QuSAM – Quality Assured Scalability of the WAAM Process for the Manufacture of Aerospace Structural Components

In the course of climate change, it is essential to design the production of components in a way that conserves resources. This also applies to the production of aerospace structural components, as there is great potential particularly with regard to the processing of titanium alloys. Depending on wall thicknesses and component geometries, up to 95% of the starting material is machined in the process. Previous research at the iwb has shown that the so-called WAAM process (Wire Arc Additive Manufacturing) is excellently suited for additively manufacturing near-net-shape component structures with high material efficiency. In the joint project QuSAM, which is funded by the sixth aeronautics research program (LuFo VI-2), the iwb and three project partners are developing a procedure for the measurably more efficient production of highly stressed structures.

Motivation

The proportion of high-strength titanium alloys is steadily increasing in the context of aerospace developments. The reason for this is that titanium alloys have the most favorable density-to-strength ratio among the technologically important metals, both statically and dynamically. In addition, titanium exhibits very high temperature and corrosion resistance, especially in combination with Carbon fiber reinforced polymer. As a result, this material is becoming increasingly popular. However, most of the starting material is lost during machining. In addition, titanium chips can no longer be returned to the material cycle once they have been contaminated with oxygen. Thus, machining involves significant costs. The WAAM process can remedy this situation. First of all, a near-net-shape component is produced that can subsequently be reworked with a significantly lower degree of metal removal. This significantly increases material efficiency.

The quality-determining relationships of the WAAM process for titanium alloys are multidimensional and very complex. Nevertheless, there is one essential factor which can decide on the quality of the component. This consists in the spatially resolved heating and cooling during the build-up. This is why a good thermal management is important. In order to be able to map this digitally, a digital twin of the WAAM process and later also of the post-process are to be created. In the QuSAM research project, building on the previous project Regulus (funding code: 20W1709D, duration: 01.01.2018 to 31.12.2021), the quality-assured scalability of the WAAM process for the production of titanium aerospace structures is therefore to be established by introducing constant monitoring.

Approach

In order to achieve the goal of the quality-assured arc process for the additive manufacturing of titanium structures, components with a size of at least 1 m in one spatial direction will be built. These components are to have the same homogeneous material properties as the high-quality small-scale samples created in previous projects. In addition, intelligent path planning and a digital twin for the WAAM process will be developed using machine learning strategies. Last, a manufacturing cell for AM titanium large-scale structures will be built, featuring a horizontal and vertical digital process chain. This will ensure continuous quality monitoring supported by appropriate hardware and software architectures.

Acknowledgements

This research and development project is funded by the German Federal Ministry of Economics and Climate Protection (BMWK) in the aeronautics research program (LuFo) VI-2 (funding code 20Q2121E) and supervised by the project management organization German Aerospace Center (DLR). We thank the BMWK for the funding and the DLR for the support as well as for the good and trustful cooperation.