Interaction of Additive Manufacturing and Forming - Merklein, Marion; Dubjella, Patrick; Schaub, Adam; Butzhammer, Lorenz; Schmidt, Michael (Proceedings of 6th International Conference on Additive Technologies, 2016)
Titanium alloys such as Ti-6Al-4V are utilized for a wide range of industrial approaches. This is primarily due to their positive material characteristics such as high biocompatibility, good corrosion resistance and outstanding specific strength. As a result of the hexagonal close packed (hcp) grain structure the achievable plastic deformation of these alloys at room temperature is limited. To overcome these limitations, forming at elevated temperatures is a promising process. A further promising manufacturing method for titanium is laser beam melting (LBM). LBM functions at melted material condition and thereby neglects most manufacturing challenges. It enables to produce individual parts by overcoming geometrical design restrictions compared to conventional manufacturing techniques. Within this work a process chain combining sheet metal forming and laser beam melting is presented and discussed. The main benefit of this combined process is a merge of the positive  characteristics of both manufacturing methods. In former researches deep drawing was used as forming process. Due to inducing a more complex stress level, which is more application oriented, bending will be investigated as a forming strategy for a combination with LBM. Therefore a tool was developed and manufactured. In this study the function of this tool will be described in detail and its qualification for bending flat sheets of Ti-6Al-4V as well as hybrid parts will be researched.
Keywords: Additive Manufacturing; Forming; Bending; Titanium alloys

Interaction of various functional elements in thin-walled cups formed by a sheet-bulk metal forming process - Schulte, Robert Karl; Schneider, Thomas; Lechner, Michael; Merklein, Marion (NUMIFORM 2016: The 12th International Conference on Numerical Methods in Industrial Forming Processes, 2016)
Sheet-bulk metal forming allows the manufacturing of sheet metal parts with integrated functional elements. The investigated process combines deep drawing and upsetting. The occurring 2D and 3D stress and strain states lead to challenges regarding material flow control due to different geometries of functional elements. The numerical analysis shows the transferability for the results of the different functional elements for their combination and the interaction between those functional elements regarding the material flow. The results are validated by experimental tests.
LFT Import::2019-08-05 (2202)

Interlaboratory comparison for heat transfer coefficient identification in hot stamping of high strength steels - Bosetti, Paolo; Bruschi, S.; Stöhr, Thomas; Lechler, Jürgen; Merklein, Marion (Proceedings of Esaform 2010, 2010)
The topic of the paper is the identification of the heat transfer coefficient (HTC) in hot stamping of boron steel sheets under conditions very close to the industrial ones. Two approaches followed by one lab in Germany and one lab in Italy are presented for HTC identification, showing the two experimental apparatuses that were set-up to conduct the tests, the procedures developed and applied to identify the HTC. The obtained results are compared in terms of dependence of HTC from the applied contact pressure, the similarities and the differences of the two approaches are outlined and commented. © 2010 Springer-Verlag France.
LFT Import::2019-08-05 (223)
Keywords: Heat transfer coefficient; Hot stamping; Inverse analysis

Interlaboratory Comparison of Forming Limit Curves for Hot Stamping of High Strength Steels - Pellegrini, D.; Lechler, Jürgen; Ghiotti, Andrea; Bruschi, S.; Merklein, Marion (SheMet'09, Proceedings of the 13th International Conference on Sheet Metal, 2009)
The paper presents the approaches followed by two labs - LFT at the University of Erlangen-Nuremberg (Germany) and DIMEG at University of Padua (Italy) - in evaluating formability limits of 22MnB5 sheets when processed under hot stamping conditions. Details about the two testing apparatuses and the testing procedures are outlined, and the results in terms of Forming Limit Curves FLC compared and critically commented. © (2009) Trans Tech Publications, Switzerland.
LFT Import::2019-08-05 (1565)
Keywords: Forming limit curve; High strength steel; Hot stamping

Interlaboratory Comparison of Friction Conditions in Hot Stamping Operations - Borsetto, F.; Ghiotti, Andrea; Bruschi, S.; Stöhr, Thomas; Lechler, Jürgen; Merklein, Marion (Key Engineering Materials, 2010)
The paper presents results obtained at two labs, on in Germany and one in Italy, in terms of friction coefficient as function of hot stamping process parameters. Even if the testing procedures and analysis tools to evaluate tribological conditions are different for the two labs, both the approaches show a similar trend as regards the friction coefficient dependence from the process parameters. © (2010) Trans Tech Publications.
LFT Import::2019-07-29 (1160)
Keywords: High strength steel; Hot stamping; Tribology

Intermediate Heat Treatment - A New Proceeding for Aluminium Alloys Using Forming Limit Diagrams - Siefert, Kathleen; Merklein, Marion; Töpperwien, Almut; Nester, Winfried; Gruenbaum, Martin (Key Engineering 473, 2011)
This paper presents a new procedure for a heat treatment embedded between two cold forming steps. A first cold forming step induces a defined strain hardening in the material. The following step is the heat treatment which takes place in a furnace at various temperatures and for certain durations. The application of such an intermediate heat treatment reduces the strain hardening of the material and enhances the elongation. This allows a higher degree of deformation in the second cold forming operation. The achievable properties of the aluminum alloy AlMg4.5Mn (AA5182) were discussed in detail. Further investigations using Nakajima test setup revealed an increased formability of the material. First the Nakajima samples were pre-strained along different linear strain paths to a predefined strain value. Afterwards the samples were heat treated without allowing the aluminum alloy to recrystallize. After cooling down the samples to room temperature, the tests are continued until the material's fracture. As a result heat treatment dependent forming limit curves (FLC) are obtained. In comparison with a measured FLC at room temperature the support of the intermediate heat treatment on enhanced formability were shown. Furthermore the method is not restricted to AA5182 aluminum alloys. © (2011) Trans Tech Publications.
LFT Import::2019-08-05 (1745)
Keywords: Aluminum alloys; Aluminum sheet forming; Forming limit diagram; Heat treatment

Introduction to sheet-bulk metal forming - Merklein, Marion; Hagenah, Hinnerk (Production Engineering, 2016)
Sheet-bulk metal forming as a new class of manufacturing processes is one of the possible answers production processes provide to the increasing demands on functional integration into light weight parts made of high strength steel. Research in this field is carried out in several places. The special issue was initiated by the Transregional Collaborative Research Centre 73. It contains newest results from this research initiative as well as international results in the field of sheet-bulk metal forming.
LFT Import::2019-07-29 (2155)
Keywords: Metal forming; Plate forging; Sheet metal; Sheet-bulk metal forming; TCRC 73

Inverse Approach to the Forming Simulation of Tailored Heat Treated Blanks - Staud, Detlev; Merklein, Marion (International Journal of Material Forming, 2008)
While climate protection and environmental conservation gain an increasingly significant role, the weight reduction of car body parts is a consequence of the need for efficient fuel consumption and for reduced CO2-emissions. Therefore advanced material and production methods have to be developed to meet this requirement. Since steel sheet metal parts cannot be substituted directly with lightweight aluminium parts, due to its minor formability, so called Tailored Heat Treated Blanks (THTB) are presented in this work. THTB are locally heat treated aluminium blanks from the 6000-series alloy, leading to a significantly improved formability for the manufacturing of complex aluminium car body parts. The enhancement of formability is reached by a local laser heat treatment before the forming operation. Since there is a strong influence of the heating on the forming process, a finite-element simulation of the process sequence is a prerequisite for the cost-effective usage of the THTB. The presented inverse approach considers first the desired forming result and enables the precise determination of heat treatment areas including the specific heat treatment temperatures. In conclusion the numerical solved appropriate strength pattern is verified with experimental test results of THTB. © Springer/ESAFORM 2008.
LFT Import::2019-07-29 (1558)
Keywords: Aluminium; Finite element simulation; Parameter identification

Inverse Identification of Kinematic Hardening Parameters with Bending Tests - Doig, M.; Kaupper, Markus; Kraska, M.; Eßer, G.; Merklein, Marion; Roll, K.; Keßler, L. (Proc. 50th Conference of IDDRG 2010, 2010)
LFT Import::2019-08-05 (212)

Inverse parameter identification of an anisotropic plasticity model for sheet metal - Friedlein, Johannes; Wituschek, Simon; Lechner, Michael; Mergheim, Julia; Steinmann, Paul (INTERNATIONAL DEEP-DRAWING RESEARCH GROUP CONFERENCE (IDDRG 2021), 2021)
CRIS-Team WoS Importer:2021-11-05

Inverse Parameteridentifikation mittels Biegeversuchen - Doig, M.; Kraska, M.; Eßer, G.; Kaupper, Markus; Merklein, Marion; Keßler, L.; Gerlach, J. (Tagungsband Werkstoffprüfung 2009, 2009)
LFT Import::2019-08-05 (210)

Inverse Parameteridentifikation mittels Wechselbiegeversuch zur Ermittlung der nicht isotropen Verfestigung von Blechwerkstoffen - Wieland, Michael; Biasutti, Manfredi; Kaupper, Markus; Merklein, Marion (LS-DYNA Forum 2012, 2012)
LFT Import::2019-08-05 (1828)

Investigation and modeling of austenite grain growth of conventional hot stamping steel and its influence on microhardness - Horn, Alexander; Merklein, Marion (Hot Sheet Metal Forming of High-Performance Steel, 2022)

Investigation into the Process Basics of Warm Forming - Neugebauer, R.; Hartwig, H.; Geiger, Manfred; Bitter, Stefan (Advanced Technology of Plasticity, Proceedings of the 7th ICTP, 2002)
LFT Import::2019-08-05 (1685)

Investigation of a novel automated surface treatment method within accumulative roll bonding of AA6016 sheets - Zettl, Bastian; Merklein, Marion (Journal of Manufacturing Processes, 2025)
In order to minimize resource utilization and fuel consumption in the transportation and construction sector, possibilities to further enhance the mechanical properties of structural metal alloys are very lucrative. Especially in times of increasing energy costs as well as prices for certain elements, conventional heat treatments as well as alloying routes can be problematic. In this context, purely mechanical methods are capable of providing significant strengthening of already established alloys. Belonging to these methods and especially suitable for sheet metals, is the so-called Accumulative Roll Bonding (ARB) process. It enables the cumulation of the forming degree within the material and can lead to the evolution of an ultrafine grain sized microstructure. However, it severely lacks in its reproducibility and efficiency due to many influencing factors in the process chain. For this, the introduced work focuses on the least investigated step in the process chain, the surface treatment. For this, a novel and automated brushing method is analyzed in terms of its reproducibility as well as feasibility within ARB. Through roughness and topography measurements, it is shown that the force as well as the dwell time of the active brushing contact has a high influence on the resulting surface condition. Additionally, the run-in behavior and the deflection of the brush must be taken into account in order to generate a homogeneous surface finish. By selecting a suitable combination of parameters within the novel surface treatment method, a significant improvement regarding the scattering of the bonding strength is proven. Whereas the conventional manual surface treatment leads to fluctuations of the bonding strength of around 35 %, the newly introduced method displays a clearly reduced deviation of only 1.6 %. This enables to derivate cause-effect relationships between the input parameters regarding brushing, the resulting surface condition and the resulting bonding properties of ARB sheets.
CRIS-Team Scopus Importer:2025-04-11
Keywords: Accumulative roll bonding; Aluminum; Automation; Surface treatment

Investigation of a novel ultrasonic-assisted staking process for mechanical fasteners - Jäckisch, Manuel; Merklein, Marion (2nd International Conference on Advanced Joining Processes AJP 2021, 2021)

Investigation of a process simulation method for flexible clamping of sheet metal parts - Bauer, Felix; Werber, Alexandra; Merklein, Marion (Procedia Engineering, 2017)
Flexibility in the body-in-white shop can be increased with the use of a running clamping technology, which enables clamping with a welding robot during laser welding. Unlike common clamping fixtures, the running clamping technology is operated force controlled. A closed gap between flanges is necessary to achieve a proper weld seam. The objective of the presented FE-simulation method is to predict required clamping forces to close the gap between sheet metal part flanges with geometrical inaccuracies. For calibration of the simulation model, clamping experiments with simple geometry are used. Steel and aluminum L-specimens are manufactured using air bending and clamped with the running clamping technology. Clamping forces are measured precisely using a load cell, which has been integrated into the running clamping technology. In this contribution a FE-simulation method for process analysis of the flexible clamping process with the running clamping technology is investigated. For clamping simulation, specimens are generated by air bending simulation, as well as by optical measurement of experimentally manufactured specimens. Since specimens are bent during clamping process in the opposite direction of the previous bending process, influences of residual stresses and kinematic hardening on the required clamping forces are expected. Thus, in FE-simulation an elastic-plastic material model with kinematic hardening parameters is used. A mapping method with springback compensation is applied to obtain specimens with optically measured geometry including forming history data of bending simulation. Simulation setups are investigated regarding results of clamping forces. Simulation results are verified using the obtained experimental data.
CRIS-Team Scopus Importer:2023-03-29
Keywords: clamping simulation; finite element method; forming history

