, where the name and award being given could be listed. To get started I needed to get the logo into the CAD system I use, SolidEdge. Usually I convert a PDF into DXF in Adobe Illustrator. I then imported this into sketch planes. But in this case I only had a bitmap (PNG) Fortunately you can paste that into a sketch plan as well, then just draw on top of it. So I made three planes: Front facing and one rotated 45 deg and another -45 about the Z axis. I then pasted the logo on to each of these centering the bottom center of the E on the global axis. This allows me to extrude and cut on each plan while keeping everything aligned The base was made by extruding the initials from the +45/-56 planes and doing a Boolean intersect, This gives the letters from two views while creating a "3D-ness" That stands out. The circle-line was then extruded on the front plane to cover the block created by the intersection. It needed a "foundation" as well as a way to hold the letters together, so I just made a simple base. That left the agave. I thought about modeling it but nah... too much work. So I went online and found a bunch of plants that people have made for video games and rendering. Cool except the format was not STL, what we need for 3D Printing. So I downloaded some crazy rendering format. Then I used a free online tool (thank you google, sorry I didn't write down the one I used) that converts between 3D graphics files. That took it to STL where I could read it into Meshlab, the open source tool for playing with this type of data. As usually with models made for graphics ,there was a lot of extra data and coordinate systems didn't really translate right. No problem, Meshlab makes it easy to select and delete objects. I also scaled it from gigantic to the size I needed for the award. Next step was to save that as STL and import that into SolidEdge so I could view it and position it properly on the award. Last was the award part itself. I played with a couple of ideas and just came up with a simple plaque that we could 3D print words on. i made it white and the "holder" blue to stand out. Then printed the award name and winner in bright colors using the text extrusion feature in SolidEdge. When I need to get fancy, I'll do the words and often a logo in Illustrator, export as DXF, then import as a sketch for extrusion. But in this case a nice simple Bold Arial font worked great. So it was done, and I have to say looked pretty good. So I asked our experts on 3D Printing if they had any suggestions. Their one comment was "this is really cool, but its going to be expensive to print as one part." Duh, I should have paid more attention in my own seminar on design for 3D Printing. I had tall thin objects and bulky objects and they were all combined. Lots of unneeded supports and flat surfaces at non-vertical or horizontal angles in the printer. Bad stuff. The solution was to design the parts so they could be printed separately and easily assembled. The resulted in an STL for the base, for the circle-line, the frame, the agave, and the award plaque with simple features that would allow us to quickly glue it all together. We also decided to print the base on FDM because it needed to be white and used the bulk of the material, and therefore cost. The rest was printed on a Stratasys Polyjet printer in color. One more change worth noting was how to connect the crazy shapes of the agave needed some simple interface to the circle-line part. So I created a simple cylinder that intersected the base of the agave. In the printer we were able to combine the STL of the cylinder and the agave with two different colors. A cylindrical cut in the orange part made assembly easy. The results came out pretty nice, and the winners seemed to really like them. The great thing about 3D Printing is the restraints it removes on making things. You still have to plan it out to align with what the printers do well, but that doesn't take a lot of effort and the results are great .
Posted on May 24, 2017, by: Eric MillerWe are very pleased to announce the launch meeting of the newest New Mexico Technology Council peer group: 3D Printing. After the success of other peer groups, and a similar committee in the Arizona Technology Council, PADT is partnering with the NMTC to start a group focused on all things Additive Manufacturing, which is the more technical name for 3D Printing. Schools, businesses, and individuals who have any involvement or interest in this exciting and transformative technology will be able to network and organize to get greater value from 3D Printing. This includes understanding the technology, working together on research projects, and getting to know what services are available locally. It will also serve as a platform to coordinate the use of 3D printing in STEM education. For this launch event, PADT's Rey Chu will share his thoughts on the latest and most interesting advancements in 3D Printing. We will kick off the meeting with introductions around the room, then listen to Rey share his views on what is new and interesting in this industry, then talk about the peer group, answer questions, and start planning our next activities. At around 6:45 or so we will commence with the networking. Please contact PADT at firstname.lastname@example.org if you have any questions before the event. We hope to see you there. Don't forget to register, and please let anyone else you think might be interested know about the event.
