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Evaluation of manufacturing processes for the production of graded ultrafine grained materials

Procedia Manufacturing 2018年 21卷 45-52页

作者： D. Landgrebe U. Götze M. Bergmann A. Schmidt R. Selbmann Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Straße 88 09126 Chemnitz Germany Technische Universität Chemnitz Professorship of Management Accounting and Control 09107 Chemnitz Germany

Scientific research results show that graded ultrafine grained aluminum-based materials offer technical advantages by possible material property improvements (e.g. yield strength, corrosion resistance) especially when applied to heavily stressed components like screws. The commercial screw production is currently conducted without gradation of the semi-finished workpiece. Until now there is no evaluation on whether and under which conditions graded materials (screws) can technically and economically compete with conventional materials. In this paper, an innovative process chain for the production of graded ultrafine grained components is presented and analyzed based on a methodology for an integrated technical-economic evaluation. The evaluation especially of the yield strength of graded materials, energy consumption of the forming steps, energy costs, and revenue effects of improved material properties will outline the technical and economic potential of the technology. Despite higher energy consumptions positive profit effects can be expected due to improved material properties.

关键词： Severe Plastic Deformation aluminium screw technical-economic evaluation process chain evaluation

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Development of an innovative lightweight piston through process combination “casting – forging”

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Procedia Manufacturing 2019年 27卷 172-176页

作者： L. Krüger E. Jentsch L. Brunke A. Keßler G. Wolf T. Lehnert N. Schubert A. Wagner D. Landgrebe Technische Universität Bergakademie Freiberg Institut für Werkstofftechnik Gustav-Zeuner-Str. 5 Freiberg 09599 Germany Technische Universität Bergakademie Freiberg Gießerei-Institut Bernhard-von-Cotta-Str. 4 Freiberg 09599 Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 Chemnitz 09126 Germany

The development of an innovative hybrid lightweight piston for marine engines is intended to help reducing emissions and operating costs. The piston consists of a piston base and a top part. In the manufacture of the piston base, a preform is cast and the final geometry is produced by means of subsequent forming (forging). This significantly improves the mechanical properties of the component. As a result of the possible material advantages in the overall process chain, the piston base can be designed as a "lightweight component". By examining the entire "primary casting – forging" process chain, the use of materials is significantly reduced, especially in the "casting" production route, since even minor internal defects can be tolerated after the preform has been cast. For the subsequent forging process, this material pre-distribution thus represents an optimum initial forging shape. The upper part of the piston is made of a thick-film composite. Here, a nickel-alloy is applied to the piston blank by laser welding or PTA build-up welding prior to the forging process. The nickel-alloy is formed together with the base material, which in turn has a positive effect on the capacity to withstand stresses. An additional heat treatment improves the high temperature resistance. Due to the higher strength and corrosion resistance of the piston head, temperature and pressure in the combustion chamber can be increased, enabling the required reduction of emissions and fuel.

关键词： Casting Forging Composite

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Different encapsulation strategies for implanted electronics

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Current Directions in Biomedical Engineering 2017年第2期3卷 725-728页

作者： Winkler, Sebastian Edelmann, Jan Welsch, Christine Ruff, Roman Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Straße 88 Chemnitz 09126 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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Predictive Analysis from numerical and experimental data in press hardening

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IOP Conference Series: Materials Science and Engineering 2019年第1期651卷

作者： Lars Penter Patrick Link Anke Stoll André Albert Steffen Ihlenfeldt Institute of Mechatronic Engineering TU Dresden Dresden 01062 Germany Fraunhofer Institute for Machine Tools and Forming Technology Chemnitz 09126 Germany

machine learning, big data and deep learning are today's catchphrases for how to improve reliability and productivity of your manufacturing equipment. Production companies implement a large number of sensors to record every activity within their production lines and learn as much as possible about their running processes in order to predict shifting product properties and to prevent stoppage due to failure. The successful application of machine learning algorithms to predict machine and process behavior depends on a reliable and balanced database. Since the foremost goal of every manufacturing business is to make sound parts and to avoid defects, there is a large amount of data available for smoothly running processes but only very little for failure production. One approach to solve this imbalance would be to link the production line data with simulation data. Simulation models allow for computing failure parts with no additional costs and therefore enable the exploration of the entire parameter space. We conducted press-hardening experiments with a variation of process parameters for a structural car body part on the press hardening line at fraunhofer IWU. As an evaluation criterion, we measured the hardness of the final part at critical spots. In order to expand the experimental data, we applied FE simulations to the entire press hardening process chain. The paper explains limitations of the model and elaborates on its parameterization. As a final task, we applied a basic machine-learning algorithm to both experimental and numerical data as well as to their combination in order to evaluate the data space expansion through simulations. The results obtained through machine learning indicate significant differences in the prediction of part quality for solely experimental data and its combination with simulation data. This is especially true for press hardening because of non-linear system behavior and a large amount of uncertain and hard-to-identify parameters. We

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Implementing thermomechanical properties of 22MnB5 steel during hot single-point incremental forming 5th

Implementing thermomechanical properties of 22MnB5 steel dur...

