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Improved lifetime estimation of shot-peened shaft bores using a numerical approach

Procedia Structural Integrity 2024年 57卷 411-419页

作者： Felix-Christian Reissner Lars Uhlmann Jörg Baumgartner Tim Herrig Thomas Bergs Fraunhofer Institute for Structural Durability and System Reliability (LBF) Bartningstr 47 64289 Darmstadt Germany Laboratory for Machine Tools and Production Engineering (WZL) Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology (IPT) Steinbachstr. 17 52074 Aachen Germany

Shot peening is commonly used to improve the fatigue strength of mechanical components. The peening process involves the use of high-energy mechanical impacts to create compressive residual stresses and a material hardening on the surface of the component, which can significantly increase its resistance to fatigue. Accurate lifetime prediction is important for optimizing the design of shot-peened components and ensuring their reliability and safety. Due to nonlinear material behavior and the simulation of contact, estimating the lifetime of shot-peened shaft bores under cyclic loading conditions remains a challenge. In this study, the lifetime estimation of shot-peened shaft bores using a combination of experimental testing and finite element analysis is investigated. A series of experiments was conducted on shot-peened shaft bores made of EN-GJS-700 and 34CrNiMo6, using different peening parameters such as intensity and coverage. The specimens with shot-peened shaft bores were subjected to cyclic loading in a fatigue testing machine and the lifetime was experimentally identified. The results were used to develop a methodology based on finite element analysis, which considers the effect of the shot peening parameters on the residual stress distribution, hardening and the resulting fatigue life. The results of the proposed methodology were validated against the experimental data and showed good agreement with the experimental results. The derived methodology can be used to estimate the lifetime of shot-peened shaft bores under different loading and peening conditions and provides a useful tool for optimizing the design of shot-peened components in fatigue engineering applications.

关键词： shot peening lifetime estimation residual stress finite element analysis cyclic loading

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Identification of surface roughness parameters for the function-oriented description of EDMed surfaces

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Procedia CIRP 2024年 123卷 131-136页

作者： Raphael Hess Ugur Küpper Tim Herrig Andreas Klink Thomas Bergs Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology IPT Steinbachstr. 17 52074 Aachen Germany

The surface properties and especially the surface roughness are important parameters to determine the functionality of components. It influences relevant properties such as corrosion resistance, wear resistance or tribological behaviour. The surface roughness is commonly described by using the arithmetic average roughness Ra. The average roughness provides a general measure of the height of the texture across a surface and indicates the quality of the surface and the properties. Due to the integral approach, the arithmetic average roughness cannot consider different surface topographies caused by different crater geometries generated during EDM. Therefore, two non-identical surfaces can have the same average roughness Ra. In order to overcome this inadequate description on EDM-generated surfaces, this work aims to identify surface parameters that can be used to describe these surfaces in a functionally oriented manner. To do so, different surface roughness values will be investigated to identify the most relevant parameters to describe the EDM‘ed surfaces. Furthermore, drop shape analysis will be conducted to identify the most influencing surface parameters on the contact angle between a liquid and the surface, which quantifies the wettability of the components surface.

关键词： EDM surface integrity surface roughness

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Influences of machine Hammer Peening on Inconel 718 Workpieces Manufactured by Wire-based Laser Metal Deposition

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Procedia CIRP 2024年 121卷 192-197页

作者： M. Dadgar S. Gräfe M. Müller T. Herrig T. Bergs Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology IPT Steinbachstr. 17 Aachen 52074 Germany

Additive manufacturing techniques, such as laser metal deposition (LMD), have been used to produce complex-shaped workpieces with high accuracy and material utilization. However, the as-built workpieces often suffer from typical defects such as porosity, surface roughness, and tensile residual stresses that may limit their mechanical properties and service life. To overcome these limitations, post-processing steps such as mechanical forming are recommended to improve the material properties. Surface treatment, such as machine hammer peening (MHP), can significantly improve wear resistance and fatigue strength of the additively manufactured workpiece. MHP is a deterministic, high-frequency forming process that can produce smooth surfaces with high compressive residual stresses. It also offers advantages in producing defined surface structures that exhibit friction-reducing properties. However, the influence of MHP process parameters, such as hammer frequency, step over distance, and stroke distance, on the surface integrity of additively manufactured workpieces is still unknown. In the present work, the influence of MHP on Inconel 718 workpieces manufactured by wire-based laser metal deposition (LMD-w) is analyzed. A Design of Experiments (DoE) of LMD-w parameters was employed to manufacture the workpieces. The workpieces with the least typical defects such as cracks and pores were then selected. In the next step, the selected workpieces were post-processed based on a DoE of MHP parameters. To investigate the influences of MHP on the microstructure of the workpieces, the resulting mechanical properties were measured. It was found that for Inconel 718 workpieces manufactured by LMD-w, MHP can significantly improve surface properties by reducing roughness and increasing hardness. Therefore, this study shows that MHP is a promising post-processing technique to enhance the surface integrity and mechanical properties of LMD-w manufactured workpieces.