Investigation of Different Joining by Forming Strategies when Connecting Different Metals without Auxiliary Elements - Römisch, David; Kraus, Martin; Merklein, Marion (Sheet Metal 2021, 2021)
Lightweight constructions become more and more important, especially in the mobility sector. In this industry, the increasingly strict regulations regarding the emissions of carbon dioxide can be achieved to a certain extent by reducing the vehicle weight. Thus, multi-material systems are used. Conventional joining techniques reach their limits when joining different materials due to different thermal expansion, unequal stiffness or chemical incompatibilities. This is why additional joining elements or adhesives are used. These must be viewed critically regarding a lightweight and resource-efficient production, since they add weight or complicate the recycling process of these components. Consequently, there is a great and growing need for new versatile joining technologies in order to overcome these challenges and to be able to react to changing process parameters and boundary conditions. Joining without an auxiliary element using pin structures formed directly from the sheet metal plane is one approach to meet these challenges. These pin structures are then joined by direct pressing into the joining partner. This is possible with a variety of material combinations, but is advantageous with regard to continuous fibre-reinforced thermoplastic composites (CFRTP), as the fibres do not have to be cut when joining CFRTP using pin structures. In this paper, the formability of pin structures made of a dual-phase steel DP600 (HCT590X + Z) is investigated. The extruded pin structures are joined by direct pin pressing with an EN AW-6014 to form tensile shear specimens. Different joining strategies are investigated to compare their influence on the joint strength. The results have shown that it is feasible to form suitable pins from a DP600 dual-phase steel to produce reliable connections with an aluminium sheet joined by direct pin pressin
Keywords: joining by forming; multi-metal-systems; pin forming; pin joining

Investigation of different surface treatment parameters in the context of roll bonding processes - Schödel, Sandra; Herrmann, Jürgen; Merklein, Marion (18th International Conference on Sheet Metal, SHEMET 2019, 2019)
LFT Import::2019-08-05 (2367)

Investigation of diffusion behavior of carburized sheet metal in hot stamping - Horn, Alexander; Merklein, Marion (Manufacturing Review, 2019)
Today, manufacturing of structural car body parts faces several challenges, like forming accuracy, passenger safety and lightweight design. One possibility to fulfill these partially rivalling demands is the application of hot stamped components. The combination of hot forming and in-die quenching reduces not only springback, but also results in tensile strengths of more than 1500 MPa. Besides conventional hot stamping, the process can be adapted to manufacture parts with tailored properties. One of the biggest issues of these state-ofthe-art processes is the formation of extensive transition zones due to heat transfer. A promising approach to adjust the mechanical properties with a minimized transition zone is tailored carburization of sheet metal. Therefore, the parts are locally coated with graphite, heat treated and subsequently quenched. In this work, the time variant process of carbon diffusion is investigated. Sheets with two different thicknesses are carburized and quenched. The resulting mechanical properties are analyzed using uniaxial tensile tests and microhardness measurements. On this basis, a process window is identified. Furthermore, the applicability of EDX and WDX analysis for the measurement of carbon concentration is investigated within this work.
CRIS-Team WoS Importer:2019-07-12

Investigation of diffusion behavior of carburized sheet metal in hot stamping - Horn, Alexander; Merklein, Marion (MATEC Web Conf, 2018)
Today’s manufacturing of structural car body parts faces several challenges, like forming accuracy and passenger safety. Besides these two requirements, lightweight design plays an important role. One possibility to fulfill these partially rivalling demands is the application of hot stamped parts. The combination of hot forming and in die quenching reduces not only springback, but also results in tensile strengths of up to 1500 MPa. This makes a simultaneous reduction of sheet thickness and therefore weight reduction possible. Further development enabled a tailored adjustment of mechanical properties, for example by applying different cooling conditions along the parts. One of the biggest issues of these state of the art processes is the formation of a transition zone due to heat transfer. A promising approach to adjust the mechanical properties with a minimized transition zone is the carburization of sheet metal. Therefore, the parts are coated with graphite, heat treated and subsequently quenched. In this work, the time variant process of carbon diffusion is investigated. Sheets with two different thicknesses are carburized and quenched. The resulting mechanical properties are analyzed using uniaxial tensile tests and microhardness measurements. The results are correlated with the carbon content measured by EDX-analysis. <
Keywords: Hot stamping; Heat treatment; Carburization

Investigation of dry lubrication systems for lightweight materials in hot forming processes. - Rigas, Nikolaos; Junker, Freidhelm; Berendt, Erik; Merklein, Marion (Produktion im Grenzbereich – Vorsprung halten, Zukunft sichern, 2019)
In the automotive industry, growing demands for lightweight solutions lead to new materials and forming methods. Because of the high specific strength and low density, high-strength aluminum alloys like 7xxx series have a big potential for safety-relevant components, in the future. With the help of thermal supported forming operations like hot forming and quenching, complex part geometries are realizable. The high formability compared with the lower forming forces and reduced springback, as well as a subsequent hardening step enables the production of complex parts. Currently, this forming process is reaching its limits because of high adhesive wear during forming. Therefore industrial use is not suitable at the moment. New developed dry lubrication systems enable hot forming operations without the generation of toxic emissions and a reduction of the adhesive wear. Therefore, different dry lubricants with varying particle size have been analyzed for deep drawing operations under quenching conditions. The influence of the particle size on the applicable lubrication thickness and the necessary consumption has not been analyzed before. Aim of this research is the characterization of different dry lubricant particle size distributions for hot forming and quenching of high-strength aluminum allo
Keywords: Hot forming and quenching; High formability; Lubricant particle size

Investigation of effects and parameter interactions in metal microforming processes - Eichenhüller, Bernd; Engel, Ulf (4M/ICOMM 2009, Proc. Global Conf on Micro Manufacture (incorp. 5th Int. Conf. on Multi-Material Micro Manufacture 4M and 4th Int. Conf. on Micro Manufacturing ICOMM), 2009)
The occurrence of size effects while miniaturising forming processes from macro to micro scale is a well known fact. Numerous research activities were established worldwide to identify and qualify these size effects and a number of models were developed in order to describe and explain the investigated behaviour. In doing so, several process parameters were found to have a strong influence on the forming behaviour, but almost exclusively the influence of single isolated parameters was investigated. This paper is focusing on parameter interactions of relevant process factors, regarding their influence on the forming behaviour. It will be shown that the process result of multiple parameter changes is not simply the accumulation of each individual parameter change. The experimental research is done using a full backward extrusion process to extrude a single form feature. In a first series of experiments an axial symmetrical pin was formed. Based on this investigation a more complex geometry, a rectangular fin is extruded. The effects and interactions of parameter changes - investigated parameters are the temperature, the size of the form feature, lubrication, grain size and velocity - can be observed in the development of the aspect ratio, defined as ratio between feature height and width or diameter of the feature.
LFT Import::2019-08-05 (316)
Keywords: Extrusion; Microforming; Parameter interaction; Size effect

Investigation of failure under shear-tension conditions with optical metrology - Merklein, Marion; Kuppert, Andreas; Biasutti, Manfredi (Proc. of GOM Conference, 2009)
LFT Import::2019-08-05 (198)

Investigation of Fatigue Strength of Tool Steels in Sheet-Bulk Metal Forming - Pilz, Florian; Gröbel, Daniel; Merklein, Marion (AIP Conference Proceedings 1960:1, 2018)
LFT Import::2019-08-05 (2316)
Keywords: Fatigue; Sheet-Bulk metal forming; Steel; Tailored Surface; Tool

Investigation of Friction Conditions at Elevated Temperatures for Hot Stamping - Schwingenschlögl, Patrik; Hildering, Sven; Merklein, Marion (Proceedings 7th International Conference on Tribology in Manufacturing Processes, 2016)
LFT Import::2019-08-05 (2162)

Investigation of Geometrical and Microstructural Influences on the Mechanical Properties of an Extruded AA7020 Tube - Reblitz, Jonas; Wiesenmayer, Sebastian; Trân, Ricardo; Merklein, Marion (Lecture Notes in Production Engineering, 2023)
In the automotive sector, an important strategy for reducing CO2- emissions is lightweight construction. In this regard, body-in-white parts offer a high potential for weight reductions by substituting conventional steel parts with tubular, aluminum-based components. Due to their high strength-to-weightratio and high crashworthiness, tube profiles are often used as safety-relevant car body components. Therefore, an exact determination of the material properties is necessary, in order to achieve a high prediction accuracy of FE-simulations. In contrast to the testing of flat semi-finished parts, there are only few standardized methods for the material characterization of tubular components. Furthermore, a profound knowledge regarding the influences of geometry and manufacturing process of the tube profiles on the material properties has to be gained. Thus, AA7020 tubes are analyzed in this research work. Tensile specimens are cut out of a tube by a laser-cutting machine. As a result, the cross-section of the samples is curved as well. To ensure a proper material testing, the clamping jaws for the tensile test are adjusted to the curvature of the samples. For the characterization of the tube properties, caused by the manufacturing process, optical measurements are performed. The mechanical properties of the different grain structures are determined by the thermo-mechanical simulator Gleeble 3500 in T6 condition. Therefore, tensile specimens with a reduced wall thickness are prepared. Afterwards the curved tensile samples are tested in T6 and W-temper condition. To validate the comparability of the determined material properties, a comparison is conducted with flat specimens prepared from the semi-finished tube profiles.<br
Keywords: Material characterization; W-temper condition; Tubes

Investigation of Geometrical and Microstructural Influences on the Mechanical Properties of an Extruded AA7020 Tube - Reblitz, Jonas; Wiesenmayer, Sebastian; Trân, Ricardo; Merklein, Marion (Production at the Leading Edge of Technology, 2023)
In the automotive sector, an important strategy for reducing CO2-emissions is lightweight construction. In this regard, body-in-white parts offer a high potential for weight reductions by substituting conventional steel parts with tubular, aluminum-based components. Due to their high strength-to-weight-ratio and high crashworthiness, tube profiles are often used as safety-relevant car body components. Therefore, an exact determination of the material properties is necessary, in order to achieve a high prediction accuracy of FE-simulations. In contrast to the testing of flat semi-finished parts, there are only few standardized methods for the material characterization of tubular components. Furthermore, a profound knowledge regarding the influences of geometry and manufacturing process of the tube profiles on the material properties has to be gained. Thus, AA7020 tubes are analyzed in this research work. Tensile specimens are cut out of a tube by a laser-cutting machine. As a result, the cross-section of the samples is curved as well. To ensure a proper material testing, the clamping jaws for the tensile test are adjusted to the curvature of the samples. For the characterization of the tube properties, caused by the manufacturing process, optical measurements are performed. The mechanical properties of the different grain structures are determined by the thermo-mechanical simulator Gleeble 3500 in T6 condition. Therefore, tensile specimens with a reduced wall thickness are prepared. Afterwards the curved tensile samples are tested in T6 and W-temper condition. To validate the comparability of the determined material properties, a comparison is conducted with flat specimens prepared from the semi-finished tube profiles.<br
Keywords: Material characterization; W-temper condition; Tubes

