If there is one service that most people connect PADT with it is our 3D Printing Services. We have been making prototypes for companies using this ever-advancing technology since we started the company in 1994. As 3D Printing has become more popular and entered the mainstream even beyond engineering, what 3D Printing means to people has changed as well. Along with that, people’s understanding of exactly what it is we do in this area has drifted a little from what goes on. In this month’s installment of our “Getting to Know PADT” series, we will work to provide insight into what 3D Printing Services are and how they can benefit your company.
To start, it should be called “Additive and Advanced Manufacturing and Prototyping Services, ” but people search for “3D Printing” so that is what we call it. 3D Printing is the common name for what is technically referred to as Additive Manufacturing, or AM. Most physical parts are made (manufactured) by casting or shaping material into a shape you want, removing material from stock to get the shapes you want, and/or combining physical parts you get by the other two methods. Instead of these well-proven methods, AM creates a part by building up material one layer at a time. That is why it is called additive – it adds layers of material to get a shape. Here is an older blog article showing the most common technologies used in AM.
The advantage of this approach is that you just need one machine to make a part, you can go straight from a computer model to that part, and you are not held back by the physical constraints of traditional processes. These features allow anyone to make a part and to make shapes we just could not create before. At first, we only used it for prototypes before parts were made. Then we started to make tools to make final products, and now 3D Printing is employed to manufacturing end-use parts.
In the world of mechanical engineering, where 3D Printing is heavily used, we call companies that use additive manufacturing to make parts for others 3D Printing Service Bureaus or 3D Printing Service Providers. Therefore, the full process of doing manufacturing using the technology is called: 3D Printing Services.
The critical word in that last sentence is “full.” Sending a computer model to a 3D Printer is just one of many steps involved in Additive Manufacturing. When the service is employed correctly, it includes identifying the right type of additive manufacturing to use, preparing the geometry, setting parameters on the machine, printing the parts, removing supports, cleaning the parts, sanding, applying a surface finish treatment, and then inspection and shipping. Anyone can send a part to a printer; the other steps are what make the difference between simply printing a part, and producing a great part.
Additive Manufacturing covers a wide range of technologies that create parts one layer at a time, using a variety of approaches. Some extrude, some harden, some use an inkjet print head, and still others melt material. What they have in common is creating solid geometry one layer at a time. Each technology has its own unique set of advantages, and that is why PADT offers so many different 3D Printing technologies for our customers. Each of these approaches has unique part preparations, machine parameters, and post-printing processes. Each with a unique set of advantages. The key to success is knowing which technology is best for each part and then executing it correctly.
Currently, PADT’s 3D Printing Services Group makes parts for customers using the following technologies. Each one listed has a brief description of its advantages. See our website for more details.
Reliability of systems
Broad material choice
Water soluble supports
Multiple materials in a single build
Broad material choices
Custom material choices
Multiple colors in single build
Water soluble supports
Fully dense metal parts
As a proud reseller for Stratasys systems, we feel strongly that the two primary technologies from Stratasys, FDM and Polyjet, are the best for customers who want to do Additive Manufacturing in-house or as a service provider. When customers need something different, they can come to PADT to take advantage of the unique capabilities found in each technology.
The difference is in what we know and how to execute the complete process. As a provider of 3D Printing services for over 23 years, very few people in the industry even come close to the amount of experience that we bring to the table. We also know product development and traditional manufacturing, so when a customer comes to us with a need, we understand what they are asking to do and why. That helps us make the right recommendation on process, material, and post-processing.
A few differentiators are:
In addition to all of these things, PADT also offers On-Demand Manufacturing as a Carbon Production Partner. We combine Carbon’s DLS technology with our existing and proven manufacturing processes to provide low volume manufacturing solutions for plastic components.
We are also always looking at the latest technologies and adding what our customers need. You can see this with the recent addition of systems from ConceptLaser, Carbon and Desktop Metal systems.
The very best way to learn more about PADT’s 3D Printing services is to have us print a part. The full experience and the final product will explain why, with so many choices, so many companies large and small count on us for their Additive Manufacturing. If you need to learn more, you can also contact us at 480.813.4884 or email@example.com.
Here are some links that you may find useful:
PADT is in the business of helping people who make products. So most people think of us as a provider of tools and services. What they do not know is that PADT actually has a few of its own products. The most successful of these is our line of Support Cleaning Apparatus systems, abbreviated as SCA. These devices are used to remove soluble support material from parts 3D printed in Stratasys Fused Deposition Modeling Systems. They are robust machines manufactured and serviced by PADT, but sold through the Stratasys worldwide sales channel. As of July of 2017, over 10,800 units have been delivered to Stratasys.
The Stratasys 3D Printing systems that use Fused Deposition Modeling extrude plastic through a heated nozzle to build parts one layer at a time. There are actually two nozzles. One puts down the building material and the other a support material that is dissolved in warm water that is slightly base. The best way to remove that support material is to put it into a warm bath where the part is gently tumbled so that the water can works its way evenly into the part. Stratasys tried several solutions for a companion washing system and eventually came to PADT and asked if we would try our hand at building a robust and efficient system.
The result was the SCA-1200. Launched at the end of 2008 it met the design requirements for reliability, part cleaning time, and noise. Over 7,000 of these systems were shipped and saw heavy usage. In fact, if you have a Stratasys FDM system there is a good chance you have an SCA-1200. It contained a unique shower head design that was optimized with simulation, and a modular assembly that could be repaired easily in the field.
