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19th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2019

作者： Uhlmann, E. Polte, M. Rolon, D.A. Kühne, S. Institute for Machine Tools Factory Management IWF Technische Universität Berlin Germany Fraunhofer Institute for Production Systems and Design Technology IPK Germany

ISBN: (纸本)9780995775145

Silicon is an important material often employed on most of micro-electro mechanical systems (MEMS), integrated circuits, microchips, and micro-fluidic devices. Therefore, strategies and process parameters to machine those planar 2.5-D geometries of silicon are essential. Moreover, silicon belongs to the group of hard-brittle materials, which means that it is very likely to originate cracks during the milling operations as a result of the intermittent interaction of the cutting edge and the silicon surface. Besides, the machining of silicon results on severe tool wear. The ductile-brittle transition and tool wear reduction of the silicon-milling are aspects still not completely investigated. Consequently, this paper aims at finding the proper parameter range for ductile ultra-precision milling (UP-milling) of 2.5-D silicon geometries employing single crystal diamond cutting tools. Furthermore,the evaluation the tool wear after the process is a crucial part of the investigations. In order to fulfil such knowledge gap, single groove experiments are proposed. The milling process to generate those grooves is monitored by means of force measurements. Also, surface aspects of the machined grooves are measured through white light interferometry (WLI). For evaluating tool wear, dry UP-milling investigations are conducted and images of the cutting edges are taken by means of a scanning electron microscope (SEM). The experiments show that the machining of silicon is feasible and the ductile material removal is possible. Moreover, the process forces Fpr generated by the UP-milling process of single crystal silicon are able to be employed for monitoring and avoid the transition from ductile to brittle material removal. © 2019 European Society for Precision Engineering and Nanotechnology, Conference Proceedings - 19th International Conference and Exhibition, EUSPEN 2019. All rights reserved.

关键词： Diamond cutting tools

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The finite cell method for the prediction of machining distortion caused by initial residual stresses in milling

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Procedia CIRP 2021年 102卷 144-149页

作者： M. Landwehr S. Schmid V. Holla P. Ganser T. Bergs M. Ruess K.-U. Schröder Fraunhofer Institute for Production Technology IPT Steinbachstrasse 17 52074 Aachen Germany Institute of Structural Mechanics and Lightweight Design (SLA) of RWTH Aachen University Wüllnerstrasse 7 52062 Aachen Germany Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Faculty of Mechanical and Process Engineering Düsseldorf University of Applied Sciences Münsterstrasse 156 40476 Düsseldorf Germany

Machining distortion caused by residual stresses is one of the major challenges in the production of thin-walled monolithic parts, which are widely used in the aerospace industry. This distortion often results in large deviations in form and position outside the tolerance requirements of the part. Time-consuming and cost-intensive running-in processes or manual reworking are therefore necessary to meet the tolerances of the parts. Current research mainly uses the finite element method (FEM) to predict machining distortion caused by residual stresses. However, the disadvantage of the FEM is the high manual effort required to generate a computational mesh of the in-process workpiece (IPW). Moreover, the FEM demands a very fine mesh, which has to be frequently updated by remeshing, to be in good agreement with the IPW. This leads to high computation times overall. In this paper, a novel machining distortion prediction method based on the Finite Cell Method (FCM) is presented. A major advantage of FCM compared to the established FEM in the context of milling simulation is the decoupling of the computational mesh and the IPW geometry, which allows for analysis updates of the modified IPW due to material removal, without the need for expensive re-meshing. Thus, the time complexity of the simulation can be reduced significantly. The milling process of a thin-walled part made of Ti-6Al-4V was considered to demonstrate the overall simulation approach.

关键词： Finite cell method Finite element method Machining distortion prediction Residual stress Milling Ti-6Al-4V

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Development and Validation of Bone Models using Structural Dynamic Measurement Methods

Development and Validation of Bone Models using Structural D...

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作者： Neupetsch, Constanze Hensel, Eric Werner, Michael Meißner, Sven Troge, Jan Drossel, Welf-Guntram Rotsch, Christian Chemnitz University of Technology Professorship for Adaptronics and Lightweight Design in Production Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz/Dresden Germany

Vibration measurement and signal analysis methods are common to evaluate the functionality and characteristics of technical components in different industrial and scientific areas. Modal analysis for example is a standard method to characterize the dynamic behavior of a structure and enables the development of validated bone models. The state of the art of analyzing bone structures does not include the modal damping, although it has a significant influence on the dynamic characteristics. Within the presented investigations, the modal analyses have been performed contactless with respect to excitation and response acquisition, which implies that there are no influences of shakers or sensor couplings. Therefore, an automatic impulse hammer and a 3D Scanning Laser Doppler Vibrometer were used for excitation and response detection. Various supports of the test specimens, surface pretreatments, excitation points and excitation impulses were examined to optimize the measurement setup and process. Experimental modal analysis data were analyzed by curve fitting methods to determine the modal parameters. To evaluate different structures and effects of damping, 3D printed artificial bones and animal in vitro bones were used to perform the measurements. To produce the cortical layer of the artificial bone models, volume models were generated based on medical image data and printed by polyamide-based selective laser sintering. The cancellous bone was represented by different foam fillings for the artificial bones. Thereby, the variation of the porosity was achieved by using different mixing ratios of polyurethane foam and hardener. Furthermore, the modal damping parameters were determined from the measurement of animal bones. The measurement time was optimized during the practical implementation of the parameter determination to minimize the influence of drying and decomposition processes on the measurement results. © 2019 by Walter de Gruyter Berlin/Boston.

