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Laser structuring with DLIP technology of tungsten carbide with different binder content

Procedia CIRP 2022年 111卷 601-604页

作者： Uwe Teicher Robert Baumann Yasmine Bouraoui Anas Ben Achour Andrés Fabián Lasagni Steffen Ihlenfeldt Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 01187 Dresden Germany Institute for Manufacturing Technology Technische Universität Dresden George-Baehr-Str. 3c 01069 Dresden Germany Fraunhofer Institute for Material and Beam Technology IWS Winterbergstraße 28 01277 Dresden Germany Institute of Mechatronic Engineering Technische Universität Dresden Helmholtzstraße 7a 01069 Dresden Germany

In machining, tool wear is one of the main influence factors for the resulting quality of the product. Several wear mechanisms have to be addressed to prevent unwanted deterioration of the tool integrity. For aluminium alloys, adhesion of the workpiece material on the cutting tool is one of the most challenging wear mechanisms. Engineering surface microtopographies has been proved as a convenient strategy to tackle this issue. Particularly, the direct laser interference patterning (DLIP) technique enables the integration of periodic structures on the micrometer or sub-micrometer scale. In this study the structuring of tungsten carbide with different cobalt content is presented. The interference of two laser beams leads to periodic line-like structures with a spatial period of 5.5 µm. A maximum structure depth of 2.2 µm is reached by controlling the processing parameters. Moreover, the wettability of the structured samples was analyzed by contact angle measurements with selected cooling lubricants, revealing a hydrophilic behavior with a decreased contact angle of 10°. This work gives an insight into the possibilities of structuring tungsten carbide materials with a picosecond laser source in combination with an innovative beam shaping setup from the point of view of an analysis to explore the formation of structured surfaces and their wetting behavior with cooling lubricants.

关键词： Laser structuring cutting tool DLIP Surface modification tungsten carbide

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Surface Integrity Characterization by Barkhausen Noise Measurement after Milling Processes with End Mills

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Procedia CIRP 2022年 115卷 202-207页

作者： Christoph Zachert Daniel Schraknepper Thomas Bergs Laboratory for Machine Tools and Production Engineering (WZL) of RWTH University Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology (IPT) Steinbachstraße 17 52074 Aachen Germany

In aerospace industry, safety-relevant parts are subject to strict testing guidelines to guarantee part functionality. Depending on the manufacturing process, the surface integrity of the part can be modified undesirably. In addition to common rim zone analyses, such as nital etching or X-ray diffractometry, Barkhausen noise measurement offers new potentials for a non-destructive surface integrity inspection. In this work, the influence of a 5-axis gear end milling process on the rim zone was investigated. A stable correlation between Barkhausen noise and material hardness and residual stress was determined.

关键词： Barkhausen noise Machining Surface Integrity Gear milling End mill

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Study on material-data-driven process parameterization in fine blanking

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Procedia CIRP 2024年 126卷 733-738页

作者： Lucia Ortjohann Andreas Peters Jens Gerhard Marco Becker Philipp Niemietz Thomas Bergs Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University 52074 Aachen Germany Mendritzki Holding GmbH & Co. KG 44793 Bochum Germany Feintool System Parts Jena GmbH 07749 Jena Germany Fraunhofer Institute for Production Technology IPT Steinbachstr. 17 52074 Aachen Germany

In industrial sheet-metal processing, processes are parameterized based on the material specifications. However, the manufacturing process of sheet-metal coils determines the material properties and as every manufacturing process is subject to variations, variations in material properties occur in the semi-finished product influencing the subsequent sheet-metal processing. The production of high-quality parts requires considering these varying material properties to adapt the processes accordingly. This paper shows that material data from non-destructive eddy current measurements and process data of the coil production enable decision support for the parameterization of fine blanking processes. A material-data-driven approach using material data recorded in an industrial setting is employed to investigate the influence of parameter settings in the fine blanking process on specific quality characteristics of fine blanked workpieces.

关键词： Fine blanking Material data NDT Data-driven study Process parameterization Micromagnetic properties

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Techno-Economic and Environmental Assessment of Short-Term Renewable Hydrogen Import Routes from Overseas

SSRN

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SSRN 2024年

作者： Scheffler, Florian Imdahl, Christoph Zellmer, Sabrina Herrmann, Christoph Fraunhofer Institute for Surface Engineering and Thin Films IST Riedenkamp 2 Braunschweig38108 Germany Technische Universität Braunschweig Institute for Particle Technology Volkmaroder Straße 4 Braunschweig38104 Germany Technische Universität Braunschweig Institute of Machine Tools and Production Technology Langer Kamp 19b Braunschweig38106 Germany

