Thursday, March 2 is PADT’s annual SciTech Festival Open House, from 5-8pm (click HERE to register). This year, three student groups working on a range of projects will be present to showcase their work, all of which involved some level of 3D printing. Please bring friends and families to meet and discuss ideas with these students from our community.
Formula SAE Team (Arizona State University)
ASU’s Formula SAE team will be onsite with their 2016 car, demonstrating specifically how they used 3D printing to manufacture the functional intake manifolds on these cars. What is specifically interesting is how they have modified their manifold design to improve performance while leveraging the advantages of 3D printing, and also they have evaluated multiple materials and processes over the recent years (FDM, SLS).
Prosthetic Arm Project (BASIS Chandler)
Rahul Jayaraman will be back to discuss how he and 30 students at BASIS Chandler manufactured, assembled and delivered about 20 prosthetic hands to an organization that distributes these to children in need across the world. Rahul and PADT were featured in the news for this event.
Cellular Structures in Nature (BASIS Chandler)
A BASIS Chandler High School senior, Amy Zhang, just started her Senior Research Project with PADT, focusing on a project at the intersection of biology and 3D printing, investigating cellular structures that occur on surfaces in nature, like the wing of a dragonfly or the shell on a turtle or the encasing of a pineapple – all of which are comprised of cellular geometries. Using 3D scanning, image analysis and mathematical methods, Amy hopes to develop models for describing these structures that can then be used in developing design principles for 3D printing. You can learn more on Amy’s blog: http://shellcells.blogspot.com/
Attending AeroDef this year in Fort Worth? Make sure you register to tour Concept Laser on March 6th before AeroDef! You’ll hear an update on the GE acquisition and presentations on customer applications and machine safety. Registration ends February 24th, 2017, so don’t miss this opportunity!
Speed, superior quality monitoring, and an open architecture that enables innovation – that is what makes Concept Laser’s Direct Metal Laser Melting (DMLM) technology a leader in the metal additive manufacturing industry. Come and hear about how Concept Laser is investing to bring you innovation through new products and processes that will lead to revenue-generating opportunities for your business.
The Tour is March 6th from 8:30am to 11:30pm and includes round trip transportation from the conference and more.
What you will see on the tour:
Direct Metal Laser Melting
In-situ Quality Assurance
Best-in-class safety guidelines when interacting with reactive and non-reactive materials
It was my first time visiting New Orleans. I have heard many stories of how good the food is and how everyone is really nice there so I was excited to visit this city for a business trip. Stratasys Launch 2017! There was some buzz going on about some new FDM printers that Stratasys has been working on and I was really excited to see them and hear what sets them apart from the competition. Rey Chu (Co-Owner of PADT), Mario Vargas (Manager of 3D Printer Sales), Norman Stucker (Account Executive in Colorado), and I (James Barker, Application Engineer) represented PADT at this year’s Launch.
The city did not disappoint! I ate the best gumbo I’ve ever tried. Below is a picture of it with some Alligator Bourbon Balls. The gumbo is Alligator Sausage and Seafood. Sooooo Good!!
My last night in New Orleans, Stratasys rented out Mardi Gras World. That is where they build all the floats for Mardi Gras. They had a few dancers and people dressed up festive. I was able to get a picture of Rey in a Mardi Gras costume.
After dinner at Mardi Gras World, I took Rey and Mario down Bourbon Street one last time and then we went to Café Du Monde for their world famous Beignets. Everyone told me that if I come home without trying the Beignets, then the trip was a waste. They were great! I recommend them as well. Below is picture of Mario and me at the restaurant.
As you can see we had a fun business trip. The best part of it was the unveiling of the new FDM printers! Mario and I sat on the closest table to the stage and shared the table with Scott Crump (President of Stratasys and inventor of FDM technology back in 1988). These new printers are replacing some of Stratasys entry level and mid-level printers. What impressed me most is that they all can print PLA, ABS, and ASA materials with the F370 being able to print PC-ABS. You also can build parts in four different layer heights (.005, .007, .010, and .013”), all while utilizing new software called GrabCad Print.
GrabCad Print is exciting because you can now monitor all of you Stratasys FDM printers from this software and setup queues. What made me and many others clap during the unveiling is that with GrabCad Print you no longer have to export STL files! You can import your native CAD assemblies and either print them as an assembly or explode the assembly and print the parts separately.
Everyone wants a 3D Printer that can print parts faster, more accurately and is dependable. You get that with the family of systems! Speed has increased big time, they are twice as fast as the Dimension line of FDM printers. Stratasys has published the accuracy of these new printers to be ±.008” up to a 4 inch tall part and then every inch past 4 inches, you add another .002”. These machines are very dependable. They are replacing the Uprint (Uprint SE Plus is still current), Dimension, and Fortus 250 machines that have been workhorses. Many of our customers still have a Dimension from 2002 when they were first launched. In addition to the 43 existing patents that Stratasys has rolled into this phenomenal product, they have an additional 15 new patents that speaks volumes as to the innovation in these 3D printers.
Stratasys Launch was a blast for me. Seeing these new printers, parts that were printed from them, and understanding why these are the best FDM printers on the market was well worth my time! I look forward to helping you with learning more about them. Please contact me at firstname.lastname@example.org for more information. If you would like to hear my recorded webinar that has even more information about the new F170, F270, and F370, here is the link. Or you can download the brochure here.
