National Lab Takes On Manufacturing Techniques
Oak Ridge makes the process truly 3D as it expands frontiers.
From elaborate buildings constructed by on-site 3D printers to synthetic fish for testing hydroelectric projects, U.S. national laboratory scientists are exploring the state of the art in additive manufacturing. Their goal is to develop new techniques that can be transitioned to commercial applications as well as explore advances that could revolutionize industrial manufacturing.
At Oak Ridge National Laboratory (ORNL), Tennessee, the primary driver for additive manufacturing research is to scale the technology and integrate it into manufacturing operations, according to Thomas Kurfess, chief manufacturing officer for the laboratory. He decries claims that the process will replace all other types of manufacturing, saying instead that, “Additive manufacturing/3D printing is going to have a place in overall manufacturing.” Understanding that role is a major part of the laboratory’s research into designing tools and perfecting the process, he adds.
“The big picture is, this technology is different from what we’re used to, so how do we take a new approach—that is not just about manufacturing but also design, energy consumption and materials—and integrate it into our current manufacturing operations,” he says.
Brian Post, research and development staff member in the Manufacturing Systems Research Group at the ORNL’s Manufacturing Demonstration Facility, explains that much of the additive manufacturing work at the laboratory focuses on rapidly expanding the size and throughput while lowering the cost of 3D printing. Success in these efforts would enable more competitive industrial utilization.
These advances aren’t happening in a vacuum, he notes. Industry partnerships play a large role in ORNL research. Partners often ask how they can deploy additive manufacturing in their work economically, and the lab strives to reduce or remove that risk for industry. “It’s developing these technologies with a purpose in mind,” Post states.
He notes that before the laboratory began its 3D printing work, the largest volume that could be printed was about 3 feet by 2 feet by 3 feet. Now, the lab is building printers with work volumes more than 20 feet by 10 feet by 8 feet. One system developed in concert with private industry is 60 feet by 20 feet by 10 feet, Post reports.
The commercial sector has watched tool and die manufacturing largely migrate overseas. Several studies have shown that additive manufacturing offers the potential to give this discipline a domestic renaissance, he says. Large U.S. manufacturing companies would like firms to be able to do their tooling in the United States, which would provide a greater variety of products in a much shorter time frame.
This would work well in the aerospace industry, Post continues. Tools need not be certified in the same manner as parts installed on aircraft, so their rapid manufacture would provide a distinct advantage. He predicts that the next step in production will be a concept known as “born qualified,” in which all types of material characteristics will be controlled. Each product will have a data equivalent—a “data passport”—against which the actual part can be verified for quality along the supply chain.
There are several hurdles that must be overcome to continue additive manufacturing improvements, Post says. One is the materials supply chain. Typical 3D polymers cost from $50 to $200 per pound, Post reports, and these materials can be deposited at a rate of up to 5 cubic inches per hour. At that rate, building a 3-foot-by-2-foot-by-3-foot volume could take many months of around-the-clock construction, he adds. The cost of the machine is amortized over the weight of parts made over the years, and that slow process raises the cost. “What we want to do is try to up the throughput rates, lower the material costs and expand the volume so we can make bigger things,” he says.
Winning this battle entails exploring and incorporating a host of technology advances. Now, he reports, the lab has increased the deposition rate from 5 cubic inches per hour to more than 2,500 per hour, and it hopes to quadruple that rate by next year.
These rates apply to polymers, Post notes, but the ORNL is working to achieve similar progress in metals. The lab is leveraging existing welding companies and processes to develop next-generation large format metal additive systems. The ORNL’s emphasis shifts depending largely on what material its specific industry partners employ.
And biomaterials may be the next substances employed in additive manufacturing. Kurfess relates that materials derived from vegetation and biomass have been adapted into polylactic acid (PLA) polymers, which come from corn and include natural fiber reinforcement such as bamboo or cellulose. These carbon-neutral “plastics” can be printed into large structures, he says. Boat manufacturers have expressed interest in biomass tooling that is easily compostable and thus recyclable. “In some cases, you could just chip it up and use it in your garden as mulch,” he suggests.
Printing concrete structures is another growth industry, but using existing technologies requires a gantry bigger than the structure envisioned. Post’s team has developed a new generation of concrete printers that can be set up in the field within about 30 minutes.
