Manufacturing in the Third Dimension

Three-dimensional (3-D) printing. Additive manufacturing. Rapid prototyping. These are all terms for the same kind of manufacturing process, and each term tells you a little bit about what exactly 3-D printing brings to the table. First, and most obviously, it’s a process that creates three-dimensional objects. Second, it is a process by which an object is created by “adding” material layer by layer, rather than shaping, shaving and trimming material, which is called subtractive manufacturing. Third, it’s fast, which is why many manufacturing companies use the method to make quick mock-ups of a medical product before mass-producing its finalized version via a different machining, molding or milling manufacturing technique.

When Orthopedic Design & Technology features a technology or manufacturing process, the editor’s task is to translate complex processes and jargon so that experts from unrelated fields—and the lay person—can understand them better. Perhaps an inventor could learn something about a manufacturing process she didn’t know about before that could apply to her product idea; perhaps a physician could learn more about a technology he didn’t know existed that could solve a difficult medical case; perhaps a manufacturer could learn about a new piece of equipment she didn’t know was on the market, and could use in her processes.

This type of “translation” is not necessary for 3-D printing. Not when a prosthetic hand can be made at home for less than the cost of lunch. Patents on 3-D printing processes are expiring as you read this, which is why anyone can go to their local Staples office supply store and buy a Cube 3-D printer for roughly $1,300. And for $3,449.99, anyone with a credit card or enough cash can buy the CubeX Duo Commercial 3-D printer. Despite being billed as “not for home use,” the printer is freely available on the Staples website, no questions asked. ODT covered the story in 2013 when Zero Point Frontiers Corporation created a prosthetic hand for 2-year old Kate Berkholtz. She was born with symbrachydactyly, a congenital abnormality that prevented her left hand from fully developing in the womb. President and CEO Jason Hundley and his design team at the Huntsville, Ala.-based aerospace engineering company came up with a design for a simple prosthetic hand. After buying a MakerBot 2X 3-D printer for approximately $3,000, they were able to 3-D-print Kate’s custom, functional prosthetic hand for less than $5. Add “cheap” to the list of benefits 3-D printing has to offer.

The recent and ongoing expiration of certain 3-D printing techniques is behind the availability of direct-to-consumer 3-D printers such as the ones offered by Staples. For instance, U.S. Patent No. 5,569,349 titled “Thermal Stereolithography” expired in October last year. This patent protected an apparatus of and method for providing 3-D objects through the principles of stereolithography using flowable materials. In December, U.S. Patent No. 5,587,913, titled “Method Employing Sequential Two-Dimensional Geometry for Producing Shells for Fabrication by a Rapid Prototyping System,” which was assigned to 3-D printing company Stratasys Ltd., expired.¹ But the new availability of cheap 3-D printers does not mean that anyone at home can now fabricate rods and screws for their own bone fractures. Manufacturing veterans tend to turn their nose up at the notion of the average citizen sitting at home fabricating useful tools.

“That model [of home-use 3-D printers] is fractured,” Matt Hlavin, owner, founder and CEO of Avon Lake, Ohio-based 3-D printing company Rapid Prototype and Manufacturing LLC (rp+m) told ODT. “It’s great because it brings a lot of press to the 3-D printing space. It sounds like it’s an overnight success, but 3-D printing has been around for about 35 years. So if you buy the Cube from staples, it’s a $3,000 machine, you bring it home, you put it under the Christmas tree, the kids want to use it…but it’s not like a paper printer where you just hit control+P and a paper comes out with ink on it. You have to understand how to drive it. You can download design files from the internet, but how long before you get bored printing existing art versus creating? The other challenge with those machines is that the heads clog up, the material doesn’t process the right way—there are a lot of mechanical faults with the machines. We even see it on the production side with our production machines, and we have both the gimmicky ones you see in the store as well as industrial production 3-D printing machines. Staples doesn’t have service technicians to go to your house and service your machine, so you have to bring it back in. If it fails twice because you have a consumer who doesn’t know how to fix or use it, they get bored and return it. Before you know it, the store is losing money on service calls and tying up resources in their tech shop in-house to try and fix those machines.”

