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

作者： Uhlmann, E. Hein, C. Schlüter, S. Wang, Y. Dürre, G. Fraunhofer Institute for Production systems and Design Technology IPK Germany Institute for Machine Tools and Factory Management IWF Technical University Berlin Germany

ISBN: (纸本)9781998999132

Drug-coated balloons were established as an improvement for coronary angioplasty in recent years. However, due to the balloons' high manufacturing variance, coating them evenly is challenging. Therefore, production is still carried out at least partially manually. Within the framework of the presented research project, a four-axis machine kinematics has been developed, enabling even coating of balloon catheters of various sizes in a controlled climate. High-precision measurement using a confocal sensor allows for compensation for the manufacturing variance of the balloon catheter by means of surface mapping. The average coating thickness as well as its distribution can be determined similarly. Thus, in case of insufficient coating, local reapplication can be carried out. With the developed machine system, it is therefore possible to produce coating area densities in the range of 4 μg mm-2 -2 with minimal inhomogeneities. © 2023 Euspen Headquarters.

关键词： Coatings

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Investigations on Case Hardening of an Additive Manufactured Steel 20MnCr5 (via PBF-LB/M)

Investigations on Case Hardening of an Additive Manufactured...

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作者： Mallow, S. Schmitt, M. Gebauer, M. Stockburger, R. Reich, M. Kessler, O. Materials Science University of Rostock Albert-Einstein-Straße 2 Rostock18059 Germany Fraunhofer Institute for Casting Composite and Processing Technology Igcv Augsburg Germany Fraunhofer Institute for Machine Tools and Forming Technology Iwu Dresden Germany Hanomag Härtol Lohnhärterei GmbH Gommern Germany

As an additive manufacturing process, powder bed fusion of metals using a laser beam (PBF-LB/M) enables the near-net-shape production of complex components in a single step. In combination with case hardening, it will thus be possible in the future to produce lightweight, functionally integrated transmission components characterized by high-strength surface layers with a sufficiently tough component core. However, the process-related new initial conditions resulting from very high solidification rates in PBF-LB/M may mean that case hardening of PBF-LB/M materials with standard parameters achieves different case hardening results than have been usual in the past. This hypothesis was investigated in the present work using the case hardening steel 20MnCr5 (material number 1.7147) after successful development of industry-relevant PBF-LB/M parameters. Besides the convincing results regarding microstructure, hardness and carbon depth profiles, case hardening with standard parameters led to irregular grain growth due to holding at high temperatures for several hours during carburization. © 2023 Walter de Gruyter GmbH, Berlin/Boston, Germany.

关键词： 3D printing

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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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DEM simulation of centrifugal disc finishing using smoothed particle hydrodynamics 23

DEM simulation of centrifugal disc finishing using smoothed ...

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

作者： Uhlmann, E. Polte, J. Kuche, Y. Hocke, T. Fraunhofer Institute for Production Systems and Design Technology IPK Germany Institute for Machine Tools and Factory Management IWF Technische Universität Berlin Germany

ISBN: (纸本)9781998999132

Centrifugal disc finishing is a widely used technology forserial post-processing of small components made of various materials. During the process, the workpieces are completely surrounded by dry or moist abrasive media, making it difficult to obtain precise information about particle contacts or the movement of the workpieces. Numerical analysis through the discrete element method (DEM) has the potential to improve the understanding of the process, but the accurate representation of moist particles with varying contact conditions remains a challenge. This paper compares different contact models using the ROCKY DEM software, including the liquid-bridge model and the smoothed particle hydrodynamics (SPH) model. The analysis indicates that, compared to other models, SPH demonstrates clear advantages in representing process water flow and is better suited for cases with higher water content in the medium. © 2023 Euspen Headquarters.

关键词： Finite difference method

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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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Implementation of a handling system for using carbon fibres as tool electrodes in micro-ED drilling 23

Implementation of a handling system for using carbon fibres ...

