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3D Printing News Briefs: October 7, 2018

We’ve got a shorter edition of 3D Printing News Briefs for you today. Siemens Corporate Technology is working on process simulation for additive manufacturing. BIOMODEX is launching a realistic, 3D printed new training product, and an orthopedic surgeon is using 3D printing to repair bone fractures. Finally, several companies are collaborating and using metal 3D printing to make a customized component for the upcoming Ironman race.

Siemens Working on 3D Printing Process Simulation

Often in metal 3D printing, all kinds of defects can occur, such as distortion and local overheating. Getting the 3D print right the first time around is the goal that experts of Siemens Corporate Technology are working to achieve. Process simulation for additive manufacturing is a pretty important step on the way to industrializing the technology, as getting complex geometries correct at the beginning of the process could save time and money down the line.

“Our vision is to develop this additive manufacturing process in such a way that we can actually print a model created in the CAD system, getting it right the first time and printing it perfectly,” said Ursus Kruger of Siemens Corporate Technology in Berlin. “We call this the first-time-right principle, which we want to achieve here.”

Learn more about Siemens’ work in the video below:

BIOMODEX Launching New 3D Printed Training Product

The Left Atrial Appendage Closure Solution (LAACS) station

With the launch of its new training product, medical technology startup BIOMODEX is officially entering the interventional cardiology space. Its new Left Atrial Appendage Closure Solution (LAACS) lets physicians work on their skills using a super realistic, 3D printed multi-material heart. The startup’s patented INVIVOTECH technology makes it possible to create 3D printed organs based on a patient’s medical imaging, like CT scans. It’s also possible to reproduce an organ’s surrounding tissue and biomechanics as well.

“Our mission is to provide as realistic an experience as possible for physician training,” said Carolyn DeVasto, the Vice President of Global Commercialization at BIOMODEX. “Our advancements in patient specific 3D printing using INVIVOTECH and ECHOTECH allow physicians to train in a clinical setting using the same techniques they use in an actual procedure.  Ultimately, we want to provide the physicians an opportunity to test drive any procedure on our solution to improve safety and clinical outcomes.”

BIOMODEX’s patented ECHOTECH also allows physicians to observe the 3D printed heart using fluoroscopy, or any TEE ultrasound system. This means that they will be training with the same techniques they’ll be using in real life procedures, which is invaluable in the operating room.

Repairing Fractures with 3D Printing

Nathan Skelley, MD, an orthopaedic surgeon and sports medicine specialist at the Missouri Orthopaedic Institute, is working on a research project about a specific issue related to trauma orthopaedics – reducing and fixing bone fractures.

“In the United States, we’re very fortunate that I have an almost endless supply of plates and screws,” Dr. Skelley said. “I’ve never been in a situation in the OR where I don’t have another screw or I don’t have another plate to fix one of these fractures. But in the developing world or in rural environments, those resources are not always the case.”

Dr. Skelley and his team are testing if they can easily replicate the plates, screws, and tools they use so often in these types of common trauma and sports procedures with 3D printing, so physicians in areas not quite as developed as the US can perform necessary orthopaedic surgery. You can learn more about his work in the video below:

Metal 3D Printing for Ironman World Championship

Next week, the Ironman World Championship, a yearly culmination of several Ironman triathlon qualification races held around the world, begins in Hawaii. For this particular race, Canyon, Swiss Side, and Sauber Engineering are working together on Project 101 for Patrick Lange, last year’s Ironman World Champion. The goal is to make the Lange, the fastest Ironman, even faster, by using metal 3D printing to fabricate a customized aero cockpit that fits Lange’s arm shape and position perfectly. CFD (Computational Fluid Dynamics) simulations were used to confirm that his tri-bar extensions were producing a decent amount of drag, so the project partners worked out a design to integrate them into Lange’s arms.