Investigation of heat treatment strategies for additively-manufactured tools of X37CrMoV5-1 - Junker, Daniel; Hentschel, Oliver; Schmidt, Michael; Merklein, Marion (Metals, 2018)
For cost-intensive products like automobiles, clients often with to personalize their product; this forces the industry to create a large diversity of combinable parts. Additionally, the life cycles of many components become shorter. For highly-stressable parts, which are commonly manufactured by forging, the short changeover cycles result in expensive products, as the costs of tools must be offset by the sale of only a few parts. To reduce the tool cost, new, flexible processes have to be established in tool manufacturing. Laser-based additive manufacturing is noted for its high flexibility; notably, Laser Metal Deposition (LMD) is gaining increasing relevance in research, as it is already used for coating and repairing forming tools; this technology makes it possible to add material onto free-formed surfaces. Therefore, investigations are being conducted to qualify this process to produce forging tools. Due to the thermal processes which are required during additive manufacturing, the microstructure of the material differs from that of wrought material. This, in turn, affects the strategy of post heat treatment in order that the required mechanical properties for tools be attained. Within this manuscript, the influence of additive manufacturing on performance characteristics of hot work tool steel X37CrMoV5-1 (1.2343) is analyzed. To investigate the behavior of additive manufactured material during the process chain of tool manufacturing, properties for different states of a heat treatment are characterized by hardness and strength. It was shown that the strength of the additive manufactured material could be increased compared to wrought material by using a tailored heat treatment. The effects that cause this behavior are investigated by comparing the microstructure at different states of heat treatment.
CRIS-Team Scopus Importer:2022-06-05
Keywords: Directed energy deposition; Heat treatment; Microstructure

Investigation of Influencing Parameters for Tribological Conditions in Dry Forming Processes - Tenner, Jennifer; Merklein, Marion (Acta Metallurgica Sinica (English Letters), 2015)
LFT Import::2019-07-29 (2140)

Investigation of influencing parameters on the joint formation of the self-piercing riveting process - Kappe, Fabian; Wituschek, Simon; Lechner, Michael; Bobbert, Mathias; Meschut, Gerson; Merklein, Marion (Material Science and Engineering Congress - MSE 2020, 2020)

Investigation of influencing parameters on the shape of experimentally determined stress limit curves - Hezler, Christian; Kaupper, Markus; Merklein, Marion; Kasparbauer, M. (Proceedings IDDRG2012, 2012)
LFT Import::2019-08-05 (1815)

Investigation of Measures for Material Flow Control for a Backward Extrusion of Geared Components from Coil - Leicht, Miriam; Henneberg, Johannes; Merklein, Marion (Lecture Notes in Mechanical Engineering, 2024)
Increasing ecological and economic demands are setting new requirements for industrial manufacturing processes and components. The use of functional integration as a strategy of lightweight design offers the possibility to meet these requirements. However, a high functional integration implies an increasing component complexity, which challenges conventional forming processes to their limits regarding formability and efficiency. The novel process class of sheet-bulk metal forming (SBMF) offers the opportunity to combine the advantages of sheet metal and bulk forming by applying bulk forming operations to sheet metal semi-finished products. SBMF from coil offers further economic and ecological benefits through high output rates, short process times by eliminating costly handling tasks and a greater material efficiency. However, forming from coil also poses coil-specific challenges such as anisotropic material flow and reduced geometric part accuracy. Against this background, in this study, a backward extrusion process from coil for forming geared functional components is investigated on a high-speed press. The objective of this study is to analyze measures for a targeted material flow control in order to avoid unequal material flow and to improve part accuracy. Therefore, the mild deep drawing steel DC04 with an initial sheet thickness of 2.0 mm is analyzed in a combined numerical-experimental approach. Within these investigations, the influences of coil width, friction and feed width are analyzed and evaluated based on component and process parameters. Finally, measures for a purposive material flow are derived.
CRIS-Team Scopus Importer:2023-10-20
Keywords: Cold forming; Extrusion; Sheet-bulk metal forming

Investigation of Nonlinear Dynamic Effects in Laser Beam Melt Ablation - Cser, Adrienn Orsolya; Donner, R.; Schwarz, U.; Bube, K.; Otto, Andreas; Feudel, U. (COLA 2003, Proceedings of the International Workshop on Collaboration Agents: Autonomous Agents for Collaborative Environments, Halifax, Canada, 2003)
LFT Import::2019-08-05 (1003)

Investigation of Parameter Interactions in Microforming - Eichenhüller, Bernd; Engel, Ulf (Proc. of the 3rd Int. Conf. on Micromanufacturing, 2008)
LFT Import::2019-08-05 (327)

Investigation of process induced changes of material behaviour using a drawbead in forming operations - Schmid, Harald; Suttner, Sebastian; Merklein, Marion (7. WGP-Jahreskongress Aachen, 5.-6. Oktober 2017, 2017)
LFT Import::2019-08-05 (2249)

Investigation of Production Limits in Manufacturing Microstructured Surfaces Using Micro Coining - Zahner, Michael; Lentz, Lukas; Steinlein, Felix; Merklein, Marion (Micromachines, 2017)
The application of microstructured surfaces is one possible method to reduce friction in lubricated contacts between components with relative movement. Due to this, the energy efficiency and the occurring wear during the operating time of the final products could be decreased. To manufacture structured surfaces economically, a micro coining process was analyzed within this study. This process offers the potential for integration into the established manufacturing processes of different final products, such as tappets used in a valve train. Thus, large-scale production is enabled. To detect the manufacturing limits of the micro coining process, the manufacturing of the coining tools as well as the coining process needs to be investigated. Within this study, the achievable accuracy and the failure of cuboid and cylindrical microstructure elements with selected dimensions were analyzed. For both types of microstructures, the minimal lateral dimensions were detected. Besides the achievable accuracy, correlations between different geometrical dimensions of the micro elements are presented. Additionally, the aspect ratio is detected as the main cause of failure for the micro coining process. In general, the suitability of a coining process for manufacturing microstructured surfaces is proven.
LFT Import::2019-07-29 (2277)
Keywords: Geometrical accuracy; Microstructures; Tribology

Investigation of Size Dependent Mechanical Properties of Metal Foils in Micro Sheet Metal Forming Processes - Diehl, Alexander; Geißdörfer, Stefan; Engel, Ulf (Proceedings of the 2nd International Conference on Micromanufacturing, 10.-13. September 2007, Greenville, USA, 2007)
LFT Import::2019-08-05 (1432)

Investigation of Size Effects in Multi-Stage Cold Forming of Metallic Micro Parts from Sheet Metal - Kraus, Martin; Merklein, Marion (Micromachines, 2021)
Product miniaturisation and functional integration are currently global trends to save weight, space, materials and costs. This leads to an increasing demand for metallic micro components. Thus, the development of appropriate production technologies is in the focus of current research activities. Due to its efficiency, accuracy and short cycle times, microforming at room temperature offers the potential to meet the steadily increasing demand. During microforming, size effects occur which negatively affect the part quality, process stability, tool life and handling. Within this contribution, a multi-stage bulk microforming process from sheet metal is investigated for the materials Cu-OFE and AA6014 with regard to the basic feasibility and the occurrence of size effects. The results reveal that the process chain is basically suitable to produce metallic micro parts with a high repeatability. Size effects are identified during the process. Since several studies postulate that size effects can be minimised by scaling down the metallic grain structure, the grain size of the aluminium material AA6014-W is scaled down to less than one micrometre by using an accumulative roll bonding process (ARB). Subsequently, the effects of the ultrafine grain (UFG) structure on the forming process are analysed. It could be shown that a strengthened material state increases the material utilization. Furthermore, too soft materials can cause damage on the part during ejection. The occurring size effects cannot be eliminated by reducing the grain size.
CRIS-Team WoS Importer:2022-01-07

Investigation of surface finishing of carbon based coated tools for dry deep drawing of aluminium alloys - Steiner, Jennifer; Andreas, Kolja; Merklein, Marion (IOP Conference Series: Materials Science and Engineering, 2016)
Global trends like growing environmental awareness and demand for resource efficiency motivate an abandonment of lubricants in metal forming. However, dry forming evokes increased friction and wear. Especially, dry deep drawing of aluminum alloys leads to intensive interaction between tool and workpiece due to its high adhesion tendency. One approach to improve the tribological behavior is the application of carbon based coatings. These coatings are characterized by high wear resistance. In order to investigate the potential of carbon based coatings for dry deep drawing, friction and wear behavior of different coating compositions are evaluated in strip drawing tests. This setup is used to model the tribological conditions in the flange area of deep drawing operations. The tribological behavior of tetrahedral amorphous (ta-C) and hydrogenated amorphous carbon coatings with and without tungsten modification (a-C:H:W, a-C:H) is investigated. The influence of tool topography is analyzed by applying different surface finishing. The results show reduced friction with decreased roughness for coated tools. Besides tool topography the coating type determines the tribological conditions. Smooth tools with ta-C and a-C:H coatings reveal low friction and prevent adhesive wear. In contrast, smooth a-C:H:W coated tools only lead to slight improvement compared to rough, uncoated specimen.
LFT Import::2019-07-29 (2211)

Investigation of Tailored Blank Production by the Process Class Sheet-Bulk Metal Forming - Merklein, Marion; Opel, Simon (International Conference on Advances in Materials and Processing Technologies (AMPT2010), 2010)
Nowadays efforts are made to improve sheet metal manufacturing processes and forming capability. Functional sheet metal components, for example toothed synchronizer rings, show closely-tolerated complex geometric features, especially in the automotive industry. Unfortunately sheet metal forming operations do not offer the possibility for complex shapes as do for example cutting technologies [1]. To avoid this restriction, the usage of semi-finished products with a material pre-distribution in the blank is investigated. So-called tailored blanks are usually made of different materials or sheet thicknesses. A common way of joining diverse blanks is welding [2]. In most cases the joining has a significant influence on the consecutively forming process due to varying local mechanical properties [3]. Hence the manufacturing of tailored blanks with a defined sheet thickness characteristic by the process class "sheet-bulk metal forming" is investigated. Subsequent the tailored blanks are provided for forming operations such as deep-drawing and the direct forming of complex functional shape elements. Aim of the project is the manufacturing of circular blanks with a sheet thickening in the exterior area by an upsetting operation. At the beginning, FE-based studies and physical experiments using blanks of DC04 are carried out, to create a fundamental knowledge base of the forming process. A comparatively large contact area between blank and forming tool, a three-dimensional material flow and the low sheet thickness cause high process forces. Building up a multi-stage upsetting process with different sequenced tool geometries is one approach to meet this challenge. The material flow out of the sheet center is realized step-by-step to lower the actual contact area and sequential the appearing forces. © 2010 American Institute of Physics.
LFT Import::2019-08-05 (887)
Keywords: FE-Simulation; Sheet-Bulk Metal Forming; Tailored Blanks

Investigation of tailored tool surfaces for improving the component quality of sheet-bulk metal forming parts produced by a combined deep-drawing and upsetting process - Henneberg, Johannes; Schulte, Robert Karl; Merklein, Marion (SCT Conference Proceedings, 2022)
Nowadays the automotive industry is confronted with increasing demands for lightweight components with integrated functional elements, as they are for instance used as synchronizers in gearboxes. Established manufacturing processes like sheet metal forming are limited producing such parts. Therefore, the innovative manufacturing technology sheet-bulk metal forming is investigated. By the application of bulk forming operations to sheet metals, functionally integrated parts can be produced in an efficient way. In this research, a combined deep-drawing and upsetting process is analyzed to form components with involute external gears. The reduced die filling of the gears is identified as a major challenge. Consequently, this research aims to increase the die filling of the gears through tool-sided adaptions. For analyzing the cause of the reduced die filling, a numerical process model is built up and validated. By analyzing this model, an undesired material flow from the functional elements to the center of the part is identified. In a next step, the potential of material flow control by global and local adaptation of the friction is numerically investigated. For this, the friction factor is varied between 0.1 and 0.5 in different areas. The numerical results indicate that by locally adjusting the friction, the material flow can be controlled and thus the shape of the gearing can be improved. Based on the numerical findings, tailored friction systems are implemented in an experimental setup. The tool surfaces are locally modified by an abrasive blasting process. Hereby, the friction is tailored according to the numerically determined requirements. Concluding, the applicability of tailored tool surfaces for material flow control and improvement of component quality is experimentally show
Keywords: Cold forming; Tribology; Surface modification; Material flow control; Numerical simulation; Lightweight design; Steel

Investigation of the Adhesive Wear Behavior of Alloyed and Not Alloyed Hot Stamping Tools in Contact with 22MnB5 - Neubauer, Franziska; Tenner, Jennifer; Andreas, Kolja; Merklein, Marion (Hot Sheet Metal Forming of high-Performance Steel - CHS2, Wissenschaftliche Skripten, 2017, 2017)
LFT Import::2019-08-05 (2250)

Investigation of the Anisotropic Strain Rate Dependency of AA5182-O and DC04 for Different Stress States - Lenzen, Matthias; Affronti, Emanuela; Rosenschon, Martin; Merklein, Marion (Advanced Materials Research, 2016)
LFT Import::2019-07-29 (2184)

