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23rd International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2023

作者： Uhlmann, Eckart Hein, Christoph Schweitzer, Luiz Fraunhofer Institute for Production Systems and Design Technology IPK Germany Institute for Machine Tools and Factory Management IWF Technische Universität Berlin Germany University Medicine Greifswald Department of Orthopedics and Orthopedic Surgery Germany

ISBN: (纸本)9781998999132

Laser drilling is being used more and more frequently in many industries, such as the aerospace, medical and electronics industries, to produce precision bores. A wide range of technically difficult-to-machine materials are applied. Laser drilling has already been intensively researched in order to investigate the basic mechanisms of the drilling process and the influences of various machining parameters on the quality of the holes. These findings have explicitly led to more successful machining processes of various technical components and industries. Despite all the advantages, there are some limitations of the laser drilling process and thereby a demand for innovative solutions to increase productivity. This paper presents a novel approach to the characterisation of the laser drilling process through the analysis of the acoustic signal characteristics. The objective is to apply a new generation of optical microphones to detect key aspects of the laser drilling process. This enables the development of new strategies to optimize the laser processing parameters, increasing repeatability and productivity for industrial applications. © 2023 Euspen Headquarters.

关键词： Optimization

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REPLICATION OF FUNCTIONAL SURFACES MICRO-STRUCTURED BY EDM 37

REPLICATION OF FUNCTIONAL SURFACES MICRO-STRUCTURED BY EDM

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37th Annual Meeting of the American Society for Precision Engineering, ASPE 2022

作者： Uhlmann, Eckart Polte, Mitchel Ludwig, Jonas Bolz, Robert Technische Universität Berlin Institute for Machine Tools and Factory Management Berlin Germany Fraunhofer Institute for Production Systems and Design Technology Berlin Germany

ISBN: (纸本)9781887706568

Functional surfaces are applied in a broad range of industries ranging from automotive over aerospace to medical technology. In this paper, the manufacturing of molds micro-structured by sinking electrical discharge machining (sEDM) and the surface replication on polycarbonat (PC) is discussed. The presented analysis shows the ability to replicate hydrophobic and hydrophilic effects on PC samples from micro-structured molds fabricated by sEDM. © 2022 Proceedings - ASPE 2022 Annual Meeting. All right reserved.

关键词： Molds

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Diamond slide burnishing for the finishing of electrical discharge machined surfaces 22

Diamond slide burnishing for the finishing of electrical dis...

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22nd International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2022

作者： Uhlmann, E. Polte, M. Yabroudi, S. Waiblinger, N. Fraunhofer Institute for Production Systems and Design Technology IPK Germany Institute for Machine Tools and Factory Management IWF Technische Universität Berlin Germany

ISBN: (纸本)9781998999118

Electrical discharge machining (EDM) represents a key manufacturing technology in a broad range of industries, e. g. aerospace, automotive and mould making. Current industrial and scientific relevant challenges are long machining times to achieve the surface roughness values needed, excessive tool electrode wear and the related huge number of tool electrodes needed. At state of the art, the challenges mentioned strongly limit the economic efficiency of precision EDM processes. To overcome these major challenges, the substitution of time consuming EDM polishing processes by diamond slide burnishing (DSB) shows great potential. During the process, a monocrystalline spherical diamond burnishing tool is moved along the surface of the workpiece with a defined process force. In this way the surface is specifically compressed and roughness peaks are smoothed. Within this work the applicability of diamond slide burnishing for the finishing of electrical discharge machined surfaces was investigated. For this purpose, three VDI grades with different surface roughness values were subsequently machined by DSB. The results show that the surfaces with different initial surface conditions can be successfully finished by DSB. The surface roughness of VDI grade 30 is identified as an upper limit for the surface preparation by EDM. A significant improvement of the surface roughness Ra by 93 % and a reduction of the processing time by 40 % could be achieved by the post-processing using DSB. Therefore, the new process chain presented shows great potential for being used in the field of tool and mould making and especially for the production of injection moulds. © European Society for Precision Engineering and Nanotechnology, Conference Proceedings - 22nd International Conference and Exhibition, EUSPEN 2022. All rights reserved.

关键词： Surface roughness

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DEM simulation of centrifugal disc finishing 22

DEM simulation of centrifugal disc finishing

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22nd International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2022

作者： Uhlmann, E. Polte, J. Kuche, Y. Landua, F. Fraunhofer Institute for Production Systems and Design Technology IPK Germany Institute for Machine Tools and Factory Management IWF Technische Universität Berlin Germany

ISBN: (纸本)9781998999118

The finishing of small components with complex geometries is a major industrial challenge. One process that is suitable for targeted post-processing is centrifugal disc finishing with wet and dry media. In this process, the workpieces float as bulk material together with the abrasive particles in a container and are completely surrounded by the abrasive medium. As shown in previous studies, the Discrete Element Method (DEM) is suitable for investigations of grinding processes with specified workpiece motions. To simulate unpredictable workpiece motion, a new approach is being tested in which the workpieces themselves are treated as particles. Within this research paper, results for the post-processing of centrifugal disc finishing with the software ROCKY DEM are presented. The investigation results show good correlation between the numerical determined pressures and the analysis results of the rounded workpiece edges on test components made of mould-steel X13NiMnCuAl4-2-1-1. © European Society for Precision Engineering and Nanotechnology, Conference Proceedings - 22nd International Conference and Exhibition, EUSPEN 2022. All rights reserved.