Swiss Side 3D printed the first concept and tested it back in May, and Lange’s arms were scanned at Sauber to ensure the perfect fit. Canyon and Swiss Side designed and optimized the aerodynamics for the new aero cockpit, and using FEM (Finite Element Method) structural analysis, the parts were optimized for weight and stiffness. The most recent iteration was 3D printed in plastic and tested in another wind tunnel session so Lange could approve its performance. Then, Sauber used titanium to 3D print the final parts; aluminum was used to create ultra-light shells for the elbow pads.

“While working on Project 101, we did something that has never been done before in triathlon,” Lange said. “I am very proud to be part of this project. We tested my new aero cockpit in the wind tunnel and the results confirmed a significance performance improvement. This will have a direct impact on my bike-splits in Kona. I can’t wait to show the world my new aero cockpit and deliver a strong performance on October 13th at the big race in Kona, Hawaii.”

What do you think? Discuss these stories and other 3D printing topics at 3DPrintBoard.com or share your thoughts in the Facebook comments below. 

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Thesis Provides Proof of Concept for Using 3D Printing to Improve Design of Internal Pressure Relief Valve

Test pumps installed on 75 HP dynamometer: Test Setup Discharge Port at 90°

Over the years, 3D printing has proven to be a pretty handy technology to have in one’s toolbox when it comes to making replacement and mechanical parts, like hand water pumps, transmissions, gears, and valves. For his Master’s of Science thesis this year, titled “3D printed relief valve analysis and validation,” John Anthony Dutcher, III, a student at the University of Northern Iowa‘s Department of Technology, used SLA 3D printing to fabricate prototypes of the internal pressure relief valve of a positive displacement pump.

The abstract states, “Additive Manufacturing allows for faster, lower cost product development including customization, print at point of use, and low cost per volume produced. This research uses Stereolithography produced prototypes to develop an improvement to an existing product, the internal pressure relief valve of a positive displacement pump. Four 3D printed prototype assemblies were developed and tested in this research. The relief valve assemblies consisted of additive manufacturing produced pressure vessel components, post processed, and installed on the positive displacement pump with no additional machining. Prototype designs were analyzed with Computational Fluid Dynamic simulation to increase flow through the valve. The simulation was validated with performance testing to reduce the cracking to full bypass pressure range of the valve. By reducing this operational range of the valve, the power requirement of the pump drive system could be reduced allowing for increased energy efficiency in pump drive systems. Performance testing of the 3D printed relief valves measured pump flow, poppet movement within the valve, and discharge pressure at operational conditions similar to existing applications. The Stereolithography prototype assemblies performed very well, demonstrating a 56% reduction in the pressure differential of the cracking to full bypass stage of the valve. This research has demonstrated the short term ability of additive manufactured produced components to replace existing metal components in pressure vessel applications.”

The gear found inside positive displacement pumps, developed over a century ago, was able to overcome existing performance limitations, but it was by no means perfect. These pumps need an internal relief valve, which provide protection against too much pressure; if there’s a reduction in discharge flow, the over-pressure system could fail.

“The primary focus of this research is to investigate the performance of an internal relief valve for a positive displacement pump, propose an improvement to flow conditions in the cracking to full bypass pressure range of the valve based on flow simulation and validate the performance improvement with 3D printed prototypes,” Dutcher wrote.

SLA Part Production

Over the years, the design of the internal relief valve in these positive displacements pumps has not changed much. But by using computer simulation, the design can be revised and optimized to make the part more efficient. As he wrote in his paper, Dutcher’s research validates the 3D printed prototypes, using Computational Fluid Dynamics simulation and perfrmance testing, “in the design development of an improvement to an existing product,” and also shows that costs and time can both be reduced by using 3D printing to manufacture the valve.

“Additive manufacturing has the benefit of customization, allowing for design changes,” Dutcher wrote.

“Developing customizable end use components that can manufactured at the point of use, allows for application specific products to be produced for pressure vessel applications.”