Investigation of the beginning of plastic yielding and the hardening behaviour under biaxial tension - Suttner, Sebastian; Kuppert, Andreas (Advanced Materials Research, 2013)
The main focus of the experimental observation deals with the investigation of the plastic yielding of DC06 and DP600 under biaxial tension in comparison to an identified material model with an isotropic hardening behaviour. The isotropic hardening law describes the hardening behaviour of the material by application and approximation of the flow curve. Prevalent hardening laws are proposed by Swift (1952) or Hockett and Sherby (1975) and lead to an expansion of the yield surface in the stress space. By reasons of good accordance in an earlier survey the given materials are modeled by the yield criterion Yld2000-2d and the isotropic hardening law of Swift. In this case the yield loci at different experimental states of plastification are compared with the yield loci given from the isotropic expansion of the Yld2000-2d yield surface. Furthermore a possible approach for modelling the change of the yield criterion's shape in the stress space during plastification is shown. With respect to further investigations additional research work is needed including extended and complex hardening laws to describe the real material behaviour sufficiently. © (2013) Trans Tech Publications, Switzerland.
LFT Import::2019-07-29 (1892)
Keywords: Material characterisation; Metal forming; Modelling

Investigation of the direct recyclability of chip waste by cold cup extrusion and identification of its potential in continuous processes - Zettl, Bastian; Kraus, Martin; Böhm, Wolfgang; Zippert, Patrick; Merklein, Marion (Forming Technology Forum 2022, 2022)
Environmental protection and the responsible use of natural resources are currently the main challenges facing our society. When machining metallic materials, the formation of chips is unavoidable caused by technological reasons. This leads to a large proportion of chip waste. This waste needs to be subsequently recycled in energy-intensive cleaning and melting processes. To face these, this work is dealing with a novel direct recyclability method of chips from technically pure aluminum EN AW-1050A and pure copper CW004A by cold cup extrusion. The cups are characterized in regard to their bonding quality by light microscopy and X-ray analysis in order to prove the feasibility of the method. The objective is to demonstrate the suitability of cold cup drawing for creating cohesive bonds even under varying chip properties. Additionally, the usage of chip waste for recycling without melting in a continuous forming process is analyzed. For this, the so called Temconex® method is introduced, which enables the production of semi-finished profiles by a combination of friction and severe plastic deformation in an extrusion process.<br
Keywords: recycling; chips; cyclic economy; extrusion; sustainability; aluminum; copper

Investigation of the impact of heat treatment on the layer formation of AlSi-coated boron-manganese steel - He, Franz; Merklein, Marion (INTERNATIONAL DEEP-DRAWING RESEARCH GROUP CONFERENCE (IDDRG 2021), 2021)
Hot stamping is a well-established technology for producing safety relevant car components. The usage of hot stamping allows for reduced sheet thicknesses and weight of formed parts due to an increase in strength because of martensitic phase transformations. To prevent surface carburization and the formation of oxide layers AlSi coatings are applied to the workpiece surface. Due to a lack of suitable lubricants at process temperatures of over 800 °C, severe friction and wear affect the final part quality. Furthermore, process temperatures influence the layer formation and surface roughness due to diffusion processes. Consequently, a deeper process understanding is needed to acquire detailed knowledge of the impact on the tribological behavior to increase part quality and reduce tool wear. To this end the influence of heat treatment parameters on the coating layer and the subsequent layer formation is analyzed by comparing the resulting material composition and surface roughness. This is achieved by analyzing the impact of the furnace temperature and holding time on an AS150 coating and determining the effect of the parameters via metallographic investigation and tactile measuremen
CRIS-Team WoS Importer:2021-11-05

Investigation of the impact of process parameters on the layer formation of AlSi coated boron-manganese steel - He, Franz; Merklein, Marion (International Deep-Drawing Research Group Conference (IDDRG 2022), 2022)
Hot stamping has established itself as a technology for manufacturing safety-relevant car body components. Its usage has found increased importance due to rising political and social pressure e.g. for improved fuel conservation. Due to reduced sheet thickness, hot stamping parts offer lightweight solutions while at the same time providing improved crash performance due to their high strength. Boron-manganese steel is commonly used in hot stamping processes. Due to hot scale formation during heat treatment and the subsequent forming process, additional coatings, typically AlSi-coatings, are applied. Since hot stamped parts are formed at temperatures of 600 °C to 800 °C no suitable lubricants have yet been found. This leads to increased friction and severe wear in the process, which negatively affect tool lifetime and overall part quality. Additionally, process temperatures influence the layer formation and surface roughness due to diffusion processes. A deeper process understanding is needed to acquire detailed knowledge of the resulting impact on tribological behavior. Within this study, the effect of coating thickness on the resulting layer is analyzed by comparing the resulting material composition and surface roughness. To this end, the layer formation and surface roughness are analyzed for two different layer thicknesses (AS150 and AS80) in relation to furnace temperature, holding time and heat up rate. Both are characterized by means of heating experiments conducted on an annealing furnace. The change in layer composition and surface roughness are determined via metallographic investigation and tactile measurement. The results of this study help to improve the process understanding of the tribological conditions within the hot stamping process and to develop future measures for reducing tool we
Keywords: Hot Stamping; 22MnB5; Coating

Investigation of the impact of the layer formation of AlSi coated boron-manganese steel in regard to friction and wear - He, Franz; Merklein, Marion (International Conference on Hot Sheet Metal Forming of High Performance Steel, 2022)
With the increase in electric vehicles, factors for limiting reach due to finite battery capacity have found increased significance. Lightweight solutions are needed, amongst which the construction with ultra-high strength steels have been established as the industrial standard. These materials are able to bridge the gap between providing reduced part weight while improving mechanical properties. While cold forming faces various challenges such as high forming resistance and spring-back behavior, hot stamping of boron manganese steels allow for reduced forming forces and increased dimensional accuracy. The sheet is austenized at temperatures above 850 °C which leads to a phase change in the material and decrease in tensile strength. Since uncoated material suffers from decarburization and scale formation, which negatively inform the forming process and final part quality, aluminum silicon coatings (Al-Si) are applied. Additionally, lubricants lose their properties at higher process temperatures, leading to increased friction and severe wear in the process. Previous investigations have shown that furnace holding times influence the layer formation of AlSi-based coatings due to diffusion processes. Within this study, the influence of furnace holding times and subsequent layer formation on the friction and wear behavior as well as interdependencies with other relevant process parameters is investigated. To this end single sided strip drawing tests are performed with an industrial standard coating AS150 and analyzed in regard to the friction coefficient. Additionally, the tool sided wear is investigated through contactless 3D measurement. The results of this study help to improve the process understanding of the tribological conditions within the hot stamping process and to develop tailored measures for reducing tool wear.
Keywords: Friction; wear; hot stamping; 22MnB5

Investigation of the Influence by Size Effects on the Material Characterization of the Uniaxial Compression Stress State - Hetz, Peter; Kraus, Martin; Merklein, Marion (Key Engineering Materials, 2022)
For the evaluation of final component properties under consideration of production-induced material characteristics, it is necessary to determine the mechanical parameters of parts and structures. Thus, there is a need of new test methods for the material characterization and quality control of produced goods. The miniaturization of the test specimens offers the potential for the local testing of the material properties at almost any position on the component. However, due to the reduction in size of the test specimens, size effects can occur which may affect the material behavior. For this reason, this contribution analyses the influence of size effects on the derived material parameters in dependence of the specimen size and material by using upsetting tests according to DIN 50106:2016 standard. The materials Cu-OFE (copper), X5CrNi18-10 (stainless steel) and AA7075-T6 (aluminum) are investigated to ensure a broad transferability of the findings. The specimens are cut from a bar stock by using a high precision 3D micro electrical discharge milling machining. Due to the small size, every specimen is measured with an optical 3D coordinate measuring system to determine the exact size. Through these investigations, the reproducibility and scatter in the determination of material properties for scaled cylindrical upsetting specimens are evaluated. Furthermore, limits of geometric dimensions at constant aspect ratios are derived. The results of this investigation enable an estimation of the geometrical influence of the specimen size in regard to the mechanical properties.
CRIS-Team Scopus Importer:2022-11-04
Keywords: Compression test; Material characterization; Miniaturization; Size effects

Investigation of the influence of formed, non-rotationally symmetrical pin geometries and their effect on the joint quality of steel and aluminium sheets by direct pin pressing - Römisch, David; Kraus, Martin; Merklein, Marion (Proceedings of the Institution of Mechanical Engineers Part L-Journal of Materials-Design and Applications, 2022)
Resource-saving and sustainable production is becoming increasingly important regarding social, political and economic aspects, thus making the use of lightweight-construction technologies a current trend. For this reason, multi-material-systems made of high-strength steel and aluminium as well as metal and fibre-reinforced plastics gain in importance. However, different material properties, e.g. stiffness, thermal expansion coefficients or chemical incompatibilities, are challenging for conventional joining technologies. Joining by cold formed pin structures has shown to have high potential for joining multi-material-systems. These pins can be joined either by direct pin pressing into an unperforated joining partner or by caulking, where the pins are inserted through a pre-punched joining partner and the pin head is upset, resulting in a form-fit joint. Usually, cylindrical pins are used for joining. However, non-rotationally symmetrical pin geometries offer the possibility of introducing a predetermined breaking point or reinforcing a connection in the principal force direction. In this work, cylindrical pins as well as non-rotationally symmetrical pin geometries, such as polygonal and oval pin structures, are cold extruded from the sheet metal plane of an HCT590X+Z dual phase steel and joined in the next step with an EN AW-6014 aluminium using direct pin pressing. Since the formation of an undercut has an crucial influence on the joint strength, the investigations will be focused on the resulting joint geometry. In addition, the effect of different pin heights will be examined to analyse the joint formation at different levels of compression of the pin structures. Finally, the joints are evaluated regarding their joint strength in tensile shear tests and cross tension tests. Here the flow resistance of the geometry used as well as the pin height and thus the strain hardening of the pin base during the extrusion of the pins play a decisive role for the shear strengt
Keywords: pin-joining; alternative pin geometries; joining by forming; versatile joining process

Investigation of the Influence of Formed, Non-rotationally Symmetrical Pin Geometries and their Effect on the Joint Quality of Steel and Aluminum Sheets by Direct Pin Pressing - Römisch, David; Kraus, Martin; Merklein, Marion (AJP2021, 2021)
Resource-saving and sustainable production is becoming increasingly important regarding social, political and economic aspects, thus making the use of lightweight construction technologies a current trend. For this reason, multi-material systems made of high-strength steel and aluminium as well as metal and fibre-reinforced plastics gain in importance. However, different material properties, e.g. stiffness, thermal expansion coefficients or chemical incompatibilities, are challenging for conventional joining technologies. Joining by using cold formed pin structures has shown to be a process with high potential for joining multi-material systems. These pin structures can be joined either by direct pin pressing into an unperforated joining partner or by caulking, where the pin structures are inserted through a pre-punched joining partner and the pin head is upset, resulting in a form fit joint. Usually, cylindrical pin structures are used for joining. However, non-rotationally symmetrical pin geometries offer the possibility of introducing a predetermined breaking point or reinforcing a connection in the principal force direction. In this work, cylindrical pin structures as well as non-rotationally symmetrical pin geometries, such as polygonal and oval pin structures, are cold extruded from the sheet metal plane of an HCT590X + Z dual phase steel and joined in the next step with an EN AW-6014 aluminium using direct pin pressing. Since the formation of an undercut is a crucial influence on the joint strength [1], the investigations will be focused on the resulting joint geometry. In addition, the effect of different pin heights will be examined in order to analyze the joint formation at different levels of compression of the pin structures. Finally, the joints are evaluated regarding their joint strength in tensile shear tests and cross tension test
Keywords: pin joining; mechanical joining; joining by forming

Investigation of the influence of material and sheet thickness on a three-stage process chain for cold forming of micro gears with a module of 0.1 mm - Leicht, Miriam; Rohrmoser, Andreas; Kraus, Martin; Merklein, Marion (The 19th International Conference on Metal Forming (MF 2022), 2022)
In many industries, there is a trend towards miniaturization of technical components, such as drive systems, which enable the solution of high-precision positioning tasks because of their low volume and high dynamics. Geared micro parts are currently mainly produced by cutting and LIGA processes, but in mass production cold forming offers ecological and economic benefits. However, the cold forming of micro gears is restricted to a lower module limit of m = 0.2 mm due to high tool stresses, size effects and handling difficulties. To solve these challenges, in this contribution a three-stage forming process chain for the manufacturing micro gears (m = 0.1 mm) is investigated. In the first stage, a pin as wheel blank is extruded from sheet metal, which is geared subsequently by lateral extrusion. Finally, the micro gear is separated from sheet by shear cutting. The aim of this study is to demonstrate the applicability of the process chain for the materials Cu-OFE and CuZn30. In addition, the influence of the sheet thickness, which has a major impact on the forming process and the material efficiency, is analyzed. The geometrical and mechanical component properties as well as the machine data are evaluated to assess the variable

