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Reduction of Sintering Distortion in Metal Binder Jetting: Measuring Friction Under Sintering Conditions

Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy 2025年 72卷 S1475-S1479页

作者： Blunk, Heiko Seibel, Arthur Fraunhofer Research Institution for Additive Manufacturing Technologies IAPT Am Schleusengraben 14 Hamburg21029 Germany Institute for Production Technology and Systems Leuphana University Lüneburg Universitätsallee 1 Lüneburg21335 Germany

As one of the additive manufacturing processes, metal binder jetting enables the resource-efficient production of highly complex metal components and is more cost-effective for small batch sizes compared to metal injection molding. At the end of the metal binder jetting process chain, the components are sintered as well, whereby they are subject to a shrinkage of up to 20 %. To effectively address this issue, a precise understanding of the friction between the component and the setter plate is indispensable. This knowledge is important for gaining insights into the phenomenon and, notably, for refining the simulation of the sintering process. Therefore, this paper aims to contribute by introducing a custom-made setup for high-temperature tribometry of metal binder jetting components and presenting measurements of the coefficients of friction at room temperature as well as 1100 °C between samples printed in 17-4 PH and aluminum oxide plates of different porosity, roughness and states of use. ©2025 Japan Society of Powder and Powder Metallurgy.

关键词： Sintering

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design model for digital shadows to support reconfiguration decisions in manufacturing

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Procedia CIRP 2025年 132卷 153-158页

作者： Michael Riesener Eric Rebentisch Alexander Keuper Aileen Blondrath Philipp Weber Günther Schuh Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Aachen Germany Sociotechnical Systems Research Center Massachusetts Institute of Technology (MIT) Cambridge USA Fraunhofer Institute for Production Technology IPT Aachen Germany

Personalized production is the result of a paradigm shift in manufacturing driven by customers who are seeking increasingly individualized solutions. Consequently, product families with a high number of variants and short innovation cycles force companies to capture smaller windows of opportunity to stay competitive in a global market. Reconfigurable Manufacturing systems can address this trend by enabling the manufacturing system to be reconfigured in response to changing environmental conditions. However, deciding when to execute a reconfiguration and selecting a suitable manufacturing system configuration for the future is a complex task that requires profound knowledge of the manufacturing system and potential environmental influences. Thus, this paper proposes utilizing Digital Shadows to substantiate reconfiguration decisions with a networked information base. To process this information into an objective decision support, Time-expanded Decision Networks evaluate a sequence of future reconfiguration decisions with regard to economic and environmental target dimensions.

关键词： Reconfigurable manufacturing system Digital twin Digital shadow Digital manufacturing Manufacturing flexibility

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DEM Simulation of Abrasive Brushing Processes on Additively Manufactured Workpieces

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Procedia CIRP 2025年 133卷 203-208页

作者： Anton Hoyer Eckart Uhlmann Institute for Machine Tools and Factory Management (IWF) Technische Universität Berlin Pascalstr. 8-9 10587 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstr. 8-9 10587 Berlin Germany

Brushing with bonded abrasives is a finishing process mainly used for deburring, edge rounding, and surface roughness reduction. The brushing tools consist of flexible polymer filaments embedded with abrasive grains, allowing them to adapt to complex workpiece shapes. However, interactions between filaments lead to complex motion, chipping, and wear behaviors, making it difficult to predict work results. The discrete element method (DEM) has been shown to be effective in simulating process forces, contact areas, and filament interactions on flat workpieces. Consequently, this article focuses on processing geometrically complex workpieces, particularly additively manufactured turbine fan blades (Ni-Cr-Co), using round brushes with bonded silicon carbide. First, a vectorized iterative method is introduced to generate artificial filament patterns, enhancing DEM simulation accuracy compared to state-of-the-art filament pattern models. Subsequently, dry brushing experiments are carried out on a fan blade feature demonstrator, aiming to achieve homogeneous roughness reduction. The qualitative analysis of the contact surface suggests that results from DEM simulations can reduce the need for costly technological investigations and prototypes.

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Simulation of ultrasonic-assisted grinding for improved efficiency in hard-to-machine materials: A direct approach to analyze material removal mechanisms

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Procedia CIRP 2025年 133卷 209-214页

作者： Eckart Uhlmann Bernhard Gülzow Xinyu Zhang Technische Universität Berlin Institute for Machine Tools and Factory Management (IWF) Pascalstr. 8-9 10587 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstr. 8-9 10587 Berlin Germany