Posted on May 16, 2017, by: Dhruv Bhate, PhDWhat are the safety risks in laser powder bed fusion metal 3D printing? This is the 3rd post in a series of 5 on things we learned installing a metal 3D printer (laser powder bed fusion). Links to previous posts are below:
- Part 1: Equipment needed (beyond the 3D printer)
- Part 2: Facilities requirements (electricity, water, ESD mats etc.)
1. Sources of RiskBroadly speaking, I like to think of two sources of risk in this process since as an operator of these machines you have to think differently about how you interact with these sources. 1.1 Metal Powder Metal 3D printing involves fusing together powder in a bed. Typical metal powders used for laser based 3D printing are spherical in shape and range from 10-70 microns in diameter, as shown in Figure 1. At this size, a metal can be prone to fire and explosion (under the right circumstances) and there is also the physiological concern of long-term inhalation of, and contact with, these powders. The powder also has a long life cycle and requires human interaction at many steps - from arriving in a container (as shown in Figure 2), through multiple recycling steps through final disposal. These risks come into play just when handling the powder (independent of its use in the process) - an additional risk comes from the melting process itself.
1.2 The Laser Fusion ProcessThe powder in the bed described before is fused together into a solid using a laser that locally melts the powder one layer at a time. This is conducted in an inert atmosphere (Argon or Nitrogen) and is the second source of risk since these gases can displace Oxygen from a closed environment. Additionally, the process of laser melting of metals creates vaporized soot (see video below), some of which deposits on the process chamber and in the extraction module and filter. The smoke particles can be even finer than the powder itself, and need to be cleaned out with care on a regular basis. https://youtu.be/BkubIhbveLY
2. RisksThere are 4 main risks arising from the laser powder bed fusion process: fire and explosion, powder inhalation and contact, inert gas asphyxiation and the environmental impact of the wastes generated.
2.1 Fire and ExplosionIn May 2014, OSHA cited a 3D printing company for 10 violations deriving from the workplace safety standards surrounding the operation of a metal 3D printer (including not having the proper Class D fire extinguisher). The disregard of multiple safety measures during a routine build setup procedure resulted in a fire which caused life-threatening burns to the operator of the printer. While this incident was the result of gross negligence, it is nonetheless a cautionary tale that should drive us to understand the fundamental reasons why a metal 3D printer can cause fires and to appreciate the underlying reasons for why suppliers recommend the safety measures they do. Fire and explosion require a combination of conditions as shown in the commonly cited image below used by OSHA and other agencies to communicate risks of powder handling. As shown in Fig. 3, when handling powder in ambient atmospheres (with oxygen), all that is needed is a suitable ignition source to initiate a fire. Further, if this occurs in the presence of a dust cloud with many particles dispersed in a contained area (such as a small room or an air duct), this could lead to a more damaging explosion.
- Fire: When handling metal powder, the user needs to be aware that she/he already has 2 of the 3 requirements of a fire met and the main aim must be to ensure protection against any ignition source. There are several sources that could cause an ignition, the most likely one for a user of a metal 3D printer is static electricity. Additionally, it is possible that a fire can be initiated by hot surfaces, flames, hot gases and particles, mechanically generated sparks and strayelectrical currents.
- Explosion: With regard to explosions, in addition to the 3 requirements above, dust clouds in contained areas can exacerbate any ignition to a much larger impact within milliseconds. Therefore, the prevention of the formation of metal dust clouds (as unlikely as that may seem), is of paramount importance.
2.2 Powder Inhalation & ContactAs discussed before, most metal 3D powder particles range in size from 10-70um. This is at the very edge of what is considered respirable and damaging to our lungs. While contact physically is to be avoided since it may initiate irritation and potential dermatitis, there is greater concern about the long-term inhalation exposure risks of these powders. Particles of the size range in this process can get deposited in the tracheo-bronchial region per Jenson  and Goldich . Ultimately, these particles are discharged from the body or swallowed, but effects of long term exposure for the wide range of metals and alloys is not fully studied - which is why suppliers insist on respirators (more on that in the next post). It is worth pointing out though, from the work published by Jenson and Goldich, that it appears that while metal 3D printing powders are small enough to travel past the nasal cavity if inhaled, their sizes are large enough that respiratory damage in the lungs is highly unlikely - only particles under 2 microns are at risk of making it all the way to the alveoli and causing lung disease .