I had a really great time designing the Metal 3D printed shift knob from my previous blog post. I was curious what the other benefits of the knob may be besides being cool to look at and show off. What better way than to use the simulation software that we use here at PADT every day!
One of the clear differences between my solid spherical knob and the Metal 3D printed version is surface area. Being that PADT is based in Tempe, AZ, some may say that we have “warm” summers down here. Couple the 120F days with a black car, and the interior can get very hot, at some points feeling like the sun itself has taken up residence inside the back seat. With modern A/C, this heat can be mitigated fairly quickly, only to attempt to shift into gear to be scalded by the shift knob!
I wanted to see what the rate of cooling for the two knobs would be in a basic situation with some basic assumptions. Using ANSYS transient thermal, I initialized the knobs to 150F, temperatures that can be quickly reached in parked cars here in AZ. I added a convection heat transfer boundary condition on the outer surface of each shift knob, assuming a film coefficient of 50 W/m^2C, and that the ambient temp in the car is at a cool 70F.
I ran the simulations for 5 minutes, and the results were in line with what I expected. As the 3D printed knob has more surface area for cooling, it’s final temperature was ~84F, compared to the solid spherical knob at a final temperature of 115F!
Did you know that PADT does scanning of parts? No? You are not alone. We recently ran into several customers who were sending their scanning out of state and didn’t know that they could have it done by PADT, someone who is already a trusted partner. So we thought it would be a good time to do an update on our Scanning services and provide some additional background on what it is.
Part Scanning 101
The idea behind part scanning is that you want to take a part in the real world, and get an accurate model in a computer. To do this you somehow measure the part with a computer, getting a three dimensional representation of the parts surface. Today, there are six basic ways to do this:
Physical Measurement (CMM)
Measure points on the part relative to some reference. This is great for measure simple geometry where you can reconstruct it by knowing key dimensions.
This process shines a laser on an object and measures the distance to the object. It does this thousands of times to build up a point array of the surface
Structured Light Scanning
This process puts down a series of parallel lines, or a grid of lines, and measures how far they distort from a flat pattern. With this information it can create a massive amount of points on the objects surface.
Cross Sectional Scanning
If you need to see inside, light based scanning does not work. In cross sectional scanning you machine away thin slices of an object and take an accurate picture of each layer as you go. This can then be turned in to an accurate representation of both the inside and outside of the object.
Another way around the fact that light can not penetrate an object is to use various types of radiation, like X-Rays, that go inside an object. Although new for industrial applications this method is growing for complex parts with internal geometry.
If accuracy is not critical, then software can take pictures taken from dozens of views and reconstruct a 3D shape. This is used most often for art and entertainment, but is not precise enough for engineering yet.
PADT offers Structured Light and Cross Sectional Scanning
All of these methods create points in space. The more sophisticated the software, the more automatic the process of assembling the points to define the surfaces of the full object. These points are sometimes called a “point cloud.”
The Point cloud can them be turned in to a faceted representation of the object. For many people, this is all they need. This faceted representation can be rendered on a computer screen or 3D Printed. It can also be used with inspection software to determine the accuracy of the part relative to its original specification as well as variations across multiple copies of the same geometry.
If users need more, like a full CAD model, that can be created from the point cloud using specialized software. PADT uses Geomagic DesignX. This tool not only creates usable geometry, but it can export in the customer’s native CAD format.
To do accurate part scanning you need:
A precision scanning device
Software to take the measured data and create an accurate point cloud. This includes repair and cleanup tools.
Software to convert the point cloud into a usable 3D CAD model
or, Software to conduct accurate inspection on the measured geometry.
All of these tools require some training and practice to use efficiently. It is fairly easy to get ball park computer models using consumer level tools. But to get accurate, engineering quality results the right tools and processes must be applied.
Why does Part Scanning Take so Long and Cost So Much?
When people ask for their first part scanning quote, they can often be surprised by the cost. The scanning process doesn’t look that hard. And to be honest, the amount of time you actually spend scanning most parts is pretty short. The time is spent on the preparation, scanning hard-to-reach areas, the clean up, and then converting the data in to usable formats.
If we are working with a light based scanner, we have to prepare the parts so that they reflect the light properly. Sometimes we have to cover the part with a find powder, sometimes we may even have to paint it. What we need is for the reflection and color of the part to not interfere with the scanning.
If we are using cross sectional scanning, the part needs to be cast inside a rigid material, so the part we are scanning does not distort as we remove layers. In addition, if the part is not a solid light or dark color, it may need to be died to provide contrast for the camera.
Both processes also require some study to determine the orientation of the part relative to the scanner and how the scanning process will take place. Once all this is worked out, the scanning often goes very fast. If there are nasty little parts that are hard to get to or that confuse the device, the engineer may have to modify things, do some special localized scanning, or even make castings that are then scanned. As is usual with technical processes, a very small portion of the surface being scanned may take up the vast majority of the scanning time.
Once the scanning is done, the real hard work begins. Although software is much better than it was in the past, the resulting point cloud needs to be massaged and cleaned. Stray data is removed, and points from different scans need to be positioned and combined. Then everything must be checked. If a CAD solid model is needed, then the engineer must spend considerable time dealing with complex features and transition areas. As with the scanning, the bulk of the time spent creating a CAD model is spent on a relatively small percentage of the geometry.
