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17th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2017

作者： Edelmann, Jan Albrecht, Mirko Zeidler, Henning Gehde, Michael Schubert, Andreas Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany Chemnitz University of Technology Plastics Chemnitz Germany Chemnitz University of Technology Micromanufacturing Technology Chemnitz Germany

ISBN: (纸本)9780995775107

The application of graphene in polymers and polymer-based composites was investigated in an application-oriented research project. The aim was the improvement of mechanical, electrical and thermal properties by using graphene as nanofiller in the polymer matrix. Research concentrated on developing appropriate formulations of graphene-based plastics for functionally integrated components, which can be processed in an industrial environment. Since most of recent studies have been done in lab environment, guaranteeing ideal processing conditions not relevant in industrial production, the approach of this project was hallmarked by using industrial equipment for compounding and further processing.

关键词： Graphene

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Investigation on the Variability of Existing Models for Simulation of Local Temperature Field during a Single Discharge for Electrical Discharge Machining (EDM)

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Procedia CIRP 2018年 68卷 260-265页

作者： Fritz Klocke Mehnoush Mohammadnejad Markus Zeis Andreas Klink Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Aachen Germany Fraunhofer Institute for Production Technology (IPT) Steibachstr 17 Aachen 52074 Germany

In electrical discharge machining (EDM) material removal and rim zone modifications are resulted by generated heat during numerous discharges. By estimating the temperature field applied on the workpiece as material loading, removal rate and induced modifications in the rim zone can be predicted. Different scientists tried to simulate the induced temperature field on the workpiece during a single or multiple discharges. However, due to the complex removal mechanism in EDM, these models are mostly incomplete and contain considerable uncertainties. In this study, the strengths and weaknesses of typical heat transfer models for a single discharge are discussed. For this propose a finite element model is constructed and influences of different modeling parameters on the obtained results have been analyzed. Moreover, potentials of reverse microstructure simulation as an assistant for modification of heat source models discussed.

关键词： reverse simulation single dischatge material modification microstructure evolution simulation electrical discharge machining (EDM)

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Different encapsulation strategies for implanted electronics

Different encapsulation strategies for implanted electronics

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作者： Winkler, Sebastian Edelmann, Jan Welsch, Christine Ruff, Roman Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Straße 88 Chemnitz09126 Germany Fraunhofer Institute for Biomedical Engineering IBMT Ensheimer Strasse 48 66386 St. Ingbert Germany

Recent advancements in implant technology include increasing application of electronic systems in the human body. Hermetic encapsulation of electronic components is necessary, specific implant functions and body environments must be considered. Additional functions such as wireless communication systems require specialized technical solutions for the encapsulation. In this paper 3 different implant strategies based on the material groups silicone, ceramics and titanium alloys are evaluated. With the background of a specific application the requirements for the encapsulation are defined and include the implementation of electrical feedthroughs, wireless communication and wireless energy transfer as well as biomedical specifications such as hermetic sealing, mechanical stability and biocompatibility. The encapsulations are manufactured and qualified experimentally. © 2017 Sebastian Winkler et al., Published by De Gruyter.

关键词： Silicones

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In-process monitoring of joining operations for piezoceramic elements 21st

In-process monitoring of joining operations for piezoceramic...

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21st Symposium on Composites, 2017

作者： Müller, Benedikt Pierer, Alexander Schmidt, Marek Schubert, Andreas Koriath, Hans-Joachim Putz, Matthias Wittstock, Volker Chemnitz University of Technology Prof. Micromanufacturing Technology Reichenhainer Str. 70 Chemnitz09126 Germany Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Str. 88 Chemnitz09126 Germany Chemnitz University of Technology Prof. for Machine Tools and Forming Technology Reichenhainer Str. 70 Chemnitz09126 Germany

ISBN: (纸本)9783035711981

The direct integration of piezo elements into micro-structured aluminum sheets is a new approach for adaptronics and lightweight constructions. With the integration of the active piezoceramic elements the aluminum sheets gain sensor and actuator functionalities. The mechanical interconnections and the preload of the piezoceramic elements are an important issue for the sensor and actuator capability of the later smart material. Post-process inspection methods to characterize the mechanical interconnection of the joining partners and the performance of the transducer after the joining operation are state of the art. Scope of the research presented in this paper is the development of a novel in-process monitoring method that utilizes the piezoceramic transducer as inherent sensor for failure mode detection and preload evaluation during the joining by forming operation. Within this study, results of forming experiments with array batches of interconnected piezoceramic elements are presented. The piezoceramic batches are electrically contacted inside the joining tool and utilized as material inherent sensor during joining by forming experiments. Test samples are characterized by impedance spectroscopy during the joining operation. Based on the experimental results, a novel in-process-monitoring method utilizing the piezoceramic joining partners as inherent sensor is outlined. It is shown, that with this method a sufficient preload can be adjusted on the basis of the intensity of the resonance peak without an overload. Furthermore, error effects to the transducer can be detected at an early stage. © 2017 Trans Tech Publications, Switzerland.