The application of ultrasonic superposition is utilized in industrial manufacturing to enhance the chip formation mechanisms, particularly when machining hard-to-machine materials. The institute for Machine Tools and Factory Management (IWF) systematically investigates the interactions between tool and workpiece during ultrasonic-assisted grinding of high-performance ceramics. To gain an in-depth understanding of the microscopic engagement conditions, these conditions are analyzed by simulation. For this purpose, a Python simulation tool based on a geometrical-kinematic modeling approach was developed to analyze the ultrasonic-assisted circumferential longitudinal grinding process. It was demonstrated that ultrasonic assistance leads to smaller and more uniform chip thicknesses which reduce grinding forces and minimizes tool wear. Also, it promotes brittle chip formation mechanisms and improves the efficiency of the grinding process compared to conventional machining. For further investigation, the simulation model was adapted to the transverse face grinding process. In this context, not only the circumferential surface but also the face surface of the grinding tool is engaged with the workpiece. Additionally, the penetration of the workpiece is no longer tangential with the rotational movement but perpendicular to the tool movement. Analogous to the results of the analysis of the circumferential longitudinal grinding process, the influences of ultrasonic excitation on the engagement conditions, particularly the resulting chip thickness and surface topography for the adapted process kinematics were determined and are presented in this paper.

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Coupled CFD model of tool environment and workspace to determine the convective heat transfer in jet cooling of milling processes in machine tools 20

Coupled CFD model of tool environment and workspace to deter...

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20th CIRP Conference on Modeling of Machining Operations in Mons, CIRP CMMO 2025

作者： Brier, Steffen Geist, Alexander Glänzel, Janine Naumann, Christian Regel, Joachim Dix, Martin Ihlenfeldt, Steffen Chemnitz University of Technology Professorship Production Systems and Processes Reichenhainer Str. 70 Chemnitz09126 Germany Fraunhofer-Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 Chemnitz09126 Germany Technical University Dresden Institute for Machine Tools Development and Adaptive Controls Helmholtzstraße 10 Dresden01069 Germany

The responsible use of resources is an essential part of the manufacturing of industrial products. This includes the economical use of cooling lubricant and requires precise knowledge of the cooling mechanisms and their effect on the accuracy of the machine tool and thus the thermal error. A temporal and spatial resolution of the dynamic coolant flow near the tool and in the entire workspace in a single model would require a large simulation time. Therefore, a composite model was developed, that consists of a near-tool model and a larger surrounding workspace model. The required static near-tool cooling lubricant distribution is obtained via data discretization methods from a separate static simulation that resolves the turbulence of the cooling lubricant created by the tool rotation. The identified coolant distribution is integrated into a CFD near-tool model (with simplified tool geometry) which is coupled with a surrounding CFD workspace model. The workspace model is thus able to identify the effects of the coolant wetting on the machine surface temperature and finally, using thermo-elastic FEM simulations, on the resulting thermal error. This approach allows the composite model to simulate the entire workspace with reduced simulation effort and map the coolant-influenced heat transfer coefficients on the machine surface. © 2025 The Author(s).

关键词： Milling machines

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Mechanical Properties of Novel Arc-Sprayed Partially Amorphous Iron-Based Alloys Under Cryogenic Temperature and Hydrogen Influence

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Journal of Thermal Spray technology 2025年 1-13页

作者： Hauer, Michél Möhrke, Lukas Biswal, Pratidhwani Brätz, Oliver Gericke, Andreas Allebrodt, Benedikt Henkel, Knuth-Michael Department Manufacturing Technologies Thermal Coating Systems Fraunhofer Institute for Large Structures in Production Engineering IGP Rostock Germany Department Manufacturing Technologies Thermal Joining Engineering Fraunhofer Institute for Large Structures in Production Engineering IGP Rostock Germany Department Manufacturing Technologies Department Lead Fraunhofer Institute for Large Structures in Production Engineering IGP Rostock Germany DURUM Verschleiss-Schutz GmbH Willich Germany Faculty of Mechanical Engineering and Marine Technologies Chair of Joining Technology University of Rostock Rostock Germany

Previous own works revealed that novel partially amorphous Fe-based alloys have a combination of properties that are beneficial for the application in liquid hydrogen (LH2) tanks, such as low thermal diffusivity, little porosity, and good adhesion. The influence of cryogenic temperatures or hydrogen on coating tensile strength, on the other hand, has not been investigated yet for this material. However, this is crucial for the long-term durability of the coatings under hydrogen and other alternative fuels. Thus, in this work, tubular coating tensile (TCT) tests were performed at room temperature, cryogenic temperatures and after hydrogen charging. For this, a methodology for hydrogen charging was developed to identify a possible regime being sufficient for inducing a measurable amount of hydrogen. Subsequently, the fracture surfaces were evaluated analytically, optically and profilometrically. Under cryogenic conditions, a significant increase in tensile strength and finer structures of the fracture surfaces were observed. The TCT tests with ex-situ hydrogen charging revealed a small reduction in tensile strength and ductility compared to specimens tested at room temperature, proven by the coarse structure of the fracture surface.