Converting renewable electricity via water electrolysis into green hydrogen and hydrogen-based products will shape a global trade in power-to-x (PtX) products. The European Union’s renewable hydrogen import target of 10 million tonnes by 2030 reflects the urgent need for PtX imports by sea to early high-demand countries like Germany. This study evaluates the cost efficiency and greenhouse gas (GHG) emissions of four hydrogen carrier ship import options considering a reconversion to H2 at the import terminal for a final delivery to offtakers via a H2 pipeline network in 2030. This includes ammonia, a liquid organic hydrogen carrier (LOHC) system and a novel CO2/e-methane and CO2/e-methanol cycle, where CO2 is captured at the reconversion plant and then shipped back to the PtX production site in a nearly closed carbon loop. The GHG emission accounting includes well-to-wake emissions of the marine fuels and direct emissions of the carbon capture plant. Two GW-scale case studies reveal the impact of a short and long-distance route from Tunisia and Australia to Germany, whereas the specific PtX carriers are either fuelled by its PtX cargo as a renewable marine fuel or by conventional heavy fuel oil (HFO). Ammonia outperforms the other PtX routes, as the total hydrogen supply cost range between 5.04-7.83 for Australia (low: NH3 HFO, high: LOHC HFO) and 4.75-6.12 € per kg H2 for Tunisia (low: NH3 HFO, high: CH4 HFO), respectively. The ammonia routes achieve thereby GHG intensities of 31% and 86% below the EU threshold of 3.4 kg CO2(e) per kg H2 for renewable hydrogen. LOHC though, unless switching to low-emission fuels, and the CO2/e-methanol cycle exceed the GHG threshold at shipping distances of 11,900 and 17,200 km. The hydrogen supply efficiencies vary between 57.9-78.8%LHV (low: CH4 PtX-fuelled, high: NH3 HFO) with a PtX marine fuel consumption of up to 15% LHV for the Australian methanol route, whereas high uncertainties remain for the ammonia and methanol reconversi

关键词： Carbon dioxide

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Examination of the variance in human pathways in HRC with heavy duty-robots for safe process planning

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Procedia CIRP 2020年 88卷 234-239页

作者： Mohamad Bdiwi Ann-Kathrin Harsch Paul Reindel Matthias Putz Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainerstr. 88 09126 Chemnitz Germany

Compared to robots, human pathways are individually changeable. Particularly the human-robot-collaboration (HRC) with heavy-duty robots carry high risk potentials. To ensure safety and efficiency, the human variance in pathways should be determined in the planning of HRC. Hence this paper presents a method to investigate human pathway variations in a real study. In systematically selected tasks, human pathways are examined for 100 participants in manual and human-robot collaboration (HRC) scenarios. As a result, the variations of pathways are presented depending on various features: in nearly all cases the variance of women’s walking pathways is smaller than that of men.

关键词： Human factors Production planning Human-Robot-Collaboration (HRC)

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CAD-based AND/OR Graph Generation Algorithms in (Dis)assembly Sequence Planning of Complex Products

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Procedia CIRP 2022年 106卷 144-149页

作者： Sören Münker Robert H. Schmitt Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology (IPT) Steinbachstrasse 17 52074 Aachen Germany

Several studies in production engineering and operations research focused on disassembly and assembly planning for improving the profitability of remanufacturing. The representation of feasible (dis)assembly sequences by analyzing geometrical and technical precedence constraints is an essential necessity of (dis)assembly planning. An AND/OR graph (AOG) is commonly used to represent a product’s feasible (dis)assembly sequences, including alternative subassemblies and parallel operations. In recent years, researchers studied the automatic extraction of geometrical precedence constraints by collision analysis within 3D models. However, since most of the existing approaches focused on collision analysis to identify complex precedence constraints, the generation of AOGs for complex products from collision analysis results remains too inefficient for industrial use cases. In this study, a Computer-Aided Design (CAD) interface from previous studies is used to extract liaison and moving wedge information from 3D models. A top-down and a bottom-up approach for generating complete AOGs from the extracted data are introduced. The approaches’ computing performances are analyzed on sample test cases and CAD models. The bottom-up approach performed better for the given samples. It has been found that the amount of moving wedge constraints has a strong effect on computing performance. It is a strong indicator to estimate the complexity of products under examination. The exponential behavior of the needed computing resources can be estimated beforehand. For complex products, graph simplification or alternative graph representations with less information richness should be considered. The results contribute to automated (dis)assembly sequence planning from complex products and, consequently, increasing remanufacturing profitability.