关键词： Grinding (machining)

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Framework of an experimental setup to enable an adaptive process control based on surrogate modelling 22

Framework of an experimental setup to enable an adaptive pro...

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22nd International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2022

作者： Uhlmann, E. Polte, J. Bösing, M. Schuler, N. Fraunhofer Institute for Production Systems and Design Technology IPK Germany Institute for Machine Tools and Factory Management IWF Technische Universität Berlin Germany

ISBN: (纸本)9781998999118

Numerical simulations can help to reduce the necessity of experimental studies. Nevertheless, these simulations are costly in terms of their computational effort resulting in significant expenditure of time and hence prevent a flexible adaption to continuously changing process conditions in real time. To address this shortcoming, the paper describes a framework for the application of surrogate models to enable an adaptive process control in real time. Following, an experimental setup to validate the general framework is designed for a laser metal deposition process. In particular, the component distortion shall be simulated and the results are then used to train the surrogate models. By measuring the final component distortion the quality of the surrogate models can be assessed. © European Society for Precision Engineering and Nanotechnology, Conference Proceedings - 22nd International Conference and Exhibition, EUSPEN 2022. All rights reserved.

关键词： Process control

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Investigation of additive manufactured tungsten carbide-cobalt tool electrodes for sinking EDM 37

Investigation of additive manufactured tungsten carbide-coba...

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37th Annual Meeting of the American Society for Precision Engineering, ASPE 2022

作者： Uhlmann, Eckart Polte, Mitchel Hörl, Robert Braun, Thomas Bolz, Robert Technische Universität Berlin Institute for Machine Tools and Factory Management Berlin Germany Fraunhofer Institute for Production Systems and Design Technology Berlin Germany

ISBN: (纸本)9781887706568

Increasing product complexity and continuous developments in related tool and mould making industry require ongoing advances in manufacturing processes like electrical discharge machining (EDM). To meet the increasing requirements, the development of adapted EDM processes and tool designs is necessary. Additive manufacturing (AM) enables the manufacturing of complex tool electrode geometries with interior flushing channels for EDM processes with very few restrictions regarding the design. This accounts even for tungsten carbide-cobalt (WC-Co), which is a suitable material for EDM tool electrodes with various advantages, e.g. thermal and mechanical stability. This paper shows first results of additive manufactured WC-Co tool electrodes for the use in sinking EDM and the related development process. © 2022 Proceedings - ASPE 2022 Annual Meeting. All right reserved.

关键词： Additives

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Zirconium dioxide-reinforced aluminium oxide ceramic for micro-milling of graphite 22

Zirconium dioxide-reinforced aluminium oxide ceramic for mic...

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22nd International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2022

作者： Uhlmann, E. Polte, M. Polte, J. Hocke, T. Wendt, M. Fraunhofer Institute for Production Systems and Design Technology IPK Germany Institute for Machine Tools and Factory Management IWF Technische Universität Berlin Germany

ISBN: (纸本)9781998999118

Tool and mould making is one of the most important sectors for production of complex parts with highest economic efficiency. Particularly the milling process is a key technology for the manufacturing of tool electrodes for electrical discharge machining (EDM). Beside copper, graphite is the most industrial relevant tool electrode material for sinking-EDM. According to the state of the art the machining of graphite results in high tool wear in consequence of strong chemical and abrasive effects. Currently, uncoated and cost intensive diamond coated cemented carbide tools are used for industrial applications. High tool costs and short tool life have a negative impact on the economic efficiency of the manufacturing process and increase the overall production costs. To reduce the production costs, the needs for innovative cutting materials and dedicated manufacturing processes are high. The zirconium dioxide-reinforced aluminium oxide ceramic used in this investigation shows a great potential because of the high hardness H, the missing binder phase and the covalent bond. The aim of this investigation is the examination of the application behaviour of ceramic cutting tools during the machining process of graphite. Therefore, dedicated milling tests in partial and full cut were carried out. For evaluation of the application behaviour of the ceramic tools, the surface quality of the machined graphite depending on the wear of the tools was considered. The results show that a minimum surface roughness of Ra = 0.80 µm and average surface roughness of Rz = 6.55 µm could be achieved in first milling tests. Due to a strong sharpening effect of the cutting edge during the machining, the possibility was provided to produce complex components with highest precision and without chipping behaviour. The machining of graphite using ceramic milling tools shows extensive advantages compared to conventional milling tools, which may positively affect the economic efficiency of machining gr

关键词： Milling (machining)

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Two-colour thermography for measurement of temperature distribution in laser beam welding 13

Two-colour thermography for measurement of temperature distr...