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5th International Conference on Material Science and Engineering technology, ICMSET 2016

作者： Al-Obaidi, Amar Kräusel, Verena Landgrebe, Dirk Institute of Machine Tools and Production Processes IWP Technische Universität Chemnitz Chemnitz Germany Fraunhofer-Institute for Machine Tools and Forming Technology IWU Chemnitz Germany

ISBN: (纸本)9783035710281

The strategy in manufacturing hardened parts used in car bodies is to tailor the mechanical properties. This is done by combining together a high-strength region and a hightoughness region to ensure the crash performance required. Other successive secondary operations such as trimming, joining and welding can be improved as a result of the tailoring process. In this work, the mechanical properties of 22MnB5 alloy sheet material produced by single-point incremental forming have been tailored. For this purpose, the sheets were locally heated by induction during the forming process and subsequently cooled. The sheet temperature was controlled by the CNC milling machine feed rate and induction power. As a result, the produced tailored parts consist of three different regions: ductile, transition and hardened regions. The Vickers hardness values were 583 HV1 and 175 HV1 for the hardened and ductile regions, respectively. The proposed application allows forming and quenching at the same time without transfer and to reduce the process time. © 2017 Trans Tech Publications, Switzerland.

关键词： Induction heating

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Approach for a Production Planning and Control System in Value-Adding Networks

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Procedia CIRP 2019年 81卷 1195-1200页

作者： Alexander Zipfel Stefan Braunreuther Gunther Reinhart Fraunhofer IGCV Fraunhofer Research Institution for Casting Composite and Processing Technology IGCV Provinostr. 52 86153 Augsburg Germany Augsburg University of Applied Sciences An der Hochschule 1 86161 Augsburg Germany Technical University of Munich Institute for Machine Tools and Industrial Management (iwb) Boltzmannstr. 15 85748 Garching b. München Germany

The increasing demand for individualised high-quality products at low cost is forcing companies to offer products based on their core competencies in value-adding networks. To reach overall objectives, such as shorter throughput times or less inventory throughout the network, an intense transfer of progress-relevant information among the network partners is required. This publication presents an approach for a network-wide production planning and control (PPC) system focusing on technical, organisational and monetary dimensions. The proposed approach comprises the modelling of the value-adding network, the development of both a system architecture and an incentive scheme, as well as a hierarchical optimisation.

关键词： Production planning Control Manufacturing network

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Combination of Hot forming with CRP and Rapid Cooling to Obtain Enhanced Formability in Thermomechanical Treatment

Combination of Hot Forming with CRP and Rapid Cooling to Obt...

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作者： Birnbaum, Peter Baumann, Markus Kunke, Andreas Kraeusel, Verena Landgrebe, Dirk Technische Universität Chemnitz Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology Chemnitz Germany

In sheet metal forming, rapid cooling of austenitized steel and CRP (cushion-ram pulsation) results in an optimized formability. An analysis is conducted regarding the influence of a stepwise deep drawing process of manganese-boron steel 22MnB5, using an oscillating ram-cushion motion at simultaneous cooling. The stops occurring in stepwise forming provide sufficient time for softening and recovery of forming properties. The microstructure can be adjusted by controlled cooling. In order to examine the newly developed process in more detail, FE simulation is applied. Thus, relevant process and material parameters can be determined. The considered values are required for profound experiments using the forming simulator BAEHR DIL 805 A/D. The softening behavior at defined forming temperatures due to CRP are examined. The experimental results of softening at distinctive temperatures provide a basis for the combined processes of stepwise hot sheet metal forming and simultaneous cooling. © 2017 Materials Research Society.

关键词： Cooling

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E-beam sterilization of microstructures in titanium surfaces for medical implants 17

E-beam sterilization of microstructures in titanium surfaces...

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

作者： Winkler, Sebastian Dietze, Marleen Edelmann, Jan Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany Fraunhofer Institute for Organic Electronics Electron Beam and Plasma Technology FEP Dresden Germany

ISBN: (纸本)9780995775107

Due to its biocompatibility titanium is the metal of choice for most medical implants. The surface in contact with the human body may be equipped with a functional microstructure for various purposes such as bone ingrowth. All implants must be sterilized before operation. Among other processes, the sterilization by low energy electron beam (e-beam-sterilization) offers a lot of advantages. The non-thermal sterilization works with short process times (milliseconds) and without microbicide gases. The radiation sterilization is a regulated process according to DIN EN ISO 11137, which describes a killing effect of microorganism after the validation of a dose of 25 kGy. In principal it is possible to sterilize all material classes, electronic devices and different geometries, so that the low energy e-beam-sterilization is a suitable method for multifunctional implants. The sterilization of surface microstructures with low energy e-beam-sterilization is challenging because of the limited penetration depth. The influence of high aspect ratio microstructures on low energy e-beam-sterilization was investigated experimentally. A microhole array with 230 μm hole diameter served as a model structure and was manufactured in the titanium surface by electrical discharge machining. Other surface microstructures were generated by laser machining and blasting. All samples were contaminated with 107 CFU/sample Escherichia coli (E. coli) K12, sterilized by e-beam and incubated in a culture medium in order to prove that the sterilization was successful. The microhole depth was varied to determine the critical depth for low energy e-beam-sterilization.