Investigation of the influence of process parameters on adhesive wear under hot stamping conditions - Schwingenschlögl, Patrik; Weldi, Maraike; Merklein, Marion (Journal of Physics: Conference Series, 2017)
LFT Import::2019-08-05 (2236)

Investigation of the Influence of Slightly Increased Process Temperatures on the Extrusion of Functional Aluminum Components in Sheet-Bulk Metal Forming - Wild, Thomas; Merklein, Marion (Production at the Leading Edge of Technology, 2023)
By using high-strength aluminum, weight savings can be achieved. However, limited formability of these alloys at room temperature is a challenging aspect regarding the manufacturing of components with filigree functional elements within sheet-bulk metal forming. So as to derive detailed process knowledge and to improve the achievable process results, forward extrusion of geared components made of EN AW 6082 sheets at room temperature is investigated within this work. Furthermore, robust large-scale industrial cold forming is a demanding task, as tool temperatures increase over time due to forming and frictional heat, leading to varying material and process properties. In order to determine measures for the compensation of these fluctuations, additional experiments are carried out with slightly increased tool temperatures. By analyzing workpiece and process related parameters for both sets of experiments, potential approaches to control the outcome of forming operations under variable conditions are discussed.<br
Keywords: Sheet-Bulk Metal Forming; Extrusion; Aluminum

Investigation of the Influence of the Tumbling Angle on a Tumbling Self-Piercing Riveting Process - Wituschek, Simon; Lechner, Michael (2nd International Conference on Advanced Joining Processes AJP 2021, 2021)

Investigation of the influence of the tumbling angle on a tumbling self-piercing riveting process - Wituschek, Simon; Lechner, Michael (Proceedings of the Institution of Mechanical Engineers Part L-Journal of Materials-Design and Applications, 2022)
To achieve the climate objectives, various measures are taken to increase the efficiency of raw materials and energies used. A sector with a large proportion of the global consumption of resources is the mobility sector. To increase the efficiency in this field, large efforts are made to reduce the weight of moving masses. One approach is the use of multi-material systems, which utilises different materials and their specific properties depending on the local requirements. Multi-material systems consist often of materials which differ in strength and density, for example, high-strength steels, aluminium alloys or polymers. Additionally, such a system can utilise different geometries of the components to be joined, characterised for example by varying sheet thicknesses. A central challenge of producing these systems is the joining of the individual components. This requires robust joining processes capable of covering the entire spectrum of possible variants and is feasible for different physical properties of the materials. Since conventional joining processes are rather rigid and have difficulty reacting to changing process and disturbance variables, new joining processes are necessary. With the objective of being able to react versatile to varying parameters, a process combination consisting of a semi-tubular self-piercing riveting process and orbital forming process with adjustable tumbling kinematic is introduced. Due to the process combination of tumbling and self-piercing riveting, mutual influences of the two process components are analysed in regard to material flow and process forces. Further, the investigations show the influence of a varying tumbling angle on the joining process itself and how the characteristic properties undercut, rivet head end position and residual sheet thickness of the joint are affected. The material used for the joining partners is an aluminium alloy EN AW-6014 typical for multi-material systems in the automotive industry and the rivets are from type Rivset C produced by the Böllhoff company.<br
Keywords: Self-piercing riveting; joining; orbital forming

Investigation of the Influence of Tool Geometry on Effective Strain Distribution in Full Forward Extrusion - Merklein, Marion; Ndzomssi, Franck; Engel, Ulf (AIP Conference Proceedings, 2011)
Due to strain hardening of the material, the hardness of cold forged parts is considerably improved. It is well known that the hardness of cold forged parts is closely related to its deformation, and that this relation is not dependent on the deformation process. The effective strain defines the local deformation, and can be determined in simulation of the cold forming process. In order to reach the required or to set specific hardness distribution with cold forging without any heat treatment processes, it is necessary to find out which manufacturing parameters influence the effective strain, and determine the effects of these parameters. The research work covered in this paper investigates the influence of the die geometry (as manufacturing parameter) on the effective strain. For that, a full forward extrusion process was modeled using the FE-software Simufact. Forming and three parameters of the die geometry, namely the deformation ratio, the shoulder radius and the opening angle were varied. The maximum effective strain from each combination is determined, and the effects of each considered parameter as well as the effects of interactions between these factors are checked. © 2011 American Institute of Physics.
LFT Import::2019-07-29 (1692)
Keywords: deformation ratio; Design of Experiments; effective strain; Finite Elements Method; full forward extrusion

Investigation of the influence of tool-sided parameters on deformation and occurring tool loads in shear-clinching processes - Han, Daxin; Hörhold, Réjane; Wiesenmayer, Sebastian; Merklein, Marion; Meschut, Gerson (Procedia Manufacturing, 2018)
Shear-clinching is a method for joining of dissimilar materials without auxiliary element. The technology combines shear-cutting and clinching in one process. Challenges of the process are the deformation of the specimens and the high process forces, which lead to high tool loads. Thus, the influence of the punch-sided tool geometry on the deformation of multi-element specimens was tested experimentally within this study. The effect of the geometrical changes on the occurring tool loads was analysed with a numerical model in order to evaluate the benefit of the adapted design with regard of the lifetime of the toolset.
LFT Import::2019-07-29 (2321)
Keywords: Clinching; Deformation of specimen; Joining by forming; Lightweight; Multi-material design; Tool load

Investigation of the influence of varying tumbling strategies on a tumbling self-piercing riveting process - Wituschek, Simon; Kappe, F.; Lechner, Michael (Production Engineering, 2021)
The increasing demands for the reduction of carbon dioxide emission require intensified efforts to increase resource efficiency. Especially in the mobility sector with large moving masses, resource savings can contribute enormously to the reduction of emissions. One possibility is to reduce the weight of the vehicles by using lightweight technologies. A frequently used method is the implementation of multi-material systems. These consist of dissimilar materials such as steel, aluminium or plastics. In the production of these systems, the joining of the different materials and geometries is a central challenge. Due to the increasing demands on the joints, the challenges for the joining processes itself are also increasing. Since conventional joining processes are rather rigid and can only react to a limited extent to disturbance variables or changing process variables, new methods and technologies are required. A widely used conventional joining method with these properties is self-piercing riveting. Because of the rigid tool combination and the fact that the rivet geometry that can be used is related to the tools, the joining of multi-material systems requires tool and rivet changes during the process. In order to extend the process window of joining with self-piercing rivet elements, the process is enhanced with a tumbling kinematic of the punch. The integration of tumbling results in a significant increase in the adjustable process parameters. This enables a higher material flow control in the joining process through a specific tumbling strategy. The materials investigated are a steel and an aluminium alloy, which differ significantly in their mechanical properties and have many applications in automotive engineering, especially for structural car body components. The steel material is a galvanized HCT590X+Z dual-phase steel, which is characterised by a low yield strength, combined with high tensile strength and a good hardening behaviour. The aluminium alloy is an EN AW-6014. The precipitation-hardening alloy consists of aluminium, magnesium and silicon with a high strength and energy absorption capability. The objective of this work is to obtain a fundamental knowledge of the new tumbling self-piercing riveting process. With different mechanical properties and different sheet thicknesses of the joining partners, the influences of these parameters on the tumbling strategy of the riveting process are analysed. Such a tumbling strategy is based on the tumbling angle, the tumbling onset and the tumbling kinematics. These parameters are investigated in the context of the work for selected combinations of multi-material systems consisting of HCT590X+Z and EN AW-6014. With the variation of the parameters, the versatility of the process can be investigated and influences of the tumbling on the self-piercing riveting process can be identified. To illustrate the results, force-displacement curves from the joining process of the individual joints are compared and the geometry of the rivet undercut and rivet heads are geometrically measured. Furthermore, micrographs allow the analysis of the characteristic joint parameters interlock, residual sheet thickness and end position of the rivet head.
CRIS-Team WoS Importer:2022-01-14

Investigation of the influence of workpiece-side parameters on the layer formation of zinc-coated boron-manganese steel - He, Franz; Merklein, Marion (Materials Research Proceedings, 2023)
The hot stamping process has been established as a technology for the production of ultrahigh-strength steel parts for safety-relevant components in lightweight construction for the automotive sector. Thanks to the reduced overall thickness combined with high tensile strength, it is possible to realize lightweight design concepts with improved crash behavior. Boron-manganese steels are usually used for this purpose. Due to initial process temperatures above 800 °C, hot stamping is considered a lubricant-free process. In addition to high friction and wear in the process, surface scaling and the need for tool repairs are the result. In light of these phenomena, hot stamping materials are coated to protect them from corrosion. Until now, aluminum-silicon-based coatings have been primarily used for the direct hot stamping route. While zinc-based coatings have so far mainly found usage in the indirect process route, they are now also become a valid alternative for the direct process route. In previous investigations, a significant influence of workpiece-side parameters on the formation of the coating during the austenitization process was found for aluminum-silicon (AlSi) coatings. In light of this, a similarly significant influence is suspected for zinc-based coatings. The parameters heating rate, furnace temperature and dwell time in the furnace and the effect on the coating formation of zinc-coated 20MnB8 during austenitization will be investigated. The resulting findings will form the basis for further experiments to investigate the influence of the parameters on friction and wear in the industry near strip drawing tests.
CRIS-Team Scopus Importer:2023-04-28
Keywords: 20MnB8; Coating; Hot Stamping

Investigation of the joinability of single- and multi-layered AA6014 sheets produced by accumulative roll bonding in the shear-clinching process - Zettl, Bastian; Wiesenmayer, Sebastian; Kraus, Martin; Merklein, Marion (Proceedings of the Institution of Mechanical Engineers Part L-Journal of Materials-Design and Applications, 2022)
Accumulative roll bonding belongs to the severe plastic deformation processes and is suitable for producing multi-layered as well as high-strength sheets through repeated rolling. After four accumulative roll bonding-cycles, the strength of the investigated AA6014-T4 alloy is elevated due to strain and fine grain hardening by 170% in yield strength and by 37% in ultimate tensile strength. This is accompanied by a significant decrease in material ductility which is disadvantageous for joining processes based on forming operations. Shear-clinching, however, can be used to join high-strength and low-ductile materials on the die side. Thus, it is a promising method for the mechanical joining of accumulative roll bonding components. The multi-layered and more brittle material is located on the die side whereas the single-layered base material with higher ductility is positioned on the punch side. At present, there is no scientific knowledge how the multi-layered material behaves in the shear-clinching process. Since the material is cut in the process, delamination effects could occur at the interfaces produced via accumulative roll bonding. Additionally, the investigation aims at the influence of the accumulative roll bonding process on the properties of the joints. They are expected to depend on the number of process cycles and thus on the change of mechanical properties of the multi-layered material. The bond strength of the shear-clinched joints is determined by shear and tensile tests. The areas of material failure are analysed via metallographic methods. From the failure behaviour and load-bearing capacity it is determined which number of accumulative roll bonding cycles is ideal for joining multi-layered sheets via shear-clinching.
CRIS-Team Scopus Importer:2022-02-04
Keywords: accumulative roll bonding; Joining; multi-layered materials; shear-clinching

Investigation of the joinability of the high-strength aluminum alloy AA7075 in shear-clinching processes - Wiesenmayer, Sebastian; Merklein, Marion (Proceedings of the Institution of Mechanical Engineers Part L-Journal of Materials-Design and Applications, 2021)
Shear-clinching has proven to be a suitable technology for joining of high-strength materials. However, the mechanical properties of the upper joining partner are limited due to the high strains, which occur during the process. Therefore, shear-clinching of the high-strength aluminum alloy AA7075 in the T6 temper is not possible. Yet, the mechanical properties of hardenable alloys of the 7000 series can be influenced by a heat treatment. Thus, within the scope of this work, the joinability of the high-strength alloy AA7075 in shear-clinching processes in dependance of its temper is investigated. The as fabricated state F, the artificially aged T6 temper, a paint baked state and the naturally aged T4 temper are compared to the fully solution annealed W temper as well as to a retrogression heat-treated state. For retrogression heat treatment, a laser is used as heat source, heating up the alloy for a short term in order to only partially dissolve precipitations. The resulting mechanical properties are determined with uniaxial tensile tests. Moreover, the influence of the mechanical properties of AA7075 on the shear-clinching process, the joint formation and the resulting joint strength is analyzed.
CRIS-Team WoS Importer:2022-01-14