The valve prototypes, 3D printed using SLA technology, were shown to reduce the amount of cracking in order to fully bypass the stage differential pressure that’s necessary to operate the internal relief valve. FDM 3D printing was used to make mounting brackets to attach an LVDT sensor to the valve prototypes; this sensor measures the movement of the poppet (internal device in the relief valve that seals its surface) during testing.

Assembled Reference Valve Extended

In his thesis, Dutcher wanted to determine if 3D printing could successfully be used to produce components of a test valve for the positive displacement pump, if the valve’s geometry was able to be optimized to reduce cracking based on flow conditions, and if the 3D printed prototype valves would perform at the same level as existing ones made with conventional methods of manufacturing. Ultimately, while he did answer these questions and demonstrated that 3D printing does indeed have applications in developing new products, his research provided a viable proof of concept for improving the existing design of a product.

“The 3D printed prototypes were developed to reduce cost and delivery lead time for prototype testing,” Dutcher wrote.

“The flexibility in design permutations that additive manufacturing allows with customization provides the opportunity to validate multiple product designs in parallel.”

SLA Support Structures

By using 3D printing to create the prototypes, Dutcher was able to develop several different design concepts at the same time, without getting caught up by the normal barriers that come with traditional manufacturing methods. SLA 3D printing also makes it possible to produce parts with “the dimensional tolerances of machined components,” which helps speed up the development of prototypes.

“This research has demonstrated the SLA 3D printing’s ability to reproduce existing machined metal components,” Dutcher concluded. “While extended performance testing was not the intent of this research, the 3D printed pressure vessel valve components performed very well in performance testing. The development of the design variations in timely manor would not have been possible without Additive Manufacturing. Testing has shown an improvement in the valve performance by reducing the cracking to full bypass pressure from 52.0 psi to 22.8 psi. The successful performance test to improve an existing product demonstrated the validity of the SLA 3D printed prototype assemblies.”

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3D Printed Fins Help Surfers Catch the Perfect Wave…and May Signal a Sports Industry Revolution

If you like 3D printing just as much as you enjoy riding those gnarly waves, you may remember when a research team from the University of Wollongong (UOW) in Australia started 3D printing surfboard fins specifically tailored to the needs of the individual surfer two years ago. This research has continued, and a multidisciplinary team of UOW students and academics from the university’s Australian National Fabrication Facility (ANFF), along with several surfers, recently took a trip to hang ten at the remote Mentawai Islands in Indonesia, and test out new shapes of surfboard fins, which were designed and 3D printed at UOW.

The project is part of UOW’s Global Challenges Program, with an initial goal of testing out several of these new 3D printed fin shapes and comparing them against conventional fins. But the researchers also hope to determine the possibility of developing a new niche manufacturing industry out of 3D printed surfboard fins.

“There is a lot to a simple surfboard fin, you have to consider the fin base, depth, rake (or sweep), foil, cant, toe and flex,” said Professor Marc in het Panhuis from the university’s School of Chemistry, who worked on the last 3D printed surfboard fin project. “Not to forget, the number of fins and their positioning on a surfboard.

“There is no such thing as a simple surfboard fin. The team has looked at things different materials that can make the fin stronger, lighter and its ability to flex.”

According to Professor in het Panhuis, ocean swell and a good surfboard, fitted with the proper fins, are both equally important to surfers. While these 3D printed fins may look like commercially available ones, Professor in het Panhuis said that “the proof is in the ride.”

Dr. Stephen Beirne with the university’s ANFF said that this is the perfect project to conduct trials on 3D printing and rapid prototyping.

“3D printing enables us to print virtually anything we can imagine and that includes surfboard fins. Our team started out creating CAD-generated fin designs on a computer, then we took those designs and used computational fluid dynamics to see how the fin was likely to perform in the water,” explained Dr. Beirne. “The last part of the process was to select the most appropriate materials to print the prototype.”

3D printing is often used today to fabricate equipment for real-life use in the sports and leisure industry, from protective gear – like soccer shin guards, helmets, and mouthguards – to apparel ranging from specialized footwear, eyewear, and racing gloves, and equipment such as improved snowboards, luge sleds, and even surfboards. By using this technology to create usable parts, the whole sports industry could see a 3D printed revolution in terms of customized products.

