PADT’s Norman Stucker joins Nathan Morimitsu from Manufacturer’s Edge to discuss the current and future state of manufacturing in Colorado. Norman speaks to the impact of 3D Printing and how it is changing manufacturing. It is a great discussion that looks beyond the hype and shares where Additive Manufacturing is today and how it is being applied in the real world.
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.
Mesostructure has a First Order Effect on FDM Properties
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.
Can we Borrow Ideas from Micromechanics Theory?
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.
So What About the Orientation in Datasheets?
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 firstname.lastname@example.org and cite this post, or connect with me directly on LinkedIn.
One of the most dramatic impacts of 3D printing on design and manufacturing is with injection molding. Companies such as Seuffer, Unilever, Arad Group and Whale report significant savings in molding costs and production time by 3D printing injection molds to test designs before mass production and produce small quantities of custom parts.
Learn more by viewing this 60-minute webinar as Gil Robinson, Stratasys senior application engineer, explains the what, why and how of 3D printed injection molding.
“Why are there so many different software solutions in Additive Manufacturing and which ones do I really need?“
This was a question I was asked at lunch during the recently concluded RAPID 3D printing conference by a manager at an aerospace company. I gave her my thoughts as I was stuffing down my very average panini, but the question lingered on long after the conference was over – several weeks later, I decided to expand on my response in this blog post.
There are over 25 software solutions available and being used for different aspects of Additive Manufacturing (AM). To answer the question above, I found it best to classify these solutions into four main categories based on their purpose, and allow sub-categories to emerge as appropriate. This classification is shown in Figure 1 below – and each of the 7 sub-categories are discussed in more detail in this post.
1. Design Modeler
You need this if you intend to create or modify designs
Most designs are created in CAD software such as SOLIDWorks, CATIA and SpaceClaim (now ANSYS SpaceClaim). These have been in use long before the more recent rise in interest in AM and most companies have access to some CAD software internally already. Wikipedia has a comparison of different CAD software that is a good starting point to get a sense of the wide range of CAD solutions out there.
2. Build Preparation
You need this if you plan on using any AM technology yourself (as opposed to sending your designs outside for manufacturing)
Once you have a CAD file, you need to ensure you get the best print possible with the printer you have available. Most equipment suppliers will provide associated software with their machines that enable this. Stand-alone software packages do exist, such as the one developed by Materialise called Magics, which is a preferred solution for Stereolithography (SLA) and metal powder bed fusion in particular – some of the features of Magics are shown in the video below.
Scanning & File Transfer
3. Geometry Repair
You need this if you deal with low-quality geometries – either from scans or since you work with customers with poor CAD generation capabilities
Geomagic Design X is arguably the industry’s most comprehensive reverse engineering software which combines history-based CAD with 3D scan data processing so you can create feature-based, editable solid models compatible with your existing CAD software. If you are using ANSYS, their SpaceClaim has a powerful repair solution as well, as demonstrated in the video below.
Improving Performance Through Analysis
4. Topology Optimization
You need this if you stand to benefit from designing towards a specific objective like reducing mass, increasing stiffness etc. such as the control-arm shown in Figure 2
Of all the ways design freedom can be meaningfully exploited, topology optimization is arguably the most promising. The ability to now bring analysis up-front in the design cycle and design towards a certain objective (such as maximizing stiffness-to-weight) is compelling, particularly for high performance, material usage sensitive applications like aerospace. The most visible commercial solutions in the AM space come from Altair: with their Optistruct solution (for advanced users) and SolidThinking Inspire (which is a more user-friendly solution that uses Altair’s solver). ANSYS and Autodesk 360 Inventor also offer optimization solutions. A complete list, including freeware, can be availed of at this link.
5. Lattice Generation
You need this if you wish to take advantage of cellular/lattice structure properties for applications like such as lightweight structural panels, energy absorption devices, thermal insulation as well as medical applications like porous implants with optimum bone integration and stiffness and scaffolds for tissue engineering.
Broadly speaking, there are 3 different approaches that have been taken to lattice design software:
I will cover the differences between these approaches in detail in a future blog post. A general guideline is that the generative design approach taken by Autodesk’s Within is well suited to medical applications, while Lattice generation through topology optimization seems to be a sensible next step for those that are already performing topology optimization, as is the case with most aerospace companies pursuing AM technology. The infill/conformal approach is limiting in that it does not enable optimization of lattice structures in response to an objective function and typically involves a-priori definition of a lattice density and type which cannot then be modified locally. This is a fast evolving field – between new software and updates to existing ones, there is a new release on an almost quarterly, if not monthly basis – some recent examples are nTopology and the open source IntraLattice.