2.3 Inert Gas AsphyxiationInert gases are used in laser metal 3D printers to reduce the reactivity of the metal for processing purposes. Most metal 3D printers either use Nitrogen or Argon. Inert gas asphyxiation is the main risk due to oxygen being displaced by either of these gases that have leaked for some reason. Since both gases are not detectable by humans, victims do not realize that they are inhaling air depleted of oxygen and as a result this can have a serious impact. The human body is used to atmospheric percentages of oxygen (21%) and values below 19.5% can be harmful and are defined as oxygen-deficient per OSHA . Thus, any user of nitrogen or argon gas (and this applies not just to any process using inert gases), especially in small spaces such as a closed room, needs to be aware of this risk and protect against it.
2.4 Environmental ImpactA key challenge with powder based processes lies in collecting and disposing the stray or "fugitive" powder from different locations such as the tool, PPE, containers and vacuum systems into temporary storage, during which the above risks of fire/explosion and inhalation remain. Additionally, the storage typically results in loose powder and solid waste as well as water with powder particles, both of which need to be disposed into the outside world and could pose an environmental hazard. I will discuss this further in a future post, when I attempt to look at some of the environmental aspects around this technology.
- This is intended to supplement the supplier training you must receive before using the equipment and not meant to replace it - in case of conflicting information, your supplier's training and equipment requirements override any discussion here. PADT assumes no legal responsibilities for any decisions or actions taken by the readers of this document.
- My personal experience derives specifically from the use of Laser-based metal 3D printing tools, specifically Concept Laser's MLab Cusing R equipment. I expect majority of this information to be of use to users of other laser based powder bed fusion metal systems and to a lesser extent to Electron Beam systems, but have no personal experience to vouch for this.
- Local, state and federal regulations vary, and are important - partner with your local fire marshal (or equivalent authority) as a starting point and take them along with you every step of the way. If in the US, familiarize yourself in particular with OSHA's guidance on dust explosions  and NFPA 484 , the National Fire Protection Association's standard for combustible metals (links below).
- J.M. Benson, "Safety considerations when handling metal powders," Southern African Institute of Mining and Metallurgy, 2012
- R. G. Goldich, "Fundamentals of Particle Technology," Chapter 15, Midland IT and Publishing, UK, 2002
- OSHA on Oxygen Deficiency
- OSHA's Guidance on Dust Explosions
- National Fire Protection Association's standard for combustible metals, NFPA 484
- D. Bhate, "Reactive and Non-Reactive Metal Alloys in Laser-based Powder Bed Fusion," PADT Blog Post, 2016
AcknowledgementsThank you to Perry Harlow-Leggett, the AM team at UL whose articles and webinars I have benefited from, and all the folks behind the scenes at OSHA and NFPA. ~ Continue to Part 3B below, where I address mitigation strategies to address the risks described in this post. In the meantime, please read my prior posts below if you haven't already, or send your inputs to me via message on LinkedIn. Thank you!
Posted on May 11, 2017, by: Trevor Rubinoff
Introducing New PolyJet Material: Agilus30
PADT is excited to introduce the newest polyjet material available from Stratasys, Agilus30! Agilus30 is a superior Rubber-like PolyJet photopolymer family ideal for advanced design verification and rapid prototyping.
Get more durable, tear-resistant prototypes that can stand up to repeated flexing and bending. With a Shore A value of 30 in clear or black, Agilus30 accurately simulates the look, feel and function of Rubber-like products. 3D print rubber surrounds, overmolds, soft-touch coatings, living hinges, jigs and fixtures, wearables, grips and seals with improved surface texture.
Agilus30 has applications in a number of areas, including:
Tooling needing rubber-like characteristics
Overmolding & many more!
Want to know more about PolyJet's toughest flexible material to date?
Join PADT's 3D Printing Application Engineer James Barker along with Stratasys Materials Business Manager Ken Burns for a presentation on the various benefits and attributes that Agilus30 has to offer, which machines are compatible with it, and how companies are making use of it's unique capabilities.