Investigation of the mechanical behaviour of advanced high strength steels under various loading conditions - Geiger, Manfred; Merklein, Marion; Kaupper, Markus (International Journal of Material Forming, 2008)
Nowadays advanced high strength steel sheets and related forming technologies play a vital role in light weight construction in the transportation sector. Within this paper the mechanical behaviour of the multi phase steels DP600, DP800 and CP800 is investigated, being focussed on the influence of various loading conditions in particular. Uniaxial tensile tests, layer compression tests and bulge tests are carried out, to characterize plastic material properties like anisotropy and work hardening. The forming behaviour is evaluated utilizing optical strain measurement, to obtain detailed information on the deformation behaviour. True stress strain curves are obtained, clearly quantifying the properties described above. The results are discussed and evaluated with regard to numerical simulation of sheet metal forming processes. © Springer/ESAFORM 2008.
LFT Import::2019-07-29 (207)
Keywords: Loading condition; Material characterization; Work hardening; Yielding

Investigation of the mechanical behaviour of thin metal sheets using the hydraulic bulge test - Diehl, Alexander; Staud, Detlev; Engel, Ulf (Proceedings of the 4th International Conference on Multi-Material Micro Manufacture, 2008)
LFT Import::2019-08-05 (1537)

Investigation of the Microstructural Evolution during Hot Stamping of a Carburized Complex Phase Steel by Laser-Ultrasonics - Horn, Alexander; Merklein, Marion (Materials, 2021)
Prior carburization of semi-finished steel sheets is a new process variant in hot stamping to manufacture parts with tailored properties. Compared to conventional hot stamping processes, a complex phase typed steel alloy is used instead of 22MnB5. Yet recent investigations focused on final mechanical properties rather than microstructural mechanisms cause an increase in strength. Thus, the influence of additional carburization on the microstructural evolution during hot stamping of a complex phase steel CP-W(R)800 is investigated within this work. The phase transformation behavior, as well as the grain growth during austenitization, is evaluated by in-situ measurements employing a laser-ultrasound sensor. The results are correlated with additional hardness measurements in as-quenched condition and supplementary micrographs. The experiments reveal that the carburization process significantly improves the hardenability of the CP-W(R)800. However, even at quenching rates of 70 K/s no fully martensitic microstructure was achievable. Still, the resulting hardness of the carburized samples might exceed the fully martensitic hardness of 22MnB5 derived from literature. Furthermore, the carburization process has no adverse effect on the fine grain stability of the complex phase steel. This makes it more robust in terms of grain size than the conventional hot stamping steel 22MnB5.
CRIS-Team WoS Importer:2021-05-07
Keywords: hot stamping; phase transformation; quenching; grain growth; carburization

Investigation of the Phase Transformation in Hot Stamping Processes with Regard to the Testing Facility - Horn, Alexander; Hart-Rawung, T.; Buhl, J.; Bambach, Markus; Merklein, Marion (Congress of the German Academic Association for Production Technology WGP 2021, 2020)
Hot stamping of boron manganese steel is a state of the art process for manufacturing safety-relevant automotive components with regard to lightweight design. In terms of the mechanical properties, the microstructural evolution is of particular interest. Besides conventional hot stamping processes, this is especially apparent for the manufacture of hot stamped parts with tailored properties. To reduce costs and scrap parts, numerical process design requires appropriate material models considering transformation kinetics during in-die quenching. The phase transformation behavior can be characterized through experiments on various testing facilities, which can lead to discrepancies in the results and therefore in the predicted mechanical properties. In this paper, the results from two testing facilities are compared to each other through dilatometry experiments on the boron-manganese steel 22MnB5. For further characterization of the differences, secondary samples are taken to analyze the hardness as well as the microstructure by optical microscopy.
Keywords: Hot stamping; Dilatometry test; Phase transformation

Investigation of the Potential for the Fabrication and Forming of Adaptronic Semi-finished Parts Joined by Cold Formed Pin Structures - Kraus, Martin; Suttner, Sebastian; Merklein, Marion (2ND INTERNATIONAL CONFERENCE ON ADVANCED JOINING PROCESSES (AJP 2021), 2021)

Investigation of the Quenching Behavior of Carburized Sheet Metal in Hot Stamping - Horn, Alexander; Merklein, Marion (Proceedings of the 7th International Conference on Hot Sheet Metal Forming of high-performance steel - CHS2, 2019)

Investigation of thermal effects during ultrasonic-assisted upsetting - Jäckisch, Manuel; Merklein, Marion (Procedia Manufacturing, 2020)
Minimizing tool wear is a crucial goal in metal forming to increase the tool durability and thus reduce costs. One approach is to superimpose the tool movement with a high frequency oscillation. The so-called ultrasonic assistance enables an immediate process force reduction and lowers the workpiece and tool loads significantly. This phenomenon has been discovered by Langenecker and Blaha in 1955 and since then been confirmed for several forming applications like wire drawing, deep drawing and forging. Nevertheless, the underlying softening mechanisms are still subject of current research. Explaining theories may be attributed to the principle of stress superposition, surface and volume effects. The latter includes the thermal softening due to ultrasonic vibration. Moreover, interactions as well as the proportional force reduction of these effects vary with the process parameters and the investigated material. Therefore, this paper aims for the separation and quantification of thermal softening with respect to the process parameters. Ultrasonic-assisted compression testing with the steel C35E is carried out with an oscillation frequency of 20 kHz. Process forces as well as specimen heating are measured with regard to the tested amplitudes and deformation rates. Based on these measurements, hot compression tests are conducted with identical temperature slopes. This way, thermal softening is determined and can be separated from acoustic softening effects. Besides, material hardening is determined for ultrasonic-assisted and temperature controlled compression. Using a shortened oscillation interval the influence of both, the superimposed oscillations as well as the specimen heating is proven.<br
Keywords: ultrasonic; steel; thermal effects; measurement; cold forming

Investigation of the Springback Behaviour of High-strength Aluminium Alloys Based on Cross Profile Deep Drawing Tests - Hetz, Peter; Suttner, Sebastian; Merklein, Marion (Procedia Manufacturing, 2020)
The prediction of springback of sheet metal parts is still a challenge in metal forming processes. To meet the requirements for dimensional accuracy of a sheet metal part, the springback must be compensated and the production process has to be designed accordingly. During forming, elastic energy is stored in the semi-finished product. When removing a part from the deep-drawing tool, the resulting residual stresses with an elastic component cause unwanted changes of the part`s geometry in forming. Especially sheet materials with low elastic modulus and high yield strength tend to an increased springback. Among others, these materials include aluminium alloys of the 7000 series. For this reason, a fundamental understanding of the material behaviour of these materials is relevant for designing a sheet metal forming process. This contribution uses a novel approach to investigate the springback behaviour of AA7020-T6 and AA7075-T6. For this purpose, cross profiles are deep-drawn with various parameter settings and subsequently digitised with a three-dimensional optical measurement system. By analysing the digitised profiles, the springback behaviour is quantified depending on the experimental parameters. Due to the right-angled structure of the cross profile, the influence of anisotropy in 0 and 90 degree to rolling direction is investigated within one forming operation.
CRIS-Team Scopus Importer:2020-06-05
Keywords: Cross profile; Deep drawing; High-strength aluminium alloys; Springback compensation

Investigation of the tensile response and the microstructural evolution during hot drawing of multi-layered, ultrafine-grained AA6014 sheets by thermomechanical analyzes - Zettl, Bastian; Merklein, Marion (IOP Conference Series: Materials Science and Engineering, 2022)
Mechanical strengthening of sheet material can be realized by accumulative roll bonding, which belongs to the severe plastic deformation processes. Beside fine-grain hardening also work and precipitation hardening is responsible for the rise of material strength. However, this is also accompanied by a significant decrease in ductility. Thus, the need for an enhancement of ductility is essential for a sufficient formability in later applications and was already introduced by tailored heat treatments. The challenge, however, is to realize a process temperature that leads to a degradation of dislocations and dissolution of MgSi-precipitations, without a recrystallization of the fine-grained microstructure to coarse grain sizes. In order to identify a suitable temperature range to avoid recrystallization, hot forming experiments are carried out at successive temperatures from 20 to 300 °C. Tensile specimens are drawn with the thermomechanical simulator Gleeble 3500 (Dynamic Systems Inc.) aided by the strain measurement system Aramis (GOM GmbH). The aim is to investigate the dependence of the mechanical properties from the forming temperature in order to identify a temperature range, in which high strength with simultaneous enhanced ductility is maintaine

Investigation of the thermal and tribological performance of localized laser dispersed tool surfaces under hot stamping conditions - Schirdewahn, Stephan; Spranger, Felix; Hilgenberg, Kai; Merklein, Marion (Wear, 2021)
In the automotive industry, hot stamping has been established as a key technology for manufacturing safety-relevant car body components with high strength-to-weight ratio. However, hot stamping tools are stressed by cyclic thermo-mechanical loads, which leads to severe wear and high friction during the forming operation. Consequently, the quality of the parts, the durability of the tools and the efficiency of the process are negatively affected. Within the scope of this work, a promising approach named laser implantation process has been investigated for improving the tribological behavior of hot stamping tools. This technique enables the fabrication of highly wear resistant, separated and elevated micro-features by embedding hard ceramic particles into the tool via pulsed laser radiation. Hence, highly stressed tool areas can be modified, which influences the thermal and tribological interactions at the blank-die interface. To clarify these cause-effect relations, numerical simulations, quenching tests as well as tribological investigations have been conducted. In this context, laser-implanted tools reveal a significantly improved tribological performance while offering the possibility to adjust the thermal properties within hot stamping. Based on these results, a tailored tool modification can be pursued in future research work, in order to enhance the effectiveness of hot stamping tooling systems.
CRIS-Team Scopus Importer:2021-03-05
Keywords: Friction; Hot stamping; Laser implantation; Surface structuring; Wear

Investigation of the Thermomechanical Properties During Hot Stamping of a Complex Phase Steel Carburized at Elevated Temperatures - Risse, Jan Henning; Merklein, Marion (Hot Sheet Metal Forming of High-Performance Steel, 2024)
In order to reduce greenhouse gas emissions or to increase the range of electrically powered vehicles, several lightweighting strategies are applied in the manufacturing of the latest cars. The hot stamping of ultrahigh-strength steels, which is becoming an increasingly common strategy, can be used to produce lighter components with reduced sheet thickness. In particular, parts with tailored properties that are already in use for B pillars for example, increase the crashworthiness and the lightweight potential at the same time. In contrast to existing processes, tailored carburization does not require complex tooling or intricate furnace technologies, material thickening, or welding processes to locally adjust the mechanical properties. The to-be-reinforced areas are geometrically flexible, which makes this process especially suitable for small batch series of lightweight components. At standardly 950 °C, the carburization takes up to 6 h to achieve the highest combination of strength and ductility. Thus, strategies are needed to shorten the total process time. Diffusion hardening at elevated temperatures seems promising to achieve a similar level of mechanical properties but in a significantly reduced time. So, this contribution aims to investigate the dependence of the thermomechanical behavior on the carburization above 950 °C, forming temperature, and strain rate of a tailored carburized material. Therefore, thermal tensile tests were performed with the complex phase steel CP-W® 800 in two different carburized states as well as in the not-carburized state. In the physical simulator Gleeble 3500 GTC the specimens pass through a simulated hot stamping process and are tested at different forming temperatures with varying strain rates. In addition to the dependency analysis, the obtained flow curves can also be used to partially generate a thermo-mechanically coupled simulation. This model is intended to replicate the hot stamping of components with customized properties induced by tailored carburization.<br