Below is a short video demo of Autodesk’s Within:
You need this if you do either topology optimization or lattice design, or need it for part performance simulation
Basic mechanical FE analysis solvers are integrated into most topology optimization and lattice generation software. For topology optimization, the digitally represented part at the end of the optimization typically has jarring surfaces that are smoothed and then need to be reanalyzed to ensure that the design changes have not shifted the part’s performance outside the required window. Beyond topology optimization & lattice design, analysis has a major role to play in simulating performance – this is also true for those seeking to compare performance between traditionally manufactured and 3D printed parts. The key challenge is the availability of valid constitutive and failure material models for AM, which needs to be sourced through independent testing, from the Senvol database or from publications.
7. Process Simulation
You need this if you would like to simulate the actual process to allow for improved part and process parameter selection, or to assess how changes in parameters influence part behavior
The real benefit for process simulation has been seen for metal AM. In this space, there are broadly speaking two approaches: simulating at the level of the part, or at the level of the powder.
Part Level Simulation: This involves either the use of stand-alone AM-specific solutions like 3DSIM and Pan Computing (acquired by Autodesk in March 2016), or the use of commercially available FE software such as ANSYS & ABAQUS. The focus of these efforts is on intelligent support design, accounting for residual stresses and part distortion, and simulating thermal gradients in the part during the process. ANSYS recently announced a new effort with the University of Pittsburgh in this regard.
Powder Level Simulation: R&D efforts in this space are led by Lawrence Livermore National Labs (LLNL) and the focus here is on fundamental understanding to explain observed defects and also to enable process optimization to accelerate new materials and process research
Part level simulation is of great interest for companies seeking to go down a production route with metal AM. In particular there is a need to predict part distortion and correct for it in the design – this distortion can be unacceptable in many geometries – one such example is shown in the Pan Computing (now Autodesk) video below.
A Note on Convergence
Some companies have ownership of more than one aspect of the 7 categories represented above, and are seeking to converge them either through enabling smooth handshakes or truly integrate them into one platform. In fact, Stratasys announced their GrabCAD solution at the RAPID conference, which aims to do some of this (minus the analysis aspects, and only limited to their printers at the moment – all of which are for polymers only). Companies like Autodesk, Dassault Systemes and ANSYS have many elements of the 7 software solutions listed above and while it is not clear what level of convergence they have in mind, all have recognized the potential for a solution that can address the AM design community’s needs. Autodesk for example, has in the past 2 years acquired Within (for lattice generation), netfabb (for build preparation) and Pan Computing (for simulation), to go with their existing design suite.
Conclusion: So what do I need again?
What you need depends primarily on what you are using AM technologies for. I recommend the following approach:
Identify which of the 4 main categories apply to you
Enumerate existing capabilities: This is a simple task of listing the software you have access to already that have capabilities described in the sub-categories
Assess gaps in software relative to meeting requirements
Develop an efficient road-map to get there: be aware that some software only make sense (or are available) for certain processes
In the end, one of the things AM enables is design freedom, and to quote the novelist Toni Morrison: “Freedom is not having no responsibilities; it is choosing the ones you want.” AT PADT, we work with design and analysis software as well as AM machines on a daily basis and would love to discuss choosing the appropriate software solutions for your needs in greater detail. Send us a note at email@example.com and cite this blog post, or contact me directly on LinkedIn. .
Western Technology is a manufacturer of specialty lighting solutions that cater to a variety of highly specialized industries such as aviation, oil and gas, and maritime. Their products are used in a variety of environments making it important that the design is both versatile and functional.
In their Utah office, they have been successfully utilizing a Stratasys PolyJet 3D Printer to create polyurethane molds. By using 3D printed molds, they have been able to save both time and money over traditional manufacturing methods.
Western Technology’s 3D Printed Toggle Mold
“Below is a pictorial of how we’ve used our new 3D printer to develop and create polyurethane parts. The parts we are producing in this mold are used to trigger a magnetic sensor inside a sealed aluminum box. Each part has a magnet and aluminum insert cast inside.” Lyal Christensen at Western Technology
The mold was printed using a Stratasys Objet 500 Connex 1 printer in a Vero Blue material (standard plastic). This is the final result after support material has been removed.
The mold is comprised of two halves that each have 3 different parts to create this Polyurethane mold. Below one side is shown in an un-assembled view.
Steel pins are press fit into the 3D printed part with ease to help with locating the magnets in the correct location. Also you can see that the part has a gloss finish to it. The parts were printed in the glossy mode which helps in minimizing the amount of support material needed to print the parts.
