Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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Process Setup and Boundaries of Wire Electron Beam Additive Manufacturing of High-Strength Aluminum Bronze

2023-08-08 , Raute, Maximilian Julius , Biegler, Max , Rethmeier, Michael

In recent years, in addition to the commonly known wire-based processes of Directed Energy Deposition using lasers, a process variant using the electron beam has also developed to industrial market maturity. The process variant offers particular potential for processing highly conductive, reflective or oxidation-prone materials. However, for industrial usage, there is a lack of comprehensive data on performance, limitations and possible applications. The present study bridges the gap using the example of the high-strength aluminum bronze CuAl8Ni6. Multi-stage test welds are used to determine the limitations of the process and to draw conclusions about the suitability of the parameters for additive manufacturing. For this purpose, optimal ranges for energy input, possible welding speeds and the scalability of the process were investigated. Finally, additive test specimens in the form of cylinders and walls are produced, and the hardness profile, microstructure and mechanical properties are investigated. It is found that the material CuAl8Ni6 can be well processed using wire electron beam additive manufacturing. The microstructure is similar to a cast structure, the hardness profile over the height of the specimens is constant, and the tensile strength and elongation at fracture values achieved the specification of the raw material.

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A Data-Driven Concept and Realization for Engineering Change Management Decision Support

2023 , Pan, Yuwei , Krüger, Jörg

In today's automotive industry, quickly reacting to engineering changes and providing market-driven products within a short period remains a competence for all Original Equipment Manufacturers (OEMs). Due to the complexity of products, changes to one component can lead to unexpected chain reactions in others. Besides, from creation to the approval of a change request can take weeks or even months without apparent reasons for the delays. To coordinate and control changes, companies established Engineering Change Management (ECM) processes. ECM processes can impact all determinants of competition of products: cost, quality, and time-to-market. Without proper management of Engineering Changes (ECs), negative impacts will happen. In the scope of this dissertation, a machine-learning based ECM decision support solution is developed which includes two main functions: change impacts prediction and lead time prediction. These functions support engineers to have an overview of change consequences in the early phase of the ECM process. The solution was evaluated based on the data from an automotive company and reached good performance. Therefore it was rated as beneficial to increase the efficiency, effectiveness, and quality of the existing ECM processes.

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Resource efficient production of car body parts - implementation of digital twins across process chains

2022-09-21 , Weber, Joshua , Lemke, Josefine , Sunderkoetter, Christina , Haase, Patrick , Hoefemann, Matthias , Joos, Paul , Merklein, Marion

Sustainable production and environmentally friendly life cycle of every car is a main goal in the automotive industry. But there is a conflict between the rising demands of crash safety, the addition of components due to electric mobility and the reduction of weight. Car body parts can increase the crash safety and have a high lightweight construction potential. Especially tailor welded blanks made of multi-phase steel with a tensile strength of 1000 MPa, which are not established in car body parts, have the potential to improve the crash safety, save resources and lower the weight. The main challenge in the manufacturing of tailor welded blanks made of highest strength steel is the complex and expensive development. Due to the heat input and geometrical changes, the welding process affects the forming properties of the metal sheets. To evaluate the influence from different welding parameters to the forming process, a high number of expensive experiments must be repeated. This includes welding and forming parameter changes as well as adjustments to the forming tool. In order to make the development and manufacturing of tailor welded blanks made of highest strength steels more resource efficient, this work discusses the development and implementation of a digital and bidirectional twin in an industry-oriented environment. The objective is to demonstrate the data management based on the sheet metal properties, the change of properties due to laser welding simulated in Simufact Welding and the final forming process in AutoForm Forming. Additionally, the concept of a life cycle assessment of a tailor welded blank during these steps is developed. As summary the challenges, limitations, and improvements of the digital and bidirectional twin as replacement or, in addition to a consisting development process are discussed.

