Manufacturers of Industrial Gas Turbines (IGT) are applying Additive Manufacturing in various applications
Traditionally AM technologies such as Vat-photopolymerisation and Binder-jetting were used to create patterns and moulds for casting of turbine / hot gas path components. These technologies
are still getting applied, but increasing productivity and repeatability of direct metal technologies are changing the industry. Selective Laser Melting / Direct Metal Laser Sintering and Electron Beam Melting are improving the design of parts and so the production, repair and overhaul processes.
Components of gas turbines for power generation are significantly larger compared to the ones of jet engines.
But the thermal and mechanical loads on the components are very similar. The hot gas path components also require
the use of high-temperature stable materials. These materials are nickel-based alloys, so-called Super Alloys, very hard to machine, especially with conventional (subtractive) machining.
Additive Manufacturing technologies allow entirely new design approaches. Thin-walled components with internal cooling channels and turbolators, to reduce the consumption cooling air, allow to operate the turbine at higher temperatures and increase their efficiency.
But in IGT the size and volume of the components can be challenging. Large components often mean high Z-axis builds = more layer = longer build times and so a higher risk of failure. But the advantages regarding efficiency and cost saving potentials are outweighing the challenge to overcome this hurdles. Taking a closer look at patent databases unveils a real arms-race of the global players in power industry.
Applications of AM in Power industry
This video by GE Power shows Industrial Gas Turbine components manufactured using laser based powder bed fusion (LB PBF)
AM in Power Industry | Reconditioning & Repair
Further advantages of using AM
Components can be upgraded with new design features for performance enhancements.
Especially when it comes to the reconditioning of turbine blades, powder bed based direct metal technologies
can offer great advantages.
Cast blades are very unique in their geometry. Core shift during the casting process and deformation through
creep during operation are making this parts unique as human bones. But If the machine data is generated based
on a scan of the component, the part can be repaired individually in an automated process. The blade is mounted
in the machine bed and the SLM process starts on the component, rebuilding the section removed before.
Custom tailored repair patches
But a damaged section of a component does not certainly need to be build up directly on the part.
Replacements can be build separately and joined with the component in a following step.
See this patent from ALSTOM explaining this technique in detail.