关键词： Structural dynamics

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The impact of varying system flexibility on market prices for electricity and balancing reserves

The impact of varying system flexibility on market prices fo...

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International Conference on European Electricity Market, EEM

作者： Hendrik Kondziella Diana Böttger Thomas Bruckner Institute for Infrastructure and Resource Management (IIRM) Leipzig University Leipzig Germany Energy Economics and System Design Fraunhofer Institute for Energy Economics and Energy System Technology IEE Kassel Germany

ISBN: (数字)9781728169194

ISBN: (纸本)9781728169200

The goal of this paper is twofold. At first, we provide a modeling framework to derive a consistent view on spot and balancing reserve markets. Secondly, we use this approach to determine the impact of increasing system flexibility via scenario analysis for day-ahead electricity and capacity reservation for balancing reserves, focusing particularly on the German electricity system for the year 2030. While fundamental modeling of spot market prices in the mid-term or long-term has been well established, it is quite ambitious to derive a consistent view on future balancing reserve markets. To achieve this goal, we use a two-step modeling approach to determine the equilibrium on both markets. Minimizing the opportunity costs for capacity reservation of the supply-side, we determine balancing reserve market bids that are consistent with spot market prices. The scenario analysis reveals a strong market position for battery storage regarding Frequency Containment Reserve (FCR) and positive automatic Frequency Restoration Reserve (aFRR). Due to the lower opportunity cost compared to fossil-fueled power plants, capacity prices for these market segments are diminished by battery storages.

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Concept and Architecture for Information Exchange between Digital Twins of the Product (CPS) and the production system (CPPS)

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Procedia CIRP 2021年 104卷 1292-1297页

作者： Anna Vogt Ralph Klaus Müller Thomas Kampa Rainer Stark Daniel Großmann Technical University of Berlin Chair Industrial Information Technology Pascalstraße 8-9 10587 Berlin Germany Audi AG Auto-Union-Str. 1 85045 Ingolstadt Germany Technische Hochschule Ingolstadt Esplanade 10 85049 Ingolstadt Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstraße 8-9 10587 Berlin Germany

The Digital Twin concept and CPS- and IIoT-based approaches are increasingly important topics concerning future Industry 4.0 architectures. They offer high potential for dynamical aspects in intelligent production planning and control as well as part traceability and documentation. Standardized information exchange is an upcoming requirement among the whole supply chain. This paper presents a concept for a Digital Twin architecture based on motor production in the automotive industry. The key aspect is an information exchange structure for Digital Twins of products and production systems that are combined using principles of Dynamic Aggregation.

关键词： Digital Twin Cyber Physical system production system Information Model Information Exchange Intelligent production systems Smart production

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Application of additive manufactured tungsten carbide-cobalt electrodes with interior flushing channels in S-EDM

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Procedia CIRP 2020年 95卷 460-465页

作者： Eckart Uhlmann Julian Polte Robert Bolz Sami Yabroudi Jan Streckenbach André Bergmann Fraunhofer Institute for Production Systems and Design Technology Pascalstrasse 8-9 Berlin 10587 Germany Technische Universität Berlin Chair of Machine Tools and Manufacturing Technology Pascalstrasse 8-9 Berlin 10587 Germany

Application fields of electrical discharge machining (EDM) are limited due to given process conditions. Manufacturing of parts with high aspect ratios and the application of multi-axis machining are limited due to process instabilities caused by removed particles. A promising approach to improve EDM process conditions, especially in sinking EDM (S-EDM), is the utilization of flushing channels in the tool electrode. However, with increasing complexity of the tool electrode geometry and the local integration of these flushing channels, conventional tool electrode manufacturing by cutting is limited. In contrast to that, the machining process selective laser melting (SLM) does not have such limitations. The appropriate integration of flushing channels, even for complex electrode geometries, improves process conditions during EDM in a variety of applications. This leads to a higher material removal rate and reduced tool wear compared to machining without flushing. Additionally, the number of required tool electrodes can be reduced, as SLM enables an efficient integration and miniaturization of all features in a single electrode. Because of its wear resistance and stability, tungsten carbide is an ideal tool electrode material, which is commonly applied in drilling EDM. After identifying suitable process parameters for roughing EDM with additively manufactured tungsten carbide cobalt tool electrodes, different forms of flushing channels were analysed in order to establish a fast process with minimum tool electrode wear. The results concerning material removal rate and the relative tool wear could be improved by applying internal flushing, though the tool wear stayed at a worse level compared to conventional tool electrode materials.