Based upon the success and lessons learned from the SCA-1200, we released the SCA-1200HT in 2014. With the same basic form factor, this design replaced the off-the-shelf magnetically coupled pump with a simpler and more reliable custom design from PADT. The new unit also had a more pleasing visual design, several usability enhancements, and a greater temperature range. It has sold over 3,000 units and continues to be a popular system. The latest release includes a no-temperature setting that allows it to be used to clean Stratasys Polyjet parts.
The success of both system lead to a request to look at building a larger machine that could clean more parts at one time as well as larger parts. The SCA 3600 has three times the volume but shares many internal parts with the SCA-1200HT. Both of the new systems are doing well in the field with even better reliability and faster part cleaning times. They are also simpler to debug and repair.
The SCA systems are sold as stand alone devices or are bundled with key Stratasys FDM machines. You can learn more about them on our SCA page: www.padtinc.com/sca or you can contact whoever you buy your Stratasys equipment from.
Here is a video for the SCA-1200HT that talks all about what it does:
One of the most rewarding aspects of designing and manufacturing the SCA family of products was that it forced us to practice what we preach. We talk to companies every day about using simulation, 3D Printing, design for manufacturing, proper product development processes, and many more things needed to get a product right. With the SCA we were the customer. We had to Walk the Walk or stop talking the talk.
It has been a phenomenal experience that has made us even better at helping our customers produce their new products. We used CFD to optimize the gentle agitation design and shower head and worked closely with our vendors to minimize the cost of manufacturing. The worst part was that when the schedule slipped, we couldn’t blame the customer (only slightly joking). One of the best set of lessons came from doing the repair and refurbishment of systems that failed. Even though the failure rate was low, we learned a lot and were able to make improvements to future designs. Now when we sit across from a customer and talk about the design, test, and manufacture of their product, we can really say that we understand where they are coming from.
It was my first time visiting New Orleans. I have heard many stories of how good the food is and how everyone is really nice there so I was excited to visit this city for a business trip. Stratasys Launch 2017! There was some buzz going on about some new FDM printers that Stratasys has been working on and I was really excited to see them and hear what sets them apart from the competition. Rey Chu (Co-Owner of PADT), Mario Vargas (Manager of 3D Printer Sales), Norman Stucker (Account Executive in Colorado), and I (James Barker, Application Engineer) represented PADT at this year’s Launch.
The city did not disappoint! I ate the best gumbo I’ve ever tried. Below is a picture of it with some Alligator Bourbon Balls. The gumbo is Alligator Sausage and Seafood. Sooooo Good!!
My last night in New Orleans, Stratasys rented out Mardi Gras World. That is where they build all the floats for Mardi Gras. They had a few dancers and people dressed up festive. I was able to get a picture of Rey in a Mardi Gras costume.
After dinner at Mardi Gras World, I took Rey and Mario down Bourbon Street one last time and then we went to Café Du Monde for their world famous Beignets. Everyone told me that if I come home without trying the Beignets, then the trip was a waste. They were great! I recommend them as well. Below is picture of Mario and me at the restaurant.
As you can see we had a fun business trip. The best part of it was the unveiling of the new FDM printers! Mario and I sat on the closest table to the stage and shared the table with Scott Crump (President of Stratasys and inventor of FDM technology back in 1988). These new printers are replacing some of Stratasys entry level and mid-level printers. What impressed me most is that they all can print PLA, ABS, and ASA materials with the F370 being able to print PC-ABS. You also can build parts in four different layer heights (.005, .007, .010, and .013”), all while utilizing new software called GrabCad Print.
GrabCad Print is exciting because you can now monitor all of you Stratasys FDM printers from this software and setup queues. What made me and many others clap during the unveiling is that with GrabCad Print you no longer have to export STL files! You can import your native CAD assemblies and either print them as an assembly or explode the assembly and print the parts separately.
Everyone wants a 3D Printer that can print parts faster, more accurately and is dependable. You get that with the family of systems! Speed has increased big time, they are twice as fast as the Dimension line of FDM printers. Stratasys has published the accuracy of these new printers to be ±.008” up to a 4 inch tall part and then every inch past 4 inches, you add another .002”. These machines are very dependable. They are replacing the Uprint (Uprint SE Plus is still current), Dimension, and Fortus 250 machines that have been workhorses. Many of our customers still have a Dimension from 2002 when they were first launched. In addition to the 43 existing patents that Stratasys has rolled into this phenomenal product, they have an additional 15 new patents that speaks volumes as to the innovation in these 3D printers.
Stratasys Launch was a blast for me. Seeing these new printers, parts that were printed from them, and understanding why these are the best FDM printers on the market was well worth my time! I look forward to helping you with learning more about them. Please contact me at firstname.lastname@example.org for more information. If you would like to hear my recorded webinar that has even more information about the new F170, F270, and F370, here is the link. Or you can download the brochure here.
A few months ago, I did a post on the Technology Trends in Laser-based Metal Additive Manufacturing where I identified 5 key directions that technology was moving in. In this post, I want to do the same, but for a different technology that we also use on a regular basis at PADT: Fused Deposition Modeling (FDM).