All of this adds up. Plus, to be honest, things rarely go as planned and unexpected issues arise that need to be dealt with.
Part Scanning Services at PADT
Now we get to the important part of this post: hiring PADT to do your scanning. We added this capability to support our 3D Printing customers that wanted copies of physical parts. But as we looked at it, we found that we also had customers who needed inspection and reverse engineering of legacy parts. We studied the problem for some time and found the right tools and people to make it happen.
Our primary scanner is a Zeiss Comet L3D 5M STructured light scanner. It used to be called a Steinbichler, till Zeiss bought them in 2015. Although it is portable and easy to manipulate, the Comet L3D 5M is highly accurate. It allows us to scan everything from small medical devices to the front end of acar, and to know that the resulting geometry will be accurate and usable. This is the best option for inspection and reverse engineering of high-precision parts.
We also have a Geomagic Capture scanner. Although less accurate it is more portable and simpler to operate. It is ideal or taking to a customer and getting geometry for reverse engineering or part copying.
If parts have internal features, and are made of plastic, we use our Cross Sectional Scanners. These high precision devices do a fantastic job and are really the best way to capture inside surfaces. Our customers love it to see how injection molded parts are coming out on well used molds.
If anything else is needed, our experts can outsource to a niche supplier.
Want to do it Yourself?
If you need to do your own scanning, no worries. PADT also sells all the tools we use inhouse to customers that need the capability internally.
Hopefully this posting has answered most of your questions and you are eager to try 3D Part Scanning. The best place to start is to get a quote from PADT. However, if you still have questions then feel free to contact us and fire away. We are passionate bout this capability and love talking about it.
Two weeks ago we were part of a fantastic open house at the ASU Polytechnic campus for the grand opening of the Additive Manufacturing Research center, a part of the Manufacturing Research and Innovation Hub. What a great event it was where the Additive Manufacturing community in Arizona gathered in one place to celebrate this important piece in the local ecosystem. A piece that puts Arizona in the lead for the practical application of 3D Printing in industry.
I could go on and on, but better writers by far have penned some great stories on the event and on the lab.
Metal 3D Printing is one of the more exciting areas of additive manufacturing, and we are learning a lot about how to safely operate our new system. Our very own Dhruv Bhate, PhD shared those lessons learned in this new video:
The video stresses the importance of keeping an inert environment to keep part quality and to ensure a safe operating environment. Our Concept Laser Metal 3D Printer uses high powered lasers to melt metal powder one layer at a time to build 3D Parts. This process produces soot that is highly flammable.
Dhruv shows the process we use to break the part from the machine, clean the chamber of soot, and replace the filter that captures the soot.
To learn more about PADT and how we can help you with your 3D Printing, product development, or Numerical Simulation needs, please visit www.padtinc.com
Use this link to see all of our blog posts on Metal 3D Printing
On January 18th, ASU will officially Launch their Manufacturing Research and Innovation Hub, the Largest Additive Manufacturing research and teaching center in the Southwestern US. PADT is proud to have partnered with ASU as well as with Concept Laser and Honeywell to get this important piece of the local manufacturing ecosystem started and to keep it growing.
Located on the Polytechnic School at ASU in Mesa, Arizona, this facility is amazing. And you can see it for yourself, the public is invited to the launch on January 18th, 2017 at 9:00 am. ASU Polytechnic Dean Kyle Squires and the Director Ann McKenna will be speaking as will our very own Rey Chu, John Murray from Concept Laser, and Don Godfrey from Honeywell. Tours will follow. Learn more and register for this free event that will bring together the local 3D Printing community here.
You can also learn more by reading the official press release from Concept Laser that outlines what the center does and the partnerships that make it possible:
Concept Laser, Honeywell, and PADT Build Largest Additive Manufacturing Center in Southwest at Arizona State University
GRAPEVINE, Texas, January 11, 2017 – The Polytechnic School at Arizona State University (ASU) offers the only manufacturing engineering undergraduate degree in Arizona; it is also one of only 22 ABET accredited manufacturing engineering programs in the United States. By forming a partnership with Concept Laser, Honeywell Aerospace, and PADT, Inc. the largest additive manufacturing research facility in the Southwest is now on the Polytechnic campus. The 15,000 square foot center holds over $2 million of plastic, polymer, and 3D metal printing equipment.
The lab has a Concept Laser M2 cusing and Mlab cusing machine which are dedicated to 3D metal printing, also known as metal additive manufacturing. Unlike conventional metal fabrication techniques, additive manufacturing produces fully-dense metal parts by melting layer upon layer of ultra-fine metal powder. The Polytechnic School is using the machines for a wide range of research and development activities including materials development and prototyping complex mechanical and energy systems.
Don Godfrey, Engineering Fellow at Honeywell: “Honeywell is thrilled to be participating in the opening of the new additive manufacturing laboratory at the Arizona State University Polytechnic campus. For many years, we have worked with ASU seniors on their capstone projects with three of these projects this school year additive manufacturing focused. In addition to our own additive manufacturing operations, we have provided mentorship to students in the program and assisted in the procurement of one machine for the schools’ new lab. We look forward to growing our relationships with the university in developing brilliant minds to tackle and overcome industry challenges associated with aviation and additive manufacturing.”