关键词： EDM SLM additive manufacturing tungsten carbide-cobalt tool electrode

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Effectivity of Learning Factories to convey problem solving competencies

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Procedia Manufacturing 2020年 45卷 228-233页

作者： Felix Sieckmann Natalie Petrusch Holger Kohl Fraunhofer Institute for Production Systems and Design Technology Pascalstraße 8-9 10587 Berlin Germany Technische Universität Berlin Pascalstraße 8-9 10587 Berlin Germany

The ability to solve problems in a structured way is an essential competence of people in a factory, from the shopfloor operator to the management level. This is already the case for established lean management approaches and is gaining relevance with the increasing complexity of production systems through progressive automation and digitisation. As learning factories have shown to be an effective approach for learning and teaching production-related topics in a practical manner, a learning module for the A3 problem solving methodology was implemented at an industrial learning factory. In order to continuously improve the learning and teaching productivity, the effectiveness of different approaches to convey the A3 methodology was investigated with over 100 participants. The results show that while the setting of learning factories can be used in a beneficial way for learning the A3 methodology, additional advantages regarding learning as well as process performance can be generated by including real und current content from the learner‘s specific workplaces.

关键词： Learning Factory Lean production systems systematic Problem Solving A3 Method

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Implementation with agile project management approaches: Case Study of an Industrie 4.0 Learning Factory in China

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Procedia Manufacturing 2020年 45卷 234-239页

作者： Julia-Anne Scholz Felix Sieckmann Holger Kohl Fraunhofer Institute for Production Systems and Design Technology Pascalstraße 8-9 10587 Berlin Germany Technische Universität Berlin Pascalstraße 8-9 10587 Berlin Germany

With the “Made in China 2025” strategy, the People’s Republic of China intends to achieve a turnaround from a cheap production location to a technology pioneer, notably through digital technologies, which necessitates qualification of employees in Chinese production companies. To facilitate this, an Industrie 4.0 Learning Factory is being set up in Jiangsu Province, China. Against the background of a rapidly developing state of the art as well as cultural peculiarities of the Chinese target group, classical project management approaches quickly reach their limits. In order to address continuously changing framework conditions, approaches for an ambidextrous project management as well as agile technical-didactic development of the Learning Factory have been established. This enabled the early adaptation of the Learning Factory to the concrete target group of learners and faster realization of a train-the-trainer concept as well as the efficient execution of repetitive processes with rigid requirements.

关键词： agile project management ambidexterity ambidextrous organization Industrie 4.0

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Evaluation Model for Mobility design of Learning Factories

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Procedia CIRP 2020年 91卷 659-664页

作者： Natalie Petrusch Wolf Schliephack Holger Kohl Fraunhofer Institute for Production Systems and Design Technology Pascalstraße 8-9 10587 Berlin Germany Technische Universität Berlin Pascalstraße 8-9 10587 Berlin Germany

Shortening product life cycles and increasing, global competition lead to the necessity for companies to become flexible and able to change. The successful conduction of change projects depends to a large extent on the understanding and cooperation of the operating people. The acquisition of knowledge and thus of competence at all levels is of fundamental importance for this. Learning Factories are one of the most sustainable concepts in this respect. Concerning the industrial application, however, Learning Factories require high investment costs and are relatively inflexible in respect to their dedicated facilities and their learning content. This reveals a connection between the success of a Learning Factory in an industrial context and its mobility. In order to be able to evaluate approaches towards the mobility design of Learning Factories more precisely, the decisive drivers for mobility are identified. The assessment of these drivers with regard to the extent of influence on mobility, but also the critical consideration of possible limits, lead to an evaluation model for the mobility design of Learning Factories. Subsequently, this model is tested by applying it to a successfully operating Learning Factory.

关键词： Learning Factories Lean production systems Lean Management mobility evaluation

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Advances in Modeling of the Kerf Formation considering the Primary and Deflection Jets for the Abrasive Water Jet technology

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Procedia CIRP 2021年 102卷 156-161页

作者： Eckart Uhlmann Harald Kruggel-Emden Constantin Männel Enrico Barth Darius Markauskas 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 Technische Universität Berlin Mechanical Process Engineering and Solids Processing Ernst-Reuter-Platz 1 10587 Berlin

Processing of difficult to machine materials is a promising application for abrasive water jet kerf cutting and milling. However, due to the large number of interactions of an energy-bound cutting process, a precise prediction of the material removal is crucial for its application. Based on an analytical approach, a material removal simulation model is introduced considering the primary and deflecting jet impacts to rapidly predict various cutting situations. The model describes fundamental cutting mechanisms considering the water jet’s material removal rate and is calibrated for titanium aluminides. The model allows for a comprehensive kerf prediction and thus potentially accelerates the process design improving the productivity and quality for abrasive water jet kerf cutting and milling.

关键词： Waterjet machining Titanium aluminides AWJ milling Modeling AWJ deflection

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