Inserts and Magnets are added to the mold along with a Urethane mold release agent. The Aluminum inserts are held in the right place by screws that keep the inserts suspended so that the Urethane can engulf all sides of it.
The clamped mold then has the Urethane fed into it which is poured at room temperature. Once all of the cavities are filled, the mold is left to cure at room temperature for just under one hour. Using this technique, they are able to complete 6 or 7 sets per day.
The following morning the screws and the insert bridge are removed.
The mold is pried apart using a flathead screwdriver at specific cutout locations that were printed into the mold. With a simple turn of the wrist, this mold is easily separated.
There is a little bit of flash which can easily be removed. These parts are almost ready for the customer.
The parts are cut away and are ready for de-flashing and finishing.
At Western Technology, Lyal estimates this mold would have cost $2,000+ to manufacture in just man hours. They were able to get 400+ parts out of this mold and are still using it.
If you would like to learn more about how to implement 3D Printing into your processes to save time and money, contact us at firstname.lastname@example.org.
Joining Two of PADT’s Favorite Things: Simulation and 3D Printing
Recent advances in Additive Manufacturing (3D Printing) have removed barriers to manufacturing certain geometry because of constraints in traditional manufacturing methods. Although you can make almost any shape, how do you figure out what shape to make. Using ANSYS products you can apply topological optimization to come up with a free-form shape that best meets your needs, and that can be made with Additive Manufacturing.
A few months ago we presented some background information on how to drive the design of this type of part using ANSYS tools to a few of our customers. It was a well received so we cleaned it up a bit (no guarantee there all the typos are gone) and recorded the presentation. Here it is on YouTube
Let us know what you think and if you have any questions or comments, please contact us.
Everyone needs a vacation. After over 15 years of service our Sinterstation 2500Plus needed some facility upgrades and machine updates. That work is now done and our SLS system is back up and running and better than ever, producing parts for customers who have come to count on its unique capabilities.
Selective Laser Sintering (SLS) is a process that uses a high power laser to fuse a bed of powdered material together, sintering the loose powder into solid geometry. It is one of the more mature and robust 3D Printing processes available and is especially well suited for making large strong parts.
We currently run Nylon 11 and Glass Filled Nylon 12 in our machine which has a build volume of 13″ x 11″ x 16.5″ and a layer thickness of 0.004″
Few service providers have as much experience as PADT with this system, we have been using it for over 15 years. During that time we have upgraded almost every component and during the recent downtime, the system was fully calibrated and tuned for maximum precision and performance. We are also experts on how to post process the parts that come out of this machine, including painting and other coatings.
Just a Part of 3D Printing at PADT
PADT features 3D Printing services using Stratasys FDM and PolyJet technologies, making precision parts with a wide variety of materials and colors. We also offer Stereolithography (SLA) Additive Manufacturing services along with soft tooling and injection molding consulting.
If you are using a big impersonal 3D Printing “mill” or are not sure where to get your 3D Printing done, reach out to PADT. We have been doing it since 1994 and have hundreds of happy and loyal customers.
“It is not just a trend, it is a Tsunami. One day you will wake up and see a giant wave headed your way, and that wave will be the Internet of Things!”
This was the opening line from a presentation given by the VP of sales for a major engineering software company. It got my attention because it wasn’t hype or hyperbole. He was just pointing out the obvious. Over the past two years the signs have been there. Smart devices will connected to the internet, and older devices will be made smart and then connected. Those that don’t, will no longer be competitive.
It is not all about smart thermostats. Far from it. I went to IoT world in San Jose last week and saw a lot of people scrambling to find their solution. And a few that found them. The best example was an older letter stamping machine, you can guess at the manufacturer, that plugged a modular device from Electric Imp in to their controller and boom – they were connected. Some back end programming and they now had a competitive IoT device.
It is time to define and execute on your IoT strategy
When we visit customers, we will often ask them what their IoT Strategy is. The answers vary from “we don’t really think our products have an IoT play” to existing products on the market. The focus in the media is on consumer IoT products, but the bigger push right now is for industrial Internet, where machines used in manufacturing, energy generation, raw material extraction, and processing are smart and connected.
Customers from consumers to other companies will be requiring the benefits of IoT devices as they look to replace older hardware. That is why every company that makes physical products needs to develop an IoT strategy.
PADT Can Help
We have been helping our customers define and implement their approach to IoT well, since before it was called the Internet of Things. From assisting semiconductor companies that make MEMS sensors to making smart medical devices we are plugged in to what is needed to make IoT work.