Many companies have released and are continuously developing composite materials for FDM. Most involve carbon fibers and are discussed in this review. Arevo Labs and Mark Forged are two of many companies that offer composite materials for higher performance, the table below lists their current offerings (CF = Carbon Fiber, CNT = Carbon Nano Tubes). Virtual Foundry are also working on developing a metal rich filament (with about 89% metal, 11% binder polymer), which they claim can be used to make mostly-metal parts for non-functional purposes using existing FDM printers and a heat treatment to vaporize the binder. In short, while ABS and PLA dominate the market, there is a wide range of materials commercially available and this list is growing each year.
|Arevo Labs||CF, CNT in PAEK|
|CF in PEEK|
|Fiberglass in PARA|
|Mark Forged||Micro-CF in Nylon|
|Fiberglass (High Strength High Temperature)|
Even with newer materials, a fundamental problem in FDM is the anisotropy of the parts and the fact that the build direction introduces weak interfaces. However, there are several efforts underway to improve the mechanical properties of FDM parts and this is an exciting space to follow with many approaches to this being taken. Some of these involve explicitly improving the interfacial strength: one of the ways this can be achieved is by pre-heating the base layer (as being investigated by Prof. Keng Hsu at the Arizona State University using lasers and presented at the RAPID 2016 conference). Another approach is being developed by a company called Essentium who combine microwave heating and CNT coated filaments as shown in the video below.
Taking a very different approach, Arevo labs has developed a 6-axis robotic FDM process that allows for conformal deposition of carbon fiber composites and uses an FEA solver to generate optimized toolpaths for improved properties.
A lot of press has centered around FDM printers that make bigger parts and at higher deposition rates: one article discusses 4 of these companies that showcased their technologies at an Amsterdam trade show. Among the companies that showcased their technologies at RAPID was 3D Platform, that showed a $27,000 3D printer for FDM with a 1m x 1m x 0.5m printing platform. Some of the key questions for large form factor printers is if and how they deal with geometries needing supports and enabling higher temperature materials. Also, while FDM is well suited among the additive technologies for high throughput, large size prints, it does have competition in this space: Massivit is one company that in the video below shows the printing of a structure 5.6 feet tall in a mere 5 hours using what they call “Gel Dispensed Printing” that reduces the need for supports.
Micro-extrusion through syringes or specialized nozzles is one of the key ways bioprinting systems operate – but this is technically not “fused” deposition in that it may not involve thermal modification of the material during deposition. However, FDM technology is being used for making scaffolds for bio-printing with synthetic, biodegradable or bio-compatible polymers such as PCL and PLGA. The idea is these scaffolds then form the structure for seeding cells (or in some cases the cells are bioprinted as well onto the scaffold). This technology is growing fast and something we are also investigating at PADT – watch this space for more updates.
Modeling FDM is an important part of being able to use simulation/analysis to design better processes and parts for functional use. This may not get a lot of press compared to the items above, but is a particular interest of mine and I believe is a critical piece of the puzzle going to true part production with FDM. I have written a few blog posts on the challenges, approaches and a micromechanics view of FDM printed structures and materials. The idea behind all of these is to represent FDM structures mathematically with valid and accurate models so that their behavior can be predicted and designs truly optimized. This space is also growing fast, the most recent paper I have come across in this space is from the University of Wisconsin-Madison that was published May 12, 2016.
Judging by media hype, metal 3D printing and 3D bioprinting are currently dominating the media spotlight – and for good reasons. But FDM has many things going for it: low cost of entry and manufacturing, user-friendliness and high market penetration. And the technology growth has no sign of abating: the most recent, 2016 Wohlers report assesses that there are over 300 manufacturers of FDM printers, though rumor on the street has it that there are over a thousand manufacturers coming up – in China alone. And as the 5 trends above show, FDM has a lot more to offer the world beyond being just the most rapidly scaling technology – and there are people working worldwide on these opportunities. When a process is as simple and elegant as extruding material from a hot nozzle, usable innovations will naturally follow.
Have you ever looked at the mechanical properties in an FDM material datasheet (one example shown below for Stratasys ULTEM-9085) and wondered why properties were prescribed in the non-traditional manner of XZ and ZX orientation? You may also have wondered, as I did, whatever happened to the XY orientation and why its values were not reported? The short (and unfortunate) answer is you may as well ignore the numbers in the datasheet. The longer answer follows in this blog post.
In the context of FDM, mesostructure is the term used to describe structural detail at the level of individual filaments. And as we show below, it is the most dominant effect in properties.
Consider this simple experiment we did a few months ago: we re-created the geometry used in the tensile test specimens reported in the datasheets and printed them on our Fortus 400mc 3D printer with ULTEM-9085. While we kept layer thickness identical throughout the experiment (0.010″), we modified the number of contours: from the default 1-contour to 10-contours, in 4 steps shown in the curves below. We used a 0.020″ value for both contour and raster widths. Each of these samples was tested mechanically on an INSTRON 8801 under tension at a displacement rate of 5mm/min.
As the figure below shows, the identical geometry had significantly different load-displacement response – as the number of contours grew, the sample grew stiffer. The calculated modulii were in the range of 180-240 kpsi. These values are lower than those reported in datasheets, but closer to published values in work done by Bagsik et al (211-303 kpsi); datasheets do not specify the meso-structure used to construct the part (number of contours, contour and raster widths etc.). Further, it is possible to modify process parameters to optimize for a certain outcome: for example, as suggested by the graph below, an all-contour design is likely to have the highest stiffness when loaded in tension.
The above result is not surprising – the more interesting question is, could we have predicted it? While this is not a composite material, I wondered if I could, in my model, separate the contours that run along the boundary from the raster, and identify each as it’s own “material” with unique properties (Er and Ec). Doing this allows us to apply the Rule of Mixtures and derive an effective property. For the figure below, the effective modulus Eeff becomes:
Eeff = f.Ec + (1-f).Er
where f represents the cross-sectional area fraction of the contours.
With four data points in the curve above, I was able to use two of those data points to solve the above equation simultaneously and derive Er and Ec as follows:
Er = 182596 psi
Ec = 305776 psi
Now the question became: how predictive are these values of experimentally observed stiffness for other combinations of raster and contours? In a preliminary evaluation for two other cases, the results look promising.