Investigation of the thermo-mechanical properties of hot stamping steels - Merklein, Marion; Lechler, Jürgen (Tagungsband Metal Forming Conference 2006, Birmingham, England, 2006)
Within the innovative hot forming process for sheet metals, called hot stamping, it is possible to combine forming and quenching in one process step. This affords the opportunity to manufacture components with complex geometric shapes, high strength and a minimum of springback which currently find applications as crash relevant components in the automotive industry. As standard material for hot stamping the quenchenable high strength steel 22MnB5 is commonly used. With regard to the numerical modeling of the process, the knowledge of thermal and thermo-mechanical properties of the material is required. To determine the thermo-mechanical material characteristics, the flow behavior of the steel 22MnB5 in the austenitic state has been investigated by conductive, hot tensile tests with a Gleeble 1500 system dependent on the time-temperature characteristic of the hot stamping process. © 2006 Elsevier B.V. All rights reserved.
LFT Import::2019-08-05 (1269)
Keywords: 22mnB5; Flow behavior; High strength steels; Hot stamping; Thermo-mechanical properties

Investigation of the tool wear behaviour in shear-clinching processes during the running-in phase - Wiesenmayer, Sebastian; Han, Daxin; Meschut, Gerson; Merklein, Marion (AIP Conference Proceedings, 2019)
The multi-material design of modern cars is a challenge for common joining technologies. Joining by welding is often not possible, due to different melting temperatures of the joining partners. Indeed, the usage of fasteners allows the joining by forming of high-strength steels with aluminium, but increases the weight and the costs. Common joining by forming technologies without additional fasteners are limited by the mechanical properties of the joining partners. Thus, clinching of ultra-high strength steels with low ductility, like press-hardened manganese-boron steels, is not possible. However, the innovative shear-clinching technology enables the joining by forming of ultra-high strength steels and aluminium without fasteners. In one combined process, the die-sided steel sheet is cut and the punch-sided aluminium is pressed into the cut out hole, resulting in a form and force fitting joint. Nevertheless, the cutting of the high-strength steel and the subsequent upsetting of the aluminium both lead to high tool loads, especially for the die. Thus, it is necessary to analyse the wear behaviour of the shear-clinching tool. Within the scope of this work, the tool wear behaviour in shear-clinching and the influence of wear on the process will be investigated experimentally. The focus will be on the die and the running-in phase, since there are no references for the wear behaviour in shear-clinching yet.
CRIS-Team Scopus Importer:2019-07-23

Investigation of the tribological behavior of car body parts in series production - Hansen, B.; Purr, S.; Meinhardt, J.; Merklein, Marion (6th ICAFT – International Conference on Accuracy in Forming Technology 25th SFU – Saxon Conference on Forming Technology 6th AutoMetForm – International Lower Silesia – Saxony Conference on Advanced Metal Forming Processes in the Automotive Industry, 2019)
CRIS-Team WoS Importer:2020-09-25

Investigation of the tribological behaviour of alloyed hot stamping tools in contact with AlSi coated 22MnB5 - Neubauer, Franziska; Rupprecht, P.; Hofmann, K.; Andreas, Kolja; Merklein, Marion (2017)
LFT Import::2019-08-05 (2270)

Investigation of the tribological behaviour of microstructures for controlling the material flow in sheet-bulk metal forming - Löffler, Maria; Engel, Ulf; Willner, Kai; Beyer, Florian; Merklein, Marion (CIRP Journal of Manufacturing Science and Technology, 2018)
Sheet-bulk metal forming (SBMF) processes are characterized by a successive and/or simultaneous occurrence of different load conditions with regard to stress and strain states. These conditions significantly influence the material flow and thus the geometrical accuracy of the produced components. To improve the product quality a control of the material flow is required. A suitable approach is given by a local modification of the tribological conditions using surface modifications of tool or workpiece. To control the material flow, methods to adjust the friction are needed. Within the present study, microstructured workpiece surfaces to reduce the friction are investigated. The aim of the study is the determination of the tribological mechanisms of this kind of surface modifications. To identify the mechanisms a combined experimental and numerical approach was used. The use of such a combined approach revealed that the structure volume and the interaction between different types of structures significantly influence the friction reducing potential of microstructured workpiece surfaces.<br
Keywords: Sheet-bulk metal forming; Tribology; Surface modification; Surface analysis; Modelling

Investigation of the Tribological Impact of the Tool Radius on a Strip Drawing Test Rig With Redirection - He, Franz; Merklein, Marion (9th International Conference on Hot Sheet Metal Forming of High-Performance Steel, CHS2 2024 - Proceedings, 2024)
With the rise in electric vehicles, the focus on the reduction in the overall weight of the personalized motorized vehicle provides a central focus point in the automotive industry. Hot stamping has been established as a suitable process for the generation of critical structural components in the body in white which provide improved strength and stiffness at reduced component weight. Due to the high process temperatures suitable lubricants have not yet been found. Direct results are both high friction and occurrences of wear on both tool and workpiece. To characterize the tribological conditions in the hot stamping process flat strip drawing tests have been commonly used. These however only accurately represent the flange area of a workpiece, while the critical sheet thinning can be observed at radii where the additional bending motion changes the contact conditions. To properly reproduce the tribological conditions in the tool radius area an existing strip drawing test rig at the Institute of Manufacturing Technology has been modified to allow for a strip drawing test with redirection. Using the test rig in combination with the results of a simulation of the process allows for an inverse determination of the friction coefficients present. The results of this study help to improve the process understanding of the contact and tribological conditions in the tool radius area in the hot stamping process. Furthermore tailored measures can be developed based on the findings of this study to improve the part quality and overall tool lifetime.
CRIS-Team Scopus Importer:2024-07-19

Investigation of the tribological performance of a-C:H coating systems by modifying adhesive layer for application in dry deep drawing - Rothammer, Benedict; Zhao, Rong; Krachenfels, Kim; Merklein, Marion; Tremmel, Stephan (International Tribology Conference Sendai 2019, 2019)
Lubricants are essential in conventional deep drawing processes to improve the tribological behavior and product quality. Requirements for increasing sustainability and resource efficiency motivate the realization of lubricant-free deep drawing processes. However, the direct contact between tool and workpiece during dry deep drawing leads to increased adhesive wear and surface damage on the sheet metal. A promising approach to face these challenges due to dry deep drawing is the application of amorphous carbon coating systems on tool surfaces. The roughness peaks on the coating surface caused by deposition have to be kept as low as possible, in order to reduce the risk of abrasive wear caused by interlocking into the ductile metal sheet and thus the initial adhesive wear can be avoided. In this study, the influence of adhesive layer on the topography of a‑C:H functional layer is investigated and its tribological performance verified. The modified deposited a‑C:H coating system exhibits similar adhesion to the substrate as the standard a‑C:H coating system. In addition, it shows a more homogeneous surface topography without formation of droplets. Due to the modified adhesion layer, the Rpk value in as-deposited state is 10 times lower by changing the deposition technique of the chromium adhesive layer. As a result, the extremely low roughness peaks of the coating penetrate only slightly into the rough sheet surface with EDT texturing. The standard and modified a‑C:H coated tool surfaces against two common used aluminum alloys (AA6014, AA5182) are applied for the tribological evaluation by the flat strip drawing test. The analysis of the resulting coefficients of friction shows that the tribological behavior is directly influenced by the roughness. The roughness of the functional layer and thus the tribological behavior can be changed by the application of different adhesive layers. Furthermore, the tool and workpiece surfaces are characterized before and after the test in order to investigate wear mechanisms on tool
Keywords: Tribology; Dry Sheet Metal Forming; Diamond-like Carbon (DLC) Coating; Roughness

Investigation of the Unloading Yield Effect in Aluminum and Magnesium Sheet Metal Alloys at Room Temperature - Degner, Julia; Suttner, Sebastian; Merklein, Marion (Key Engineering Materials, 2016)
LFT Import::2019-07-29 (2178)
Keywords: Advanced Lightweight Materials; Material Characterization; Unloading Yield

Investigation of the wear behavior for not alloyed and alloyed hot forming tools - Neubauer, Franziska; Hofmann, K.; Andreas, Kolja; Merklein, Marion (WGP Congress 2016, 2016)
LFT Import::2019-08-05 (2201)

Investigation of Tribological Behavior of Carbon Coatings in Dry Sheet Metal Forming - Steiner, Jennifer; Zhao, Rong; Tremmel, Stephan; Merklein, Marion (Proceedings 12th International Conference THE "A" Coatings 2016, 2016)
Keywords: Dry Sheet Metal Forming; Carbon Coating; Tribology; Friction

Investigation of Tribological Behaviour of a-C:H Coatings for Dry Deep Drawing of Aluminium Alloys - Zhao, Rong; Steiner, Jennifer; Andreas, Kolja; Merklein, Marion; Tremmel, Stephan (Abstracts Programme, 2016)
Keywords: Dry metal forming; DLC; aluminium; adhesive wear

Investigation of tribological behaviour of a-C:H coatings for dry deep drawing of aluminium alloys - Zhao, Rong; Steiner, Jennifer; Andreas, Kolja; Merklein, Marion; Tremmel, Stephan (Tribology International, 2017)
Lubricant‑free sheet metal forming increases resource efficiency and contributes to environmental protection. One approach to reducing friction and wear in dry forming is the tool-sided application of carbon-based coatings. In this work, amorphous hydrogenated carbon (a‑C:H) coatings were prepared by plasma‑enhanced chemical vapour deposition (PECVD). The coating samples were deposited under different amounts and ratios of acetylene (C2H2) and argon (Ar) gas atmospheres. The coating samples were characterized regarding their thickness, roughness and mechanical as well as chemical bond structures. The tribological behaviour against aluminium alloys was investigated under lubricant‑free conditions with a ring‑on‑disc tribometer. The relationships between chemical bond composition and coating properties were clarified. Finally, one a-C:H coating variant with promising tribological performance against aluminium alloys was exemplarily tested in a flat strip drawing test, which models the tribological conditions in the flange area of a deep drawing process.
Keywords: Dry sheet metal forming; DLC; aluminium; adhesive wear

Investigation of Tribological Conditions within Partial Hot Stamping - Schwingenschlögl, Patrik; Steiner, Jennifer; Andreas, Kolja; Merklein, Marion (Hot Sheet Metal Forming of high-Performance Steel - CHS2, 2017)
The importance of lightweight construction in modem car bodies is motivated by current challenges like reducing the fuel consumption and increasing safety standards. Besides the substitution of common steel grades with aluminum alloys and high strength steels, hot stamping has been established for producing safety relevant components. By using hot stamped parts, the fuel consumption can be reduced while improving the crash performance due to the substitution of conventional steel grades by hot stamped high strength steels with thinner sheet thickness. Partial hot stamping represents a variation of direct hot stamping and provides the opportunity of adjusting the final mechanical properties by altering the tool temperature. Thus, the passenger safety can be further improved by producing structural components with tailored properties considering the final requirements. Finite-element (FE) simulation plays an important role for the design of partial hot stamping processes due to thermo-mechanical interdependences taking place during the forming. In order to achieve an accurate modelling of the process, reliable input parameters are necessary. Currently, hot stamping processes are modelled assuming a constant friction coefficient due to the knowledge gap regarding the tribological behavior within hot stamping. For the experimental investigation of the tribological conditions under direct hot stamping conditions, a hot strip drawing test rig is used within this study. The influence of tool temperature on the friction is examined for varied workpiece temperatures, contact pressures and drawing velocities. The experiments are performed with AISi coated 22MnB5. For analyzing friction and wear mechanisms, the surfaces of the specimens are characterized.
LFT Import::2019-08-05 (2234)

Investigation of Tribological Systems for Dry Deep Drawing by Tailored Surfaces - Merklein, Marion; Schmidt, Michael; Tremmel, Stephan; Wartzack, Sandro; Andreas, Kolja; Häfner, Tom; Zhao, Rong; Steiner, Jennifer (Dry Metal Forming Open Access Journal, 2015)

Investigation on a Microextrusion Process of Parallel Protrusions from Metal Strip - Stellin, Tommaso; Merklein, Marion; Engel, Ulf (Proc. 8th Int. Conf. Micro Manufacturing, 2013)
LFT Import::2019-08-05 (1898)