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

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

ISBN: (纸本)9781998999132

Electrical discharge machining (EDM) processes represent an established process for the machining of complex geometries in hard to cut and electrically conductive materials. Nevertheless, micro-electrical discharge drilling still poses the challenge of machining holes with diameters dh ≤ 50 μm. The preparation of even smaller pin tool electrodes demands a great amount of non-productive time, which often involves the use of additional electrical discharge dressing processes for its manufacturing. A possible solution is the use of single carbon fibres with diameters 5 μm ≤ del ≤ 10 μm as tool electrodes. The use of these single fibres comprises a challenge due to their geometrical and mechanical properties, e.g. diameter and brittleness. To overcome this challenge, an existing handling system for carbon fibres was re-designed considering the obstacles that arose with the use of previous versions of such systems. This includes the replacement of the liquid rubber coating of the movable clamping jaw in order to use foam rubber to achieve a better distribution of the clamping force that establishes the electrical contact between the carbon fibre and a conducting copper plate. The geometry of the borosilicate glass micro-pipette was redesigned to ensure an accurate positioning of the carbon fibre due to its inner tip diameter 15 μm ≤ dt ≤ 35 μm and to enable the use of fibre electrodes with a length of 15 mm ≤ le ≤ 25 mm. This hinders the deflection of the fibre tip during the machining process and enables the precise guidance of the fibre. Furthermore, the developed handling system was implemented for performing single discharge experiments, in which parameters such as open circuit voltage, charge current and discharge capacity were varied in order to determine their influence on the material removal process. © 2023 Euspen Headquarters.

关键词： Rubber

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Characterisation and investigation of ion-implanted boron-doped single crystal diamonds as temperature sensor for ultra-precision machining 23

Characterisation and investigation of ion-implanted boron-do...

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

作者： Uhlmann, E. Polte, M. Hocke, T. Thißen, K. Fraunhofer Institute for Production Systems and Design Technology IPK Germany Institute for Machine Tools and Factory Management IWF Technische Universität Berlin Germany

ISBN: (纸本)9781998999132

Ultra-precision machining is a crucial manufacturing process for the production of optical components in automotive, medical and aerospace industry and enables high dimensional accuracies and low surface roughness values. Dedicated single crystal diamond tools enable the manufacturing of optical and functional surfaces such as mirrors or lenses. Despite the high mechanical hardness, temperature induced chemical wear of the diamond tools occures during the process. To characterise und interpret the wear behaviour of diamond tools, the cutting temperature needs to be analysed. At state of the art, there are no precise methods available for analysing temperatures in the cutting zone of a single crystal diamond tool in order to identify the wear behaviour online during the process. Therefore, a dedicated measurement system based on boron-doped CVD single crystal diamonds as temperature sensor was developed. The electrosensory features of the fully boron-doped diamonds enable a direct temperature measurement in the cutting zone. To enable high sensitive temperature measurements, ion-implantation was used for partial and specific boron-doping close to the cutting edge of single crystal diamonds. To fundamentally evaluate the quality of the doping and contacting structures as well as the general process of the ion-implantation three different doping structures were investigated using single crystal diamond blanks prior doping the cutting tools. For this purpose, the boron-doped structures were optically characterised and the correlations between the resistances and the temperatures were evaluated as a function of different doping-levels and doping-lengths. First results show the successful application of the ion-implantation for boron-doping of single crystal diamonds. It could be proven that the selected boron-levels as well as boron-lengths lead to different initial conditions of the analysed specimens. Dedicated ionimplantation of single crystal diamond tools represents

关键词： Surface roughness

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Wear mechanism of single crystal diamonds in ultra-precision cutting of graphite for air bearing applications 23

Wear mechanism of single crystal diamonds in ultra-precision...