Below is a typical image showing the different orientations data are typically attributed to. From our micromechanics argument above, the orientation is not the correct way to look at this data. The more pertinent question is: what is the mesostructure of the load-bearing cross-section? And the answer to the question I posed at the start, as to why the XY values are not typically reported, is apparent if you look at the image below closely and imagine the XZ and XY samples being tested under tension. You will see that from the perspective of the load-bearing cross-section, XY and XZ effectively have the similar (not the same) mesostructure at the load-bearing cross-sectional area, but with a different distribution of contours and rasters – these are NOT different orientations in the conventional X-Y-Z sense that we as users of 3D printers are familiar with.
The point of this preliminary work is not to propose a new way to model FDM structures using the Rule of Mixtures, but to emphasize the significance of the role of the mesostructure on mechanical properties. FDM mesostructure determines properties, and is not just an annoying second order effect. While property numbers from datasheets may serve as useful insights for qualitative, comparative purposes, the numbers are not extendable beyond the specific process conditions and geometry used in the testing. As such, any attempts to model FDM structure that do not account for the mesostructure are not valid, and unlikely to be accurate. To be fair to the creators of FDM datasheets, it is worth noting that the disclaimers at the bottom of these datasheets typically do inform the user that these numbers “should not be used for design specifications or quality control purposes.”
If you would like to learn more and discuss this, and other ideas in the modeling of FDM, tune in to my webinar on June 28, 2016 at 11am Eastern using the link here, or read more of my posts on this subject below. If you are reading this post after that date, drop us a line at email@example.com and cite this post, or connect with me directly on LinkedIn.
Thanks for reading!
While much has been (justifiably) written about HP and XJet releasing new, potentially game-changing products at RAPID 2016, I wanted to write this post about some of the smaller, unexpected joys that I discovered. If I sound overly enthusiastic about the people and companies behind them, it is likely due to the fact that I wrote this on the flight back, staring out at the clouds and reflecting on what had been a wonderful trip: I own no locks, stocks or barrels in any of these companies.
1. Essentium Materials – Carbon Nanotubes and Microwaves to improve FDM mechanical properties
Over the past year, I have studied, written and made presentations about the challenges of developing models for describing Fused Deposition Modeling (FDM) given their complex and part-specific meso-structure. And while I worked on developing analytical and numerical techniques for extracting the best performance from parts in the presence of significant anisotropy, the team at Essentium has developed a process to coat FDM filaments with Carbon nanotubes and extrude them in the presence of microwave radiation. In the limited data they showed for test specimens constructed of unidirectional tool-paths, they demonstrated significant reduction in anisotropy and increase in strength for PLA. What I liked most about their work is how they are developing this solution on a foundation of understanding the contributions of both the meso-structure and inter-filament strength to overall part performance. Essentium was awarded the “RAPID Innovations award”, first among the 27 exhibitors that competed and are, in my opinion, addressing an important problem that is holding back greater expansion of FDM as a process in the production space.
2. Hyrel 3D – Maker meets Researcher meets The-Kid-in-All-of-Us
I only heard of Hyrel 3D a few days prior to RAPID, but neglected to verify if they were exhibiting at RAPID and was pleasantly surprised to see them there. Consider the options this 3D printer has that you would be hard pressed to find in several 3D printers combined: variable extrusion head temperatures (room temp to 450 C), sterile head options for biological materials, a 6W laser (yes, a laser), spindle tools, quad head dispensing with individual flow control and UV crosslinking options. Read that again slowly. This is true multiple degree-of-freedom material manipulation. What makes their products even more compelling is the direct involvement of the team and the community they are building up over time, particularly in academia, across the world, and the passion with which they engage their technology and its users.
3. Technic-Print: New Chemistry for Improved FDM Support Removal
If you manufacture FDM parts with soluble supports, keep reading. A chemist at Technic Inc. has developed a new solution that is claimed to be 400% faster than the current Sodium-Hydroxide solution we use to dissolve parts. Additionally, the solution is cited as being cleaner on the tank, leaving no residue, has a color indicator that changes the solution’s color from blue to clear. And finally, through an additional agent, the dissolved support material can be reclaimed as a clump and removed from the solution, leaving behind a solution that has a pH less than 9. Since PADT manufactures one of the most popular machines that are used to dissolve these supports that unbeknown to us, were used in the testing and development of the new solution, we had an enriching conversation with the lead chemist behind the solution. I was left wondering about the fundamental chemistry behind color changing, dissolution rates for supports and the reclaiming of support – and how these different features were optimized together to develop a usable end-solution.
4. Project Pan: Computationally Efficient Metal Powder Bed Fusion Simulation
I presented a literature review at AMUG (another Additive Manufacturing conference) last month, on the simulation of the laser-based powder bed fusion. At the time, I thought I had captured all the key players between the work being done at Lawrence Livermore National Labs by Wayne King’s group, the work of Brent Stucker at 3DSIM and the many academics using mostly commercially available software (mostly ANSYS) to simulate this problem. I learned at RAPID that I had neglected to include a company called “Project Pan” in my review. This team emerged from Prof. Pan Michaleris’s academic work. In 2012, he started a company that was acquired by Autodesk two months ago. In a series of 3 presentations at RAPID, Pan’s team demonstrated their simulation techniques (at a very high level) along with experimental validation work they had done with GE, Honeywell and others through America Makes and other efforts. What was most impressive about their work was both the speed of their computations and the fact that this team actually had complex part experimental validations to back up their simulation work. What most users of the powder bed fusion need is information on temperatures, stresses and distortion – and within time frames of a few hours ideally. It seems to me that Pan and his team took an approach that delivers exactly that information and little else using different numerical methods listed on their site (novel Hex8 elements, an element activation method and intelligent mesh refinement) that were likely developed by Pan over the years in his academic career and found the perfect application, first in welding simulation and then in the powder bed fusion process. With the recent Autodesk acquisition, it will be interesting to see how this rolls out commercially. Details of some of the numerical techniques used in the code can be found at their website, along with a list of related publications.
