Near-net-shape refers to the geometry of a component that is printed as close to final size and shape as possible, greatly reducing the finishing steps that traditional metal fabrication requires. Convergent manufacturing provides a path toward achieving the desired net shape by incorporating necessary machining and finishing into the AM process. Turbines used for hydropower have complex designs and are complicated to produce, currently requiring months of manual welding and finishing.
The third Francis runner will be manufactured for potential installation in the TVA’s Wilson Dam, which has 21 generating units producing 653 megawatts of electricity. The turbine will be about 15 ft in diameter, 8 ft tall, and weigh more than 46 tons. The TVA, based in Knoxville, Tennessee, is the largest public power company in the nation, operating 113 power generators in 29 dams.
The project will produce runners using 3D printing, or additive manufacturing, combined with conventional tools, all produced domestically. The process will use robotic welders to deposit metal layer by layer to form the runners.
A unique manufacturing program for large metal parts holds promise to help revitalize American manufacturing and return clean-energy manufacturing technologies to the United States. The approach could greatly reduce waiting times for critical components and enable economic growth in the manufacturing sector for energy, according to scientists at the U.S. Department of Energy’s Oak Ridge National Laboratory.
“Right now, it takes around 18 months to produce one of these,” Stevens says. “If you can’t operate a hydropower turbine because you’re waiting for a part, that’s 18 months of clean energy you’re not generating. This approach can fill the gap in the domestic industrial base.”
“Traditional production of these runners, all overseas, takes a lot of time and is very labor intensive,” says Curt Jawdy, head of R&D at TVA. “All these foundries have a pretty big backlog, and we find that it takes two years from the time we place an order to the time we get a runner.”
Brian Post, leader of ORNL’s Disruptive Manufacturing Systems Development group, and Jay Tiley, head of the lab’s Materials Structures and Processing Section, are project principal investigators for systems and materials, respectively. The Manufacturing Demonstration Facility at ORNL is providing resources and expertise. The MDF, supported by the DOE’s Advanced Materials and Manufacturing Technologies Office, is the hub for a nationwide consortium of collaborators working with ORNL to innovate, inspire, and catalyze the transformation of U.S. manufacturing.
Time for a really big demo
At the end of the three-year term, the project will have created a newly distributed hybrid-manufacturing platform that could be used by many industries, “that will allow for domestic production of infrastructure-scale net-shape components for energy, defense, shipbuilding, hydropower, and municipal water supply—any industry that requires a large piece of metal could benefit from this,” Stevens says. “This will increase worker productivity and provide a healthier domestic industrial base.”
The DOE’s award consists of $13 million from the Advanced Materials and Manufacturing Technologies Office, and $2 million from the DOE’s Water Power Technologies Office.
Jawdy said hydro runners have cavitation-prone areas that can cause turbines to fail due to erosion of the vane surfaces under the cumulative force of millions of collapsing air bubbles. But through AM, a cavitation-resistant coating can be applied.
‘This program offers an innovative way for ORNL to fulfill TVA’s mission summarized by three ‘E’s: for energy, it improves reliability; for the environment, it maximizes renewable energy produced; and for economic development, it brings great jobs back to the U.S.’
—Joe Hoagland, TVA’s vice president of innovation and research
Bringing hydropower home
This program covers development of the software, hardware, robotics, and manufacturing strategies necessary to produce these large components. Partnering with ORNL on development are several organizations, in addition to TVA. These include: Huntington Ingalls-Newport News Shipbuilding, where the largest Francis runner will be 3D printed; the Electric Power Research Institute, contributing to technoeconomic analyses; Open Mind Technologies, assisting with manufacturing strategy development; ARC Specialties, providing robotic hardware and integration; and Voith Group-Hydropower, a hydro unit manufacturer.
“This has the potential to transform forging and casting of large-scale metal components,” says Adam Stevens, an R&D staff member at ORNL and technical lead for the project.
University of Tennessee-Battelle manages ORNL for the DOE’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, visit energy.gov/science.
“We are always looking for new ways to do things better. Innovation is a part of TVA’s DNA, and it’s something that we focus on in all things we do,” says Joe Hoagland, TVA’s vice president of innovation and research. “This program offers an innovative way for us to fulfill TVA’s mission summarized by three ‘E’s: for energy, it improves reliability; for the environment, it maximizes renewable energy produced; and for economic development, it brings great jobs back to the U.S.”
TVA expects that, eventually, many of its turbines and steel components—in this case, steel known as 410 stainless—will be produced domestically by AM processes, which enable unique capabilities.
The project, Rapid Research on Universal Near Net Shape Fabrication Strategies for Expedited Runner Systems, or Rapid RUNNERS, received DOE funding of $15 million over three years to create a system to produce the large runners used in dams for hydropower. A runner is the rotating part of a hydropower turbine that enables the pressure and movement of water to be converted into electricity.
These large metal components are produced almost exclusively overseas, and when they fail it can take years to fabricate and receive replacements. That means lost time, money, and renewable energy. For every month a hydropower turbine is idled waiting for components, thousands of megawatt-hours of renewable electricity are forfeited.
But automated additive manufacturing (AM) methods can quickly produce metal components that are close to the final dimensions of the parts, known as near-net-shape. Traditional machining techniques are then used to finalize the shape, reducing waste and downtime compared to existing processes.
“You can do things with additive manufacturing that you can’t do otherwise,” Jawdy says. “There are shapes you can make that you wouldn’t be able to make otherwise, and you can combine materials.”
Partners aplenty
Published Sept. 5, 2024, in ORNL News.