There you can find some basic information about how PADT is a more comprehensive and technically capable solution then most design houses that claim to have IoT solutions. We are uniquely qualified to make sure the “Thing” in your IoT strategy is designed and manufactured right.
We also published a series of articles in the Phoenix Business Journal that provide some fundamental background information on the Internet of Things and how to deal with the challenges it presents:
Simulation can play a big role in almost every aspect of making your IoT device development faster and more productive. PADT uses ANSYS, Inc.’s comprehensive Multiphysics simulation tool set to model everything from the chip to the embedded system software.
Make sure you subscribe to PADT’s email list so you don’t miss future Events
Talking is the Best Approach
We hope that you find all of the material above, and the information we will provide in the coming months useful. But they are no substitute for giving us a call or sending us an email and setting up a face-to-face to talk about your IoT strategy and device development needs. If you are doing the work in-house, we have the hardware and software tools you need to be successful. If you need outside help, you won’t find engineers with more applicable experience.
Give us a call at 1-800-293-PADT or email email@example.com.
For several years now PADT has 3D Printed special thank you awards for the fantastic companies that sponsor the Arizona SciTech Festival. This year we decided to stick with the color of the Stratasys Connex3 but add some moving parts. This gear design spins around and was made as one part, we just wash the support material out of the gaps between parts.
This is a great example of going directly from a CAD model to a custom part. Each award has the recipient’s name printed on the smaller gear. Everything was designed in an hour or so and it took about another hour to add in the 30 or so names. We think these may be the best awards we have made so far.
Here is a video showing off how they spin:
Awards are kind of simple and fun. But the same technology is applied by PADT to help our customers design and build better medical devices, rockets, aircraft engines, computers, and pretty much any physical product you can think of. Give us a call at 1-800-293-PADT or email firstname.lastname@example.org to see how “We Make Innovation Work”
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”).
PADT talks a lot about synergy as a key strength and a key element of the value we provide to our customers. Our three departments, Manufacturing, Services, and Sales, are in constant communication, always leveraging one another’s expertise to solve problems. Strong internal relationships — a consequence of being under the same roof — precipitate easy and abundant information and resource sharing. Communication, paradigm, alignment, synergy: clear as day.
But what does any of that mean?
When a PADT product development customer meets us for the first time, he or she may be shown a slide that looks like this:
Strong bilateral communication among the Product Development, 3D Printing, and Analysis groups means that the project is enriched by contributions from experts across several fields, multiplying the value we add in the development process. For instance, the product will likely someday run into a sticky problem without a clear solution. PADT can attack it from multiple angles, such as design adjustment, finite element analysis (FEA) optimization, and the iterative testing of 3D printed prototypes.
Ok, but still: what does any of that mean?
A longtime customer of PADT’s product development group recently ran into an urgent problem without a clear path to a solution. Their manufacturing partner called them and said that a particular subassembly in their design will cost three times more than expected, which would raise the price of the product above the maximum the market would bear. PADT was presented with the problem: how do we reduce the subassembly cost by 66% while maintaining overall performance, and how do we confidently select a solution in under a week?
PADT’s three engineering groups jumped in to help.
The Product Development group held a brainstorming session and came out with two adjustments to bring overall cost down. First, the subassembly of three bonded unique steel parts would be replaced by a single injection molded plastic part. This change reduces component cost to within the target, but also significantly reduces the final assembly’s structural integrity.
Secondly, a plastic stiffener truss was added between components to mitigate the reduction in overall stiffness. This change adds a little assembly cost, but also significantly increases the final assembly’s structural integrity, which had been weakened by the first change.
The Analysis group conducted a series of FEA simulations, first to determine the increased bending under load and second to select a material to balance the conflicting requirements for stiffness, strength, and cost. After multiple simulation iterations, it was determined that Product Development had selected a permissible path forward and that a glass-filled polypropylene provides the best combination of the three parameters.
The 3D Printing group then printed the new design for qualitative “look and feel” testing and quantitative force/deflection study. The group was able to closely match the properties of the selected material from their collection of printable filaments and top-shelf industrial printers, reproducing even the fine details — subtle fillets, radii — that boost strength but are missed with lower quality printers. Through prototype tests, it was determined that Analysis selected an appropriate material and Product Development selected an appropriate design.
In the end, PADT was able to confidently select a solution to the customer’s unique cost problem in under a week. Thanks to the synergy of three groups — Product Development, Analysis, and 3D Printing — the customer was able to stay on schedule and enter the market at a relevant price.