5. FDA Participation: Regulating through education and partnership
On a different note from the above, I was pleasantly surprised by the presence of the FDA, represented by Matthew Di Prima, PhD. He taught part of a workshop I attended on the first day, took the time to talk to everyone who had an interest and also gave a talk of his own in the conference sessions, describing the details of the recently released draft guidance from the FDA on 3D printing in medical applications. It was good to connect the regulatory agency to a person who clearly has the passion, knowledge, intelligence and commitment to make a difference in the Additive Manufacturing medical community. Yes, the barriers to entry in this space are high (ISO certifications, QSR systems, 510(k) & Pre-Market Approvals) but it seems clear that the FDA, at least as represented by Dr. Di Prima, are doing their best to be a transparent and willing partner.
What really makes a trip to a conference like RAPID worth it are the new ideas, connections and possibilities you come away with that you may not stumble upon during your day job – and on that account, RAPID 2016 did not disappoint. As a line in one of my favorite song’s goes:
“We’ll never know, unless we grow.
There’s too much world outside the door.”
– Fran Healy (Travis, “Turn”).
Over the past two academic semesters (2015/16), I had the opportunity to work closely with six senior-year undergraduate engineering students from the Arizona State University (ASU), as their industry adviser on an eProject (similar to a Capstone or Senior Design project). The area we wanted to explore with the students was in 3D printed lattice structures, and more specifically, address the material modeling aspects of these structures. PADT provided access to our 3D printing equipment and materials, ASU to their mechanical testing and characterization facilities and we both used ANSYS for simulation, as well as a weekly meeting with a whiteboard to discuss our ideas.
While there are several efforts ongoing in developing design and optimization software for lattice structures, there has been little progress in developing a robust, validated material model that accurately describes how these structures behave – this is what our eProject set out to do. The complex internal meso- and microstructure of these structures makes them particularly sensitive to process variables such as build orientation, layer thickness, deposition or fusion width etc., none of which are accounted for in models for lattice structures available today. As a result, the use of published values for bulk materials are not accurately predictive of true lattice structure behavior.
In this work, we combined analytical, experimental and numerical techniques to extract and validate material parameters that describe mechanical response of lattice structures. We demonstrated our approach on regular honeycomb structures of ULTEM-9085 material, made with the Fused Deposition Modeling (FDM) process. Our results showed that we were able to predict low strain responses within 5-10% error, compared to 40-60% error with the use of bulk properties.
This work is to be presented in full at the upcoming RAPID conference on May 18, 2016 (details at this link) and has also been accepted for full length paper submission to the SFF Symposium. We are also submitting a research proposal that builds on this work and extends it into more complex geometries, metals and failure modeling. If you are interested in the findings of this work and/or would like to collaborate, please meet us at RAPID or send us an email (firstname.lastname@example.org).
ULTEM-9085 is one of my favorite materials to 3D-print: one of the reasons is it is a high performance polymer that can and has been used for end part manufacturing (see my blog post about ULTEM in functional aerospace parts), but the other is because it is a demanding material to print, in ways that ABS, Polycarbonate and even Nylon are not. What makes it demanding is primarily that ULTEM supports are not soluble and need to be removed mechanically. An additional challenge comes from the fact that the support is best removed when the part is at a high temperature (175-195 C), which requires the use of gloves and reduces the user’s dexterity. For complex geometries with internal channels, this is particularly challenging and occasionally results in an inability to print a certain part in ULTEM-9085, which runs contrary to the design freedom this technology otherwise enables.
In this post, I accumulate what I have learned through working (and failing) on many an ULTEM-9085 job, as well as through discussions with other users, and share this here in terms of design and process guidelines. To demonstrate these guidelines, I use a recent geometry that we printed for the Arizona State University’s (ASU) SAE team for an engine intake manifold. These guidelines apply to the Stratasys Fortus platform (for Fused Deposition Modeling, or FDM) using the Insight software that accompanies these tools. The screen shots are from Insight 10.6, and a Fortus 400 was used to print the parts shown.
Summary of Guidelines:
The single most important factor in simplifying support removal is part orientation. Most users of the FDM process know that part orientation determines the amount of support material consumed and also impacts the time to build the part. When working with ULTEM-9085, the additional challenge is that it is possible to design in supports that cannot be removed and will require you to scrap the job. This is especially true of internal features. While the automatic orientation feature in Insight allows you to minimize supports, it does not account for the difficulty of removing them. Thus when you are dealing with internal features, you may need to manually orient your part such that the internal features are aligned as close to the vertical as possible, and above the support angle (to be covered later).
As shown in Figure 1, for the intake manifold, I oriented the internal pipe structure close to the vertical and had to iterate a few times and verify that I had no support in the hard-to-reach areas. While I did have supports internally, they were limited to areas that were easy to access.
In a recent software upgrade, Insight added the ability to create box supports. The support structures consist of adjacent boxes instead of a continuous raster, which has the effect of allowing for easier separation of the support, though does slow down the build time. In my experience this support strategy does help with removal – the one parameter to consider here is the “Perforations” setting, though the default values were used for this part. The perforation is a layer of model material that is inserted into the support to make for easier breaking off of the support material. All cleavage surfaces in Fig. 3 are at perforation edges and you can see the building like construction with each floor distinguished by a layer of model material. When you have supports in hard to access regions, consider increasing the interval height so as to ensure you get separation at the model-support interface on the part before it occurs within the support on a perforation layer.
