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Antibacterial Surface Protection using Electrical Discharge Machining with Zinc Tool Electrode for Medical Devices

Procedia CIRP 2024年 125卷 278-283页

作者： Viet D. Bui André Martin Thomas Berger Philipp Steinert Andreas Schubert Chemnitz University of Technology Professorship Micromanufacturing Technology Reichenhainer Str. 70 09126 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Str. 88 09126 Chemnitz Germany

Electrical discharge machining (EDM), widely used to fabricate medical devices, is applicable for antibacterial surface protection. Silver, transferred from tool electrode or powder suspended in the dielectric to the modified layer during the EDM process, significantly enhanced antibacterial properties of the modified surface. However, bacterial resistance to silver, which was widespread in clinical, still posed challenges for the modified surfaces containing silver. Zinc, owing to its strong antibacterial effects and no challenge related to Zn-resistant bacteria hitherto reported in clinical, was therefore used as tool electrode material to modify Ti6Al4V surfaces during the EDM process. Discharge energies up to 170 µJ with different polarities were applied in the EDM milling process using deionized water-based dielectric fluid. Results show that discharge energy and polarity play a vital role in chemical composition and roughness of the modified surfaces as well as material removal rate and tool wear rate. The surfaces containing zinc contents up to 28 % can be generated. The use of a low energy generates zinc-rich surfaces with less micro-cracks. The EDM process using zinc tool electrode shows a promising potential for antibacterial surface modification of medical devices.

关键词： EDM Zinc electrode Medical device Antibacterial surface

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In-process evaluation of the grinding process using a new Barkhausen noise method 14

In-process evaluation of the grinding process using a new Ba...

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14th CIRP Conference on Intelligent Computation in Manufacturing Engineering, CIRP ICME 2020

作者： Rößler, Maximilian Putz, Matthias Hochmuth, Carsten Gentzen, Jens Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Strasse 88 Chemnitz09126 Germany

While the achievement of size and form tolerances is already state of the art for grinding, there are hardly any industrial solutions to identify thermo-mechanical process loads such as grinding burn. A system was developed, presented, and tested, which allows for the first time the in-process measurement of Barkhausen noise to indicate changes of the boundary zone's state using a novel kind of sensor. The system enables tactile and non-contact measurement at sampling rates of up to 10 ms. During investigations on hardened shafts of 100Cr6, relevant influences on the in-process Barkhausen noise were identified and evaluated. Furthermore, cause-effect relationships between microstructural effects and the Barkhausen noise were detected. © 2021 The Authors. Published by Elsevier B.V.

关键词： Grinding (machining)

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Developments in Powder Mixed EDM and its perspective Application for targeted Surface Modification 15

Developments in Powder Mixed EDM and its perspective Applica...

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

作者： Schubert, Andreas Bui, Viet D. Schaarschmidt, Ingo Berger, Thomas Martin, André Chemnitz University of Technology Professorship of Micromanufacturing Technology Reichenhainer Strasse 70 Chemnitz09107 Germany Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Str. 88 Chemnitz09126 Germany

Although widely studied over the few decades, there are conflicting theories on the discharge mechanisms of powder mixed electrical discharge machining (PMEDM). Additionally, the dielectric flow plays a vital role in the distribution of powder particles in the machining gap, which significantly affects the powder deposition to the modified surface. In this paper, the literature on PMEDM surface modification is thoroughly reported. The conflicting mechanisms and the effects of PMEDM main machining conditions, such as powder and electrical parameters on improving mechanical and antibacterial properties as well as biocompatibility of the surface, have been discussed. To verify the separation mechanism of the discharge in PMEDM, single discharge investigations have been performed when silver nano-powder is mixed into the hydrocarbon-based dielectric fluid to modify Ti6Al4V surfaces. Surface topography, chemical composition as well as the deposited silver content and distribution over the crater surface when using positive and negative polarities are analyzed and discussed. Current waveforms of PMEDM and EDM without powder at varying discharge energies as well as with and without ultrasonic vibration assistance are recorded and analyzed. For the transfer of fundamental results to a perspective application, CFD simulation is used to calculate the flow field of the dielectric fluid and analyze the velocity and distribution of the nano-powder within the working gap of a setup with internal flushing. The results show that PMEDM is a potential technology for machining medical devices with simultaneous antibacterial surface modification. © 2022 The Authors. Published by Elsevier B.V.

关键词： Titanium alloys

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Influence of the cutting edge preparation of carbide punching tools for punching of ultra-high strength steel strips

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Procedia CIRP 2024年 123卷 268-273页

作者： Nermin Redžić Sven Winter Elmar Galiev Sarah Baron Christian Stein Markus Höfer Joachim Regel Verena Kräusel Martin Dix Chemnitz University of Technology Institute for Machine Tools and Production Processes IWP Reichenhainer Str. 70 09126 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany Fraunhofer Institute for Surface Engineering and Thin Films IST Riedenkamp 2 38108 Braunschweig Germany

In order to ensure a robust punching process of ultra-high strength steel spring strips using carbide punching tools, a high stability of the cutting edge is required. Here the cutting edge preparation process has a significant influence. In the presented study, high-pressure abrasive water jet technology for cutting edge preparation was designed, investigated and analysed. For defining the optimal cutting edge shape regarding stresses, a numerical analysis using LS-DYNA was conducted. Within this analysis, the influence of the cutting edge rounding and symmetry was numerically tested and evaluated. Based on the results, two cutting edge shapes were selected and prepared using the high-pressure abrasive water injection jet technology. The tools were applied in the punching process up to 50,000 strokes in order to analyse the cutting performance and tool wear. With regard to a highly wear resistant tool for punching, a combination of the abrasive water injection jet preparation routine and a CVD diamond coating are under further investigation and first insights are presented additionally.