Three-D printing for the home is brand new, which is why it is far from perfect. Home 3-D printers certainly are not about to put large additive manufacturing companies out of business just yet. But most medical device manufacturers in the orthopedic space agreed to ODT that 3-D printing in the hands of expert manufacturers certainly has the potential to change manufacturing as we know it.

“Fifty years ago, if you wanted something professionally printed, you would have to find an artist to illustrate your image or find a professional typesetter,” said Zero Point’s Hundley, putting things in perspective. “Now you can press a button and it’s printed. 3-D printing will do the same thing for the manufacturing world.”

Since successfully creating a prosthetic hand for little Kate, Hundley and his team at Zero Point have been trying to fund a project to create an open-sourced template for their design that is customizable by any user. Makerbot has a database of such designs and Hundley wants to see the template for the prosthetic be used by anyone who needs it. An Indiegogo funding campaign was unsuccessful, but Zero Point now is in conversations with the University of Alabama, Huntsville, to secure a grant either through the Veteran’s Association or the National Science Foundation.

New York, N.Y.-based Makerbot Industries LLC, the company that makes the printer Zero Point used for Kate’s hand, has a database of 3-D designs called Thingiverse. The database is full of free, open-source designs that anyone can download and use on a 3-D printer. This is the type of database Hundley envisions for open-sourced prosthetic designs.

“I get lost searching on that because there are just so many designs,” Hundley said. “We wanted to prototype several conditions, because each human being’s condition is like a snowflake. One person could be missing three fingers and another could be missing a whole hand. What we want to be able to do is template out what we think the most common cases are and come up with a few variations of designs so that somebody could either take a picture or scan their hand and we could build a very simplified database to do a likeness matching. Hey, here is a design that fits your need 90 percent—so all you have to do is tweak a very simple design. Or if it’s a 90 percent match or greater, you can print it with instructions, and locate through our database someone in your state with a printer who has agreed to donate extra printing time for this project. It basically ‘unsecrets’ the sauce for the design and manufacturing of the prosthetic.”

Hundley’s vision is to see meaningful use of 3-D printing in the hand of the average citizen. In terms of pediatric prosthetics, it’s a worthy goal. Children are a neglected demographic in orthopedics because they grow so fast it often is prohibitively expensive to create prosthetics for them and next to impossible to place an orthopedic implant in them without having to perform frequent revision surgeries to adjust or replace the implant.

Mass Customization
Mass customization is the golden egg of 3-D printing. The process allows cheap, quick runs in small volume, eliminating the need to make large batches to recoup overhead. This allows for the creation of truly customized orthopedic implants made to the unique specifications of each patient, which in turn leads to better surgical outcomes and better patient care.

Drew Roberts, engineering manager for 3D Material Technologies LLC (3DMT), was immersed in manufacturing technology from a young age. His father was a mechanical engineer and designer, and he owned his own plastic injection molding company in Illinois. When Roberts was about 13 years old in the late 1990s, his father’s company rolled out 3-D printing, and Roberts was fascinated.

“That was also the time I was introduced to SolidWorks, which is a 3-D design program,” Roberts recalled. “I started using it at that age, I used to come home from school and design. I thought it was the coolest thing. I was always kind of an inventor at that age, I always had ideas, and now I could actually put those ideas into 3-D objects. I was designing three-cylinder motorcycle engines—I thought I was going to revolutionize things.”

3DMT is part of Deland, Fla.-based advanced manufacturing company ARC Group Worldwide. ARC operates three U.S.-based metal injection molding (MIM) facilities under the umbrella of ARC MIM, and runs two 3-D printing operations currently. Roberts runs the 3DMT facility in Longmont, Colo.

