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 Department of Energy’s Oak Ridge National Laboratory.
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.
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.
“This has the potential to transform forging and casting of large-scale metal components,” said Adam Stevens, an R&D staff member at ORNL and technical lead for the project.
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, or 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.
“Right now, it takes around 18 months to produce one of these. 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,” Stevens said.
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.
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 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.
To demonstrate the capability of the manufacturing system, the program will fabricate three Francis runners, a particular style of large stainless-steel turbines used in dams to generate hydropower. The first runner is a prototype to be used for testing. The second, about 5 feet in diameter, is being made for potential installation in the Tennessee Valley Authority’s Ocoee Dam in Parksville, Tennessee. The Ocoee Dam is an 840-foot-wide, 135-foot tall hydropower dam spanning the Ocoee River with five generating units that produce 24 megawatts of electricity.