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Integrated weld preparation designs for the joining of L-PBF and conventional components via TIG welding

2022-04-18 , Geisen, Ole , Müller, Vinzenz , Graf, Benjamin , Rethmeier, Michael

Laser powder bed fusion (L-PBF) of entire assemblies is not typically practical for technical and economic reasons. The build size limitations and high production costs of L-PBF make it competitive for smaller, highly complex components, while the less complex elements of an assembly are manufactured conventionally. This leads to scenarios that use L-PBF only where it's beneficial, and it require an integration and joining to form the final product. For example, L-PBF combustion swirlers are welded onto cast parts to produce combustion systems for stationary gas turbines. Today, the welding process requires complex welding fixtures and tack welds to ensure the correct alignment and positioning of the parts for repeatable weld results. In this paper, L-PBF and milled weld preparations are presented as a way to simplify the Tungsten inert gas (TIG) welding of rotationally symmetrical geometries using integrated features for alignment and fixation. Pipe specimens with the proposed designs are manufactured in Inconel 625 using L-PBF and milling. The pipe assembly is tested and TIG welding is performed for validation. 3D scans of the pipes before and after welding are evaluated, and the weld quality is examined via metallography and computed tomography (CT) scans. All welds produced in this study passed the highest evaluation group B according to DIN 5817. Thanks to good component alignment, safe handling, and a stable welding process, the developed designs eliminate the need for part-specific fixtures, simplify the process chain, and increase the process reliability. The results are applicable to a wide range of components with similar requirements.

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Studie zur Stärkung der Holzbauwirtschaft in der Metropolregion Berlin-Brandenburg

2023 , Kohl, Holger , Bunschoten, Raoul , Oertwig, Nicole , Kulick, Christian , Karl, Moritz Maria , Blackburn, Phoebe , Kohl, Holger

Berlin verfolgt das Ziel, sich bis zum Jahr 2050 zu einer klimaneutralen Stadt zu entwickeln: Im Vergleich zur Gesamtsumme der CO2-Emissionen des Jahres 1990, sollen diese bis 2030 um mindestens 60 Prozent und bis zum Jahr 2050 um mindestens 85 Prozent verringert werden. Fast ein Drittel der CO2-Emissionen in Deutschland kann dem Gebäudebereich zugerechnet werden. Einen enormen Hebel zur Verbesserung der Klimabilanz bietet der konsequente Einsatz von Baumaterialien auf Basis nachwachsender Rohstoffe. Insbesondere der Baustoff Holz kann für die Metropolregion Berlin-Brandenburg eine zentrale Stellung zur Erreichung der Klimaziele einnehmen. Hierzu wurde bereits im Frühjahr 2021, in der Vorhabensliste1 des Strategischen Gesamtrahmens Hauptstadtregion, eine regionale Holzbau-Offensive festgehalten. Diese hat zum Ziel, die Region Berlin-Brandenburg zu einer Region des Holzbaus zu entwickeln. Damit die holzbasierte Transformation des Bauens in der Hauptstadtregion nachhaltig gelingt, ist insbesondere eine starke kreislaufwirtschaftsbasierte regionale Holzbauwirtschaft von Bedeutung.

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Entwicklung eines Prozess- und Informationsmodells für das Produktlebenszyklusmanagement in der digitalen Transformation

2023 , Schindlbeck, Roman , Rethmeier, Michael , Stark, Rainer , Dust, Robert

Die Digitalisierung erfordert von industriellen Unternehmen, reaktionsfähig neue Kundenbedürfnisse zu bedienen. Der tägliche Umgang mit digitalen Technologien verändert die Erwartungen der Nutzer an Produkte und Services. Um im Wettbewerb zu bestehen, sind Geschäftsmodelle konsequent kundenorientiert auszurichten und permanent anzupassen. Innovationen ressourceneffizient und schnell in Form von Produkten und Services zu operationalisieren, setzt voraus, dass die Prozesse und Systeme von Unternehmen ein durchgängiges, anpassbares und transparentes Wissens-, Informations- und Datenmanagement gewährleisten. In dieser Arbeit wird ein Modell für ein strukturiertes Vorgehen entwickelt, um neue Geschäftsmodelle zu gestalten und die dafür notwendigen Adaptionen des Produktlebenszyklusmanagements vorzunehmen. Die Anforderungen an das Modell werden anhand der praxisbezogenen Aktionsforschung und qualitativer Untersuchungsmethoden abgeleitet. Darauf aufbauend erfolgt die Modellbildung, in die konkrete Techniken und Handlungsanleitungen einfließen. Anschließend wird das Modell durch den Use Case „Automatisiertes Laden“ evaluiert.