“At my first job, I worked as machinist and designer, where we had one 3-D printer,” Roberts said. “I unrolled some 3-D printing into our designs and was able to get away from traditional metal machining. When I moved to Colorado and joined AFT (an ARC MIM company), I really pushed 3-D printing. We started printing a lot of our projects. In the first 10 or 12 months I spent with ARC MIM, we saved $150,000 on approximately 90 projects that would have cost about $200,000 without 3-D printing. Using 3-D printing they only cost $35,000-$40,000 and the turnaround time was significantly quicker as well.”

The moniker “rapid prototyping” often used to describe 3-D printing comes from its common use as a quick tool for mock-up designs. While a finished product might require several different processes to connect different components, sometimes made of different materials, 3-D printing was and still is used to create a prototype in order to show the designer, whether it’s an engineer, a surgeon or a design team, what it might look like. Because the process is fast and cheap, this is a useful tool to use until the product shape and dimensions are just right, at which point it will be ready to go to mass production under whatever machining process the manufacturing company uses. Today, however, 3-D printing is advanced enough that it can be and is used to create finished products.

3DMT does both. Roberts explained to ODT that the company makes low-run production batches of finished products, and leaves the large-batch production to ARC’s MIM capabilities.

“With MIM, there’s not much you can do until you have a tool, a mold, and which can take months and almost $50,000 to $100,000 before you ever get a chance to try out that part,” he said. “So 3DMT will do an early stage run of five, 10, 100 or 1,000 parts, and then once they’re ready to go into larger quantities we can roll them over to our MIM side and they can take it to 10,000 to a million plus parts per year. We’re attacking both sides, because sometimes if a customer only wants 1,000 parts, it doesn’t make sense to spend $50,000 on a tool and wait for months. We can 3-D print 1,000 parts in a couple weeks and lower the cost quite a bit.”

Orthopedic devices, however, must be manufactured under extremely stringent quality assurance standards, because so many of them are implantable. From rods and compression screws to vertebral implants, any implantable needs to be manufactured in sterile conditions and the processes must be highly validated.

“The medical industry is very concerned with contamination, so with a machine that has run cobalt chrome, for instance, and then switched to titanium, regulatory authorities are concerned with the seal still having a little bit of that cobalt chrome, or some of the different components being contaminated,” Roberts explained. “So one of the things 3DMT is unrolling is that one of the new machines we’re going to be getting down the road is going to be tested, proven and calibrated with titanium and shipped to us with nothing but titanium ever touching it. It’s something we really want to get into—having a strictly titanium, non-contaminated machine.”

“The landscape is so litigious out there with product design and development for implantables specifically,” said rp+m’s Hlavin. “An engineered product from some of the big companies can get into the operating room, and stresses and fractures in the implant itself can cause adverse effects which leads to recalls. Three-D printing is going to move more down a path of a snowflake process, where we can take CT [computed tomography] data from a hospital or surgeon, delineate that and create a one-off specific implant for the patient that is safer, true to form, and fits the specific patient.”

Belgian company Materialise NV, which has been working in the rapid prototyping space since 1990, is doing exactly that. The company makes patient-specific surgical guides built to fit the unique shape of a patient’s bone, indicating the drill holes or osteotomies defined in a surgeon’s surgical plan, based on CT or magnetic resonance imaging scans. These guides are 3-D printed out of a nylon material.
“Materialise also creates implants for niche markets in Europe and Asia,” Director of Orthopaedics Jeroen Dille told ODT. “For instance, for patients with severe hip revisions, who have had multiple implants that have resulted in a great loss of bone stock, we create titanium implants catered specifically to that patient because the pattern of loss will be different for each one.”

Three-D printing is in everyone’s hands now, productively or otherwise. While in the hands of the home user, the technology may not be of much use, but in the hands of physicians, 3-D printing certainly could bring patient-specific, meaningful technology to patients faster.