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

作者： Uhlmann, E. Polte, M. Hocke, T. Felder, F. Institute for Machine Tools and Factory Management IWF Technische Universität Berlin Germany Fraunhofer Institute for Production Systems and Design Technology IPK Germany

ISBN: (纸本)9781998999132

In order to meet the continuously increasing function-determining requirements of complex precision components, advances in machine tool components are necessary in addition to technological developments. In this context, motorized spindles in particular show great potential for enabling further increases in accuracy. To achieve high stiffness and damping behaviour of spindle systems, aerostatic bearings made of graphite with bearing gaps Sg S ≤ 1 μm are necessary. Regarding the state of the art, uncoated tungsten carbide tools, diamond coated carbide tools and thick film chemical vapour deposition (CVD) diamonds are used for cutting graphite materials. Cutting with these tools leads to asymmetric breakout behaviour of the graphite grains as well as high tool wear during machining, resulting in insufficient shape accuracies and surface qualities. A promising approach to overcome the current challenges for aerostatic bearing components made of graphite is the use of single crystal diamonds (SCD) with characteristic low rounded cutting edge radii rß ≤ 20 nm as well as cutting-edge waviness wa ≤ 200 nm. Besides the material-specific properties of the SCD, tool wear occurs during the cutting of graphite. For this purpose, the abrasive wear mechanism and surface attrition of SCD were analysed concerning specific blasting tests with defined time intervals of 60 s ≤ tb ≤ 3,000 s and different process conditions. Furthermore, two types of graphite granulate with grain sizes in a range of 200 μm ≤ gs ≤ 400 μm were used. First results show a dimensional loss of material on the investigated specimens made of SCD depending on the process conditions, whereby an influence of the surface attrition could be proven. © 2023 Euspen Headquarters.

关键词： Graphite

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Innovative actuating process for machining CFRP with force-controlled radial feed movement

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Procedia CIRP 2023年 119卷 669-674页

作者： Marie Peter Konstantin Sauer Joachim Regel Martin Dix Institute for Machine Tools and Production Processes Chemnitz University of Technology Reichenhainer Str. 70 09126 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany

The use of lightweight materials such as carbon fibre reinforced plastics (CFRP) is increasing due to the demand for rising resource and energy efficiency, especially in the aerospace and automotive industries. Because of the high delamination tendency of these materials and their abrasive impact on the tool, the challenges in machining CFRP lie primarily in the drilling process and thus in the design of the drilling tool. In this paper, an innovative design of a drilling tool for machining CFRP with force-controlled radial feed movement of the cutting edges is presented. The aim of this tool is to create a tool axial force free process that uses a force-controlled radial feed motion, which matches the chip cross-section to the wear condition of the cutting edge. The tool concept is explained based on the functionality of the actuating process. Tests were evaluated with regard to process forces and drilling quality to show that the tool is capable of producing delamination-free bores in a tool axial force free process.

关键词： tool design adaptive control actuator drilling composite

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Increasing the Relative Density of Additively Manufactured Tungsten Carbide-Cobalt Tool Electrodes for EDM 38

Increasing the Relative Density of Additively Manufactured T...

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38th Annual Meeting of the American Society for Precision Engineering, ASPE 2023

作者： Uhlmann, Eckart Polte, Mitchel Hörl, Robert Reimann, Robert Braun, Thomas Hocke, Toni Technische Universität Berlin Institute for Machine Tools and Factory Management Berlin Germany Fraunhofer Institute for Production Systems and Design Technology Berlin Germany

ISBN: (纸本)9781887706599

The investigation of novel materials for the use of tool electrodes for electrical discharge machining (EDM) is necessary to meet the increasing demands for complex products to be machined. Continuous product developments require improvements in manufacturing processes such as Sinking Electrical Discharge Machining (S-EDM). To meet these requirements, the development of customized EDM-processes and innovative tool designs is essential. Additive Manufacturing (AM) enables the production of sophisticated tool electrode geometries. This includes internal flushing channels for EDM-processes with minimal design constraints. Laser Powder Bed Fusion (LPBF) is a suitable method for this purpose. The presented paper shows an investigation to further increase the relative density ρrel of additively manufactured S-EDM tool electrodes using tungsten carbide-cobalt (WC-Co) as material for tool electrodes. © 2023 Proceedings - ASPE 2023 Annual Meeting. All rights reserved.

关键词： Electrodes

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