While orientation will have the most significant impact on the support you need, another variable to be aware of is the “Self-Support Angle” parameter. This angle is measured from the horizontal, and represents the minimum angle of the part wall that will be built without supports. As a result, to reduce support requirements, you want this number to be as low as possible so that a greater volume of the part can be self-supported. Stratasys recommends default values, but these scale as a function of the contour width, and layer thickness, as shown in Fig. 4. The values bottom out at 40 degrees for the 0.013″ layer thickness and 43 degrees for the 0.010″ layer thickness. Thus, all other things being equal, you will be able to reduce the support needed by choosing a 0.013″ layer thickness and a 0.026″ or larger contour width. Note that both of these will impact your ability to resolve thin walls and fine features, so ensure you scan through all the tool-paths to validate that the geometry is accurately filled in.
Supports are best removed when the model-support interface is hot. The best time to do this is right after you remove the parts from the print chamber, which is held at 195 C for ULTEM-9085. Ensure you have safety glasses on, work with thermal gloves and have a plier handy to pull out the support. In theory the parts can be re-heated again (175 C is a reasonable value for the oven), but Stratasys suggests that each re-heat cycle actually strengthens the interface, making it harder to remove. As a result, the best time to remove the supports is immediately out of the printer. Figure 5 shows the results of support removal for the intake manifold parts, including the build sheet.
It helps to visualize what we are trying to do when we remove supports. There are two interfaces in question here, as shown in Figure 6. One is the model-support interface, the other is the support-box structure interface. We need separation at the model-support interface since removing the thin piece of interface material can prove challenging if the box supports have broken off (as happened for the piece below). What this means is as you remove support, you need to not just pull the supports but also add some peeling force that creates the separation. Once you create separation at the correct interface, you can pull the supports and should have proper cleavage.
One final point to keep in mind is that in some cases, eliminating internal supports may be impossible, as shown for a different part in Figure 7 below. The point is to eliminate the support in places you cannot reach with your pliers and get enough peeling force applied to. In the case below, I chose to have supports at the wide opening since I had adequate access to them. With practice, you will get a better sense of what supports can and cannot be removed and use that intuition to better shape your design and process layout decisions before you print.
In part 1 of this two-part post, I reviewed the challenges in the constitutive modeling of 3D printed parts using the Fused Deposition Modeling (FDM) process. In this second part, I discuss some of the approaches that may be used to enable analyses of FDM parts even in presence of these challenges. I present them below in increasing order of the detail captured by the model.
Good agreement between numerical and experimental results can be achieved using orthotropic properties when the structures being modeled are simple rectangular structures with uniaxial loading states. In addition to require extensive testing to collect this data set (as shown in this 2007 Master’s thesis), this approach does have a few limitations. Like the isotropic assumption, it is only valid for the specific set of build parameters that were used to manufacture the test samples from which the data was initially obtained. Additionally, since the model has no explicit sense of layers and inter-layer effects, it is unlikely to perform well at stresses leading up to failure, especially for complex loading conditions. This was shown in a 2010 paper that demonstrated these limitations in the analysis of a bracket that itself was built in three different orientations. The authors concluded however that there was good agreement at low loads and deflections for all build directions, and that the margin of error as load increased varied across the three build orientations.
Discussion: At the present moment, the orthotropic approach is perhaps the most appropriate method for modeling parts since it is allows some level of build orientation optimization, as well as for meaningful design comparisons and comparison to bulk properties one may expect from alternative technologies such as injection molding. However, as the application of FDM in end-use parts increases, the demands on simulation are also likely to increase, one of which will involve representing these materials more accurately than continuum solids.
As I showed in a prior blog post, Fused Deposition Modeling (FDM) is increasingly being used to make functional plastic parts in the aerospace industry. All functional parts have an expected performance that they must sustain during their lifetime. Ensuring this performance is attained is crucial for aerospace components, but important in all applications. Finite Element Analysis (FEA) is an important predictor of part performance in a wide range of indusrties, but this is not straightforward for the simulation of FDM parts due to difficulties in accurately representing the material behavior in a constitutive model. In part 1 of this article, I list some of the challenges in the development of constitutive models for FDM parts. In part 2, I will discuss possible approaches to addressing these challenges while developing constitutive models that offer some value to the analyst.
It helps to first take a look at the fundamental multi-scale structure of an FDM part. A 2002 paper by Li et. al. details the multi-scale structure of an FDM part as it is built up from individually deposited filaments all the way to a three-dimensional part as shown in the image below.
This multi-scale structure, and the deposition process inherent to FDM, make for 4 challenges that need to be accounted for in any constitutive modeling effort.
Thus, any constitutive model for FDM that is to accurately predict a part’s response needs to account for its anisotropy, be informed by the specifics of the process parameters that were involved in creating the part and ensure that geometric non-idealities are comprehended or shown to be insignificant. In my next blog post, I will describe a few ways these challenges can be addressed, along with the pros and cons of each approach.
Fused Deposition Modeling (FDM) is the most widely used 3D printing technology today, ranging from desktop printers to industrial scale manufacturing tools. While the use of FDM for prototyping and rapid tooling is well established, its use for manufacturing end-use parts in aerospace is a more recent phenomenon. This has been brought about primarily due to the availability of one material choice in particular: ULTEM. ULTEM is a thermoplastic that delivers compliance with FAA FAR 25.853 requirements. It features inherent flame retardant behavior and provides a high strength-to-weight ratio, outstanding elevated thermal resistance, high strength and stiffness and broad chemical resistance (official SABIC press release).