“For surgeons, 3-D printing is unchartered waters so there are a lot of questions out there about it,” said Scott Leube, business development manager for JALEX Medical LLC, a biomedical engineering, product development and regulatory/quality assistance sister company to rp+m. “Surgeons and physician practices are always looking for extenders, ways that they can increase revenue within their practice or within their revenue stream. With the snowflake-type mentality with a printed customized product, they can charge a premium for it. Once this comes to fruition the floodgates are going to open and you’re going to have a large market that these doctors are actively going to pursue.”

Behind the veil
What drives the success of 3-D printing technology is the design software. As Hlavin noted, 3-D printing can get pretty boring without robust software design technology and adept engineers behind the process to create complex, creative devices.

EOS has been in the rapid prototyping and additive manufacturing business since 1989. Still family owned, the company now operates globally with headquarters in Germany. The company makes laser sintering machines. Sintering is a process by which a powdered material is made to coalesce into a solid or porous mass via heat and compression without liquefaction. In laser sintering, the heat comes from the lasers. EOS recently partnered with Within, a young design consultancy based in London, United Kingdom. Within provides EOS with a powerful software design tool that allows EOS to create complex devices it could not make before.

Adrian Keppler, Ph.D., executive vice president of sales and service for EOS, gave an example of how valuable Within’s design software is to EOS.

Figure 1. A bone rasp is a medical device used by surgeons to clean out and hollow a femur bone before the insertion of an implant. The bent and tapering surface of the bones rasp allows it to fit well to the shape of the femur bone. Image courtesy of Within.

““Two years ago we had a customer visiting us. His motivation was to understand the potential of the technology for his field of work,” Keppler said “He came to us and he wanted to just understand the technology. He brought a component that he wanted to have light-weighted. We tried to use the normal standard CAD [computer aided design] software. It wasn’t possible to create structures like that with this software because there were so many data points that the system is not powerful enough to create these kinds of bionic structures. That’s the reason that we needed software that enables the customer to create bionic, lightweight structure, which is why we are partnering with Within. Within developed a software specifically adapted to this type of technology. They understand the advantages but also the limitations of our process, they translate that into a software package, and create very complex algorithms to create structures with a lot of design points [see figure 1]. We partner with them in the design space, and they create different kinds of structures depending on the application, load, stress level, etc., that are buildable with our technology. For example, they take into consideration that in the end you must remove loose powder from the finished structures. If this isn’t possible—if you block the loose powder in the structure—it cannot be implanted. It has to be cleaned, finished, and all these requirements are integrated into the software.”

EOSINT M 280 is based on the direct metal laser sintering (DMLS) system by EOS. It produces components by means of selective laser sintering–fully automatically, without tools and based directly on 3-D CAD design data. For this purpose it is equipped with a 200 W or 400 W fiber laser which melts fine metal powder and builds up the product layer by layer. Image courtesy of EOS.

“Within adds value to our process as it allows us to do randomized porous lattice structure on the surface or on the substrate of an acetabular hip cup, for instance,” said Andrew Snow, regional
director of North America for EOS. “How does the traditional manufacturing process go about doing that? It’s a laborious step-by-step process. You have to get into some heat-treating; you have to put on a coating to get the trabecular metal surface. It’s very costly and takes a long time. In this case, you can do it all in one step. So not only do you have process improvement, but you also have part number reduction. You don’t have multiple components being assembled into a single unit—just one component.”

EOS also partners with Materialise, which has an installed base of six EOS laser sintering systems for plastic, and in turn Materialise has developed software programs for use by EOS machines. This dedicated software links Materialise software, such as Magics and Streamics, with the EOS systems.

Promises and Limitations
Because 3-D printing is such a fast process and because the equipment is so much cheaper than the equipment required for other types of device machining, manufacturers are seeing the extremely attractive cost-savings benefits of the process.