关键词： Punching Carbide Tool geometry Waterjet machining Ultra-high strength steel

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Tool-holder integrated printed piezoceramic sensors for process state classification and tool-wear progress evaluation in turning

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Procedia CIRP 2025年 133卷 382-387页

作者： Miguel Panesso Jan Berthold Lucas Hamm Zongshuo Li Welf-Guntram Drossel Thomas Bergs Fraunhofer Institute for Machine Tools and Forming Technology Nöthnitzer Str. 44 01187 Dresden Germany Manufacturing Technology Institute (MTI) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany

Tool condition monitoring strategies in turning processes, using multiple sensor sources to measure dynamic quantities (e.g., force, acoustic emissions, acceleration), has gained significant attention in conjunction with machine learning methods. As a novel approach, the introduction of printed piezoceramic thick films in machine tools allows the customization of sensor shape and placement, optimized to fit the tool holder’s geometry and process boundary conditions. This work proposes integration concepts using two configurations of printed piezoceramic sensors. This includes the use of a finite element simulation to estimate the generated electric charge from sensors on three locations on the tool holder, induced by transient mechanical loading. The design is validated under controlled mechanical loading and tested across various cutting conditions and tool-wear states. Signal information content from each sensor location, relative to different machining conditions, is assessed through recursive feature elimination and validated using dimensionality reduction. Finally, tool-wear progress is evaluated using the selected features.

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Design and Damping Characterization of Sandwich Composite Made of Particle-Filled Hollow Spheres and Steel Sheets

SSRN

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SSRN 2024年

作者： Zhou, Xin Penter, Lars Jehring, Ulrike Göhler, Hartmut Weißgärber, Thomas Ihlenfeldt, Steffen Chair of Machine Tools Development and Adaptive Control Institute of Mechatronic Engineering Technische Universität Dresden Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Germany Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM Branch Lab Dresden Germany

Sandwich composites of particle-filled hollow sphere structures (PHSS) and steel plates offer outstanding lightweight and damping properties, making them ideal for high-speed machine tool components under dynamic loads. Previous research has focused on single particle-filled hollow sphere (PHS) and small-sized PHSS, leaving gap in understanding of the behavior of PHSS/steel sandwich composites. As a result, this material cannot yet be used in the design of machine tools. In this study, a test rig was developed, a design of experiments approach and response surface analysis were used to investigate the effect of design parameters (shell and core thickness), and particle parameters (filling ratio and particle size) on the damping performance of PHSS/steel sandwich. The experimental results indicate that the design parameters have a more significant influence on damping, so they should be given priority in the design of PHSS/steel sandwiches. Secondly, the correlation between design and particle parameters substantially affects the damping performance of the sandwich. Minimizing particle size, increasing filling ratio, thinning the face layer, and thickening the core layer significantly increase structural *** address the manufacturing tolerances of the cellular structure, this study develops a finite element (FE) model-based optimization approach that accurately determines the material parameters of PHSS. These parameters were used in a FE-model of PHSS/steel composite using identified contact parameters by minimizing the difference of measurement and simulation. It shows that the homogenized material model and linear model using global damping parameters accurately replicates the dynamic properties of PHSS/steel sandwich composite in low vibration modes. © 2024, The Authors. All rights reserved.

关键词： Damping

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The Impact of Post-Processing Heat Treatment on the Magnetic Properties of Additively Manufactured Nd-Fe-B Magnets

SSRN

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SSRN 2024年

作者： Bittner, Florian Kumar Putta, Akhil Juerries, Florian Woodcock, Thomas George Drossel, Welf-Guntram Thielsch, Juliane Fraunhofer Institute for Machine Tools and Forming Technology IWU Dresden Germany Leibniz IFW Dresden Institute for Metallic Materials Dresden Germany Chemnitz University of Technology Institute for Machine Tools and Production Processes IWP Chemnitz Germany

The effect of post-process heat treatment on microstructure and magnetic properties by laser powder bed fusion (LPBF) additively manufactured Nd-Fe-B magnets was studied in dependence of heat treatment temperature and as built condition. The microstructure of the magnets in the as built condition is partly amorphous. The volume fraction of the amorphous phase depends on the LPBF manufacturing parameters of the magnets, and a subsequent heat treatment above 550°C leads to its crystallization with a corresponding, remarkable improvement in the magnetic properties. Higher heat treatment temperatures allow the precipitation of a-Fe in the microstructure, which deteriorates coercivity but increases remanence. Magnets with high initial volume fraction of amorphous constituents require higher heat treatment temperatures to obtain optimal magnetic performance and show an increased stability against overaging. © 2024, The Authors. All rights reserved.