John Murray, President and CEO of US-based subsidiary Concept Laser Inc: “Changing the future of metal additive manufacturing begins with educated teachers and curious students. The educational leadership that the ASU Polytechnic School provides to the Southwest region and the industry will certainly be impactful. Concept Laser is proud to be a partner in this initiative.”
Rey Chu, Principal, Manufacturing Technologies at PADT, Inc: This partnership is the next and obvious step in the progression of additive manufacturing in the Southwest. With Concept Laser’s outstanding technology, Honeywell’s leadership in applying additive manufacturing to practical Aerospace needs, PADT’s extensive network of customers and industry experience, and ASU’s proven ability to educate and work with industry, the effort will establish a strong foundation for the entire regional ecosystem.
Ann McKenna, Director of ASU’s Polytechnic School: “Partnering with these industry leaders provides us the capability to do additional research and enhance our education programs. With so few of these types of centers, this makes ASU more attractive among academic partners, federal agencies and corporations to advance additive manufacturing.
The ASU Polytechnic School will be hosting an open house to celebrate the launch of their Manufacturing Research and Innovation Hub on January 18, 2017 at 9am. There will be guided tours showcasing student projects. Honeywell, Concept Laser, and PADT will be in attendance. Please register your attendance at www.mrihlaunch.eventbrite.com.
About Concept Laser
Concept Laser GmbH is one of the world’s leading providers of machine and plant technology for the 3D printing of metal components. Founded by Frank Herzog in 2000, the patented LaserCUSING® process – powder-bed-based laser melting of metals – opens up new freedom to configuring components and also permits the tool-free, economic fabrication of highly complex parts in fairly small batch sizes.
Concept Laser serves various industries, ranging from medical, dental, aerospace, toolmaking and mold construction, automotive and jewelry. Concept Laser machines are compatible with a diverse set of powder materials, such as stainless steel and hot-work steels, aluminum and titanium alloys, as well as precious metals for jewelry and dental applications.
Concept Laser Inc. is headquartered in Grapevine, Texas and is a US-based wholly owned subsidiary of Concept Laser GmbH. For more information, visit our website at www.conceptlaserinc.com
LaserCUSING® is a registered trademark of Concept Laser.
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 3D Printing 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 www.PADTINC.com.
About Arizona State University
The Ira A. Fulton Schools of Engineering at Arizona State University include nearly 19,000 students and more than 300 faculty members who conduct nearly $100 million in research, spanning a broad range of engineering, construction and technology fields. Across the six schools contained within the Fulton Schools, 24 undergraduate and 32 graduate programs are offered on ASU’s Tempe and Polytechnic campuses and online. The schools’ educational programs emphasize problem solving, entrepreneurship, multidisciplinary interactions, social context and connections. Arizona State University includes more than 80,000 students and 1,600 tenured or tenure-track faculty on multiple campuses in metropolitan Phoenix as well as online. For more information, please visit www.asu.edu or asuonline.asu.edu.
Our 10-page article on “Modeling the Mechanical Behavior of Cellular Structures for Additive Manufacturing” was published in the Winter 2016 edition of the Metal AM magazine. This article represents a high-level summary of the different challenges and approaches in addressing the modeling specific aspects of cellular structures, along with some discussion of the design, manufacturing and implementation aspects associated with AM.
Click HERE for link to the entire magazine, our article starts on page 51. Digital editions are free to download. Swing by PADT in the new year to pick up a hard copy or look for it at our table when you visit us at trade shows.
To stay in touch with the latest developments at the intersection of AM and Cellular Structures, connect with me on LinkedIn, where I typically post 1-2 blog posts every month on this, or related subjects in Additive Manufacturing.
I have always had an issue with leaving well enough alone since the day I bought my Subaru. I have altered everything from the crank pulley to the exhaust, the wheels and tires to the steering wheel. I’ve even 3D printed parts for my roof rack to increase its functionality. One of the things that I have altered multiple times has been the shift knob. It’s something that I use every time and all the time when I am driving my car, as it is equipped with a good ol’ manual transmission, a feature that is unfortunately lost on most cars in this day and age.
I have had plastic shift knobs, a solid steel spherical shift knob, a black shift knob, a white shift knob, and of course some weird factory equipment shift knob that came with the car. What I have yet to have is a 3D printed shift knob. For this project, not any old plastic will do, so with the help of Concept Laser, I’m going straight for some glorious Remanium Star CL!
One of the great things about metal 3D printing is that during the design process, I was not bound by the traditional need for a staple of design engineering, Design For Manufacturing (DFM). The metal 3D printer uses a powder bed which is drawn over the build plate and then locally melted using high-energy fiber lasers. The build plate is then lowered, another layer of powder is drawn across the plate, and melted again. This process continues until the part is complete.
The design for the knob was based off my previously owned shift knobs, mainly the 50.8 mm diameter solid steel spherical knob. I then needed to decide how best to include features that would render traditional manufacturing techniques, especially for a one-off part, cost prohibitive, if not impossible. I used ANSYS Spaceclaim Direct Modeler as my design software, as I have become very familiar with it using it daily for simulation geometry preparation and cleanup, but I digress, my initial concept can be seen below:
I was quickly informed that, while this design was possible, the amount of small features and overhangs would require support structure that would make post-processing the part very tedious. Armed with some additional pointers on creating self supporting parts that are better suited for metal 3D printing, I came up with a new concept.