“Objects are going to be freely available online instantaneously and you’ll just be able to print them at your leisure,” Zero Point’s Hundley said. “So rather having to go and invest in a manufacturing infrastructure, it allows a whole host of different companies to be able to produce things who would have never thought of producing things before. It’s object creation on-demand, customizable when you want it, and the cost is a fraction of what it would take to do things in a traditional method. It’s going to change our fundamental global economy in the next 10 years.”

But not everyone is ready to declare 3-D printing the Messiah of manufacturing methods just yet. There are, for instance, some materials limitations. EOS’ Keppler told ODT that EOS can laser sinter “any weldable material,” which includes most metals. For orthopedic applications, that means mainly titanium, cobalt chrome and stainless steel. However, ceramic, which is a mainstay in orthopedic implants, remains a challenge.

“We are working on different materials right now and I do not see any limitations today on the metal side,” Keppler said, “But one interesting material would be ceramic which is difficult to process. It can be processed but it requires a very, very high temperature in the build chamber, so today we are not able to do that on a large scale. There are some research activities dealing with that.”

As for polymers, semi-crystalline polymers (e.g. PEEK (polyetheretherketone) and PEKK (polyetherketoneketone)) are easier to manipulate in 3-D printing than amorphous polymers.
Amorphous materials take a longer period of time to set after being heated, and have a wider range of melt points than crystalline and semi-crystalline materials.

In Living Color: 3-D Printing Live Tissue and Bioabsorbables Companies that have been working in the 3-D printing space for decades are reluctant to speak much to the printing of live tissue, but research on this particular opportunity from 3-D printing has been active for some years now. In February, researchers at Harvard University in Boston, Mass., published a paper titled “Vascularized, Heterogeneous Cell-Laden Tissue Constructs” in the journal Advanced Materials. They had succeeded in “fabricating 3-D tissue constructs replete with vasculature, multiple types of cells, and extracellular matrix,”according to the paper abstract. According to the researchers, “These intricate, heterogeneous structures are created by precisely co-printing multiple materials, known as bioinks, in three dimensions. These 3-D micro-engineered environments open new avenues for drug screening and fundamental studies of wound healing, angiogenesis, and stem-cell niches.” The bioengineers behind this extraordinary achievement actually created the machine responsible for printing the vascularized tissue. The machine has multiple printer heads that each extrude a different biological component to make the complex tissue. A research team at the University of Michigan is using an EOS machine to print bioabsorbable implants made of polycaprolactone (PCL), a bioabsorbable polymer. Last year, Glenn Green, M.D., associate professor, Otolaryngology and Scott Hollister, Ph.D., professor of biomedical engineering, designed a tracheal splint from PCL for which it had to win special approval from the U.S. Food and Drug Administration (FDA) to use in a newborn, Kaiba Gionfridoo, who had a collapsed bronchus. After implantation of the bioabsorbable splint, the baby was taken off respiratory support, and 20 months later was still able to breathe on his own. The case was featured in the New England Journal of Medicine. Bioabsorbables such as PCL address the issue of the dearth of pediatric orthopedic and other medical implants due to the high rate of growth. The tracheal splint was designed so the development of Kaiba’s bronchus would correspond with the reabsorption of the splint, eliminating the need for revision surgery to remove or replace it. The university just incorporated a spin-off company called Tissue Research Systems, and once it obtains 510(k) clearance from the FDA, it will be marketing the implant in the United States. Organovo Holdings Inc. is a San Diego, Calif.-based company whose sole purpose is to 3-D print live human tissue for disease modeling and toxicology studies; drug testing; and implantation. In February, CEO Keith Murphy told Businessweek that the company is preparing to sell strips of liver tissue to pharmaceutical companies to be used in toxicity testing. — R.A.

Editor’s note: For more on materials in 3-D printing, see this issue’s materials feature.

Reference

1. http://3-Dprintingindustry.com/2013/12/29/many-3-D-printing-patents-expiring-soon-heres-round-overview/