So how can PADT help my product?
PADT’s system for delivering services is a textbook example of synergy in action, and it represents a uniquely effective solution to your company’s product problems. Whether you’re in concept design or high-volume production, PADT will tailor-make a solution that fits your budget, schedule, and technical requirements.
Give us a call at 1–800–293-PADT or email email@example.com.
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).
One of the more difficult things about being at the Additive Manufacturing Users Group (AMUG) is dealing with the fact that there is more to do than you can hope to accomplish in four and a half days. So I decided to focus on two themes: laser-based metal additive manufacturing (AM); and design & simulation for AM. In this post, I focus on the former and try to distill the trends I noticed across the laser-based metal AM system manufacturers that were present at the conference: Concept Laser, SLM, Renishaw, EOS and 3D Systems (listed here in the decreasing order of the time I spent at each supplier’s booth). While it is interesting to study how 5 different suppliers interpret the same technology and develop machines around it, it is not my objective to compare them here, but to extract common trends that most suppliers seem to be working on to push their machines to the next level. For the purposes of this post, I have picked the top-of-the-line machine that each supplier offers as an indication of the technology’s capabilities: they span a range of price points, so once again this is not meant to be a comparison.
As a point of observation, the 5 key trends I noticed turned out to be all really aspects of taking the technology from short run builds towards continuous production. This was not my intent, so I believe it is an accurate indication of what suppliers are prioritizing at this stage of the technology’s growth and see as providing key levers for differentiation.
1. Quality Monitoring
Most customers of AM machines that wish to use it for functional part production bemoan the lack of controls during manufacturing that allow them to assess the quality of a part and screen for excursionary behavior without requiring expensive post-processing inspection. Third party companies like Sigma Labs and Stratonics have developed platform-independent solutions that can be integrated with most metal AM systems. Metal AM suppliers themselves have developed a range of in-situ monitors that were discussed in a few presentations during AMUG, and they generally fall into the following categories:
Laser: Sensors monitor laser powder as well as temperature across the different critical components in the system
Oxygen Level: Sensors in the build chamber as well as in sieving stations track O2 levels to ensure the flushing of air with inert Argon or Nitrogen has been effective and that there are no leaks in the system
Live video: simple but useful, this allows users to get a live video stream of the top layer as it is being built and can help detection of recoater blade damage and part interaction
Meltpool: Concept Laser showed how its Meltpool monitoring system can be used to develop 2D and 3D plots that can be superimposed with the 3D CAD file to identify problematic areas – the video is also on YouTube and embedded below. SLM and EOS offer similar meltpool monitoring solutions.
Coater consistency: Concept Laser also described a monitor that captures before and after pictures to assess the consistency of the coater thickness across the build area – and this information is fed forward to adjust subsequent coater thicknesses in an intelligent manner.
Quality monitoring systems are still in their infancy with regard to what is done with the information generated, either in terms of feed forward (active) process control or even having high confidence in using the data to validate part quality. A combination of supplier development and academic and industry R&D is ongoing to get us to the next level.
2. Powder Handling
In a previous post, I touched upon the fire and explosion risks posed by metal powder handling. To lower the bar for an operator to gain access to a metal AM machine, one of the considerations is operator safety and the associated training they would need. Suppliers are constantly trying to improve the methods by which they can minimize powder handling. For a mechanical engineer, it is intriguing to see how reactive metal powders can be moved around in inert atmospheres using different strategies. The SLM 500HL uses a screw system to move the powder around in narrow tubes that stick out of the machine and direct the material to a sieving station after which they are returned to the feed area. The Renishaw RenAM 500M on the other hand uses a pneumatically driven recirculation system powered by Argon gas that is well integrated into the machine frame. Concept Laser also offers automated powder handling on the XLine 2000R, while EOS and 3DSystems do not offer this at the moment. Figure 2 below does not do justice to the level of complexity and thought that needs to go into this.
One of the limitations of automating powder handling is the ability to change materials, which is very hard to impossible to do with high enough confidence with these systems. As a result, their use is limited to cases where one machine can be dedicated to one material and efficiency gains of powder handling can be fully realized. The jury is still out on the long term performance of these systems, and I suspect this is one area that will continue to see improvements and refinements in subsequent model releases.
3. Multi-Laser Processing
In the quest for productivity improvement, one of the biggest gains comes from increasing the number and power of available lasers for manufacturing. In my previous experience with laser based systems (albeit not for this application), an additional laser can increase overall machine throughput by 50-80% (it does not double due to steps like the recoater blade movement that does not scale with the number of lasers).