This design is much less complex, while still containing features that would be difficult to machine. However, with a material density of 0.0086 g/mm^3, I would be falling just short of total weight of 1 lb, my magic number. But what about really running away from DFM like it was the plague?
There we go!!! Much better, this design iteration is spec’d to come out at 1.04 lbs, and with that, it was time to let the sparks fly!
Here it is emerging as the metal powder that has not been melted during the process is brushed away.
The competed knob then underwent a bit of post processing and the final result is amazing! I haven’t been able to stop sharing images of it with friends and running it around the office to show my co-workers. However, one thing remains to make the knob functional… it must be tapped.
In order to do this, we need a good way to hold the knob in a vise. Lucky for us here at PADT, we have the ability to quickly design and print these parts. I came up with a design that we made using our PolyJet machine so we could have multiple material durometers in a single part. The part you need below utilizes softer material around the knob to cradle it and distribute the load of the vise onto the spherical lattice surface of the knob.
We quickly found out that the Remanium material was not able to be simply tapped. We attempted to bore the hole out in order to be able to press in an insert, and also found out the High Speed Steel (HSS) was not capable of machining the hole. Carbide however does the trick, and we bored the hole out in order to press in a brass insert, which was then tapped.
Finally, the shift knob is completed and installed!
How can the mechanical behavior of cellular structures (honeycombs, foams and lattices) be modeled?
This is the second in a two-part post on the modeling aspects of 3D printed cellular structures. If you haven’t already, please read the first part here, where I detail the challenges associated with modeling 3D printed cellular structures.
The literature on the 3D printing of cellular structures is vast, and growing. While the majority of the focus in this field is on the design and process aspects, there is a significant body of work on characterizing behavior for the purposes of developing analytical material models. I have found that these approaches fall into 3 different categories depending on the level of discretization at which the property is modeled: at the level of each material point, or at the level of the connecting member or finally, at the level of the cell. At the end of this article I have compiled some of the best references I could find for each of the 3 broad approaches.
1. Continuum Modeling
The most straightforward approach is to use bulk material properties to represent what is happening to the material at the cellular level [1-4]. This approach does away with the need for any cellular level characterization and in so doing, we do not have to worry about size or contact effects described in the previous post that are artifacts of having to characterize behavior at the cellular level. However, the assumption that the connecting struts/walls in a cellular structure behave the same way the bulk material does can particularly be erroneous for AM processes that can introduce significant size specific behavior and large anisotropy. It is important to keep in mind that factors that may not be significant at a bulk level (such as surface roughness, local microstructure or dimensional tolerances) can be very significant when the connecting member is under 1 mm thick, as is often the case.
The level of error introduced by a continuum assumption is likely to vary by process: processes like Fused Deposition Modeling (FDM) are already strongly anisotropic with highly geometry-specific meso-structures and an assumption like this will generate large errors as shown in Figure 1. On the other hand, it is possible that better results may be had for powder based fusion processes used for metal alloys, especially when the connecting members are large enough and the key property being solved for is mechanical stiffness (as opposed to fracture toughness or fatigue life).
2. Cell Level Homogenization
The most common approach in the literature is the use of homogenization – representing the effective property of the cellular structure without regard to the cellular geometry itself. This approach has significantly lower computational expense associated with its implementation. Additionally, it is relatively straightforward to develop a model by fitting a power law to experimental data [5-8] as shown in the equation below, relating the effective modulus E* to the bulk material property Es and their respective densities (ρ and ρs), by solving for the constants C and n.
While a homogenization approach is useful in generating comparative, qualitative data, it has some difficulties in being used as a reliable material model in analysis & simulation. This is first and foremost since the majority of the experiments do not consider size and contact effects. Secondly, even if these were considered, the homogenization of the cells only works for the specific cell in question (e.g. octet truss or hexagonal honeycomb) – so every new cell type needs to be re-characterized. Finally, the homogenization of these cells can lose insight into how structures behave in the transition region between different volume fractions, even if each cell type is calibrated at a range of volume fractions – this is likely to be exacerbated for failure modeling.
3. Member Modeling
The third approach involves describing behavior not at each material point or at the level of the cell, but at a level in-between: the connecting member (also referred to as strut or beam). This approach has been used by researchers [9-11] including us at PADT  by invoking beam theory to first describe what is happening at the level of the member and then use that information to build up to the level of the cells.
This approach, while promising, is beset with some challenges as well: it requires experimental characterization at the cellular level, which brings in the previously mentioned challenges. Additionally, from a computational standpoint, the validation of these models typically requires a modeling of the full cellular geometry, which can be prohibitively expensive. Finally, the theory involved in representing member level detail is more complex, makes assumptions of its own (e.g. modeling the “fixed” ends) and it is not proven adequately at this point if this is justified by a significant improvement in the model’s predictability compared to the above two approaches. This approach does have one significant promise: if we are able to accurately describe behavior at the level of a member, it is a first step towards a truly shape and size independent model that can bridge with ease between say, an octet truss and an auxetic structure, or different sizes of cells, as well as the transitions between them – thus enabling true freedom to the designer and analyst. It is for this reason that we are focusing on this approach.
Continuum models are easy to implement and for relatively isotropic processes and materials such as metal fusion, may be a good approximation of stiffness and deformation behavior. We know through our own experience that these models perform very poorly when the process is anisotropic (such as FDM), even when the bulk constitutive model incorporates the anisotropy.
