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DEM Simulation of Abrasive Brushing Processes on Additively Manufactured Workpieces

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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Impact of illumination technique on the detectability of irregularities in high-resolution images of visual in-situ process monitoring in Laser Powder Bed Fusion 13

Impact of illumination technique on the detectability of irr...

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13th CIRP Conference on Photonic Technologies, LANE 2024

作者： Merz, Benjamin Schmidt, Jonathan Poka, Konstantin Mohr, Gunther Polte, Julian Hilgenberg, Kai Bundesanstalt für Materialforschung Und-prüfung Unter den Eichen 87 Berlin12205 Germany Institute for Machine Tools and Factory Management IWF Technische Universität Berlin Pascalstraße 8-9 Berlin10587 Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstraße 8-9 Berlin10587 Germany

The layerwise geometry build-up of additive manufacturing (AM) enables the possibility of in-situ process monitoring. The objective is the detection of irregularities during the build cycle, ensuring component quality and process stability. Focus of this work is the visual in-situ monitoring of the process of powder bed fusion with laser beam of metals (PBF-LB/M). Current state of the art visual monitoring systems for PBF-LB/M are limited by low resolution, allowing the detection of gross flaws. In this work a 65 Mpixel high-resolution monochrome camera is integrated into a commercial PBF-LB/M machine enabling a spatial resolution of approx. 17.2 μm/Pixel. The observed inhomogeneities are clustered into directly detectable irregularities, and indirectly detectable irregularities that can be inferred from the surface. In parallel, two different illumination techniques are realized in the process chamber and compared. The impact of the distinct illumination technique, direct light and dark field, on the identification of irregularities is evaluated. © 2024 The Authors.

关键词： Laser beams

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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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Signal conditioning of a novel ultrasonic transducer with integrated temperature and amplitude sensors

Signal conditioning of a novel ultrasonic transducer with in...

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IEEE Southeastcon

作者： Bsher Karbouj Jörg Krüger Institute of Machine Tools and Factory Management Technical University of Berlin Berlin Germany Fraunhofer Institute for Production Systems and Design Technology Berlin Germany

Vibration amplitude of ultrasonic transducer has an impact on the overall process quality, process speed and ultrasonic transducer lifetime in industrial applications. A new ultrasonic transducer design has been developed with integrated sensor disks that have different electrical and mechanical properties. The combination of sensor has been designed for amplitude measurements and is also able to measure the transducer temperature in the real time. This paper deals with the analog signal processing that combines the different "raw" signals from the sensor disks to extract the information such as amplitude and temperature. For this goal, a chain of different signal filters and adjustment elements was used. Reliable amplitude and temperature measurements during real-time operation were obtained by the applied signal processing. The obtained results were validated with an external temperature sensor and a laser vibrometer.

关键词： Temperature measurement Ultrasonic transducers Temperature sensors Vibrations Temperature Ultrasonic variables measurement Vibrometers

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On the Selection and Application of a Convenient Energy Management Software for Industrial Purposes 13

On the Selection and Application of a Convenient Energy Mana...

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13th International DAAAM Baltic Conference and 29th International Baltic Conference, BALTMATTRIB 2021

作者： Wurster, Larissa Thiele, Gregor Briese, Clemens Krüger, Jörg Daimler Truck AG Germany Department for Process automation and Robotics Fraunhofer Institute for Production Systems and Design Technology Germany Department for Machine Vision Fraunhofer Institute for Production Systems and Design Technology Germany Department for Industrial automation The Institute for Machine Tools and Factory Management Technical University of Berlin Germany

The profitability of companies, especially in Germany, is affected by rising energy prices and increasingly stringent energy legislation. Certification according to ISO 50.001, an international standard for energy management systems, can help to meet legal requirements and increase energy efficiency. This article offers assistance in the form of a methodology that provides a structure for the selection process of an energy management system (EnMS). Considering properties of the individual company, it helps to identify an appropriate software solution. It is applied to a globally operating metalworking company in an example study. Furthermore, the measurement infrastructure in particular is a basic requirement that should not be overlooked in addition to the process of choosing an appropriate software solution. In this context, suitable metering points or criteria must be defined as well as sufficient attention paid to the anticipated costs for acquiring and integrating new measuring transducer and energy meters. The type and number of relevant measuring points must be considered in particular. Discussing these aspects, this article facilitates the process of planning and implementing an energy monitoring. © 2021 DAAAM International. All rights reserved.

关键词： Energy efficiency

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IEEE Microwave Theory and technology Society Membership and Geographic Activities: Women in Microwaves Subcommittee

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IEEE Microwave Magazine 2024年第5期25卷 20-21页

作者： Hagelauer, Amelie Grosinger, Jasmin Che, Wenquan Hess, Sherry Fraunhofer Institute for Electronic Microsystems and Solid State Technologies EMFT Munich80686 Germany Technical University of Munich Chair of Micro- and Nanosystems Technology Garching85748 Germany Graz University of Technology Graz8010 Austria South China University of Technology Guangzhou510006 China Cadence Design Systems San JoseCA95134 United States

In this column, we would like to provide you with a recent update on the activities of the Women in Microwaves (WIM) subcommittee within the IEEE Microwave Theory and technology Society (MTT-S) Membership and Geographic Activities. WIM is dedicated to establishing an inclusive network of women in the field of microwaves that attracts, scales, and connects. We do that by promoting women engineers/scientists in the microwave community, attracting women graduate students and professionals to join MTT-S, and increasing the visibility of women within MTT-S. © 2000-2012 IEEE.

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Comparing the performance of a nested to a continuous evolution strategy with covariance matrix adaption for optimization of drilling EDM 15

Comparing the performance of a nested to a continuous evolut...