Posted on May 5, 2017, by: Eric MillerThe project to keep a 1944 P-51 Mustang flying was covered again, this time in 3D Metal Printing Magazine (Pg 23-33). Concept Laser worked with PADT to reverse engineer and print the exhaust manifold from a P-51 to keep it flying. Unlike the other article and video on the project, this reporter used this example as a great way to look at the readiness of military aircraft, and not just antique planes. As PADT's Rey Chu says "“This was a great exercise that’s suitable for numerous military applications and very relevant to the future use of 3D metal printing to maintain fleets in the field,” Chu says. “Maintaining spare-parts inventory has become a significant challenge, for example, to the Air Force. Additive manufacturing could be the solution.”
Posted on May 2, 2017, by: Eric MillerMostly we make boxes. Pretty boxes but the bulk of what we 3D Print is some sort of plastic box that people stuff electronics in to. Most of the time we also don't really know what customers do with the objects we make for them. But every once in a while you get involved in a project that really makes a difference. That could not be more true than two recent medical applications for 3D Printing that we worked on with Intermountain Healthcare (IHC) in Salt Lake City, Utah. KSL, a local TV station, did a story on our IHC was deploying 3D Printing to produce better outcomes for their patients. You can view the story here. PADT was fortunate enough to be part of two of the cases mentioned in the story. The first was a St George man who was feeling some pain in his back. He had a scan and they found 12 kidney stones. On top of that, his kidney was not in the right place and was distorted. PADT helped print a model of the scan so that the doctors could just get a real feel for what they were dealing with, and then plan the surgery. The second situation really pulled at our heart strings. A 10 year old boy needs heart surgery and its a complicated problem. They need a model fast so we worked with Stratasy to quickly print an accurate model so tha the surgeons could come up with a plan. We still have not heard how it went, they are scheduling things, but the feedback from the team was that the 3D model was extremely helpful. We are talking life saving. Both of these recent situations build on years of examples where we have worked the doctors and their technical assistance to convert scans of patients into usable 3D Models. If you are in the surgery or surgery planning space and want to learn more about how accurate 3D models printed directly from scan data can be used to improve patient outcome, contact PADT at email@example.com and we will connect you with our 3D Printing team.
Posted on April 25, 2017, by: Dhruv Bhate, PhDThis is part 2 of a 5-part post on the lessons we learned installing our first Metal 3D printer, a Concept Laser MLab Cusing R. Please read the first post if you haven't already, where I listed all the different equipment (in addition to the 3D printer itself) one needs to run this process, available at this link. A reminder at the outset: these posts are meant to be informative only, to give you a sense of what questions you need to ask and get answers to. Specific requirements will vary by equipment and your site specific needs.
1. ElectricalMost metal 3D printers, including the Concept Laser machines, are manufactured in Europe and have electrical requirements that differ from what most American machine shops are setup for (which is the scope of this section). If you have installed 230 V European equipment before and know what L-N and PE stand for and how they differ between European and American systems, you can skip this section. If not, read on. There are two key items here one needs to be aware of: first of course is the fact that these pieces of equipment typically run on single-phase 230 V (3-phase 400V for the very large machines like Concept Laser's XLine 2000R) as opposed to the standard 110V. Secondly, and this is easier to miss, European electrical connections have one "hot" line (L) for a single-phase, one Neutral line (N) and one Protected Earth (PE) - this is different from the US standard where you have 2 "hot" lines and 1 ground. The reason for these differences and how to address them electrically is beyond the scope of this post (or my understanding), but the main point is to have an electrician familiar with European codes review this early on. A dedicated custom transformer for all your European 230V equipment is one solution, and the one we employed here at PADT, as shown in Figure 1. (I rarely give shout-outs, but our experience with Fargo Electric on procuring a custom, affordable transformer was one of the best transactions I have ever had.)
2. Inert GasLaser melting of powder metals needs to be conducted in an inert atmosphere. Most suppliers recommend using Argon for Aluminum and Titanium alloys, but that Nitrogen is fine for the non-reactive alloys such as steel, Inconel and Cobalt-Chrome alloys. At PADT, we leveraged our existing nitrogen generator and added an additional line running to our metal 3D printer (Figure 2). Before doing this, you need to add up all the consumption rates for the machines (at their peaks) to make sure you don't exceed the generator's capabilities. It is a good idea to demarcate space for Argon cylinders should you need them at a later stage.