Homogenization at the level of the cell is an intuitive improvement and the experimental insights gained are invaluable – comparison between cell type performances, or dependencies on member thickness & cell size etc. are worthy data points. However, caution needs to be exercised when developing models from them for use in analysis (simulation), though the relative ease of their computational implementation is a very powerful argument for pursuing this line of work.
Finally, the member level approach, while beset with challenges of its own, is a promising direction forward since it attempts to address behavior at a level that incorporates process and geometric detail. The approach we have taken at PADT is in line with this approach, but specifically seeks to bridge the continuum and cell level models by using cellular structure response to extract a point-wise material property. Our preliminary work has shown promise for cells of similar sizes and ongoing work, funded by America Makes, is looking to expand this into a larger, non-empirical model that can span cell types. If this is an area of interest to you, please connect with me on LinkedIn for updates. If you have questions or comments, please email us at email@example.com or drop me a message on LinkedIn.
Building on the worldwide success of previous products in the family, PADT has just released the new SCA 3600, a large capacity cleaning system for removing the support material from Stratasys FDM parts. This new system adds capacity and capability over the existing benchtop SCA-1200HT System.
The SCA 3600 can dissolve support from all the SST-compatible materials you use – ABS, PC, and nylon. A “no heat” option provides agitation at room temperature for the removal of Polyjet SUP706 material as well. The SCA 3600’s versatility and efficient cleaning performance are built on the success of earlier models with all the features you have come to expect, in a larger and more capable model.
Since the launch of the original SCA-1200 in 2008, PADT has successfully manufactured and supported the SCA family of products for users worldwide. Common requests from desktop SCA users were for a larger system for bigger parts, the ability to clean many parts at the same time, and the option to remove supports from PolyJet parts. The SCA 3600 is the answer: Faster, larger, and more capable.
SCA 3600 Key Features are:
Removes soluble support from ABS, PC, and nylon 3D printed FDM parts
Removes soluble support from PolyJet 3D Printed parts
User-selectable temperature presets at 50, 60, 70, and 85°C and “No Heat” for PolyJet
Uses cleaning solutions from Stratasys
Unique spray nozzle optimizes flow coverage
230 VAC +/- 10%, 15A
Includes rolling cart for easy movement, filling, and draining.
Capacity: 27 gal / 102 L
Size: 42.8″ x 22.8″ x 36.5″/ 1,086 x 578 x 927 mm
16” x 16” x 14” / 406 x 406 x 356 mm removable large parts basket
Integral hinged lid and small part basket
Stainless steel tub and basket
Over temperature and water level alarms
Automatic halt of operation with alarms
Field replaceable sub-assemblies
Regulatory Compliance: CE/cTUVus/RoHS/WEEE
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Official copies of the press release can be found in HTML and PDF.
New 3D Printing Support Cleaning Apparatus Features Large Capacity for Stratasys FDM Systems
Offered Worldwide, the SCA 3600 is Big Enough to Handle Large 3D Printed Parts, Effortlessly Dissolving Support Material
TEMPE, Ariz., November 17, 2016 – Phoenix Analysis & Design Technologies, Inc. (PADT), the Southwest’s largest provider of simulation, product development, and rapid prototyping services and products, today introduced its new SCA3600 3D Printing Support Cleaning Apparatus (SCA). The systems are sold exclusively by Stratasys, Ltd. (SSYS) for use with its FORTUS line of 3D Printers. The hands-free support removal technology is a huge advantage to people who use Fused Deposition Modeling (FDM) systems for their 3D Printing.
“With more than 10,000 of our benchtop SCA units in the field, we gathered a wealth of knowledge on performance and reliability,” said Rey Chu, Co-owner and Principal of PADT. “We used that information to design and manufacture a system that cleans larger parts, or multiple small parts, while keeping the speed, easy maintenance and great user experience of the benchtop system.”
A powerful upgrade over PADT’s successful SCA-1200HT and SCA-1200 support removal products that have been in use around the world since 2008, the SCA 3600 features a simpler, more user-friendly design. The new versatile SCA offers temperature choices of 50, 60, 70 and 80 degrees Celsius, as well as no-heat, that readily cleans supports from all SST compatible materials – ABS, PC and Nylon. The SCA 3600 also features a large 16” x 16” x 14” parts basket, 3400 watts of heating for faster warm-up and a wheeled cart design for mobility.
The advantages of the system were highlighted by Sanja Wallace, Sr. Director of Product Marketing and Management at Stratasys, Ltd. when she commented, “the addition of the SCA 3600 as an accessory to our very successful FORTUS systems simplifies the support removal process with increased speed and capacity for multiple large parts.”
Once parts are printed, users simply remove them from their Stratasys FDM system, place them in the SCA 3600, set a cleaning cycle time and temperature, and then walk away. The device gently agitates the 3D printed parts in the heated cleaning solution, effortlessly dissolving away all of the support material. This process is more efficient and user friendly than those of other additive manufacturing systems using messy powders or support material that must be manually removed.
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.
In the Fused Deposition Modeling (FDM) process, support structures are needed for features with overhang incline angle less than 45-degree from horizontal. Stratasys developed a series of support materials for different model materials: SR-30TM for ABS, SR-100TM for polycarbonate and SR-110TM for nylon. Also, they developed the Waterworks Soluble Concentrate, P400-SC, to be used to dissolve these support materials. In this blog post, I develop a theory for the chemical reaction how P400-SC Waterworks dissolves SR-30TM, SR-100TM and SR-110TM support materials. As part of this, I explain how PADT’s Support Cleaning Apparatus (SCA) tank, with its heating and unique circulation and agitation capabilities that are important for the support dissolving process.