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Result quality evaluation of Directed Energy Deposition Additive Manufacturing simulations with progressive simplification of transient heat-source motion

2022-09-05 , Biegler, Max , Elsner, Beatrix A.M. , Neubauer, Ingo , Lemke, Josefine , Rethmeier, Michael

Directed Energy Deposition (DED) additive manufacturing has recently been adopted in the industry for the build-up of structural components with weld lengths up to kilometers. As with all welding processes, DED suffers from thermal distortion, causing loss of dimensional accuracy and risk of cracking. Currently, process optimization with objective to minimize distortion requires expensive experimental trial-and-error. With numerical simulation of the DED process, this distortion compensation can be performed virtually, significantly reducing experimental trials. Although such approaches are generally available, their widespread adoption is currently being hampered by long computational times for large builds. This work presents a novel approach to reduce the calculation time by a simplification of the transient heat-source motion. This approach is assessed in terms of result accuracy for an industrial-scale component by progressively reducing the resolution of the heat-source motion. Calculation times as well as distortions in comparison to experimental trials are investigated.

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A life cycle assessment of joining processes in the automotive industry, illustrated by the example of an EV battery case

2023 , Brunner-Schwer, Christian , Lemke, Josefine , Biegler, Max , Schmolke, Tobias , Spohr, Sebastian , Meschut, Gerson , Eckstein, Lutz , Rethmeier, Michael

Current ecological, economic and social changes are leading to a change in development, design and production of future vehicles. In this context, it is the stated goal of many manufacturers to advance the development of an environmentally friendly vehicle and climate-neutral production throughout the entire supply chain. This study presents a comparative life cycle assessment of the joining processes laser beam welding, laser brazing and resistance spot welding. For this purpose, an approach tailored to welding processes is presented and applied to the example of a battery case for electric vehicles. For the welding process under consideration, the main influences on the resulting environmental impact categories are evaluated and compared. The requirements for ecologically efficient welding processes are discussed and outlined. The results show that particularly the materials involved, such as the consumption of the filler material, have the greatest environmental impact and thus offer the greatest potential for savings.

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Infraschallunterstütztes Dornhonen

2023 , Zimmermann, Sascha , Uhlmann, Eckart

Der Einsatz von Schwingungen bei Fertigungsverfahren ist seit Jahrzehnten ein allgegenwärtiges Thema in der Forschung. Die Vorteile lassen sich insbesondere an verringerten Bearbeitungskräften und damit an der Steigerung der Wirtschaftlichkeit und Ressourcenschonung erkennen. Die Komplexität des zielgerichteten Einsatzes, wie die Notwendigkeit zusätzlicher Aktuatoren und die konstruktive und schwingungstechnische Auslegung der Komponenten und Prozessbedingungen, verhindert jedoch den industriellen Einsatz. Innerhalb dieser Arbeit werden Dornhonprozesse untersucht, bei denen zusätzliche Schwingungen mit Hilfe der integrierten Antriebe eines Bearbeitungszentrums realisiert werden. Dafür werden realisierbare Schwingungsparameter und resultierende Veränderungen der Prozessparameter analysiert. Zur Identifikation von Prozessveränderungen dienen ein geometrisch kinematisches Durchdringungsmodell sowie Einkornritzversuche. An Werkstücken aus Gusseisen mit Lamellengraphit werden die Auswirkungen von erzwungenen Schwingungen beim Dornhonen technologisch untersucht. Die Arbeit leistet einen Beitrag zum Verständnis sowie zur Auslegung und Nutzung der infraschallunterstützten Dornhonbearbeitung.

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Investigation of liquid metal embrittlement avoidance strategies for dual phase steels via electro-thermomechanical finite element simulation

2022-06 , Biegler, Max , Böhne, Christoph , Seitz, Georg , Meschut, Gerson , Rethmeier, Michael

Modern advanced high-strength steel (AHSS) sheets used in automotive body construction are mostly zinc coated for corrosion resistance. The presence of zinc can cause cracking in steels due to liquid metal embrittlement (LME) during resistance spot welding (RSW). In combination with factors such as tensile strains, liquid zinc can lead to the formation of brittle, intergranular cracks in the weld and heat affected zone. While practical investigations to mitigate LME occurrence exist, the reason why a certain parameter might cause or prevent LME is often unknown. Numerical resistance spot welding simulation can visualize the underlying stresses, strains and temperatures during the welding process and investigate experimentally unmeasurable phenomena. In this work, a 3-dimensional electro-thermomechanical finite element approach is used to assess and investigate the critical parameters leading to LME occurrence. Experimentally observed crack sizes are correlated with the corresponding local strain rates and temperature exposure durations in the simulation. With this data, a map of LME occurrence over driving influence factors is drafted and discussed for effectiveness.

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