The suppliers I visited at AMUG have very different approaches to this: SLM provides the widest range of customizable options for laser selection with their 500HL, which can accept either 2 or 4 lasers with power selection choices of 400W or 1000W (the 4 laser option was on display, YouTube video from the same machine in action is below) – the lasers of different powers can also be combined to have two 400W and two 1000W lasers. Concept Laser’s XLine 2000R allows for either 1 or 2 1000W lasers and their smaller, M2 machine that was showcased at AMUG has options for 1 or 2 lasers, with power selection of 200W or 400W. EOS, Renishaw and 3D Systems presently offer only single laser solutions: the EOS M 400 has one 1000W laser, Renishaw’s RenAM 500M has one 500W laser and the ProX DMP 320 from 3D Systems has one 500W laser.
There are a few considerations to be aware of when assessing a multi-laser machine: Each laser drives an increase in machine capital cost. But there is another point of note to remember when using multi-laser systems for manufacturing that centers around matching process outputs from different lasers: laser-to-laser variation can be a dominant source of overall process variation and can drive a need to calibrate, maintain and control both lasers as if they were independent machine systems. Additionally, development of a process on one particular laser power (100W, 400W, 500W, 1000W) may not scale easily to another and is something to remember when developing a long term strategy for metal AM that involves different kinds of machines, even if from the same supplier.
4. Software Integration
Renishaw spent a significant amount of time talking about their easy-to-use QuantAM software which is designed to integrate Renishaw process parameters and part processing information more tightly and allow for seamless process parameter development without needing third part software like Magics. Additive Industries announced in their presentation at AMUG that they had just signed an agreement with 3DSIM to integrate their support design software solution into their MetalFab1 machine. Software integration is likely to be an increasing trend especially around the following areas:
Improving support design methods and reducing its empirical nature and reducing the material, build time and support removal costs associated with them as well as eliminating the need for iterative builds
Increasing process options available to the user (for example for the outer skin vs the inner core, or for thick vs thin walls)
Simplifying the development of optimized process parameters for the user working on new materials
Integrating design and process optimization to increase effective part performance
In a future blog post, I will look specifically at the many design and simulation tools available around AM and how they are connected today even if not well-synergized.
5. Modular System Architectures
In a list of mostly evolutionary changes, this is the one area that struck me as being a step-change in how this technology will make an impact, even if it will be felt only by larger scale manufacturers. Concept Laser and Additive Industries are two companies that delivered presentations discussing how they were approaching the challenge of revolutionizing the technology for true production and minimizing the need for human touch. Common to both is the notion of modularity, allowing for stacking of printing, powder removal, heat treating and other stations. While Additive Industries are developing a flow resembling a series production line, Concept Laser have taken the more radical approach of having autonomous vehicles delivering the powder bed to the different stations, with travel channels for the vehicles, for the operator and for maintenance access (Figure 3). Both companies expect to have solutions out by the end of this year.
It is an interesting time to be a manufacturer of laser-based metal 3D printers, and an even more interesting time to be a consumer of this technology. The laser-material interaction fundamentals of the process are now fairly well-established. Competitors abound both in existing and emerging markets with machines that share many of the same capabilities. Alternative technologies (E-Beam melting, deposition and jetting) are making strides and may start to play in some applications currently dominated by laser-based technologies. A post early-adopter chasm may be around the corner. This will continuously drive the intense need to innovate and differentiate, and possibly also lead to a merger or two. And while most of the news coming out of conferences is justifiably centered around new process technologies (as was the case with Carbon’s CLIP and XJET’s metal nanoparticle jetting at AMUG this year), I think there is an interesting story developing in laser-based powder bed fusion and can’t wait to see what AMUG 2017 looks like!
Many of you may have seen the recent launch of an Atlas V rocket from United Launch Alliance (ULA). We are honored to have lent our expertise to ULA’s 3D Printing efforts that resulted in the use of parts on that rocket made with additive manufacturing. We will be talking about that and other ways we help the Aerospace Industry at the 32nd Space Symposium this week in Colorado Springs Colorado. Please stop by!
3D Printing Expertise from PADT Advances Aerospace Industry
Product design and development leader provides additive manufacturing support for United Launch Alliance Atlas V rocket
COLORADO SPRINGS, Colo. – April 11, 2016 – PRLog — Phoenix Analysis & Design Technologies Inc. (PADT), the Southwest’s largest provider of Numerical Simulation, Product Development, and 3D Printing services and products, is highlighting its expertise this week at the 32nd Space Symposium, the premier global, commercial, civil, military and emergent space conference.