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13th CIRP Conference on Photonic Technologies, LANE 2024

作者： Gumenyuk, A. Bakir, N. Rethmeier, M. Unter den Eichen 87 Berlin12205 Germany Technische Universität Berlin Pascalstrasse 8-9 Berlin10587 Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstrasse 8-9 Berlin10587 Germany

Solidification cracking is a frequently observed phenomenon in laser beam welding of austenitic stainless steels and other metallic alloys. Characterisation of cracking susceptibility requires knowledge of the precise and spatially resolved temperature distribution near the solidification front in the welding process. Thermography is a standard tool that provides a qualitative estimate of the 2D temperature field. The general disadvantage of this method is its dependence on the emission characteristics of the measured object. For welding applications, these can vary significantly in the temperature range above and below the melting temperature. For this purpose, we have developed a thermography-based measurement technique using a SWIR camera system in combination with two narrow bandpass filters that use the principle of two-wavelength pyrometry to estimate absolute temperature values. This technique was used to determine the temperature distributions and gradients near the solidification front of laser-welded austenitic steel. The results were validated by other measurements. © 2024 The Authors.

关键词： Laser beam welding

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Prediction of Quality in Thermographic Spray Spot Applications with Machine Learning Algorithms 56

Prediction of Quality in Thermographic Spray Spot Applicatio...

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56th CIRP International Conference on Manufacturing systems, CIRP CMS 2023

作者： Uhlmann, Eckart Polte, Julian Koutrakis, Nikolaos-Stefanos Pyka, Lasse Ider, Müslüm Thomas, Georg Rupprecht, Christian Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstraße 8-9 Berlin10587 Germany Technische Universität Berlin Pascalstraße 8-9 Berlin10587 Germany

Due to the high number of influences in production applications, quality fluctuation and deviating results in thermal spray applications are a challenging issue in manufacturing processes. This paper presents a concept for an adaptive process control based on different machine learning algorithms that are utilized to correlate input parameters with output results in thermal spray processes. For that purpose, a test environment was developed, incorporating different application scenarios with various input parameters. During the experiments, a series of measurements was performed, that is used to describe and evaluate the process. The extracted data of the conducted experiments are transformed into features and serve as the data input for the development of machine learning models based on various algorithms. These algorithms offer a prediction of the peak position, which describes the deviation of the programmed application spot, thus offering a quality prediction by utilizing solely the input process parameters. This work provides an approach based on the compared algorithms, that can be applied to create an adaptive process control, by adjusting the input parameters during the thermal spray application process. © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://***/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the 56th CIRP International Conference on Manufacturing systems 2023.

关键词： Machine learning process control quality prediction thermal spray process

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Auto-encoder-based algorithm for the selection of key characteristics for products to reduce inspection efforts

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International Journal of Quality and Reliability Management 2023年第7期40卷 1597-1620页

作者： Greipel, Jonathan S. Frank, Regina M. Huber, Meike Steland, Ansgar Schmitt, Robert H. Department of Model-based Systems Chair of Production Metrology and Quality Management WZL | RWTH Aachen University Aachen Germany Institute of Statistics RWTH Aachen University Aachen Germany Fraunhofer Institute for Production Technology IPT Aachen Germany

Purpose: To ensure product quality within a manufacturing process, inspection processes are indispensable. One task of inspection planning is the selection of inspection characteristics. For optimization of costs and benefits, key characteristics can be defined by which the product quality can be checked with sufficient accuracy. The manual selection of key characteristics requires substantial planning effort and becomes uneconomic if many product variants prevail. This paper, therefore, aims to show a method for the efficient determination of key characteristics. design/methodology/approach: The authors present a novel Algorithm for the Selection of Key Characteristics (ASKC) based on an auto-encoder and a risk analysis. Given historical measurement data and tolerances, the algorithm clusters characteristics with redundant information and selects key characteristics based on a risk assessment. The authors compare ASKC with the algorithm Principal Feature Analysis (PFA) using artificial and historical measurement data. Findings: The authors find that ASKC delivers superior results than PFA. Findings show that the algorithms enable the cost-efficient selection of key characteristics while maintaining the informative value of the inspection concerning the quality. Originality/value: This paper fills an identified gap for simplified inspection planning with the method for the efficient selection of key features via ASKC. © 2022, Emerald Publishing Limited.

关键词： Feature selection Inspection planning Key characteristics Machine learning Simulation

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