The UOW researchers took their time coming up with designs for the 3D printed fins, and after a long search to find the most consistent ocean waves in which to test the fins in real-world conditions, they chose the island chain off the western coast of Sumatra, as it provides both dependable waves and a variety of surf breaks, including the left-hand-breaking Macaronis wave the team used.

“Macaronis is a unique surfing spot because the waves always break on a reef in the same spot,” explained Professor in het Panhuis. “The waves also roll over a long distance and surfers can get a maximum of turns, which is perfect for collecting surfboard fin data.”



The surfers were tasked with catching a variety of waves, and performing as many turns as they could manage on each, with multiple different surfboard fins. Surfboard shaper Dylan Perese of DP Surfboards, who participated in the testing and data collection, also produced standardized surfboards for the project, so everyone had the same base.

Professor in het Panhuis then added embedded sensors and GPS tracking devices to the surfboards to gather performance data on the fins. He explained:

“The devices tracked everything from wave count, speed, number of turns to the amount of rail engaged during turning (to name but a few of the parameters). The surfers also filled out a fin performance rating scale immediately after they completed riding each set of fins. The information is then used to compare the different sets of fins.”

Professor Julie Steele, the Director of UOW’s Biomechanics Research Laboratory, has nearly four decades of experience running human trials, and collected the data during the trials, while also taking pains to ensure that the surfers were not biased toward any particular fin designs.

The surfers were tracked on over 450 waves, performing more than 1,700 turns, in multiple weather conditions, on three different 3D printed fin designs. The results, which should be published soon, were then compared against fins sold by two mainstream fin producers, and there was a clear winner.

“Preliminary analysis of the fin performance rating data has revealed that the surfers, on average, have rated one of the 3D printed fins as feeling the best to surf on. We were surprised that there was such a strong preference for this one fin, given the six surfers all had very different surfing styles,” said Professor Steele.

The 3D printed ‘Crinkle Cut’ fin has a series of grooves on one side, in order to increase the lift to drag ratio and propel surfers along the waves.

“The reason this fin shape works so well is because the contours improve the way the water flows past it,” Professor in het Panhuis explained. “These contours ultimately give the surfer more speed. The fins also seemed to offer plenty of drive and projection out of turns.”


So whether you’re hoping to catch the perfect wave, hit the track, or try for an Olympic medal, 3D printing could help you get to the finish line.

Discuss of this story and other 3D printing topics at 3DPrintBoard.com, or share your thoughts below.

[Images provided by UOW]

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Use of Simulation to Evaluate How Well 3D Printing Bioinks Work

[Image: CollPlant]

Plenty of research has been completed regarding the different materials we use to create biomedical parts. Many innovative bioinks – biomaterials loaded with cells to 3D print biological structures – have been developed for 3D bioprinting purposes, from materials like stem cells, gelatin hydrogels, and even sugarcane waste. 3D bioprinting itself is changing the field of medicine as we know it, because we can now fabricate patient-specific human tissues in a laboratory setting.

However, this technology only works if researchers and doctors have good bioinks on hand…and how do we know the materials are good? It’s expensive, difficult, and can take a long time to evaluate if these bioinks are 3D printable. That’s why many many researchers, like a team from the Wallenberg Wood Science Center (WWSC) in Sweden are starting to rely more and more on computer simulations to optimize these biomaterials.

Kajsa Markstedt, a PhD student of chemistry and chemical engineering and biopolymer technology at WWSC, and her colleagues recently partnered up with Johan Göhl’s Computational Engineering and Design team at the Fraunhofer Chalmers Centre (FCC) to test out a process for using a computational fluid dynamics tool to model the way bioinks are dispensed.

“As well as allowing us to evaluate the printability of a bioink, simulations could also help us choose the printing technique that should be employed depending on the target tissue. Such techniques vary depending on the viscosity and nature of the ink being printed, and include ink-jet printing, laser-induced forward transfer, microvalve- and extrusion-based bioprinting,” said Markstedt.

