The other day, I saw a post on Engadget about a special case for Pokemon Go users to solve the problem of missing your prized Jigglypuff that you have happened across in the wild (or let’s face it, probably a CP 10 Rattata who is going to break out multiple times before disappearing in a puff of smoke…). The case is designed to give the user access to on screen controls and a nice channel to keep your Pokeball flinging finger straight and true.
As pointed out in the article on Engadget, this case is only useful in the capture screen. This caveat aside, the other issue with the case is that it obscures the screen. Here at PADT, we are fortunate to sell a wide variety of 3D Printing machines, some of which are capable of multiple colors and material durometers. I decided to design my own take on the case from Jon Clever to be prototyped on our Stratasys Connex 3.
The case was made with black and clear material. The black material can be combined to produce a custom stiffness, so we made that part soft and rubber like and kept the clear portion rigid. The clear has good optical quality, which could be increased with a layer of “clearcoat.”
If you have a Stratasys Connex 3 or J750 and an iPhone 6, you can make your own with these STL files, one for the rubber part and one for the clear part.
Other variations and additional possibilities would be made possible with the new Stratasys J750, the first true full color printer that can also mix clear and solid as well as hard and soft materials. The J750 was just released and highlighted on our recent road show. Visit our blog article on the Scottsdale show to learn more about this incredible printer.
Additional information about PADT and our wide range of 3D Printing offerings here.
Is PolyJet MED610 truly biocompatible? And what does that mean anyway?
A couple of months ago, our product development team contacted me to see if I could 3D print them a small bio-compatible masking device that was needed for temporary attachment to an invasive device prior to insertion for surgery. That led me to investigate all the different bio-compatible materials we did have access to at PADT on our FDM (Fused Deposition Modeling) and PolyJet machines. Given the tiny size and high detail required in the part, I decided to opt for PolyJet, which does offer the MED610 material that is claimed to be biocompatible. As it so happens, we have an Objet Eden 260V PolyJet machine that has been dedicated to running MED610 exclusively since it’s installation a year ago.
We printed the mask, followed all the post-processing instructions per supplier recommendations (more on that later) and delivered the parts for further testing. And that is when I asked myself the questions at the top of this post.
I set off on a quest to see what I could find. My first stop was the RAPID conference in (May 2016), where the supplier (Stratasys Inc.) had a well-staffed booth – but no one there knew much about MED610 apart from the fact that some orthodontists were using it. I did pick up one interesting insight: one of the engineers there hypothesized that MED610 was not very popular because it was cost-prohibitive since its proper use required machine dedication. I then went to the Stratasys Direct Manufacturing (a service bureau owned by Stratasys) booth, but it turned out they don’t even offer MED610 as a material option for service jobs – presumably because of the low demand for this material, consistent with our own observations.
So I took a step back and began searching for all I could find in the public domain on MED610 – and while it wasn’t much, here is the summary of my findings that I hope help anyone interested in this. I categorize it in three sources of information: claims made by the supplier, published work on in vitro studies and finally, some in vivo animal trials. But first, we must ask…
What does it mean for a Material to be Biocompatible?
A definition by Williams (The Williams Dictionary of Biomaterials, 1999) is in order: “Biocompatibility is the ability of a material to perform with an appropriate host response in a specific application.” So if PolyJet MED610 is to be called biocompatible, we must ask – what application do we have in mind? Fortunately, the supplier has a recommendation.
MED610 was launched by Objet in 2011 (Objet was acquired by Stratasys in 2012) as a biocompatible material, ideal for “applications requiring prolonged skin contact of more than 30 days and short-term mucosal-membrane contact of up to 24 hours“. Stratasys claims that parts printed according to Objet MED610 Use and Maintenance Terms were evaluated for biocompatibility in accordance with standard “DIN EN ISO 10993-1: 2009, Biological Evaluation of Medical Devices-Part 1: Evaluation and testing within a risk management process. This addresses cytotoxicity, genotoxicity, delayed hypersensitivity, and USP plastic Class VI, which includes the test for irritation, acute systemic toxicity and implantation”. Unfortunately, the actual data from the biocompatibility study conducted by Objet have not been made publicly available.
It is important to remember that Stratasys publishes a “Use and Maintenance Terms” document that details the steps needed not just to clean the part after printing, but also on the proper setup of the machine for ensuring best chances of meeting biocompatibility requirements. These are published online at this link and include a 3 hour soak in a 1-percent NaOH solution, a 30 min soak in IPA and multiple water jet rinses, among other steps. In other words, the claimed biocompatibility of MED610 is only valid if these instructions are followed. These steps are primarily driven by the need to completely remove supports and any support-residue, but it is not clear if this is needed if a part can be printed without supports. Given such strong process dependencies, it is only to be expected that Stratasys provide a disclaimer at the end of the document clarifying that the users of their machines are responsible for independently validating biocompatibility of any device they make with MED610.