关键词： Process monitoring

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Application of laser scanning as a Pre-machining metrology technique in Jet-ECM 17

Application of laser scanning as a Pre-machining metrology t...

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17th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2017

作者： Zanjani, Matin Yahyavi Zeidler, Henning Martin, André Schubert, Andreas Prof. Micromanufacturing Technology Faculty of Mechanical Engineering Technische Universität Chemnitz Chemnitz09107 Germany Fraunhofer Institute for Machine Tools and Forming Technology Chemnitz09126 Germany

ISBN: (纸本)9780995775107

In Electrochemical Machining (ECM), where the material removal takes place based on the anodic dissolution of the workpiece material, the working distance is one of the most important parameters. Especially in Jet Electrochemical Machining (Jet-ECM), where a micro nozzle is moved over the initial surface of the workpiece in order to apply an electrolytic free jet to produce the desired shapes, the distance between the nozzle and the workpiece becomes even more important. On the one hand a small working distance is aspired to achieve high current densities resulting in a high efficiency of the process. On the other hand the working distance needs to be large enough to avoid damages on the micro nozzle caused by electrical discharges or mechanical contact. Hence, the adjustment of the working gap is essential to realize a precise, effective and secure Jet-ECM process. The control of the gap size is done based on the data gathered before machining by surface measurement. Until now, the initial surface has been detected by electrostatic probing through moving the nozzle stepwise to the work piece surface and detect the voltage drop between the nozzle and the work piece. With this strategy, only a limited number of points can be detected within adequate time. Hence, in most cases only three points of the initial surface are detected in order to adjust the working distance according to the planar inclination of the workpiece. The coordinates of the three detected points are used to calculate the normal vector of the initial surface. In recent studies, another strategy was analysed, which is realized by dividing the surface into smaller areas and respectively calculating the normal vector of each area in order to obtain more accurate data of the initial surface. A further strategy is to use probing along the machining path of the tool and to gather the coordinates of a number of points along the path. The above mentioned methods usually do not ensure the precise control of

关键词： Surface analysis

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Ecological and functional optimization of the pretreatment process for plasma based coatings of cutting tools

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Procedia Manufacturing 2019年 33卷 618-624页

作者： E. Uhlmann H. Riemer S. An M. Fröhlich H. Paschke M. Petersen Institute for Machine Tools and Factory Management (IWF) Technische Universität Berlin Pascalstr. 8-9 10587 Berlin Germany Leibniz Institute for Plasma Science and Technology (INP) Felix-Hausdorff-Str. 2 17489 Greifswald Germany Fraunhofer Institute for Surface Engineering and Thin Films (IST) Eberhardstr. 12 44145 Dortmund Germany Albrecht + Schumacher Oberflächentechnik GmbH Graf-Zeppelin-Ring 15 27211 Bassum Germany

Increasing demands in machining of high-tech materials and dry machining lead to higher thermal and mechanical loads on cutting tools. In response to these challenges, enhanced coating solutions are applied to increase performance and life of cutting tools. However, during the production process the cemented carbide substrates are contaminated with grinding oils and residues of organic material. For the subsequent physical vapor deposition (PVD) coating process an intensive and high-quality cleaning process is necessary. In this contribution, plasma electrolytic polishing (PEP) is used as a novel alternative to conventional ecologically harmful cleaning baths. Apart from the ecological advantage, the surface of the substrate can be optimized with regard to the coating adhesion. To examine the performance of the different cleaning processes, machining tests were performed at the IWF to evaluate the layer adhesion and tool life of the tools.

关键词： PVD-coating Turning Plasma electrolytic polishing

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Process analysis for magnetic pulse welding of similar and dissimilar material sheet metal joints

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Procedia Engineering 2017年 207卷 353-358页

作者： Verena Psyk Christian Scheffler Maik Linnemann Dirk Landgrebe Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Strasse 88 09126 Chemnitz Germany

Magnetic pulse welding (MPW) is an impact welding technology for producing metallic bonds of similar and dissimilar materials offering advantages such as avoidance of temperature induced problems. Based on the parameters describing the collision of the joining partners, specifically the impact angle and impact velocity, so-called welding windows describe whether or not welding will be successful for a specific material combination. However, as in MPW collision parameters depend on equipment and setup dependent parameters, using these welding windows for process design requires knowledge about the adjustment of the collision parameters via the adjustable process parameters. Therefore, the influence of adjustable process parameters on collision parameters and resulting weld quality is analyzed and trends, for a target oriented process and joint design, are deduced. Specifically, joining of copper to aluminum, copper to copper, aluminum to copper and aluminum to stainless steel is regarded.

