A team from the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) has produced a scaled gas turbine demonstrator model using additive manufacturing to showcase both the potentials and limitations of powder bed fusion technologies. The model, a 1:25 scale version of a power generation gas turbine, was almost entirely 3D printed (with the exception of the shaft) using either Electron or Laser Beam Melting technologies.
The gas turbine assembly, developed in collaboration with H+E-Produktentwicklung GmbH, is made up of just 68 3D printed parts, made from a variety of aluminum, steel and titanium. This shows a considerable degree of part consolidation compared to the original component, which consists of nearly 3,000 individual parts.
Thanks to part optimization and the manufacturing capabilities of Electron and Laser Beam Melting technologies, the original part was redesigned to exploit the advantages of AM, such as geometric complexity. The resulting assembly, called Siemens SGT6-8000 H, is a fully functional gas turbine.
But first, planning
Despite the overall success of the project, the team at Fraunhofer IFAM did faced a challenging production planning stage, which required researchers to find the best manufacturing solution for each of the turbine’s components. Factors such as the roughness of surfaces, accuracy, component size and how many support structures were needed had to be taken into account. The key goal throughout the production planning process was to ensure that the final gas turbine model would be fully functional.
As Fraunhofer IFAM explained: “The functionality of the demonstrator was a prerequisite for all considerations. For example, the shaft and turbine stages had to be able to rotate freely between the stator stages and the individual components of the demonstrator had to be connected to each other with minimum effort—by screwing and plugging on.”
Each of the turbine’s components was also modified by Fraunhofer IFAM’s process experts to ensure “first time right” 3D printing. This was largely a success in the production process. For instance, a housing segment made from 316L stainless steel was successfully printed using Laser Beam Melting without any support structures.
Into production
Moving into the turbine’s production, Fraunhofer IFAM was responsible for manufacturing many of the components, leveraging the AM resources at the Innovation Center Additive Manufacturing (ICAM) in Dresden, Germany. The housing components with stator stages were produced in-house using Arcam Q20+ EBM technology and Ti-6Al-4V. Other components, such as the turbine stages and other housing components were produced at H+E using Laser Beam Melting.
The main limitation in the production of the scaled gas turbine using AM was in respect to the materials. Fraunhofer IFAM and H+E worked with a selection of commercially available metal AM powders, however, not all the materials corresponded to the target materials for gas turbines.
As the team said: “The combination of different materials commercially available from the respective plant manufacturers is demonstrated in the component. Not all processed materials correspond to the target materials for turbines. The limitation lies in the fact that these materials cannot yet be processed in such a way that they can be offered commercially.”
Despite the material limitations, the functional 3D printed gas turbine still presents an impressive feat. In future, when materials that meet the requirements of gas turbine applications become qualified for AM, the technology’s potential will only grow.
The industrial front
In the energy sector, Siemens has played a key role in the exploration and adoption of additive manufacturing for the production of gas turbines. Some years ago, the company recognized the potential benefits of AM in gas turbine production, and set out to develop solutions for the series production of gas turbine burner nozzles and repairing burner heads.
Other milestones followed, including testing the first gas turbine blades produced using AM under full load conditions in 2017, and the successful 3D printing and engine-testing of a dry low emission (DLE) pre-mixer for the SGT-A05 aeroderivative gas turbine in 2018. Last year, the company also announced that a 3D printed burner for an SGT-700 gas turbine has successfully been in operation for a whole year.
All that to say, the use of additive manufacturing for the production of gas turbines is being seriously explored and invested in, both at an industrial and research level.