The next question is: have there been any relevant published, independent studies that have used MED610? In my search, I could only find two instances, which I discuss below.
Primary Human Cells Response (In Vitro)
In a recent (January 2016) study published in the Journal of Medical and Biological Engineering, Schmelzer et al. studied the response of primary human cells to four 3D printed materials in vitro: ABS, PC, PLA and MED610 – the only such study I could find. All samples instead went through a 100% ethanol brief rinse and were washed 5 times with de-mineralized water – this seems like a less stringent process than what the supplier recommends (3 hour 1-percent NaOH solution soak, 30 minutes IPA soak and 10 times waterjet blasting) but was designed to be identical across all the materials tested.
There were some very interesting findings:
Different cells had different responses:
MED610 had the most negative impact on cell viability for keratinocytes (epidermal cells that produce keratin) – and the only material that showed statistically significant difference from the control.
For bone marrow mesenchymal (stem) cells, a different effect was observed: direct culture on ABS and PC showed significant growth (7X compared to control) but MED610 and PLA showed no significant effect
Surface Roughness influences cell attachment and proliferation:
In agreement with other work, the authors showed that while rougher surfaces promote initial cell attachment, subsequent cell proliferation and overall cell numbers are higher on smoother surfaces. The MED610 samples had rougher surfaces than the FDM samples (possibly due to the use of the “matte” finish option) and could be one of the contributors to the observed negative effects on cell viability, along with the leached contents from the specimen.
Glaucoma Drainage Device (In Vivo, Rabbit studies)
The devices were printed on a Connex 350 PolyJet machine, after which the supports were removed from the devices with a water jet and “were repeatedly washed and inspected for consistency and integrity.” Tubes were attached with Silicone adhesive and the entire assembly was then “washed and sterilized with a hospital-grade hydrogen peroxide system before use”. The researchers did not examine the cellular and extracellular reactions in great detail, but did conclude that the reactions were similar between the MED610 device and the more standard polypropylene injection-molded device.
A short video recorded by some of the researchers as part of a Bioprinting course also provides some details into the 3D printing aspects of the work done.
In conclusion, the question I posed at the start of this post (Is PolyJet MED610 truly biocompatible?) is too simplistic. A process and a material together are not sufficient – there are procedures that need to be defined and controlled and further and more importantly, biocompatibility itself has to be viewed in the context of the application and the specific toxicity and interaction demands of that application. And that brings us to our key takeaways:
MED610 is only recommended at best for applications requiring prolonged skin contactof more than 30 days and short-term mucosal-membrane contact of up to 24 hours and there is no data to dispute the suppliers claim that it is biocompatible in this context once all recommended procedures are implemented
The work done by Australian researchers in using PolyJet MED610 for devoloping their Glaucoma Drainage Device in animal trials is perhaps the best example of how this material and the technology can be pushed further for evaluating designs and hypothesis in vivo when really fine features are needed. Stratasys’s FDM PC-ISO or ABS M30i materials, or other FDM extrusion capable materials like PLA, PCL and PLGA may be better options when the resolution allows – but this is a topic for a follow-on blog post.
More in vitro work needs to be done to extend the work done by Schmelzer et al., which suggests that MED610 potentially has leachables that do impact cell viability negatively. Specifically, effects of surface finish (“matte” vs “gloss”) and sterilization on cell viability is a worthwhile follow-on step. In the interim, MED610 is expected to perform well for mucosal membrane contact under 24 hours (and why this is a great technology for dental guides and other temporary in-mouth placement).
If you have any thoughts on this matter or would like to collaborate with us and take advantage of our access to a PolyJet printer that is dedicated to MED610 or other bio-compatible FDM materials, as well as our extensive post-processing and design & analysis facilities, please connect with me on LinkedIn or send us a note at firstname.lastname@example.org and cite this blog post.
Schmelzer, E., Over, P., Gridelli, B., & Gerlach, J. (2016). Response of Primary Human Bone Marrow Mesenchymal Stromal Cells and Dermal Keratinocytes to Thermal Printer Materials In Vitro. Journal of Medical and Biological Engineering, 36, 153-167.
Ross C, Pandav S, Li Y, et al. Determination of Bleb Capsule Porosity With an Experimental Glaucoma Drainage Device and Measurement System. JAMA Ophthalmol.2015;133(5):549-554. doi:10.1001/jamaophthalmol.2015.30.