We begin by looking at the composition of the different materials involved in the table below.
Polymer can swell and then dissolve into water as a consequence of abundant hydrophilic groups, like carboxyl group (-COOH), ether group (-O-), hydroxyl group (-OH) and so on in its molecular structure. Theoretically, SR-30TM and SR-100TM /SR-110TM Soluble Support Materials including a carboxyl group (-COOH) in their repeat unit are likely to be water soluble. However, they also have a hydrophobic ester group (-COO-) in their repeat unit, which counteracts the efficacy of the hydrophilic group on the long carbon chain. Thus, the key to making SR-30TM and SR-100TM /SR-110TM soluble, is to somehow get rid of the ester group.
Hydrolysis of ester in pure water is a slow process even the system is heated. Both acid and alkaline conditions can catalyze and speed up the process. Under the acid condition, the hydrolysis is a reversible process until it reaches an equilibrium state, whereas alkaline conditions promote a thorough hydrolysis with a stirring and heating system.
P400-SC Waterworks contains sodium carbonate, sodium hydroxide, sodium lauryl sulfate and sodium metasilicate. The last two constituents, with 1-5 wt% respectively, are auxiliaries in the P400-SC Waterworks. The remaining two react with carboxylic acid and ester group per the following chemical reaction:
where R is the remaining carbon chain apart from carboxyl group and R1, R2 represent the two-side segments of ester group. Ester hydrolysis is the main reaction we need, which ionizes the ester group and makes it water soluble with an increased polarity. These reactions would happen when SR-30TM or SR-100TM /SR-110TM supports are dropped into a tank with P400-SC Waterworks cleaning solution inside.
From the table above, we can see that ABS-M30TM and PC-10TM don’t have hydrophilic groups, which restrains their solubility into water. Nylon is semi-crystalline polymer and difficult to dissolve into water and most organic solvent, despite the presence of the hydrophilic group acylamino (-CONH-), which still results in a nice water-absorbing ability. All these model materials are common-use engineering plastic with nice chemical resistance (depending on their functional groups), they can be safe in the cleaning solution.
PADT’s Support Cleaning Apparatus (SCA)
The SCA tank offers an optimized environment with agitation and heating for the ester hydrolysis reaction. The tank has four preset temperature options (50 ℃, 60℃, 70℃, 85℃) for ABS-M30TM, PC-10TM, and FDMTM Nylon 12 model materials, due to their different thermal resistance. The innovative custom designed pump is key to cause the solution to effectively and efficiently dissolve and remove the support materials.
The Wake Forest Institute of Regenerative Medicine (WFIRM) hosted about 400 attendees at the annual Biofabrication conference, held this year at Winston-Salem, NC (Oct 28-Nov 1, 2016). The conference included a 2 hour tour of WFIRM’s incredible facilities, 145 posters, 200 or so presentations and a small trade show with about 30 exhibitors. As a mechanical engineer attending my first bio-related conference, I struggled to fully comprehend many concepts and terms in some of the deeper technical presentations. Nonetheless, there was a lot I DID learn, and this post serves to summarize my thoughts on the four high-level insights I gleaned amidst the pile of information on offer. I hope these are of value to the larger community that is not on the front lines of this exciting and impactful area of research.
More than Organs
To say biofabrication is all about making organs is like saying manufacturing is all about making spacecrafts carrying humans to Mars. It misses a lot of the other valid human needs that can be met and suggests organs are the end of the biofabrication R&D curve, when they only represent one manifestation (arguably the most difficult one in our current sense of the world) of the application of the science. If we take a step back, biofabrication is fundamentally about “manufacturing with living materials” – in that sense, biofabrication blurs the lines between natural and man-made entities. If you could manipulate and engineer living cells in physical constructs, what all could you do? Here is a list of some examples of the different applications that were discussed at the conference:
Toxicology Studies – Organovo’s examples of skin, liver and kidney tissue being used to evaluate drug efficacy
Body-on-a-Chip – A solution to aid in pre-clinical work to study whole systems (a key regulatory hurdle) and potentially displace animal studies in the future
Tissues for Therapy – This could involve patches, stents and other such fixes of a therapeutic nature (as opposed to replacing the entire organ in question)
Non-Medical Applications – Modern Meadow is a company that is using biofabrication techniques to make leather and thereby help reduce our dependency on animal agriculture. Biofabricated meat is another potential application.
Functional Tissues and Organs – An interesting thought presented by Prof. Rashid Bashir is that replacing organs with matched constructs may not be optimal – we may be able to develop biological entities that get the job done without necessarily replicating every aspect of the organ being replaced. A similar thought is to to use biological materials to do engineering tasks. The challenge with this approach is living cells need to be kept alive – this is easier done when the fabricated entity is part of a living system, but harder to do when it is independent of one.
Full Organ Replacement – Replicating an organ in all its detail: structurally and functionally – WFIRM has done this for a few organs that they consider Level 1-3 in terms of complexity (see Figure 1). Level 4 organs (like the heart) are at the moment exceedingly challenging due to their needs for high vascularity and large size.