These cable-driven robotic systems can work in three dimensions. Instead of simply providing straightforward additive manufacturing on a prepared level environment—which would make the process commercially unfeasible—an overhead crane would join a pair of static objects on the workspace. The printers would be attached to the crane by cables, which would help steer them around the area as they printed. The next step will be to scale them up so they can be used economically by industry.
Kurfess adds that this robot-driven three-axis system also could be building with metal. A welding gun would deposit weld material, thus avoiding the problem of metal powder. One system, known as MedUSA, features three robots, each with 60 degrees of freedom, capable of spewing different materials.
Another approach addresses the challenge of printing a long structure, such as a beam, without equal-length support structures underneath. The solution is to print a beam upright, let it cool and then rotate it 90 degrees, Kurfess relates. “A lot of times we think about planar stacking layer by layer. Now, we can rotate things around … to a certain extent, change the direction of gravity,” he suggests.
And advances in concrete additive manufacturing could lead to new methods of constructing buildings. Kurfess cites automotive manufacturing as an example: Cars have multiple parts that nowadays include Bluetooth, audio systems, climate control, GPS, internal combustion engines, computerized monitors, fluid circulation and other elements that also are found in houses. Yet the complex mobile machines cost a fraction of a house, which is custom-built by hand on a fixed site.
Applying the same principal to additive manufacturing can enable new home manufacturing methods that could bring the price of a house down, Kurfess offers. “As with all things, I don’t think additive manufacturing is a replacement for conventional methods, but it’s a great tool in the tool box to be able to improve the efficiency of your workflow and your process,” he says.
And those car parts could be printed on demand. Instead of having to keep large inventories in auto supply shops or order a part from a distributor, a retailer could download the part’s additive manufacturing code from the vehicle’s manufacturer and print it out while the customer waits. This would be especially useful for older cars with declining parts inventories, Kurfess offers.
Even with additive manufacturing, the laboratory has not completely abandoned its atomic roots. One major project Post describes is the transformational challenge reactor, or TCR. Over the next couple of years, the lab will be testing the born qualified process by building a functioning nuclear reactor using 3D printing. Neutronics and modeling and simulation experts are coming together on this project, and they will be working with a host of additive manufacturing technologies and capabilities.
Kurfess adds that this effort goes beyond simply printing a small reactor. “The issue really is, ‘Let’s redesign it,’ so that we’re not printing something that was designed back in the 1970s or ’80s,” he explains. “We’re redesigning this so that we can leverage two things.” Tool geometry for easier design and production of the reactor is one, and the other is to advance materials development to make a safer and more efficient reactor. Success could lead to more small reactors distributed around the grid supplanting large generating plants, he adds.
The Energy Department laboratory views many additive manufacturing applications in the realm of a reduced carbon footprint. Kurfess relates that one of the big applications being targeted for the cable-driven 3D printer is building foundations for wind turbines. Being able to set up a manufacturing device in 30 minutes in the middle of a field would enable much easier construction of wind energy devices, he points out. “You start to dig into it, and stuff is so interconnected in terms of what we do,” he declares.
With a diverse set of partners, the ORNL is working on a broad spectrum of additive manufacturing projects. One project, which Post describes as “printing fish,” originated within the ORNL as part of its work on energy systems. It entails scanning fish by a laser, making lifelike molds and reconstructing them in a 3D printer so the faux fish can be used to study how their live counterparts move through hydropower installations. Post explains how hydroelectric dams invariably draw marine life into their turbines, which is an outcome neither party desires.
The fish project is working toward being able to design interfaces between these energy systems and wildlife that are less impactful to the life forms. With turbine intakes swallowing up different species of fish, the additive manufacturing project is fabricating crash test dummy fish with embedded sensors to help study the impacts on the turbines. “We need a way to quickly develop a surrogate fish,” he explains.
All these additive manufacturing capabilities eventually will add up to a new methodology that changes the relationship between suppliers, manufacturers, their workers, wholesalers and retailers. “We will have to rethink how all of this comes together and how we leverage it,” Kurfess declares. Indirect manufacturing—tool and die making—will become dominant first, followed by large-scale direct manufacturing.
“What we’re doing here is enabling advanced manufacturing in the United States,” he continues. “Technology is moving right along, and there is a lot of opportunity for innovation—and I see us as the enablers for innovation. What we’re about is innovating faster than the competition can copy.”