Our loop around the Southwest with the new Stratasys J750 Full Color 3D Printer finished strong with a well attended gathering at ASU’s Skysong in Scottsdale. The event was so popular, Channel 10 did a story on it. Over 130 people signed up to learn more about this fantastic device, get caught up on latest industry trends, and talk with other users of Additive Manufacturing.
This event had a great mix of users from multiple industries as well as students and people wanting to just learn more about the technology.
The presentations were a big hit from every seminar, and Dhruv’s was especially popular in Arizona. You can download the presentations here:
During the breaks and after the presentations, we had a chance to interact one-on-one with customers, show off parts, and answer questions. If you have any questions, please feel free to contact us at 480.813.4884 or email@example.com.
Lastly, we were visited by local TV channel 10, KSAZ who did a short but really informative segment on the show and the Stratasys J750:
The second stop on our trip around the Southwest for Stratasys’ new J750 Full Color 3D Printer was in fantastic downtown Salt Lake City. This device is reinventing 3D printing, and we are showing it off in person so people can see it up close along with holding incredible parts it makes in their hands.
The 3D Printing community in Utah is very mature and the attendees were mostly very experienced users of many different additive manufacturing technologies. So we focused on real world applications for the J750 as well as other Stratasys systems.
We were fortunate enought to have a customer, Ultradent, present the fantastic ways that they use their FDM and Polyjet printers to make prototypes, tooling, and production parts.
As is usual in this type of an event, the discussion between and after presentations are the best part. People from Aerospace, sporting goods, medical devices, and consumer products swapped stories, suggestions, and tips.
It was also a family affair. with Jame Barker’s latest family addition was in attendence to help spread the word on the value of 3D Printing with Stratasys solutions:Beyond the little guy, the other hit of the afternoon was the J750. As seasoned additive manufacturing profesionals they see the incredible leap forward this machine represents – truly reinventing 3D Printing and opening up a huge range of oportunities.
Denver was the first stop on a trip around the Southwest for Stratasys’ new J750 Full Color 3D Printer. We are showing this machine that is reinventing 3D printing off in person so people can see the device up close and hold the incredible parts it makes in their hands.
The Denver event was hosted by St. Patrick’s Brewery in Littleton, right down the street from PADT’s Colorado Office. Several customers and PADT employees gave talks on how to better use 3D Printing, including a presentation from Mario Vargas on the new Stratasys J750.
On top of all of that, local radio station KDMT, Denver’s Money Talk 1690, did a live broadcast from the event. You can listen in here. Again, PADT employees and customers talked about 3D Printing as well as the new Stratasys J750.
We also made the local paper, check that out here.
We are pleased to announce that PADT has been awarded a grant from America Makes to further our research into combining our three favorite things: Simulation, 3D Printing, and Product Development. We will work with our partners at ASU, Honeywell Aerospace, and LAI International to study lattice structures created in 3D Printing, how to model them in ANSYS simulation software, and then how to use that information to drive product design.
A copy of the press release is below. Or read the official press release or download a PDF .
Innovative Additive Manufacturing Research Project Led by PADT Approved as Part of America Makes Multi-Million Dollar Grants
Arizona State University, Honeywell Aerospace and LAI International join PADT in technical research and educational outreach in 3D Printing
TEMPE, Ariz., July 25, 2016 — In one of the most critically needed areas of research in Additive Manufacturing, Phoenix Analysis & Design Technologies (PADT), the Southwest’s largest provider of numerical simulation, product development and 3D Printing services and products, today announced its project proposal titled “A Non-Empirical Predictive Model for Additively Manufactured Lattice Structures,” has been accepted as part of a multi-million dollar grant from the National Additive Manufacturing Innovation Institute, America Makes. PADT’s proposal was one of only seven selected, and one of only two where the leading organization was a small business.
To complete the deliverables, Arizona State University (ASU), Honeywell Aerospace and LAI International are assisting PADT in technical research with contributions from Prof. Howard Kuhn, a Professor at the University of Pittsburgh and a leading educator in Additive Manufacturing, for workforce and educational outreach.
“While there are several efforts ongoing in developing design and optimization software for lattice structures in additive manufacturing, there has been little progress in developing a robust, validated material model that accurately describes how these structures behave,” said Dhruv Bhate, PhD, senior technologist, PADT and author and principal investigator of the proposal. “We are honored to be chosen to research this important issue and provide the tools to enable entrepreneurs, manufacturers and makers to integrate lattice structures in their designs.”