关键词： Sterilization (cleaning)

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Microstructure of Inconel 718 parts with constant mass energy input manufactured with direct energy deposition

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Procedia Manufacturing 2019年 36卷 256-266页

作者： Torsten Petrat Christian Brunner-Schwer Benjamin Graf Michael Rethmeier Fraunhofer Institut for Production Systems and Design Technology Pascalstraße 8-9 10587 Berlin Germany Federal Institute for Materials Research and Testing Unter den Eichen 87 12205 Berlin Germany Technical University Berlin Institute of Machine Tools and Factory Management Pascalstraße 8-9 10587 Berlin Germany

The laser-based direct energy deposition (DED) as a technology for additive manufacturing allows the production of near net shape components. Industrial applications require a stable process to ensure reproducible quality. Instabilities in the manufacturing process can lead to faulty components which do not meet the required properties. The DED process is adjusted by various parameters such as laser power, velocity, powder mass flow and spot diameter, which interact with each other. A frequently used comparative parameter in welding is the energy per unit length and is calculated from the laser power and the velocity in laser welding. The powder per unit length comparative parameter in the DED process has also be considered, because this filler material absorbs energy in addition to the base material. This paper deals with the influence of mass energy as a comparative parameter for determining the properties of additively manufactured parts. The same energy per unit length of 60 J/mm as well as the same powder per unit length of 7.2 mg/mm can be adjusted with different parameter sets. The energy per unit length and the powder per unit length determine the mass energy. The laser power is varied within the experiments between 400 W and 900 W. Energy per unit length and powder per unit length are kept constant by adjusting velocity and powder mass flow. Using the example of Inconel 718, experiments are carried out with the determined parameter sets. In a first step, individual tracks are produced and analyzed by means of micro section. The geometry of the tracks shows differences in height and width. In addition, the increasing laser power leads to a higher dilution of the base material. To determine the suitability of the parameters for additive manufacturing use, the individual tracks are used to build up parts with a square base area of 20×20 mm². An investigation by Archimedean principle shows a higher porosity with lower laser power. By further analysis of the mic

关键词： direct energy deposition porosity Inconel 718 additive manufacturing laser metal deposition

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Biomechanical validation of additively manufactured artificial femoral bones

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BMC biomedical engineering 2022年第1期4卷 6页

作者： F Metzner C Neupetsch A Carabello M Pietsch T Wendler W-G Drossel ZESBO Centre for Research on Musculoskeletal Systems Leipzig University Semmelweisstraße 14 04103 Leipzig Germany. florian.metzner@medizin.uni-leipzig.de. Department of Orthopaedics Trauma and Plastic Surgery Leipzig University Leipzig Germany. florian.metzner@medizin.uni-leipzig.de. Department of Orthopaedics Trauma and Plastic Surgery Leipzig University Leipzig Germany. Fraunhofer Institute for Machine Tools and Forming Technology Dresden Germany. Professorship of Adaptronics and Lightweight Design Chemnitz Universtiy of Technology Chemnitz Germany. ZESBO Centre for Research on Musculoskeletal Systems Leipzig University Semmelweisstraße 14 04103 Leipzig Germany.

Replicating the mechanical behavior of human bones, especially cancellous bone tissue, is challenging. Typically, conventional bone models primarily consist of polyurethane foam surrounded by a solid shell. Although nearly isotropic foam components have mechanical properties similar to cancellous bone, they do not represent the anisotropy and inhomogeneity of bone architecture. To consider the architecture of bone, models were developed whose core was additively manufactured based on CT data. This core was subsequently coated with glass fiber composite. Specimens consisting of a gyroid-structure were fabricated using fused filament fabrication (FFF) techniques from different materials and various filler levels. Subsequent compression tests showed good accordance between the mechanical behavior of the printed specimens and human bone. The unidirectional fiberglass composite showed higher strength and stiffness than human cortical bone in 3-point bending tests, with comparable material behaviors being observed. During biomechanical investigation of the entire assembly, femoral prosthetic stems were inserted into both artificial and human bones under controlled conditions, while recording occurring forces and strains. All of the artificial prototypes, made of different materials, showed analogous behavior to human bone. In conclusion, it was shown that low-cost FFF technique can be used to generate valid bone models and selectively modify their properties by changing the infill.

关键词： 3D-printing 3d-printing Additive manufacturing Artificial bone Biomechanics Bone model Femoral Femur Hip

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