关键词： Additive Manufacturing Laser Metal Deposition (LMD) machine Hammer Peening (MHP) Hybrid manufacturing Post-processing

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Increasing Resilience of Production Systems by Dynamic Context Modelling and Process Adaption

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Procedia CIRP 2023年 118卷 282-287页

作者： Tim Wunderlich Jonas Hansert Sandro Koch Robert Heinrich Thomas Schlegel Steffen Ihlenfeldt Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany Karlsruhe University of Applied Sciences Moltkestr. 30 76133 Karlsruhe Germany Karlsruhe Institute of Technology Am Fasanengarten 5 76131 Karlsruhe Germany Institute of Mechatronic Engineering Technische Universität Dresden 01062 Dresden Germany

The requirements for cyber-physical production systems (CPPS) grow steadily, leading to increased complexity of such systems. To address issues due to reconfiguration or failures, we present an approach to creating a context model of the CPPS components during runtime and to detect deviations from the planned production processes. Furthermore, we present a concept for modelling production processes that allows for dynamic process adaption during runtime. We then utilize this process adaption and the context model to cope with unforeseen failures and increase the resilience of the system. Finally, we evaluate the feasibility of our approach by applying it to an Industry 4.0 production system.

关键词： resilience cyber-physical production systems process adaption context awareness

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Numerical and Experimental Investigation of the Thermomechanical Loads on the machined Surface when Cutting Inconel DA718

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Procedia CIRP 2024年 126卷 492-497页

作者： Pascal Behrens genannt Wäcken Nicklas Gerhard Markus Meurer Thomas Bergs Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology IPT Steinbachstr. 17 52074 Aachen Germany

In metal cutting processes, the thermomechanical loads lead to modifications of the residual stress state of the workpiece rim zone. Especially for aerospace components, such as turbine disks made of nickel-based alloys, this modification affects the functionality and dimensional accuracy of the machined part. Therefore, the thermomechanical loads occurring in the orthogonal cutting of Inconel DA718 are investigated in this paper and chip formation simulations are performed and evaluated with the experimental results. The outcome of this work forms the basis for a research project, where it is intended to develop a multiscale prediction model for residual stresses.

关键词： Process signatures Surface integrity Metal cutting

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Evaluation of process stability in precise electrochemical machining using machine learning models based on extracted features

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Procedia CIRP 2024年 126卷 498-503页

作者： E. Tchoupe L. Heidemanns U. Küpper A. Klink T. Herrig T. Bergs Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 Aachen 52074 Germany Fraunhofer Institute for Production Technology IPT Steinbachstr. 17 52074 Aachen Germany

The process advantages of precise electrochemical machining are confronted with demanding technology development due to the absence of adaptive process control. Consequently, sporadic process instabilities occur even in series production. However, it is known that process signals can provide valuable information about the working gap conditions necessary to predict such instabilities. Therefore, this paper presents the developments of a data-driven model based on process signals for evaluating machining stability. For this, process data are generated via experimental trials and suitable predictors capable of monitoring process stability are determined using feature extraction. Three machine learning models are then trained and tested.

关键词： Feature extraction machine learning Online process monitoring Precise ECM Closed-loop control

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Evaluating task executability of mobile robots with performance maps

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Procedia CIRP 2024年 127卷 38-43页

作者： Aline Kluge-Wilkes Presley Demuner Reverdito Stefanus Kohar Amon Göppert Robert H. Schmitt Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 Aachen 52074 Germany Fraunhofer Institute for Production Technology (IPT) Steinbachstraße 17 Aachen 52074 Germany