关键词： AND/OR graph Computer-Aided Design Disassembly Sequence Planning Assembly Sequence Planning

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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

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Procedia CIRP 2024年 124卷 98-103页

作者： Benjamin Merz Jonathan Schmidt Konstantin Poka Gunther Mohr Julian Polte Kai Hilgenberg Bundesanstalt für Materialforschung und -prüfung Unter den Eichen 87 12205 Berlin Germany Institute for Machine Tools and Factory Management IWF Technische Universität Berlin Pascalstraße 8-9 10587 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstraße 8-9 10587 Berlin 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.

关键词： powder bed fusion with laser beam of metals in-situ monitoring high-resolution camera illumination technique

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Towards accurate failure prediction in manual assembly by establishing a System Dynamics model

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Procedia CIRP 2022年 112卷 495-500页

作者： Robin Guenther Junjie Liang Robin Exner Robert H. Schmitt Laboratory or Machine Tools and Production Engineering (WZL) RWTH Aachen University Aachen Germany Kostal Industrie Elektrik GmbH Hagen Germany Fraunhofer Institute for Production Technology IPT 52074 Aachen Germany

The objective of this paper is the optimization of failure management in manual assembly. An advanced System Dynamics model is applied to indicate the interactions between production and quality processes. To quantify the model, the determination of the probability of failure occurrence is considered a necessary prerequisite. In manual assembly, the failure occurrence is directly related to workers' failure. Therefore, this paper analyses existing methods for calculating the human failure probability and evaluates them based on their suitability for the application in manual assembly. Subsequently, the best-evaluated method is further developed to fulfil industrial requirements. A mathematical model is developed according to the specific requirements of manual assembly, which enables the determination of the probability of failure occurrence.

关键词： Failure management manual assembly system dynamics production engineering

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AI-Based Failure Management: Value Chain Approach in Commercial Vehicle Industry

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Procedia CIRP 2022年 109卷 251-256页

作者： Robin Guenther Sebastian Beckschulte Martin Wende Hendrik Mende Robert H. Schmitt Laboratory for Machine Tools and Production Engineering WZL of RWTH University Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology IPT Steinbachstraße 17 52074 Aachen Germany

This paper describes an artificial intelligence (AI) based failure management approach across the value chain for the commercial vehicle industry by integrating and utilizing lifecycle data for product and production optimization. The amount of available data throughout a product lifecycle has increased significantly in previous years, primarily driven by the development and deployment of cyber-physical systems. While data from a single entity in the value chain already enables failure management-related analysis and services, including AI-based methods such as predictive maintenance, there remains a lack of systematic approaches to utilize data across the entire value chain. This paper proposes an AI-based failure management approach, which relies on integrating a variety of diverse data sources along the value chain. At first, three so-called application areas were defined: process and product optimization, availability optimization, and performance optimization. Consequently, practice-relevant use cases are identified for each area, for which it is shown how failures in the value chain can be proactively eliminated with the support of AI. Methods for predictive analytics are adapted for cross-value chain failure management to derive correlations between different stages of the production process and product usage. Based on these results and human expert knowledge, proactive measures are recommended by a decision support system (DSS) to resolve failures before arising. The commercial vehicle industry serves as an overarching validation case study for the practice-relevant verification of the targeted applications. The paper gives an outlook on the envisaged research work for the realization of holistic failure management.

关键词： Artificial intelligence failure detection failure management machine learning production value chain

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Investigations on five-axis milling and subsequent five-axis grinding of gears

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Procedia CIRP 2022年 107卷 705-711页

作者： T. Bergs S.A.M. Schneider C. Janßen K. Jahnel P. Ganser J. Brimmers Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology IPT Steinbachstrasse 17 52074 Aachen Germany

High-productivity processes such as gear hobbing and gear grinding are normally used in the manufacturing of gears. In some applications, however, the use of these processes is not possible due to accessibility. One example is the production of planetary gears with double helical teeth for the gear box in modern aircraft engines. The gear boxes are used to increase the efficiency of the engines but should be as light and compact as possible. Thus, the tool runout area for gear hobbing or gear grinding tools is too small. One way of manufacturing these gears is five-axis machining. While five-axis milling of gears has been the subject of several publications, five-axis grinding of gears has hardly been a topic. This paper presents the results of investigations on five-axis milling and subsequent five-axis grinding of gears in comparison to conventionally manufactured gears. For this purpose, after hardening, gears were first five-axis milled and then five-axis ground using different process parameters and then investigated on back-to-back test rigs regarding load carrying capacity. In addition, the dimensional accuracy was measured and the surfaces were examined metallographically. The dimensional accuracy became worse after five-axis grinding. However, in terms of gear life, the five-axis milled and then five-axis ground variant showed an increase of 8.2 % compared to the conventionally manufactured gear which indicates a high potential for further research in regard to the presented five-axis machining process chain of gears.

关键词： gear manufacturing double helical gear five axis milling five axis grinding 5-axis milling 5-axis grinding

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