3. ESD Mats or Floors (for Reactive Metals)As we will see in the next blog post in this series, avoiding charge dissipation into metal powder is a key safety requirement for operating metal 3D printers - this is achieved through a range of strategies like ESD (Electro Static Discharge) armbands, grounding wires etc. If you plan on running reactive metals and especially if you expect to have many operators, an ESD coated floor with ESD shoes or boot straps, along with an ESD meter (like the one Honeywell installed at their facility) is a good strategy. From personal experience with ESD boot straps, I know these can be fickle in passing an ESD meter test. Connecting the ESD meter to the entryway door so entry is only provided after passing the test is one way to ensure only those with functioning straps enter the workspace. For those without this strategy, grounded ESD mats and ESD armbands connected to the machine are also alternative strategies which I will discuss in more detail in the next post. From a facilities standpoint, if you do want to enable ESD coated floors, boot straps and ESD meters, you need to plan this early, which is why I have included it here.
4. WaterAccess to running water is essential for cleaning the wet separator (vacuum) that is used for sucking up fugitive powder - ideally the water source is near your liquid waste storage so you can clean out the wet separator and pour the powder-contaminated water into storage. Alternatively, you can also use a garden sprayer for smaller machines, like we do at PADT. Fill up the sprayer with water and use it to rinse out the wet separator right on top of the waste storage bin. Another reason you need access to water is to passivate the filter. While not all OEMs recommend water passivation, Concept Laser does and we find it to be very user friendly, as I demonstrate in the video below (video starts 2:58 in, which is when I discuss filter passivation with water). https://youtu.be/0wQhXle6VEA?t=2m58s
5. Access ControlIt is important to restrict access to your metal AM laboratory through badge scanning or key pad entry to those who are trained on using the machine, and your building facilities team. It also helps to provide as much visibility through glass windows so that folks that are entering can study what activity is in progress before entering.
6. Structure & VentilationHere I move into the subjective (gray area) domain - I request anyone who has more specific information on these matters to kindly share them with me for inclusion in this post (with due credit). I have heard anecdotally that in some places the city has required the supplier to install blast walls and other explosion resistant infrastructure - yet others have not required such infrastructure (including ours). I am not well informed in this space and can only emphasize the need to have these discussions out in the open in the early stage of planning your facility and ask your city's building safety person if the walls you have planned (or already have installed) are adequate or not - this is likely to be a function of the amount and reactivity of the powder you are handling, proximity to vulnerable areas, human occupancy and other concerns. With regard to ventilation, the more open the space the better (these machines can heat up a small, closed room) - at the same time the space needs to be sealed off from the elements including wind. I know this too is a subjective matter, so discussions with city representatives are the best way to go.
-Please send any of your comments, questions or suggestions for improvement to firstname.lastname@example.org, citing this blog post, or connect with me on LinkedIn. And now go on to PART 3 (SAFETY) Acknowledgements Special thanks to Gregg Rand at PADT, Martin Perez (City of Phoenix) and Dave Tallman (City of Tempe), and engineers at Concept Laser Inc.
Posted on April 20, 2017, by: Trevor RubinoffFast, easy to use lightweighting for structural analysis is now only a few clicks away thanks to the introduction of Topology Optimization in ANSYS 18.
Engineers who use Finite Element Analysis (FEA) can reduce weight, materials, and cost without switching tools or environments. Along with this, Topology Optimization frees designers from constraints or preconceptions, helping to produce the best shape to fulfill their project's requirements.
Topology Optimization also works hand-in-hand with Additive Manufacturing; a form of 3D printing where parts are designed, validated, and then produced by adding layers of material until the full piece is formed. Pairing the two simply allows users to carry out the trend of more efficient manufacturing through the entirety of their process.
