Over 1,000 turbine blades produced with Gefertec’s wire arc Additive Manufacturing
March 4, 2025
Gefertec GmbH, based in Berlin, Germany, has highlighted the use of its Wire Arc Additive Manufacturing (WAAM), also known as wire/arc Directed Energy Deposition (DED), to produce turbine blades for a major manufacturer.
Steam turbines feature blades on both the rotor and stator, ensuring efficiency when converting thermal energy to electricity. Depending on the application, turbines can range in size from compact, car-sized units to structures up to 20 meters long with seventy stages and weighing several hundred tons. The applications of steam turbines span from combined heat and power plants to biomass power stations and large-scale solar thermal plants. Because applications vary significantly, steam turbines are often bespoke.
Gefertec reported that the range of possible configurations made production planning increasingly complex for this project; maintaining an inventory was only feasible to a limited extent. In the case of turbine blades, for example, the flat material for machining these blades is sourced from China: due to supply chain issues, lead times can extend to several months. This is in direct opposition to customer demand, which requires shorter delivery timetables. Further, because the blades are twisted, the machining volume from flat material can be as high as 70%; as well as significant cost, this manufacturing method also results in extensive machining times and tooling wear.
Considering all of the above circumstances, Gefertec’s client began considering the use of Additive Manufacturing to produce 300-700 mm long stator blades back in 2018. The first AM technology considered was Powder Bed Fusion (PBF), but the initial investment and slower manufacturing times meant that desired cost savings would not be achieved, explained Gefertec.
After ruling out PBF technologies, the client moved into discussions with Gefertec on the suitability of its Wire Arc Additive Manufacturing technology.
The WAAM machine selected by the turbine manufacturer uses a high-alloy, heat-resistant 1.2 mm steel wire as feedstock. Because this feedstock is readily available, long lead times, like those which come into play during machining, are eliminated.
Qualification of the manufacturing process
Before serial production could begin, the processes needed qualification and, since there were no existing standards, extensive groundwork was required to move forward.
In the first production batches, all turbine blades underwent CT scans to detect any potential porosity. Destructive testing was then conducted to measure hardness and bending strength, along with metallurgical examinations and chemical analyses. Based on these results, the WAAM machine’s build parameters were continually optimised.
The outcome was stable enough to qualify the WAAM process as suitable for serial production. These extensive quality control measures during the qualification phase meant that the client only conducts occasional sample inspections during ongoing production, an approach used for cast components.
Over 1,000 turbine blades already produced
Gefertec stated that the benefits of the now fully implemented series production are clear. Instead of a machining volume of 70%, only about 20% remains. The client targeted cost savings of around 15% due to reduced material expenses and shorter milling machine times; delivery times were also said to be reduced by up to 75%.
In series production, either nine or sixteen turbine blades are manufactured simultaneously in the machine. This represents optimal utilisation of the WAAM machine’s capacity while also eliminating idle times for cooling the top layer.
Although the journey from initial concept to qualification and serial production was long, Gefertec reported that the turbine manufacturer is now fully convinced of WAAM for series production. This is attributed to the ability of its WAAM machine to enhance production flexibility, particularly by eliminating the time-consuming procurement process for raw materials.
To date, well over 1,000 turbine blades have already been produced on the machine. Manufacturing operates around the clock in a three-shift system, with the process being largely automated.
The steam turbine manufacturer is now working closely with Gefertec to further enhance the machines. Areas of focus include increased automation (e.g. fully automated replacement of the contact tube without operator intervention) and additional in-situ sensors for quality assurance. Future research is expected to explore new design opportunities enabled by AM and integrate them into new products.
Gefertec’s WAAM machines
Gefertec‘s 3DMP integrates WAAM, CAM software, and a machine tool into a turnkey Additive Manufacturing solution. They are available in three- and five-axis configurations with various size options. The largest model features a build volume of 8 m³, enabling the production of components weighing up to 8,000 kg.
All of the company’s machines operate with Siemens controls similar to those used in conventional machine tools. Specialised CAM software converts CAD data into instructions for precise CNC-controlled positioning of the welding head, enabling the automated fabrication of near-net shape components.
