Fraunhofer Institute for Casting, Composite and Processing Technology IGCV

Abstract In metal casting, creating undercuts in components requires cores, typically made from sand–binder mixtures such as environmentally friendly sodium silicate binders. For intricate geometries like cooling channels, higher binder content is used to achieve sufficient core strength. However, removing inorganic-bound high-strength sand cores mechanically without residue remains challenging, limiting cavity complexity in thin-walled aluminum parts. This research develops an alternative process chain for aluminum gravity casting, using sodium chloride (NaCl) salt without binding agents as the core material in the core shooting process. Moist salt powder is fluidized with compressed air and injected into a mold, where crystallization—controlled by moisture content and drying—yields a stable, temperature-resistant core. After casting, the water-soluble cores are removed and can be recycled, eliminating harmful emissions and worker exposure to respirable dust. This study examines the influence of core-shooting parameters and in-mold drying on the three-point flexural strength of porous salt cores. Increasing the fine-particle fraction is found to enhance strength, and complete drying is essential. Binder-free, salt-based cores provide superior surface quality and sufficient strength for gravity casting and can be removed either dry or by washout with water. Future work will focus on strengthening the cores to meet typical sand casting standards and reducing the crystallization process time.

Electromobility as a key factor of the energy transition places high demands on its core technology: the lithium‐ion cell. In particular, fast charging is one of the critical prerequisites and is associated with major challenges, as improving the fast‐charging capability often comes at the cost of reduced energy density. Electrode structuring can enhance the fast‐charging capability of lithium‐ion cells without compromising energy density. Simple and meaningful characterization methods are essential for rapid development of such processes. However, conventional charge rate tests can lead to misleading results when testing transport‐limited electrodes. This study demonstrates that, for transport‐limited electrodes, conventional rate tests may yield similar results despite significantly different transport parameters, such as tortuosity. Conventional graphite anodes are compared with electrodes processed via structure calendering—a novel method that combines structuring and calendering within a single roller process step. Using rate tests and half‐cell measurements, it is shown how lithium plating contributes to this effect and the underlying electrochemical phenomena are explained. Furthermore, an adapted charge rate test procedure is proposed, which effectively demonstrates the advantage of structured electrodes in the charging direction. The novel method can be implemented using standard cell testers enabling widespread application.

Abstract Durch steigenden Wettbewerb müssen Fabrikbetreiber immer häufiger Teile ihrer Produktion an neue Standorte verlagern. Zur Vermeidung wirtschaftlicher Schäden ist eine verlässliche Umzugsplanung essentiell. Bisherige Ansätze beschreiben häufig nur einseitig die Gebäudeausführung oder den Umzug des Produktionssystems. Dieser Beitrag beschreibt eine Methode zur integrierten, modellbasierten Zeitplanung inklusive einer Ausführungsüberwachung mittels Bestandsdigitalisierung sowie die Validierung am Anwendungsfall einer Batteriezellproduktionslinie.

Abstract High-strength Titanium Aluminide (TiAl) alloys hold great potential for future applications in lightweight turbine blades. Their success depends on reliably achieving a consistent transformation from the initial cast microstructure to a globular target microstructure throughout all critical areas of the blade. The exclusive use of a multi-stage closed-die forging process means that TiAl alloys cannot be reliably formed into turbine blades. The process chain must therefore be extended by a multi-stroke open-die forging process in order to integrate further degrees of freedom into the process. During the open-die forging of TiAl alloys, however, unexpected process disturbances often occur, e.g. in the form of a fluctuation in temperature or forming speed, which has an unwanted effect on the microstructure. For the simulations within the present work, a finite element model of the considered process is included, which is extended by a corresponding material model to describe the globularization state of the material and a closed-loop control. The exponentially damping controller developed in the research project is intended to regulate disturbance variables as quickly as possible to achieve a minimum deviation from the target microstructure state. The function of the controller is simulatively tested, discussed and evaluated as part of the work.

ABSTRACTIn this work, Opuntia (commonly called prickly pear cactus) was investigated as a source for reinforcing plant fibers, as it represents a low‐cost and widely available alternative to other commonly used natural fibers, such as kenaf, hemp, sisal, or flax. A fiber network that reflects the shape of the leaf structure can be found in the cladodes of Opuntia. Water retting was identified as the most promising method to extract the fiber network from the plant. Tensile tests and thermogravimetric analysis were performed on the extracted fibers to evaluate the quality of the extraction process. Different parameters such as time, surface exposure, and temperature were investigated to optimize the water retting process. The results indicate that an increase in surface exposure and higher water temperature leads to a reduction in time needed for fiber extraction. The extracted fibers were then embedded in a PLA matrix by compression molding to fabricate a fiber‐reinforced composite. The mechanical performance of the Opuntia fiber‐reinforced plastic was investigated. Analysis (particularly mechanical, optical and fiber volume content) indicates that the impregnating quality was insufficient, leading to a weak performance of the material.

Abstract Eine Studie zu ganzheitlichen digitalen Fabrikmodellen im produzierenden Gewerbe identifizierte acht Thesen von Fabrikbetreibenden. Dieser Beitrag stellt diese Thesen dem aktuellen Stand der Forschung gegenüber. Durch Kombination von Literaturrecherche und Gruppendiskussion werden insbesondere die Notwendigkeit lebenszyklusübergreifender Informationsdurchgängigkeit und Herausforderungen bei Datenintegration und -austausch beleuchtet. Die Erkenntnisse weisen auf zukünftige Forschungsfelder hin.

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<div class="section abstract"><div class="htmlview paragraph">Nowadays, more than in the recent decades, the design process for the body in white for passenger cars is driven by efficiency. This results in the enhanced usage of large-scale cast components made of aluminum, for the battery compartment, the front or rear body and other components. While the automotive industry is striving towards even larger structures made with so-called “Giga-Casting”, challenges in the casting and supply chain processes, but also maintenance and repair processes of these large structures, arise. Other tasks to solve might follow from controlling local microstructures, and thus the strength of the parts, when the flow length of the molten metal increases with component size, especially in relation to an increased fraction of recycled aluminum. Within the Fraunhofer-internal project “FutureCarProduction”, focus is directed towards understanding what drives efficiency, availability and sustainability of modern processes for the production of a car body. Moreover, the project addresses questions along the complete product chain of a car body, in terms of optimization of casting and joining, and quality assurance processes and seeks to give solutions for the efficiency and quality of different manufacturing processes. In the present paper, an overview of the project scope itself and the recent findings of “FutureCarProduction” are presented with a focus on the influences of higher fractions of secondary/recycled aluminum on the casting process, the occurring microstructure and defect situation in body in white components. This forms the basis for further investigations on the performance of different manufacturing and design opportunities for automotive components.</div></div>