During the symposium, PADT experts in additive manufacturing will be on hand to discuss the company’s technical expertise, logistics, sales and service capabilities in the exciting aerospace sector, which contributed to the successful launch on March 22 of a United Launch Alliance (ULA) Atlas V rocket. The Atlas V rocket made use of lightweight thermoplastic 3D printed parts, with the application of Stratasys technology supplied by PADT and consulting from PADT on how best to apply that technology to engineering, tooling, and production.
“PADT continues to be both a great supplier of both polymer and metal additive manufacturing technologies and an additive manufacturing technical consultant to ULA, supporting our Atlas V, Delta IV and future Vulcan Centaur launch vehicles,” said Greg Arend, ULA manager, Additive Manufacturing. “By consulting with PADT, we were able to understand how these technologies enhance our design and manufacturing process, saving time, money and weight. PADT’s knowledge of the use of both polymer and metal materials was instrumental in helping us achieve our success.”
In addition to supplying ULA with Stratasys’ polymer 3D Printing machines, PADT consulted with them early on andled a tour of Oakridge National Labs to help them understand the state of the art for both metal and polymer applications and produced a technological roadmap for both technologies that has largely been followed. Assisted by PADT, both companies made use of additive manufacturing for engineering prototypes, then advanced to the production of tooling for manufacturing and developed the confidence needed to move to flight hardware.
The founders of PADT have been involved with additive manufacturing since the late 1980’s and the company was the first service provider in the Southwest in 1994. Over the years, PADT has built a reputation for technical excellence and a deep understanding of how to apply various 3D printing technologies to enable real world applications. Their sales team has shown the ability to sell sophisticated engineering products to companies large and small, and to provide excellent support to their customers.
“3D Printing is not just about makers, nor is it just about engineering prototypes,” said Rey Chu, co-owner, principal and director of Manufacturing Technologies at PADT. “Every day users are creating production hardware to produce usable parts that save them time and money. Ducts for rockets are a perfect application of 3D printed parts because they are complex, low volume, and can make single parts that need to be made in multiple pieces using traditional methods.”
About Phoenix Analysis and Design Technologies
Phoenix Analysis and Design Technologies, Inc. (PADT) is an engineering product and services company that focuses on helping customers who develop physical products by providing Numerical Simulation, Product Development, and Rapid Prototyping solutions. PADT’s worldwide reputation for technical excellence and experienced staff is based on its proven record of building long term win-win partnerships with vendors and customers. Since its establishment in 1994, companies have relied on PADT because “We Make Innovation Work.” With over 80 employees, PADT services customers from its headquarters at the Arizona State University Research Park in Tempe, Arizona, and from offices in Torrance, California, Littleton, Colorado, Albuquerque, New Mexico, and Murray, Utah, as well as through staff members located around the country. More information on PADT can be found at http://www.PADTINC.com
One of the first concepts you come across in metal 3D printing is the notion of reactivity of the powder metal alloys – in this post, I investigate why some of these powder alloys are classified as reactive and others as non-reactive, and briefly touch upon the implications of this to the user of metal 3D printing tools, scoping the discussion to laser-based powder bed fusion. Ultimately, this boils down to a safety issue and I believe it is important that we, the users of these technologies, truly understand the fundamentals behind the measures we are trained to follow. If you are looking to get something chemical etched visit https://interplex.com/technology/process-capability/chemical-etching/.
Figure 1 below is indicative of the range of materials available currently for the laser-based powder bed fusion process (this selection is from Concept Laser). I have separated these into non-reactive and reactive metal alloys. The former includes steels, Inconels, bronze and CoCrW alloys. The reactive metal alloys on the other hand are Aluminum or Titanium based. The question is: what classifies them as such in the context of this process?
Reactivity in this process really pertains to the likelihood of the alloy in question serving as a fuel for a fire and/or an explosion, which are two related but distinct phenomena. To truly understand the risk associated with powder metals, we must first understand a few basic concepts.
1. Fire and Explosion Criteria
Figure 2 is a commonly used representation of the criteria that need to be met to initiate a fire (fuel, oxygen and an ignition source) and an explosion (the same three criteria for a fire, plus a dust cloud and confined space). When handling reactive metal alloy powders, it is important to remember that two of the three requirements for a fire are almost always met and the key lies in avoiding the other criterion. When not processing the powder in the machine, it is often subject to ambient oxygen content and thus all precautions are taken to prevent an ignition source (an ESD spark, for example). When the metal is being processed with a high power laser, it is done in an inert atmosphere at very low Oxygen levels. This thought process of appreciating you are one criterion away from a fire is useful, if sobering, to bear in mind when working with these powders.