During an industry scan I conducted for a recent research proposal PADT submitted, I came across several examples of the aerospace industry using the FDM process to manufacture end-use parts. Each of these examples is interesting because they demonstrate the different criteria that make FDM preferable over traditional options, and I have classified them accordingly into: design opportunity, cost and lead-time reduction, and supply complexity.
Design Opportunity: In this category, I include parts that were primarily selected for 3D printing because of the unique design freedom that layer-wise additive manufacturing offers. This applies to all 3D printing technologies, the two examples below are for FDM in ducts.
ULA Environmental Control System (ECS) duct: As reported in a prior blog post, United Launch Alliance (ULA) leveraged FDM technology to manufacture an ECS duct and reduce the overall assembly from 140 parts to only 16, while reducing production costs by 57%. The ECS ducts distribute temperature and humidity controlled air onto sensitive avionics equipment during launch and need to withstand strong vibrations. The first Atlas V with these ducts is expected to launch in 2016.
Orbis Flying Eye Hospital aircraft duct: The Flying Eye Hospital is an amazing concept from Orbis, who use a refurbished DC-10 plane to deliver eye care around the world. The plane actually houses all the surgical rooms to conduct operations and also has educational classrooms. The refurbishment posed a particular challenge when it came to air conditioning: a duct had to transfer air over a rigid barrier while maintaining the volume. Due to the required geometric complexity, the team selected FDM and ULTEM to manufacture this duct, and installed it and met with FAA approval. The story is described in more detail in this video.
Supply Complexity: 3D printing has a significant role to play in retro-fitting of components on legacy aircraft. The challenge with maintaining these aircrafts is that often the original manufacturer either no longer is in business or makes the parts.
Airbus Safety belt holder: Airbus shared an interesting case of a safety belt holder that had to be retrofitted for the A310 aircraft. The original supplier made these 30 years ago and since went out of business and rebuilding the molds would cost thousands of dollars and be time-consuming. Airbus decided to use FDM to print these safety belt holders as described in this video. They took a mere 2 hours to design the part from existing drawings, and had the actual part printed and ready for evaluation within a week!
Incidentally, the US Air Force has also recognized this as a critical opportunity to drive down costs and reduce the downtime spent by aircrafts awaiting parts, as indicated by a recent research grant they are funding to enable them to leverage 3D printing for the purpose of improving the availability of parts that are difficult and/or expensive to procure. As of 2014, The Department of Defense (DOD) reported that they have maintenance crews supporting a staggering 31,900 combat vehicles, 239 ships and 16,900 aircraft – and identified 3D printing as a key factor in improving parts availability for these crews.
Cost & Lead-time Reduction: In low-volume, high-value industries such as aerospace, 3D printing has a very strong proposition to make as a technology that will bring products to market faster and cheaper. What is often a surprise is the levels of reduction that can be obtained with 3D printing, as borne out by the three examples below.
Airbus A350 Electric wire covers: The Airbus A350 has several hundred plastic covers that are 3D printed with FDM. These covers are used for housing electric wires at junction boxes. Airbus claims it took 70% less time to make these parts, and the manufacturing costs plunged 80%. See this video for more information.
Kelly Manufacturing Toroid housing: Kelly Manufacturing selected FDM to manufacture toroid housings that are assembled into their M3500 instrument, which is a “turn and bank” indicator which provides the pilot information regarding the rate of aircraft turn. These housings were previously made of urethane castings and required manual sanding to remove artifacts from the casting process, and also had high costs and lead times associated with tooling. Using FDM, they were able to eliminate the need to do sanding and reduced the lead time 93% and also reduced per-piece costs by 5% while eliminating the large tooling costs. See the official case study from Stratasys here.
These examples help demonstrate that 3D printing parts can be a cost savings solution and almost always results in significant lead time reduction – both of vital interest in the increasingly competitive aerospace industry. Further, design freedom offered by 3D printing allows manufacturing geometries that are otherwise impossible or cost prohibitive to make using other processes, and also have enormous benefit in overcoming roadblocks in the supply chain. At the same time, not every part on an aircraft is a suitable candidate for 3D printing. As we have just seen, selection criteria involve the readily quantifiable metrics of part cost and lead time, but also involve less tangible factors such as supply chain complexity, and the design benefits available to additive manufacturing. An additional factor not explicitly mentioned in any of the previous examples is the criticality of the part to the flight and the safety of the crew and passengers on board. All these factors need to be taken into consideration when determining the suitability of the part for 3D printing.
PADT has been in this prototyping business for a while, even before we called the machines that make physical parts directly from computer models a 3D Printer. When we started it was rapid prototyping and we have purchased maybe a dozen machines for our own use, and sold several hundred to our customers. As the cost of these systems comes down and the number of people interested in having their own 3D Printer goes up, we thought it would be a good time to share our experience with choosing systems with the community.
Here are six things that every person should do when they are shopping for a 3D printer. We even recommend that you write these down and fill out a form before you contact the first vendor.
This seems obvious. You would not be looking for a 3D printer unless you knew you needed one and you knew what you needed it for. But in reality it is very easy to get caught up in how powerful and just plane cool this technology is and you start thinking about what you can do, and you forget what you need to do. The best way to approach this is to not think about which technology you may end up with, that will point you in one direction or another. Just assume you push a button and a prototype of your part comes out. What would you actually use it for?
