Scientists from the Fraunhofer Institute for Laser Technology (ILT) and for Production Technology (IPT) have jointly developed new process chains for producing jet engine components that allows for more design freedom as well as more efficient and cost effective production and repair processes. The processes, demonstrated recently at the ILA Berlin Air Show in May, use Selective Laser Manufacturing (SLM) and Laser Material Deposition (LMD) to build components layer by layer, reducing waste and allowing for the construction of more complex geometries.
The SLM technique has enabled Fraunhofer ILT's scientists to produce components that previously could not be manufactured. In the method, laser radiation is scanned across a powder bed and traces out the form of the component, each layer at a time. Wherever the laser radiation impacts the powder, the powder initially melts and then solidifies to form a solid mass. In this way, the component is built-up layer by layer. Until now, parts were subtractively produced, for example by milling. This process results in a greater loss of material, and there are geometric restrictions in the production of certain designs.
The researchers are now working with their colleagues from the Fraunhofer IPT on the integration of the additive manufacturing technique into an entire, continuous process chain. To illustrate what the new process chain can achieve, the team produced a Nozzle Guide Vane (NGV) cluster consisting of six double vanes. Previously, the vanes for turbines could only be produced in sets of two, so were more difficult and took longer to install into the engine.
The team also managed to improve the base of the NGV cluster with internal honeycomb-like structures, which makes the entire component around 30 per cent lighter as a result.
The researchers have also considered the Maintenance, Repair and Overhaul (MRO) of engine blades. While the technicians previously had to repair these blades manually, the new process is now fully automated. ‘We do not even need half the processing time. And more importantly, the method is reproducible and ensures high-quality repairs,’ said Bergs.
An important step toward automation was the development of the ‘CAx framework’. This software approach allows all the various repair technologies to be operated from a single platform. Firstly, the geometric data of a damaged or worn-out blade is acquired, for instance, by digital imaging. Secondly, a milling machine blends out the defect, and thirdly, laser radiation builds-up the blade again layer by layer via Laser Material Deposition (LMD).
The research is a subproject of the Cluster of Innovation AdaM, short for ‘Adaptive production for Resource Efficiency in Energy and Mobility’: This is where the Fraunhofer Institutes IPT and ILT as well as 21 industrial partners pool their skills. The goal is to technically implement new concepts for turbo machinery – for engines, among other components – so that they can convert energy more efficiently and reduce CO2 emissions.