关键词： Magnetic properties

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AI-driven force torque control strategies for further automate flexible high-precision, contact-intensive assemblies

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Procedia CIRP 2024年 130卷 348-354页

作者： Yunqi Gu Ruth Maria Otto Martin Naumann Leutrim Gjakova Rico Löser Martin Dix University of Applied Sciences Munich Lothstr. 34 80335 Munich Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU 09126 Chemnitz Germany Chemnitz University of Technology 09111 Chemnitz Germany

Robotic assembly processes are integral to industrial manufacturing, traditionally relying on pre-programmed sequences that exhibit limited adaptability to uncertain conditions. Recent advancements propose AI-enhanced vision systems as viable solutions to mitigate uncertainty in automated tasks. Despite the potential of vision, contact-intensive, high-precision assembly processes need customized force-torque feedback strategies to perform the task. Parametrization for setup and adaption of force-torque processes are time consuming, but decisive for quality. This work outlines an AI-driven force-torque control strategic solution for peg-in-hole assembly task, which employs object detection algorithm to grasp the workpiece and determine flexible assembly position, with force-torque-informed DNN algorithm for error correction in terms of position, and digital twin to monitor the process and collect virtual data.

关键词： Robotic Assembly Force-torque control Deep-Neural-Network Cognitive Robotics

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forming Limit of Dual Phase Steel: An Experimental and Numerical Investigation 14th

Forming Limit of Dual Phase Steel: An Experimental and Numer...

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14th International Conference on technology of Plasticity, ICTP 2023

作者： Müller, Martina Fehlemann, Niklas Herrig, Tim Lenz, David Könemann, Markus Bergs, Thomas Münstermann, Sebastian Laboratory for Machine Tools and Production Engineering WZL of RWTH Aachen University Campus-Boulevard 30 Aachen52074 Germany Fraunhofer Institute for Production Technology IPT Steinbachstrasse 17 Aachen52074 Germany Institute of Metal Forming IBF RWTH Aachen University Intzestrasse 10 Aachen52074 Germany

ISBN: (纸本)9783031409196

forming limit diagrams and forming limit curves are used to determine the failure limits of sheet metal materials by conducting a forming limit analysis. The aim is to enable the selection of suitable materials, geometries and process parameters at an early stage in the component development. In this way, engineering time and costs can be reduced. In addition to experimental forming limit analyses, different models and model approaches exist to numerically predict damage and failure. All have in common that calibration is necessary based on experimental investigations. The correspondingly determined parameters specify when ductile damage initiation begins, how it evolves, and how the material finally fails. Thus, the calibration and the parameters determined have a significant impact on the models’ accuracy. The present work focuses on the numerical prediction of DP 800 dual phase steel in a Nakajima test using a modified Bai-Wierzbicki model. Besides the calibration influence of the damage model coming from a non-unique parameter selection is investigated. A sensitivity analysis of the experimentally determined parameters of the damage model is carried out with the aim of predicting the crack initiation with high accuracy and to determine the influence of the calibrated parameters, especially the range between the damage initiation locus, the failure locus and the damage evolution rate. The objective is to determine which damage model parameters possess a high influence on the failure prediction, in order to be able to make a risk assessment with regard to the prediction accuracy for later applications. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Calibration

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Robotic Visual Servoing for Tracking Structureless Moving Parts

Robotic Visual Servoing for Tracking Structureless Moving Pa...

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Iberian Robotics Conference (ROBOT)

作者： Christian Schroder Marco Schumann Rico Loser Philipp Klimant Martin Dix Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany Professorship Virtual Technologies Hochschule Mittweida - University of Applied Sciences Mittweida Germany Institute for Machine Tools and Production Processes Chemnitz University of Technology Chemnitz Germany

ISBN: (数字)9798350376364

ISBN: (纸本)9798350376371

The European Union has committed to achieving the 1.5-degree Celsius limit set by the Paris Climate Agreement, emphasizing the necessity for substantial energy savings across various sectors, particularly in industry. This ambitious goal requires a delicate balance between reducing energy consumption and maintaining economic strength. Concurrently, there is a noticeable shift from mass production to mass customization, driven by the need for more flexible and adaptable manufacturing processes. Cognitive robotics emerges as a pivotal technology in this context, offering enhanced capabilities for flexible production lines. One significant advantage is the ability to assemble moving parts which optimizes cycle times and therefore contributes to energy savings. This paper presents a novel approach to object tracking using NC robot-based position control, demonstrating its potential to support the industry's transition towards more sustainable and efficient manufacturing practices. The image processing algorithm, which consists of a fused methodology merging an iterative 2D image registration and stereo vision-based point cloud registration, demonstrates the ability to track an object with a mean L2-error of 3.5 mm in a dynamic environment.

关键词： Industries Point cloud compression Service robots Heuristic algorithms Energy conservation Position control Production Visual servoing Object tracking Meteorology

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