From Print Direction to Precision: Mastering Material Behaviour in LSAM Tooling

What if molds could be produced faster, cheaper, and with far greater design freedom? 💡 

Within the TorPropel project, the Technical University of Munich (TUM) applies Large-Scale Additive Manufacturing (LSAM)❗to enable near-net-shape mold fabrication with reduced material consumption and increased design flexibility. Adoption of this technology aims on application in aerospace, automotive and advanced propulsion sectors.

The manufacturing process typically begins with large-scale 3D printing of the mold in a near-net-shape geometry, allowing for efficient material usage and high design flexibility. This is followed by machining of critical surfaces to achieve the required dimensional accuracy and surface finish. Finally, post-processing steps, such as coating or sealing, are applied to enhance surface quality and improve the overall performance and durability of the mold.

At the Technical University of Munich (TUM), we are employing LSAM in the EU project TORPROPEL ✈️ to manufacture mold for the toroidal propeller. This method enables the fabrication of highly complex geometries that are challenging or inefficient to achieve with conventional subtractive techniques.

However, the use of additively manufactured molds in high-performance applications introduces significant challenges. The layer-by-layer fabrication process results in anisotropic material behavior, where properties vary with print direction. In particular, the coefficient of thermal expansion (CTE) and thermal conductivity exhibit substantial differences across orientations.

These anisotropic properties directly affect the thermal and dimensional stability of the mold, both of which are essential for achieving precision in toroidal propeller manufacturing.

To address these challenges, we are actively investigating the following aspects:

💡 Direction-dependent coefficient of thermal expansion (CTE)

💡 Anisotropic thermal conductivity

💡 The combined impact of these properties on mold performance

By systematically measuring these properties in multiple directions, we are developing a comprehensive materials dataset. This information is used for the optimization of design and manufacturing strategies for the final additively manufactured mold, improving both performance and repeatability.

LSAM is not solely focused on achieving faster or more sustainable production; it also demands a comprehensive understanding of material behavior. At TUM, through the TORPROPEL project, we aim to bridge this knowledge gap and realize the full potential of LSAM for advanced tooling applications.