关键词： Magnetic pulse welding Process analysis Multi-material joints

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Polypropylene based piezo ceramic compounds for micro injection molded sensors 21st

Polypropylene based piezo ceramic compounds for micro inject...

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21st Symposium on Composites, 2017

作者： Doerffel, Christoph Decker, Ricardo Heinrich, Michael Tröltzsch, Jürgen Spieler, Mirko Nendel, Wolfgang Kroll, Lothar Institute of Lightweight Structures Chemnitz University of Technology ChemnitzD-09107 Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 ChemnitzD-09126 Germany

ISBN: (纸本)9783035711981

Polymer matrix compounds based on piezo ceramic and electrically conducting particles within a thermoplastic matrix show distinctive piezoelectric and dielectric effects which can used for sensor applications. The electrical and mechanical properties can be adjusted in a wide range by varying the ratio of active filling particles and the matrix materials. The sensor effect of the compound is generated by the ceramic particles. A large ratio of piezo ceramic powder facilitates a high sensitivity. The electrical permittivity of the otherwise insulating matrix polymer can be adjusted by the amount of conductive filler. An aligned permittivity leads to a stronger electrical field in the ceramic particles. In contrast, too many conductive particles create a conductive network in the compound which short-circuits the sensors. The piezo ceramic compounds can be processed via micro injection molding for application as ceramic sensors. This offers a wide range of new sensor design variants, notably three-dimensional and highly complex geometries. However, there are two main demands for a highly sensitive sensor, which are conflicting. On the one hand the filler content of piezo ceramic particles in combination with electrical conductive carbon nanotubes must be very high;on the other hand the wall thickness should be as thin as possible. For filling cavities with a high aspect-ratio in an injection molding process, low viscosity polymer melts are necessary. These process characteristics conflict with the increasing viscosity by filling the melt with the particles. The sensor measuring area has to be designed as thin walled as possible. In order to overcome this obstacle a dynamically tempered mold design is applied to avoid solidification of the melt, before the mold is completely filled. The mold can be tempered by Peltier elements. The fully electric tempering is cleaner, more precise and more reliable than conventional water or oil tempering. © 2017 Trans Tech Publication

关键词： Molds

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Study for Combined Wire + Powder Laser Metal Deposition of H11 and Niobium

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Procedia Manufacturing 2018年 25卷 426-434页

作者： Mahesh Teli Fritz Klocke Kristian Arntz Kai Winands Martin Schulz Stella Oliari Fraunhofer Institute for Production Technology IPT D-52074 Aachen Germany Laboratory for Machine Tools and Production Engineering (WZL) RWTH Aachen University D-52074 Aachen Germany

Laser additive manufacturing (LAM) has been proved to be a successful technique to fabricate metallic components for a number of industries; for instance, die & mold, forging and cutting tools, and aerospace. It is, however, facing multitude obstacles due to lack of maturity in terms of process knowledge, design, and qualification. This paper deals with parameters’ study and optimization of combined hot-work tool steel wire (H11) and niobium powder (Nb) deposition by laser. The process is closely analysed and compared with as well as without using Nb powder. Especially, the importance of Nb in order to refine the microstructure is discussed while taking into account the microstructure-property relationships of H11.

关键词： Laser additive manufacturing Laser metal deposition Hot-work tool steel H11 Niobium (Nb)

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Simulation of Error-prone Continuous Generating Production Processes of Helical Gears and the Influence on the Vibration Excitation in Gear Mesh

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Procedia CIRP 2017年 62卷 256-261页

作者： Simon Kimme Ruben Bauer Welf-Guntram Drossel Matthias Putz Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Str. 44 01187 Dresden Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenainer Str. 88 09126 Chemnitz Germany

A very important feature of high quality gears is a low noise emission in all operating conditions. Micro-geometry of the gear is of relevance for the vibration excitation in the tooth contact and significantly affected by the manufacturing process, especially the finishing operations. Besides known process related effects, uncontrolled variations such as inaccuracies in the speed synchronization of different axes or vibrations influence the surface structure of the tooth flanks. In this paper a detailed simulation of the production process is presented, providing crucial information about characteristic process properties and enabling investigations on the impact of manufacturing process on gear mesh acoustics.

关键词： simulation of gear machining defective cutting process acoustic relevant vibrations

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