The key here is to be honest. If the reality is that your receptionist really likes models of Japanese Anime characters, and you plan on making models of such in an attempt to get her attention, then be honest about that. You need a printer with the detail and perhaps color capability for that. But if you really think about it you probably need one to make patterns for doing custom composite layups, so your use will be very different and the so will the system you need. She probably will be just impressed with your layup tooling. Well, maybe not but your boss will.
Our experience tells us that customers often get hung up on features that they get excited about, but when you look at the end use of their prototypes, they really do not need some of those features. We have seen people buy a machine because it was the only one that did this one thing they got fixated on. But in the end, they only make two prototypes that need it a year and the other 137 prototypes they make are kind of sucky. Make a list of all the uses and put a guess next to them that shows the percentage of parts that fit into that use. A typical example would be:
When we run into someone that is unhappy with their 3D Printer, three out of four timeswe find out that it just does not perform like they thought it would. And if we dig deeper we find out that when they were shopping for a printer, they just looked at parts that the various vendors gave them. Demo parts. They never made a variety of their own typical parts. This is especially true if they ended up buying a lower cost machine.
Here is a secret of every person selling a 3D Printer, that probably is no secret to you. They pick the demo parts they show you because those parts look really good on their technology. And if you are not closely familiar with the strengths and weaknesses of each technology, there is no way for you to know that the parts they showed you may be the only parts that actually look good on that technology.
Get four or five parts that are typical parts that you would prototype, and have them made on each technology. Even if the vendor tells you they can only afford to make one sample part for you (with the cost coming down the margins on these machines is low so few in the business can do a bunch of free parts for every potential sale), go ahead and pay money to get your geometry made. You may be shocked by the results, especially on some of the newer low cost machines.
Any fast growing industry has a lot of hype, and a lot of mob pressure to go with one technology over another. 3D Printing is no different, and in fact it is worse because this technology is so cool and interesting. The problem with hype and herd mentality is that the company with the best public relations people or with the “hippest” story gets all the attention regardless of the technology. And it feeds on itself. They get more attention because they got more attention.
A case in point is the recent introduction of a hand-held fused deposition modeling system. Very cool, lots of hype and interest. But really, who could use that for real work? Even a hobbyist is going to struggle with making anything useful with a tool like that. But there is a lot of hype around it right now and a huge amount of interest. I’ve had a taxi driver mention it to me when he asked what I do.
It is human nature to want to be part of something big. So it is hard to push that aside and look at each 3D Printer you are evaluating on its own merit. Not what the press is saying, not what other people are touting, not what is the newest and flashiest. We are talking basic “make me a useable part” here. Look at it with basic and non-influenced eyes.
Of all the things listed here, this may be the hardest to do. There are so many costs that go into making prototypes. The initial cost of the machine is small compared to all the other costs. What we recommend you do is make a spreadsheet and list cost items in the first column, and create rows for each 3D Printer you are looking at, then fill it out. We like to put in the cost over three years.
Here are some cost items we recommend people include:
It is always a good idea to make a “want” and “need” list, regardless of what you are purchasing. When you are dealing with a set of technologies with so much buzz around it, we feel it is doubly important. Sitting down and making a list, then justifying it to someone else clarifies what you should be looking for more than anything.
We also recommend that you prioritize the list. Marking things as Want and Need is a first step, then every one of those should also be ranked in order of importance. You can use a point scheme or you can just put them in order from most to least. This will help you sort through the gee-whiz stuff and truly understand where the value of your investment in 3D Printing can be found.
Needless to say, it is critical that you finish Thing 1, and refer to it, when completing this step.
OK, maybe this one sounds like a sales pitch: “You know what you really want, but really, trust me, you need more.” Experience tells us that this is actually true. When you are talking 3D Printing we run into customer after customer that felt the system they purchased was “good enough” for their needs then they realize it does not do what they need. And in most cases it is because they really needed a bigger machine, or they needed a more robust material than they thought.
The last thing you want to do is invest in a 3D Printer then six months later try and turn it in to get one that is bigger, faster, more precise, or that runs a better material. Now you are still paying for the more expensive system and you wasted money on the less expensive one. Be honest, upgrade in the beginning to what you really need in the long run not what you think you can get by with in the short run. Because, in the end, you will save money and have better parts.
You know you want one. You actually probably need one. We have been doing this for a long time and almost every customer that has made an intelligent investment feels like the investment has been a positive one. And by intelligent investment, we do not want to imply that they bought a system from PADT (although statistically that may be true). What we have found is that these companies took their time, they used some variation of the steps listed above, and they treated their purchase as a long term investment.
You too can make a smart choice and make in-house 3D Printing part of your company, job, or even hobby. PADT is here ready to help you with that choice. We can show you the complete line of fused deposition and Polyjet 3D Printers from Stratasys. We can also provide some advice on what we think is a good fit for your needs, and help you capture data for the six things we have outlined here. And don’t forget, we have a full 3D Printing services offering, with all the major systems and materials. So we can show you the advantages of all of them by providing you with your outsourced parts while you look for an in-house solution.
Every once in a while we get asked to go out and do presentations on Rapid Prototyping. As part of that, we like to explain the four major technologies: SLA, SLS, FDM, and Polyjet. No matter how many hand gestures we use people just don’t seem to get it unless we show an animation.
So we thought it would be good to share those with the community so that they can either learn about the basics of the technology or use these to help educate others. They are crude, we are engineers and not artists. But they get the point across. We hope to have time to update them and add text.
They are in the form of animated GIF’s, so you can put them on a website or throw them in a PowerPoint and you don’t need a viewer or special software to view them. Click on the images to get the larger version.
Use as you see fit, just remember to mention where you found them: P – A – D – T.