It Takes a Village (and a Vivarium)
Imagine this is the early 2000s and you are tasked with establishing a center dedicated to accelerating the progress of regenerative medicine. What are the parts this center needs to house? This was probably what Dr. Anthony Atala and others were working out prior to establishing WFIRM in 2004. To give you a sense of what goes on in WFIRM today, here is a (partial) list of the different rooms/groups we visited on our tour: decellularization, imaging, tissue maturation, bioprinting, electrospinning, lab-on-a-chip, direct writing, vivarium that cares for animals (mice, ferrets, sheep, pigs, dogs – beagles to be specific, and “non-human primates”) and a cleanroom for pre-clinical studies. Add administrative, outreach and regulatory staff. Today, about 450 people work at WFIRM and many more collaborate. Going into this conference, I was well aware this field was an inter-disciplinary one. The tour opened my eyes to just how many interdependent parts there are that make an end-to-end solution possible, some more interdisciplinary in nature than others and just how advantageous it must be to have all these capabilities under one roof dedicated to a larger mission instead of spread across a large university campus, serving many masters.
“I Have a Hammer, Where is the Nail?”
I will be honest – I justified my interest in biofabrication on the very dubious basis of my experience with 3D printing, a long standing interest in the life sciences that I had hitherto suppressed, and the fact that I am married to a cancer researching biochemist – bioprinting was my justification for finally getting my feet (close to a) wet (lab). I suspect I am not alone in this (support group, anyone?). When I described this to the only surgeon who entertains my questions, he accurately summarized my approach in the afore mentioned hammer-nail analogy. So, armed with my hammer, I headed to the biofabrication conference seeking nails. The good news is I found a couple. As in exactly two. The bad news? See the section above – this stuff is hard and multi-faceted – and there are folks with a multi-decade head start. So for those of us not on the front lines of this work or not in college planning our next move, the question becomes how best can we serve the scientists and engineers that are already in this field. Better tools are one option, and the trade show had examples of these: companies that make bioprinters (see Figure 2 below), improved nozzles for bioprinting, clean-room alternatives, biomaterials like hydrogels, and characterization and testing equipment. But solving problems that will help the biofabrication community is another approach and there were about 5-10 posters and
presentations (mine included) which attempted to do just that. What are some of the areas that could benefit from such peripheral R&D engagement? My somewhat biased feeling is that there is opportunity for bringing some of the same challenges Additive Manufacturing is going through to this area as well:
Design for Bioprinting: fully exploiting the possibilities of bioprinting – “in Silico” has made some progress with medical devices – a similar window of value exists for biofabrication due to the design freedom of 3D printing
Modeling: Biofabrication almost always involves multi-materials, often with varying constitutive behaviors and further are in complex, time-varying environments – getting some handle on this is a precursor to item 1 above
Challenges of Scale: This has many elements: quality control, cost, automation, data security, bio-safety. This is one of the key drivers behind the recent DOD call for an Advanced Tissue Biofabrication Manufacturing Innovation Institute and is likely to drive several projects in this space over the next 5-7 years.
Moral of the story for me: carry your hammer with pride but take the time to learn, ask and probe to find the pain points that are either already there or are likely to arise in the future, and keep refining your hammer with input from the biofabrication community – conferences are the best place to do this – IF you go in with that intent and prepare ahead of time identifying the people you want to talk to and the questions you wish to ask them – something I hope to be better at next time around.
The Rate-of-Progress Paradox
Finally, a more abstract point. From the sidelines, we may ask how far has the field of biofabrication come and how fast is it progressing? It is one thing to sift through media hype and reconcile it with ground realities. It is quite another to discover this conflict seemingly exists even in the trenches – there are several examples of transplanted biofabricated entities, yet there is a common refrain that we have a long way to go to doing just so. And that struck me initially as a paradox as I heard the plenary talks that were alternatingly cautious and wild – but on the very last day I started to appreciate why this was not a paradox at all, it is just the nature of the science itself. Unlike a lot of engineering paradigms, there are limits to efficiencies that can be gained in the life sciences – and once these are gained (shared resources, improved methods etc.), success in one particular tissue or organ may not make the next one progress much faster. Take Wake Forest’s own commonly used approach for regenerative medicine, for example: harvest cells, culture them, build scaffold constructs, mature cells on these constructs, implant and monitor. Sounds simple, but takes 5-10 years to get to clinical implantation and another 5-10 of observation before the results are published. And just because you have shown this in one area, bladder for example, doesn’t make the next one much faster at all. All the same steps have to be followed: pathways to be re-evaluated, developmental studies to be done – prior to extensive animal and clinical trials. The solution? Pursue multiple tissues/organs in parallel, follow each step diligently and be patient. Wake Forest seems to have envisioned this over a decade ago and I expect the coming decade will show a cascade of biofabrication successes hit us with increasingly boring steadiness.
Finally, we should all be thankful to the many PhD students and post-docs from all over the world putting in the bulk of the disciplined, hard work this field demands, most of them, in my opinion, at salaries not reflective of their extensive education and societal value. We should also spare a thought for all the animals being sacrificed for this and other research, even in the context of best veterinary practices – my personal hope is that biofabrication enables us to stop all animal trials at some point in the near future – indeed, this seems to be the only technology that can. Then we can truly say with confidence, that we have first and foremost, done no harm.
Thank you WFIRM, for a wonderful conference and all the work you do everyday!