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Machine Learning Pipeline for Structure-Property Modeling in Mg-Alloys Using Microstructure and Texture Descriptors

SSRN

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SSRN 2025年

作者： Guru, Mahish K. Bohlen, Jan Aydin, Roland C. Khalifa, Noomane Ben Institute of Material and Process Design Helmholtz-Zentrum Hereon Geesthacht Germany Institute for Production Technology and Systems Leuphana Universität Lüneburg Lüneburg Germany Hamburg Germany

Identifying the relationships between material structure and mechanical propertiesis crucial for accelerating the exploration of the material design space for advanced alloys. However, traditional approaches for magnesium alloys often fall short in providing quantitative and generalized structure-property linkages. To address this challenge, a comprehensive machine learning pipeline is presented for structure-property modeling in extruded Mg-alloys, leveraging both microstructure and texture descriptors derived from experimental data. The pipeline encompasses a robust workflow for data extraction from optical microscopy and X-ray diffraction, image processing and deep learning techniques for microstructure binarization and grain statistics, and computation of statistical descriptors including n-point spatial correlations, gram matrices for microstructure, and generalized spherical harmonics for texture. Dimensionality reduction techniques such as principal component analysis, isomap, and autoencoders are employed to high-dimensional descriptors. Subsequently, non-linear regression models – Gaussian Process, XGBoost, and Multi-Layer Perceptron regressors – are evaluated to predict mechanical properties, specifically strain hardening exponent (n) and yield stress (σy). Our results demonstrate that XGBoost consistently outperforms other regressors, achieving a notably low mean absolute percentage error of 6.67% for n and 7.01% for σy, using a combination of PCA-reduced 3-point spatial correlations and isomap-reduced gram matrices as microstructure descriptors, and isomap-reduced GSH coefficients as texture descriptors at a 150 μm length scale. Shapley Additive exPlanations analysis further reveals that texture and aspect ratio are the most influential features in predicting mechanical properties. This established ML framework for structure-property modeling in Mg-alloys surpasses state-of-the-art benchmarks and provides a valuable template for materials design and disc

关键词： Magnesium alloys

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ROBOT CALIBRATION - METHOD AND RESULTS

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ROBOTICS AND COMPUTER-INTEGRATED MANUFACTURING 1991年第4期8卷 223-231页

作者： DUELEN, G SCHROER, K Fraunhofer Institute for Production Systems and Design Technology (IPK) Berlin Germany

For many applications, robots are needed which have an absolute Cartesian pose accuracy of the same order of magnitude as their repeatability. Calibration procedures must be applied to reach this aim. In this paper, a calibration procedure is presented which allows the automatic determination of all kinematic parameters, gear parameters, and static elasticity effects. With the aid of these results it is possible to increase pose accuracy up to the robot's system limit as determined by its repeatability. Moreover, information can be acquired which suggests improvements in robot design, thereby also improving repeatability.

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Coupled CFD model of tool environment and workspace to determine the convective heat transfer in jet cooling of milling processes in machine tools

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Procedia CIRP 2025年 133卷 280-285页

作者： Steffen Brier Alexander Geist Janine Glänzel Christian Naumann Joachim Regel Martin Dix Steffen Ihlenfeldt Chemnitz University of Technology Professorship Production Systems and Processes Reichenhainer Str. 70 09126 Chemnitz Germany Fraunhofer-Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany Technical University Dresden Institute for Machine Tools Development and Adaptive Controls Helmholtzstraße 10 01069 Dresden Germany

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Friction stir lap weld-brazing of AA7050 aluminium alloy to Ti6Al4V titanium alloy – Limitations in dissimilar metal joining

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Manufacturing Letters 2025年 44卷 37-41页

作者： Felix Grassel Benjamin Klusemann Solid State Materials Processing Institute of Material and Process Design Helmholtz-Zentrum Hereon Max-Planck-Strasse 1 21502 Geesthacht Germany Institute for Production Technology and Systems Leuphana University Lüneburg Universitätsallee 1 21335 Lüneburg Germany

Joining of high-strength aluminium and titanium alloys gives new opportunities for cost- and energy-efficient designs especially in the transportation industry. In the present study, friction stir lap joining of AA7050 and Ti6Al4V was conducted, investigating the thermal cycle in the interface via variation of energy input by the spindle rotation rate. Temperature measurements reveal that the interface temperature exceeds the solidus temperature of the aluminium alloy and reached up to 570 °C, so that the process should be classified as semi-solid-state. Additionally, no indication for intermetallic compounds was found. Lap-shear strength of the joint is found to be limited by low diffusion kinetics at low temperatures and liquation cracking at high temperatures, revealing clear indications for the limitations of this specific material combination for the first time.

关键词： Friction Stir Welding Interface Temperature Mechanical Properties

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