2. Terms Used to Describe Fire and Explosion Risk
There are several terms used to describe fire and explosion risk. I have picked 5 here that tie into the overall “index” I will discuss in the following section. All these parameters are in turn functions of the material in question, both with regard to its composition and its size distribution and are co-dependent. These definitions are adapted from Benson (2012) and Prodan et al. (2012).
Fire Related:These two terms describe the sensitivity of a metal dust cloud to ignition.
Ignition Temperature: This is the lowest surface temperature capable of igniting a powder or dust dispersed in the form of a dust cloud
Minimum Ignition Energy: This measures the ease of ignition of a dust cloud by electrical and electrostatic discharges.
Explosion Related: These terms describe the severity of an explosion arising from a fire once ignited.
Minimum Explosion Concentration (MEC): This is the smallest amount of dust which when suspended in air, under a set of test conditions, will initiate an explosion and propagate even after the action of the ignition source has ceased.
Maximum Explosion Pressure: This is a measure of the highest pressure that occurs during of an explosion of a flammable mixture in a closed vessel.
Maximum Rate of Pressure Rise: This is the maximum slope of the pressure/time curve during a flammable mixture explosion in a closed vessel.
3. Index of Explosibility
Having defined these terms, the question is how they can be tied together to give some sense of the hazard associated with each metal powder. I came across a 1964 US Bureau of Mines study that defined an Index of Explosibility as a measure of the hazard risk posed by powder metal alloys. The index represents both the sensitivity of the powder to ignition, and once ignited, the severity of the resulting explosion. Since this is a subjective metric, it is normalized by comparison against a “standard”, which was selected as Pittsburgh coal dust in the 1964 study. Importantly though, this normalization enables us to do qualitative comparisons between metal powders and have some sense of the hazard risk posed by them. Figure 3 is the equation reproduced from the original 1964 report and shows how this term is estimated.
The study also showed how the index was a direct function of particle size. Most powders for 3D metal printing are in the 20-100um range, and as shown in Fig. 4 for atomized Aluminum, the risk of an explosion increases with reducing particle diameter.
The authors tested a range of metals and computed the different variables, which I have compiled anew in the table in Figure 5 for the ones we are interested in for metal 3D printing. The particle sizes in the 1964 study were ones that made it through a No. 200 sieve (less than 75 microns), but did not include sub-micron particles – this makes it an appropriate comparison for metal 3D printing. It is clear from the Index of Explosibility values, as well as the Cloud Ignition Temperatures in the table below why Aluminum and Titanium are classified as reactive metals requiring special attention and care.
4. Implications for Metal 3D Printing
So what does this mean for metal 3D printing? There are three things to be aware of that are influenced by whether you are working with non-reactive or reactive alloys – I only provide a general discussion here, specific instructions will be provided to you in supplier training and manuals and must be followed.
Personal Protective Equipment (PPE): There are typically two levels of PPE: standard and extended. The standard PPE can be used for non-reactive alloy handling, but the reactive alloys require the more stringent, extended PPE. The main difference is that the extended PPE requires the use of a full bunny suit, ESD grounding straps and thermal gloves.
Need for Inert Gas Handling: Many tasks on a metal 3D printer require handling of powder (pouring the powder into the chamber, excavating a part, cleaning the chamber of powder etc.). Most of these tasks can be performed in the ambient for non-reactive metal alloys with standard PPE, but for reactive alloys these tasks must be performed in an inert atmosphere.
Local authority approvals: It is important that your local authorities including the fire marshall, are aware of the materials you are processing and review and authorize their use in your facility before you turn on the machine. Local regulations may require special procedures be implemented for preparing the room for use of reactive metal alloys, that do not apply to non-reactive metals. It is vital that the authorities are brought into the discussion early on and necessary certifications obtained, keeping in mind that reactive metal alloy use may drive additional investment in safety measures.
Safe operation of metal 3D printers requires installation of all the necessary safety equipment, extensive hands-on training and the use of checklists as memory aides. In addition to that, it helps to connect these to the fundamental reasons why these steps are important so as to gain a clearer appreciation of the source of the hazard and the nature of the risk it poses. In this article I have tried to demonstrate why reactivity in metal 3D printing matters and what the basis is for the classification of these metal alloys into reactive and non-reactive by leveraging an old 1964 study. I wish to close with a reminder that this information is meant to supplement formal training from your equipment supplier – if there is any conflict in the information presented here, please revert to your supplier’s recommendations.