Join PADT's simulation support manager Ted Harris for a live presentation on the full benefits of introducing Topology Optimization into your manufacturing process. This webinar will cover:
A brief introduction into the background of Topology Optimization and Additive Manufacturing, along with an overview of it's capabilities
An explanation of the features available within this tool and a run through of it's user interface and overall usage
An in-depth look at some of the intricacies involved with using the tool as well as the effectiveness of it's design workflow
Posted on April 19, 2017, by: Eric MillerWhen I was asked to take part in a demonstration put on by one of our local communication companies, Cox Communications, showing off what a "smart home" looks like, I of course said yes. I love gadgets, and smart gadgets more. On top of that it was another chance to evangelise on the power of 3D Printing. And I got to hang out in a brand new luxury condo in Downtown Phoenix, a post kid lifestyle change that is very appealing. Plus we deal with customers designing and improving Internet of Things (IoT) devices all the time, and this is the perfect chance to see such products in action. So I packed up one of our Makerbots, none of our Fortus machines fits in the back of my Prius, and headed downtown. The first thing that shocked me was that I had the printer, my iPhone, iPad, and laptop connected to their network in about one minute. The printer showed up on the Makerbot Print app on my iPad and I was printing a part in about three minutes. The whole point of the demonstration was to show how the new high-speed Internet offering from Cox, Gigablast, can enable a true smart home. So I was focused on the speed of the connection to the Internet, which was fast. What I didn't get till I connected was that the speed and bandwidth of the WiFi in the house was even more important. When everything was connected, we had 55 devices on the local network talking to each other and the Internet. At one point I was downloading a large STL file to the printer while on a teleconference on my iPhone and my "roommate" was giving a violin lesson to one of his students in Canada. Oh, and the roomba started to vacuum the floor. On the balcony someone was giving a golf lesson and a doctor was diagnosing a patient in the master bedroom. That was on top of the smart kitchen gadgets. And it all worked. Yes, it all worked. I'm trying to convey shock and surprise because the reality is that nine times out of ten when I show up for some event, at a customer, or at a friends house and we try and connect things to the internet... it doesn't work. If you are a technical guy you know that feeling when your vacation or visit for dinner turns into an IT house call. All I could think of was how awesome it was that everything worked and it was fast. So I went to work printing little plastic Arizona style houses with COX on the roof. And then a reporter showed up. "3D Printing, interesting. Hmmmm... they are cool and all but really, what does that have to do with a smart house?" Damn reporters and their questions. I was still reveling in the fact that everything worked so well, I hadn't taken to time to think about the "so what." Then I thought about it. 3D Printing in the home is just now starting to take off, and the reason why is actually high-speed internet connections. If you wanted a 3D Printer in your home in the past you needed the printer, a high end computer, and some good 3D modeling software on that computer. Basically you had to create whatever you wanted to make. Unless you are a trained engineer, that may not be so easy. But with a well connected home you have access to places like Thingiverse and Grabcad to download stuff you want to print. And if you do want to create your own, you can go to Tinkercad or Onshape and use a free online 3D modeler to create your geometry. All over the web, even on a pad, phone (I don't recommend trying to do modeling on a phone, but it does work), or on a basic computer. The files are stored in the cloud and downloaded directly to your printer. No muss, no fuss. All you need is a reliable and fast connection to the internet and in your home.
High speed internet and a smart 3D printer makes anyone a maker.And when we had a three hour break, I went downstairs to a coffee shop on the ground floor of the condo and worked, while monitoring my builds using the camera in the smart 3D Printer. Pretty cool when you step back and think about how far we have come from that first Stereolithography machine that PADT bought in 1994. We had to use floppy disks to get the data from our high-end Unix workstation to the machine. Now it sits on the web and can be monitored. This may be what we have been waiting for when it comes to 3D Printers in the home moving beyond that technologists and makers. I've been focused on my experience with the 3D printing in the smart home, but there was a lot more to look at. Check out these stories to learn more: Phoenix Business Journal: Cox shows off a smart home with 55 connected devices and fast gigabyte internet The Arizona Republic: Cox 'smart home' in Phoenix displays future at the push of a button I also did a piece for the Phoenix Business Journal while I was at the event on "3 keys to success for smart home devices" based on what I learned while playing with the other devices in the smart home. All and all a good day. Oh, and being a 10 minute walk from my favorite pub made the idea of living downtown not such a bad idea, which doesn't have much to do with high speed internet, connected devices, or 3D Printing. But one of my goals was to check out post-child urban living...