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Investigation of Surface Characteristics in Magnetic Field assisted Electrical Discharge Machining

Procedia CIRP 2024年 123卷 416-421页

作者： Viet D. Bui André Martin Thomas Berger 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) has demonstrated its promising potential for surface modification. The integration of materials from tool electrode or powder that is mixed into the dielectric fluid has proven to modify the workpiece surface to enhance its mechanical properties, realize antibacterial effects, or increase biocompatibility. Recent EDM studies showed that due to non-contact forces, properties of the modified surface such as roughness values and the thickness of modified layer were significantly influenced when using magnetic field assisted EDM. Consequently, in this study, an external magnetic field with a strength of 0.66 T is used to assist the material transfer from tool electrode to workpiece surfaces during the EDM process. Pure silver and copper tools with a diameter of 2 mm are used to modify surfaces of Ti6Al4V workpieces at a discharge energy of 125 µJ with different polarities. Results show that the assistance by magnetic field significantly increases the content of transferred material from tool electrode to the workpiece surface. Additionally, it increases material removal rate and reduces the modified layer thickness. Magnetic field assisted EDM is a potential technology for improving the efficacy of the EDM surface modification.

关键词： EDM magnetic field deposition modified surface

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Target Costing as an Approach to reduce Costs in closed-loop Agriculture Systems - Application for the Cultivation of Algae in Photobioreactors 30

Target Costing as an Approach to reduce Costs in closed-loop...

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30th CIRP Life Cycle Engineering Conference, LCE 2023

作者： Stange, Maximilian Tieding, Marc Brinitzer, Gordon Ihlenfeldt, Steffen Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Strasse 88 Chemnitz09126 Germany Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB Nobelstrasse 12 Stuttgart70569 Germany Institute of Mechatronic Engineering Technische Universität Dresden Dresden01069 Germany

The rapidly growing world population, the consequences of climate change and conventional agriculture as well as the limited resources of our planet threaten the food supply of humanity, especially with vital proteins. Therefore, innovation of agricultural systems is crucial for global food security and sustainable development. One proposed system is the cultivation of algae in artificially illuminated photobioreactors, which is a promising technology to limit land and water use. To achieve a competitive position between other agricultural systems and to reduce costs in a systematic and proactive approach, we suggest using Target Costing (TC) at an early stage of development. The paper aims to provide an overview of the state of the art in TC of agricultural systems. The authors identify a suitable approach for the economic evaluation of algae cultivation in bioreactors and adapt it specifically for the extraction of proteins. Based on this, different scenarios are discussed how a cost reduction of the existing systems can be achieved. The focus is on the reduction of energy costs, a suitable site selection and the use of side streams and products. © 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)

关键词： Proteins

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Effects of ultrasonic vibration on the silver deposition in powder mixed EDM for antibacterial surface modification 23

Effects of ultrasonic vibration on the silver deposition in ...

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

作者： Bui, Viet D. Berger, Thomas Martin, André Harnisch, Karsten Döring, Joachim Bertrand, Jessica Schubert, Andreas Chemnitz University of Technology Institute for Machine Tools and Production Processes Professorship Micromanufacturing Technology Reichenhainer Str. 70 Chemnitz09126 Germany Otto-von-Guericke University Magdeburg Institute of Materials and Joining Technology Universitätsplatz 2 Magdeburg39106 Germany Otto-von-Guericke University Magdeburg Department of Orthopaedic Surgery Leipziger Str. 44 Magdeburg39120 Germany Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Str. 88 Chemnitz09126 Germany

ISBN: (纸本)9781998999132

Previous studies have demonstrated that silver nano-powder mixed electrical discharge machining (PMEDM) is a potential technique for concurrent ablative shaping medical implants and generating antibacterial layers on the surfaces. PMEDM modified surfaces with deposited silver offer excellent antibacterial properties along with very good biocompatibility. However, for medical applications, PMEDM is still facing challenges providing sufficiently uniform distribution of deposited silver and preventing spattered layers that might lead to delamination from the modified surface. It was indicated that ultrasonic vibration (UV) has remarkable effects on the fluid dynamics in the spark gap, which positively affect the silver distribution and reduce the generation of spattered layers. Consequently, in this study, a Ti6Al4V workpiece is vibrated with an ultrasonic frequency of 22.3 kHz and an amplitude of 2.5 μm during the PMEDM process. The effect of vibration direction in X and Z axis on the silver deposition is evaluated while discharge energy is varied up to 125 μJ. For comparative analyses also PMEDM without vibration assistance is investigated. Ti6Al4V hollow tool electrodes with an outer diameter of 3 mm and an inner diameter of 2.5 mm are utilised for internal flushing with a pressure of 4 bar. A hydrocarbon-based dielectric fluid is mixed with silver nanopowder at a concentration of 15 g/l. Results show that UV assisted PMEDM increases the content of deposited silver up to 1.7 times compared to PMEDM without vibration. UV with vibration in Z direction and pulse energies of 55 μJ and 125 μJ results in uniform silver distribution and significantly decreases spattered layer formation, whereas the use of vibration in X-direction leads to negative effects. By carefully selecting machining conditions such as vibration direction and amplitude, wall thickness of hollow tool electrode and powder concentration, PMEDM provides surfaces with promising characteristics for medical