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15th CIRP Conference on Intelligent Computation in Manufacturing Engineering, CIRP ICME 2021

作者： Uhlmann, E. Streckenbach, J. Polte, M. Osmanovic, M. Schick, F. Institute for Machine Tools and Factory Management IWF Technische Universität Berlin Pascalstr. 8-9 10587 Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstr. 8-9 10587 Germany

Electrical discharge machining (EDM) is a complex manufacturing process where the correlation of the individual process parameters is not fully known. When introducing new materials or complex, individual geometries in EDM, a satisfactory vector of parameters for the process must be found. This challenge is often encountered in the aerospace industry as well as in mold and tool making. One previously successful method to tackle this challenge is the stochastic optimization procedure Evolutionary Strategy (ES). Utilizing an appropriately chosen objective function, the search for a suitable vector of input parameters may be formulated as a mathematical minimization problem over the parameter space. The ES with a covariance matrix adaption (CMA) was utilized to sample from this parameter space in a stochastic manner. Examining the impact of the CMA within an ES is a promising way to gain better insight into the performance of ES. For this purpose, a vector of input parameters was optimized for a drilling EDM process with a comma and a nested comma ES with CMA. It was found that the comma ES led to a reduction in erosion duration tero of 38 % compared to the initially chosen parameters and the nested comma ES led to a reduction in erosion duration tero of 27 % compared to the same initial parameters. The additional information stored in the covariance matrix enables the ES to find a local optimum of the parameter vector faster and more consistently. This fact is verified by use of visualizations of the covariance matrix on a two-dimensional subspace. From these findings it can be concluded, that for the application of the ES to the optimization of EDM processes the CMA should be performed continuously over all generations as opposed to resetting this matrix after a number of generations. © 2022 The Authors. Published by Elsevier B.V.

关键词： Optimization

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Validation of different tungsten carbide-cobalt grades as tool electrode material for sinking EDM 15

Validation of different tungsten carbide-cobalt grades as to...

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15th CIRP Conference on Intelligent Computation in Manufacturing Engineering, CIRP ICME 2021

作者： Uhlmann, Eckart Bolz, Robert Polte, Mitchel Börnstein, Julian Technische Universität Berlin Institute for Machine Tools and Factory Management IWF Pascalstrasse 8-9 Berlin10587 Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstrasse 8-9 Berlin10587 Germany

In sinking electrical discharge machining (EDM), tool electrode wear is crucial for an economical production. The tool electrode wear affects the process efficiency and determines the number of required tool electrodes for a specific machining process. Therefore, the relative tool wear, describing the relation of removed material volume between tool and workpiece electrode, needs to be minimised. The tool wear characteristics in sinking EDM depend strongly on EDM processing parameters and the applied electrode materials. Especially in micro-EDM, a significant increase of relative tool wear is representative. Because of its thermophysical properties tungsten carbide-cobalt (WC-Co) is a suitable material for the application as sinking EDM tool electrode. The economical production of WC-Co form electrodes for EDM sinking is enabled by recent advancements in precision milling of hard materials. Due to non-existent research on which composition of WC-Co is most advantageous for the application as sinking EDM tool electrode material, previous investigations have been intensified to describe correlations between material properties, EDM processing parameters and EDM processing results concerning material removal rate and relative tool wear. Therefore, various WC-Co grades with differing grain size and cobalt content were analysed in sinking EDM experimental studies. It was observed that the factor grain size showed an ambiguous effect concerning the process results. An increasing cobalt content led to a reduction of relative tool wear, which can be explained by the microstructure of the cobalt binder phase with its higher electrical conductivity. The WC-Co grades with beneficial EDM processing results have been further investigated in EDM parameter studies with differing tool electrode geometries. The experimental results concerning relative tool wear, with a minimum of 3 % for macro- and 5 % for micro-sized geometries, proved the suitability of specific WC-Co compositions

关键词： Electrodes

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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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Reproducibility analysis for different numerical models and experimental setups in dry orthogonal cutting of AISI 4140 steel 34

Reproducibility analysis for different numerical models and ...

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34th CIRP design Conference, CIRP 2024

作者： Grimm, Christian Menze, Christian Saelzer, Jannis Sauer, Florian Eisseler, Rocco Möhring, Hans-Christian Schulze, Volker Zabel, Andreas Uhlmann, Eckart Technische Universität Berlin Pascalstr. 8-9 Berlin10587 Germany University of Stuttgart Holzgartenstr. 17 Stuttgart70174 Germany TU Dortmund University Baroper Str. 303 Dortmund44227 Germany Karlsruhe Institute of Technology Kaiserstr. 12 Karlsruhe76131 Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstr. 8-9 Berlin10587 Germany

The design of machining processes still requires iterative parameter optimisation on the real process to achieve the demanded quality. In order to use simulation results as input for models of lubricated machining processes, which is the final aim of the presented work, it is necessary to assure that already the chip forming simulations under dry conditions produce valid results. Due to extreme conditions in the chip formation zone, including high contact stresses, temperatures and deformations, advanced requirements are imposed on a numerical model. In this work, orthogonal turning of AISI 4140 steel is simulated and experimentally investigated. Aiming for a critical examination of the conventional practice to validate simulation results only through a single experimental setup, the experiments are carried out redundantly on three varying turning lathes and measurement systems. Numerical simulations are performed using finite element analysis (FEA) within the software packages ABAQUS, AdvantEdge, DEFORM and Marc, as well as meshfree methods in the form of the finite pointset method (FPM) within MESHFREE and an element-free Galerkin method (EFG) in LS-DYNA. The obtained results demonstrate the characteristics of the individual simulation methods as well as the degree of reproducibility in experiments. © 2024 The Authors. Published by Elsevier B.V.

关键词： design informatics Machining Simulation

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