Volatility in supply and demand caused by global disruptions such as wars or pandemics requires adaptable and changeable production systems. Since assembly accounts for significant production time and costs, the demand for changeable, line-less assembly systems is advancing. Controlling mobile robots in line-less assembly depends on understanding task executability. We propose the implementation of performance maps to evaluate the executability of assembly tasks within robot workspaces. Firstly, established performance metrics and typical assembly tasks are categorized to identify which metrics evaluate the executability of which type of tasks. The assembly tasks are grouped according to the type of movement (continuous or discrete), the required execution precision (high or low), and the amount of poses for execution (reachable or dexterous). The metrics are categorized according to their range (local or global), their physics (kinematic or dynamic), task reference (intrinsic or extrinsic), and scale (absolute or relative). Metrics are then matched to task types. This matching provides a systematic way to identify metrics to assess the executability of a task. Secondly, the performance map is presented. The performance map is a discretized representation of the distribution of chosen performance metrics for a specific robot. The current implementation is restricted to calculating the manipulability, dexterity, and condition number. Based on the input of a robot model and a task type, the metrics are calculated in distributed poses for a given resolution in the robot’s workspace to form the performance map. The performance map is applied to exemplary tasks and robots. Previous approaches to workspace evaluation fail to consider the suitability of performance metrics to evaluate specific tasks, as different metrics are more or less relevant for different tasks. Consequently, the paper contributes by introducing performance maps and providing quantific metrics for com

关键词： Formation Planning Mobile Robots Changeable Assembly Robot Performance Metrics Capability Map Performance Map

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Strategies for Resilient Manufacturing: A Systematic Literature Review of Failure Management in Production

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Procedia CIRP 2024年 130卷 1393-1402页

作者： Charlotte Wachter Sebastian Beckschulte Marcos Padrón Hinrichs Felix Sohnius 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

The need for strategies to manage failures and disruptions becomes increasingly crucial, as Industry 4.0 continues to redefine manufacturing and industrial processes. This systematic literature review aims to provide a comprehensive overview of the current state of knowledge regarding resilience strategies towards the paradigm of Industry 5.0. The integration of advanced technologies and the growing complexity of modern production systems introduce new challenges, such as the potential for cascading failures and disruptions in production environments. These challenges highlight the urgency of identifying effective resilience strategies to maintain system integrity, minimize downtime, and increase product and process quality. This review identifies existing research on resilience strategies in manufacturing, focusing on their applicability, trends, and potential research gaps. Insights are intended to guide researchers and industry practitioners in developing robust failure management approaches. A systematic literature analysis in major academic databases was conducted, selecting peer-reviewed articles published between 2013 and 2023. Keywords related to failure management and associated concepts were used to identify relevant studies. The inclusion criteria focused on research that presented empirical evidence or theoretical insights into resilience strategies. Our review reveals a diverse body of literature that explores various resilience strategies towards the vision of Industry 5.0, including a stronger focus on supporting operators, predictive failure analysis, supply chain modelling, and data management. These strategies aim to enhance system robustness, adaptability, and recovery capabilities. However, there is a notable lack of standardization and consensus on the most effective approaches. This paper contributes to synthesizing and categorizing the findings, highlighting both the strengths and limitations of the current research landscape.

关键词： Failure Management Industry 5.0 Literature review Resilience

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Novel Advances in machine tools, Tool Electrodes and Processes for High-Performance and High-Precision EDM 15

Novel Advances in Machine Tools, Tool Electrodes and Process...

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

作者： Uhlmann, Eckart Polte, Mitchel Yabroudi, Sami Technische Universität Berlin Institute for Machine Tools and Factory Management Pascalstrasse 8-9 Berlin10587 Germany Fraunhofer Institute for Production Systems and Design Technology Pascalstrasse 8-9 Berlin10587 Germany

High-performance electrical discharge machining (EDM) is a key technology for manufacturing high-precision components in a broad range of industrially relevant applications. Formation of debris in the working gap leads to arcing and short-circuits on the surface as well as related inaccuracies and process instabilities. Despite decades of research in the field of EDM excessive tool wear and limited process performance are still challenging. In order to overcome highly complex state-of-the-art challenges, dedicated processes, machine tools, peripheral systems, software, tool electrodes and technologies for the application of alternative dielectric fluids have been developed. Within this work novel advances in the development of a sophisticated dry EDM machine tool, including generator and process control technology based on open architecture, open source software, and commonly available machine tool components, are presented. Solutions for challenges regarding remaining debris and gas bubbles as well as related arc discharge and short-circuit pulses in sinking EDM are presented by new flushing methods, technologies and devices. A new system for inverted pressure flushing of a dielectric fluid in ED-drilling enables a highly efficient removal of debris and gas bubbles through the interior channels of the tool electrode. A new multi-luidic spindle system for EDM provides the ability to use performance- and material-related application of gaseous, near-dry and liquid dielectric fluids sequentially within a single machining process. Recent advances in tool electrode design, tool electrode material application, modification and production have led to essential process improvements. A helical tool electrode design significantly improved flushing conditions and related material removal rate in ED-drilling. Modification of ED-drilling tool electrode surfaces by thermal oxidation of copper reveals a promising approach to minimize ineffective discharges. Application of a speci

关键词： Debris

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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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