关键词： Medical applications

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

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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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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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Digital Twins in 3d Concrete Printing: Information Model, Enablers, and Major Challenges

SSRN

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SSRN 2024年

作者： Sokolov, Dmitrii Dementyev, Alexander Hänel, Albrecht Ihlenfeldt, Steffen Mechtcherine, Viktor Institute of Construction Materials TU Dresden Dresden Germany Fraunhofer Institute for Machine Tools and Forming Technology Dresden Germany TU Dresden Dresden Germany

The Digital Twin (DT) is one of the most promising approaches to digitalisation of industrial processes in Industry 4.0. The interconnection of two entities – a real world and its virtual replica via two-way data communication is the key feature of the Digital Twins, which should enable the handling of high complexity systems. In the field of 3D Concrete Printing (3DCP), DTs have great potential not only to improve design, construction, and maintenance of concrete structures, but foremost to facilitate technological development in regard to robustness, reliability, scalability and market readiness. Combining a pool of well-established and yet growing technologies, DTs in 3DCP deal with highly demanding materials whilst facing their own, unique challenges. This paper explores the burgeoning landscape of DT enablers, highlights their specificities in regard to integration into a DT in 3DCP, addresses particular challenges, reveals technical boundaries, and proposes possible ways to overcome some of them. © 2024, The Authors. All rights reserved.

关键词： Cyber Physical System

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Shaping of Sharp-Edged Design Elements by Electromagnetic forming 13th

Shaping of Sharp-Edged Design Elements by Electromagnetic Fo...

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13th International Conference on the technology of Plasticity, ICTP 2021

作者： Psyk, Verena Scheffler, Christian Stalmann, Albrecht Goede, Martin Fraunhofer Institute for Machine Tools and Forming Technology Chemnitz Germany Volkswagen AG Wolfsburg Germany

ISBN: (纸本)9783030753801

Modern car body design includes parts with sharp-edged elements, which are challenging for conventional sheet metal forming technologies. This is especially critical when implementing aluminum parts in order to consider lightweight design requirements. Applying high strain rates allows increasing formability for numerous materials, including typical aluminum alloys used in the automotive industry. Therefore, integrating high-speed forming into a conventional process can help to extend forming limits. The feasibility of locally sharpening a deep-drawn radius by integrated electromagnetic forming was proved in the literature, but up to now, the investigated target radii were much larger compared to the sheet thickness. The presented paper shows that target radii in and below the size of the sheet thickness are possible by this process combination. Based on a simplified 2D component geometry, complementary experimental and numerical investigations served for developing different variants of a modular test tool and analyzing the influence of important process and tool parameters on the forming result. © 2021, The Minerals, Metals & Materials Society.

关键词： Automotive industry

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Planar 3D-Printing and Intrinsic Heat Generation Thermoforming of a Fully Customizable Ankle Orthosis – A Feasibility Approach

Planar 3D-Printing and Intrinsic Heat Generation Thermoformi...

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Integrated Systems in Medical Technologies (ISMT)

作者： Johannes Knecht Marcel Müller Franziska Valerie Hagenauer Linda Weisheit Valentin Wilhelm Mauersberger Lukas Boxberger Biomechatronics Fraunhofer Institute for Machine Tools and Forming Technology IWU Dresden Germany Technical Design Technical University of Dresden Dresden Germany

ISBN: (数字)9798350375527

ISBN: (纸本)9798350375534

There is a wide spectrum of injuries and medical conditions that are treated with the use of orthoses. For better comfort fully customized orthoses are designed and manufactured via 3D-printing or thermoforming thermoplastic casts with a low glass transition and softening temperature nowadays. This study aims to print a planar orthosis design and then thermoform the orthotic blank with intrinsic heating to get the final customized design depending on patient's needs. After identifying possible thermoplastic polymers for the application with differential scanning calorimetry (DSC) to determine thermal properties, tensile testing for mechanical properties and peel-off testing to measure multi material printing adhesion, the final orthosis blank is printed using Wire-EncapsulatingAdditiveManufacturing to integrate heating wires into the structure and create the intrinsic ability of heat generation for the thermoforming process.

关键词： Heating systems Printing Temperature Wires Thermoforming Mechanical factors Softening Plastics Wearable devices Testing

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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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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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