“To model how a bioink is dispensed, we used its mass flow rate and density as input in our calculations. These parameters are the ones most commonly evaluated in experiments when printing designs such as lines, grids or cylinders.”

The team published a paper, titled “Simulations of 3D bioprinting: predicting bioprintability of nanofibrillar inks,” in the Biofabrication journal; co-authors include Göhl, Markstedt, Andreas Mark, Karl Håkansson, Paul Gatenholm, and Fredrik Edelvik.

The abstract reads, “To fulfill the multiple requirements of a bioink, a wide range of materials and bioink composition are being developed and evaluated with regard to cell viability, mechanical performance and printability. It is essential that the printability and printing fidelity is not neglected since failure in printing the targeted architecture may be catastrophic for the survival of the cells and consequently the function of the printed tissue. However, experimental evaluation of bioinks printability is time-consuming and must be kept at a minimum, especially when 3D bioprinting with cells that are valuable and costly. This paper demonstrates how experimental evaluation could be complemented with computer based simulations to evaluate newly developed bioinks. Here, a computational fluid dynamics simulation tool was used to study the influence of different printing parameters and evaluate the predictability of the printing process. Based on data from oscillation frequency measurements of the evaluated bioinks, a full stress rheology model was used, where the viscoelastic behaviour of the material was captured.”

Visual comparison between (L) photo of printed grid structure and (R) simulation of printed grid structure when using 4% CNF ink.

According to Markstedt, 3D printability of a bioink is most often determined by the ratio of line width to the diameter of a 3D printer’s nozzle, the curvature of 3D printed lines, and how many layers can be printed before structure collapse. The FCC scientists also used a dynamic contact-angle model, which uses surface tension and a contact angle as input, to the bioinks’ wettability on a substracte.

“In our simulations, we also used the printing path of a grid structure as input,” Markstedt said.

The full rheology model was based on the material’s viscoelastic behavior and the ink-oscillation frequency data obtained in the team’s experiments. For cellulose nanofibril (CNF) bioinks with different rheological properties, simulations produced outcomes that were similar to experimental results in lab evaluations. Additionally, the researchers could use the computer model the follow the real-time 3D printing process and study the behavior of various inks during dispensing.

Markstedt said, “In experimental evaluations, we often only have the properties of the final, printed grid structure to go on. This is a time-consuming way to develop new bioinks or to optimize printing parameters for a specific ink. It is also expensive since the prepared bioink containing cells is precious.”

It’s also important to test the biostructure soon after it’s 3D printed, because the cells are still viable at that point; this limits how long evaluations can last.

“This often leads to many bioinks being printed at printing parameters that have not been optimized for a specific bioink composition. The result is that the right architecture is not produced, which can be catastrophic because the printed tissue does not function properly,” said Markstedt. “For example, the printed line may be too thin causing the structure to break, or too thick, which prevents nutrients and oxygen reaching all the cells in the bioink.”

Comparison of the distribution of viscoelastic stresses in lines printed with 4% CNF ink and ink 6040 at 0.3, 0.4 and $0.5,mathrm{mm}$ distance between nozzle and plate.

The researchers are fairly certain that their new simulation tool will be able to provide them with far more feedback during 3D printing, like how viscoelastic- and shear stresses are distributed in the ink, while still surmounting all of these issues.

Markstedt said, “This provides a better understanding of why certain printer settings and bioinks work better than others. For example, it allows us to isolate individual parameters, such as printing speed, printer nozzle height, ink flow rate and printing path to study how they influence printing.”

The team will now work on modeling bioink flow inside nozzle geometries that are pre-defined.

“This addition to the model will allow us to observe what effect shear stresses from the nozzle have on the printing process. This will help us to determine how different printing pressures and nozzle shapes affect the bioprintability of a bioink,” explained Göhl.

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[Source: Physics World / Images: Göhl et. al.]