One of the most definitive benefits of additive manufacturing is the ability to reduce weight while maintaining mechanical performance. A way to achieve this is by adding lattice structures to parts before manufacturing. The advantages are crucial and can result in increased design flexibility, lower material costs and significant reductions in production time for industries such as aerospace and automotive.
Another aspect of PADT’s winning proposal is the development of a first-of-a-kind online, collaborative living textbook on Additive Manufacturing that seeks to provide comprehensive, up-to-date and structured information in a field where over 50 papers are published worldwide every day. In addition, the team will develop a training class that addresses manufacturing, testing, theory and simulation as well as how they are combined together to deliver robust predictions of lattice behavior.
“We have identified Additive Manufacturing as a key lever of innovation in our company and recognize lattice structures as an important design capability to reduce mass, improve performance and reduce costs,” said Suraj Rawal, Technical Fellow, Advanced Technology Center at Lockheed Martin Space Systems Company – a leader in implementing Additive Manufacturing. “We also recognize the significance of this work in lattice behavior modeling and prediction as an important contribution to help implement the design, manufacturing, and performance validation of structures in our innovative designs.”
The award of this grant is another example of the leadership role that Arizona is playing in advancing the practical application of Additive Manufacturing, better known as 3D Printing. PADT’s leadership role in the Arizona Technology Council’s Arizona Additive Manufacturing Committee, support of basic research in the area at ASU, and involvement with educating the next generation of users underscores PADT’s contribution to this effort and furthers the company’s commitment to “Make Innovation Work.”
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.
According to some, the novelty of 3D printing has been wearing off — its mentioned in daily conversations, used on Grey’s Anatomy episodes, incorporated in high school and college classes. Most iPhone-wielding millennials know what it is and how it works. It’s not a “new thing” anymore, right?
Coming to Denver, Salt Lake City, and Phoenix — Phoenix Analysis & Design Technologies (PADT) invites you to be one of the first to meet the Stratasys J750 3D Printer: the latest introduction in the portfolio of PolyJet 3D Printers. The Stratasys J750 is the first-ever full-color, multi-material system, which finally addresses the frustration of designers who want realistic models but have to contend with inconsistent color results and rough finishes from current technology.
Unlike other 3D printers currently in existence, the Stratasys J750 can operate with five different colors: cyan, magenta, yellow, black and white — all of the primary colors in the CMYK color process, just like day-to-day 2D full-color printers. The Stratasys J750 also achieves very fine layer thicknesses, enabling high surface quality and the creation of models and parts with very fine, delicate details, where current 3D printers usually result in relatively rough surface finishes.
What does this mean for those who use 3D printing? The Stratasys J750 not only delivers incredible realism but it’s also the most versatile 3D printer available. Designers and producers can say goodbye to the days of adopting multiple 3D-printing technologies and still resorting afterwards to extensive post-processing, such as sanding, painting and bonding.
Before the Stratasys J750, no single 3D printer could deliver full color, smooth surfaces and multiple materials. Now, however, you can print realistic prototypes, presentation models, Digital ABS injection molds, jigs, fixtures, educational and promotional pieces, production parts – or all of the above, with one system.
The Stratasys J750 even goes one step past versatile, simultaneously being the fastest, simplest, and easiest 3D printer to use. The printer includes several user-requested upgrades, such as server functionality, six-material capacity, and even three print modes that are suitable for different priorities: high speed, high mix and high quality. Additionally, where some 3D printing processes must run in a dedicated facility due to the possible hazard of the materials, chemicals and post-processing steps involved, the Stratasys J750 3D Printer uses a clean, easy process, with no hazardous chemicals to handle.
The Stratasys J750 is one choice among an ever-growing array of 3D printers in the marketplace. But its capabilities and versatility make it more than just a 3D printer; It’s a solution-maker.
In other words, Stratasys has just invented 3D printing. Again. PADT’s 3D Printing team can help you pick the best printer for your job and provide you with one-on-one engineering and prototype support.
If you’re at all interested in technology, you won’t want to miss this printer’s big coming-out day.
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).
1. New Materials with Improved Properties
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.
2. Improved Properties through Process Enhancements
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.
3. Faster & Bigger
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.
4. Bioprinting Applications
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.
5. Material Modeling Improvements
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.
The Committee aims to meet once a month, our second meeting occurs Monday, July 11 2016 at the ASU Polytechnic Campus and is open to anyone in Arizona that works in Additive Manufacturing and has an interest in promoting its growth statewide through collaboration. For more info, connect with me on LinkedIn or send a note to firstname.lastname@example.org and cite this blog post.
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 email@example.com 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 firstname.lastname@example.org 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 email@example.com.
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.