Investigation on a quasi-incremental tool concept to manufacture functional components with sheet thickness gradient - Hetzel, Andreas; Lechner, Michael; Merklein, Marion (12th Tooling 2022 Conference and Exhibition, 2022)
Efficient processes offer a promising approach to meet requirements from global trends like sustainability or resource shortage. The process of orbital forming is established for the manufacturing of functional components with a gradient in sheet thickness, like for example in a clutch. Nevertheless, the present tool setup disposes a lack in economic efficiency and is restricted by a maximum tumbling angle and a complex tool design. In this context, an innovative quasi-incremental process combination of tilting and turning is investigated with regard to the manufacturability of functional components with circumferential and cyclic symmetric elements. Due to the adapted kinematics, the contact area between tool and workpiece increases from the center in radial direction, resulting in a predominantly radial material flow. The aim within this research is the establishment of a comprehensive process understanding of the forming parameters. Therefore, components out of the case-hardening steel C10 are manufactured and evaluated, regarding the geometrical and mechanical properties. Different process strategies, like a varying number of tilting steps or the forming along different axis, are applied in order to improve the forming results. The potential of the alternative tool setup for the manufacturing of the components is qualified by comparing the parts with conventionally orbital formed specimens.<br
Keywords: Sheet-Bulk Metal Forming; Orbital Forming; Incremental Forming; Sheet Metal; Functional Component

Investigation on basic friction and wear mechanisms within hot stamping considering the influence of tool steel and hardness - Schwingenschlögl, Patrik; Niederhofer, Philipp; Merklein, Marion (Wear, 2019)
Hot stamping is a well-established technology for producing safety relevant car components. The use of hot stamped components in modern car bodies offers the possibility of improving crash performance due to their high strength while simultaneously decreasing the fuel consumption by reducing sheet thicknesses and thus weight. Hot stamped components are mainly produced using the boron-manganese-alloyed steel 22MnB5. To prevent formation of oxide layer during heat treatment and subsequent forming process, AlSi-coatings are applied on the workpiece surface. Since hot stamped parts are formed at temperatures between 600 degrees C and 800 degrees C, no suitable lubricants have been found yet. Thus, severe wear and high friction occur during the forming process affecting final part quality as well as life-time of hot stamping tools. Consequently, measures for reducing tribological load during the forming operation have to be found in order to improve part quality and increase efficiency of industrial hot stamping applications. Within this study, the impact of the tool material on friction and wear is analyzed by comparing the tribological behavior of the newly developed high thermal conductivity hot work tool steel Thermodur 2383 Supercool with the reference material 1.2367. Both are characterized by means of flat strip drawing experiments under hot stamping conditions. The experiments are performed with different hardness values for each of the two tool materials. Furthermore, wear behavior is analyzed using scanning electron microscope and confocal microscope measurements of workpiece and tool. Hereby, fundamental wear and friction mechanisms within hot stamping applications are identified. The results of this study help to increase the process understanding regarding the tribological conditions during hot stamping. In future research work tool-side measures for increasing the life-time of hot stamping tools will be developed.
CRIS-Team WoS Importer:2019-04-30

Investigation on blasted tool surfaces as a measure for material flow control in sheet-bulk metal forming - Merklein, Marion; Löffler, Maria; Gröbel, Daniel; Henneberg, Johannes (Manufacturing Review, 2019)
Highly integrated and closely tolerated functional components can be produced by sheet-bulk metal forming which is the application of bulk forming operations on sheet metal. These processes are characterized by a successive and/or simultaneous occurrence of different load conditions which reduce the geometrical accuracy of the parts. One challenge within sheet-bulk metal forming is the identification of methods to control the material flow to improve the product quality. A suitable approach is the local modification of the tribological conditions. Within this study, requirements regarding the needed adaption of the tribological system for a specific process were defined by numerical investigations. The results reveal that a local increase of the friction leads to an improved geometrical accuracy. Based on these results, abrasive blasting as a method to modify the tool surface and thus influencing the tribological behaviour was investigated. For the determination of the tribological mechanism of blasted tool surfaces, the influence of different blasting media as well as blasting pressures on the surface integrity and the friction were determined. Additionally, the functional stability of a modification was investigated. Finally, the correlations between surface properties and friction conditions were used to derive the mechanisms of blasted tool surfaces.
CRIS-Team WoS Importer:2019-06-07

Investigation on extrusion processes in sheet-bulk metal forming from coil - Henneberg, Johannes; Merklein, Marion (CIRP Journal of Manufacturing Science and Technology, 2020)
The increasing demand for functional-integrated lightweight components is bringing established manufacturing technologies to their limits and motivates research into the innovative process class of sheet-bulk metal forming (SBMF). By applying bulk forming operations to sheet metal, thin-walled components with integrated functional elements can be produced in short process chains by a three dimensional material flow. Currently, pre-cut blanks are frequently used for this purpose. Manufacturing components from coil would combine the advantages of SBMF with those of production from coil regarding high output quantities. Therefore, the objective of the present research is to develop a fundamental process understanding for SBMF of parts from coil. For this purpose, a lateral and a backward extrusion process are set up and numerically mapped for a process analysis. Known challenges in SBMF of pre-cut blanks are a limited component accuracy due to a partly uncontrolled material flow and high tool loads. Consequently, both are addressed in context of a production from coil in a combined numerical-experimental approach. An anisotropic material flow is identified as a coil-specific challenge and fundamental difference to the SBMF of blanks. It causes an unequal forming of the components. The sheet geometry as well as a local pre-hardening induced by the forming of previous parts are found to determine the anisotropic material flow. In addition, an understanding of the effects of anisotropic material flow on tool loads is developed. An unequal deflection of tools is found as a tool-specific challenge. The obtained process knowledge provides a basis for research into measures to counteract the anisotropic material flow as a central challenge of SBMF of coils in future work.
CRIS-Team Scopus Importer:2020-09-04
Keywords: Coil; Cold forming; Extrusion; Sheet metal; Sheet-bulk metal forming

Investigation on heating strategies for hot stamping of boron alloyed steels - Kolleck, R.; Veit, R.; Merklein, Marion; Lechler, Jürgen; Geiger, Manfred (CIRP Annals - Manufacturing Technology, 2009)
LFT Import::2019-08-05 (1572)

Investigation on micro textured tappets from design and production to the application properties - Reck, Manuel; Orgeldinger, Christian; Tremmel, Stephan; Merklein, Marion (Proceedings of the Institution of Mechanical Engineers Part L-Journal of Materials-Design and Applications, 2022)

Investigation on pin caulking as a versatile joining process - Römisch, David; Merklein, Marion (Materials Research Proceedings, 2023)

Investigation on tailored blanks in a full forward extrusion process of sheet-bulk metal forming - Reck, Manuel; Merklein, Marion (ESAFORM 2021, 2021)

Investigation on the influence of manufacturing parameters on the fatigue strength of components - Reiss, Andrea; Engel, Ulf; Merklein, Marion (Key Engineering Materials, 2013)
With cold forging processes it is possible to produce parts characterized by high strength, high dimensional accuracy and high surface quality. In order to optimize the forming process and to be able to use the advantages of cold forging specifically and combined, it is necessary to find correlations between the manufacturing parameters, the strength and the properties, like hardness distribution and surface quality, of the component. The research work covered in this paper focuses on the influence of the components properties influenced by its manufacturing history on their fatigue strength. The used component is a flange hub, produced by a four-stage cold forging process. To obtain different component properties the production process of the hub was varied for example by changing the heat treatment or by producing the parts by turning process. First of all, the components' properties, for example hardness distribution, remaining residual stresses, orientation of fibers and surface quality, were determined. Moreover, a special experimental setup for the fatigue tests has been designed. The components' fatigue behavior was determined using a high frequency pulsator and evaluated in terms of finite life fatigue strength and fatigue endurance limit. These examinations were used to produce Woehler curves for the differently manufactured components with a certain statistical data analysis method. Copyright © 2013 Trans Tech Publications Ltd.
LFT Import::2019-07-29 (1878)
Keywords: 1.0570; Cold forging; Fatigue strength; Influence of components properties on fatigue life

Investigation on the limp properties of formed foils for hydrogen applications - Wituschek, Simon; Römisch, David; Lechner, Michael; Merklein, Marion (IOP Conference Series: Materials Science and Engineering, 2024)
The mass production of bipolar plates for electrolyzers and fuel cells is a central step towards the realization of efficient and cost-effective energy systems of the future. However, current production processes are reaching their limits and can hardly realize the quantities that will soon be demanded, nor can they scale up to the required volumes. Particularly for the handling of half-plates and bipolar plates, major challenges are to be expected, especially with regard to production rates. Existing handling systems have restricted scalability and precision. Therefore, new stacking technologies are necessary, which have to be adaptable to the mechanical properties of the components and maintain tight tolerances during stacking to ensure hydrogen sealing for safety and efficiency. An important property in the handling of the plates is their limpness, which is distinguished by instability of the components as well as plastic deformation at low forces and moments. Therefore, the limp behavior of the components must be analyzed. To investigate the limpness of foil components, a flowfield is first formed using a 1.4404 stainless steel foil with a sheet thickness of 0.075 mm. Subsequently, the workpieces are analyzed in terms of their limp properties by means of a 3-point bending test.<br

Investigation on the load-bearing capacity and joint formation of hybrid functional components joined by orbital forming - Hetzel, Andreas; Wituschek, Simon; Römisch, David; Sippel, Frank; Lechner, Michael; Merklein, Marion (Proceedings of the Institution of Mechanical Engineers Part E-Journal of Process Mechanical Engineering, 2024)
Increasing material costs, decreasing availability, and ever-higher demands on environmental compatibility and complexity require new strategies in the development and production of functional components. Consequently, a combined approach from the areas of design, material science, and manufacturing is mandatory, in order to meet the requirements. Reducing the number of parts, using lightweight materials and applying hybrid components with a multimaterial mix are possible solutions. Nevertheless, conventional joining operations like welding or riveting are reaching their limits in terms of material utilization, load-bearing capacity as well as versatility of the process. Thus, innovative and versatile joining by forming operations and process combinations are focus of current research. In this context, the innovative process of orbital forming had been investigated as a joining by forming operation to manufacture load-adapted hybrid functional components. By tilting of one tool component during the process, a radial material flow is generated, allowing the crimping of the two joining partners. Nevertheless, the load-bearing capacity in axial direction could be identified as limiting factor for a possible application. Therefore, the aim of this investigation is the development of a fundamental process understanding on the influence of a novel geometrical adaption of the joint on the resulting load bearing capacity. The influence of varying geometrical proportions of the joint on the quality is evaluated, considering the form filling, the geometrical properties of the components as well as the maximum transmittable axial load. As joining partners, the dual-phase steel DP600 and the aluminum alloy EN AW-5754 with a thickness of 2.0 mm are use

Investigation on the Process Parameters and Process Window of "Three-Roll-Push-Bending" - Plettke, Raoul; Vatter, Peter; Vipavc, Daniel; Cojutti, Massimo; Hagenah, Hinnerk (Proc. 36th Matador Conf., 2010)
LFT Import::2019-08-05 (129)

Investigation on the shear cutting of functional components manufactured in an orbital forming process - Hetzel, Andreas; Lechner, Michael; Merklein, Marion (Materials Research Proceedings, 2023)
Applying forming operations for the manufacturing of complex functional components instead of conventional shearing or milling is an effective way to increase the material efficiency of the process as well as the mechanical properties of the part. Nevertheless, in many cases subsequent cutting operations are mandatory to reach the final geometry or to add functional surfaces for the later assembly. During forming, hardening effects or different strain states can cause difficulties for the subsequent cutting operation. These characteristics are commonly determined for sheet metal forming processes like deep drawing or bending. However, the complex stress and strain states during sheet-bulk metal forming operations and their influence on the cutting parameters or the part properties have not been investigated comprehensively so far. Furthermore, different assigned processes, like for example orbital forming, allow a local material distribution, realizing a gradient in sheet thickness. Therefore, this contribution focuses on the establishment of a fundamental process understanding on the influence of a sheet-bulk metal forming process on the cutting parameters and the resulting part properties. Functional components are manufactured from C10 sheet metal by orbital forming and subsequently shear cut to generate the final contour. During cutting, specific force-stroke diagrams are evaluated, in order to analyze the influence on the process parameters. The resulting properties of the parts are investigated regarding the quality of the cutting surface and a potential geometrical distortion in consequence of elastic spring back. The influence of the forming process is outlined by a direct comparison with conventionally cut components.<br
Keywords: Metal forming; Cutting; Orbital forming

Investigation on the thermo-mechanical properties of hot stamped parts by using laser-implanted tool surfaces - Schirdewahn, Stephan; Carstensen, Niels; Hilgenberg, Kai; Merklein, Marion (IOP Conf. Ser.: Mater. Sci. Eng. 1270 012114, 2022)
In the automotive industry, hot stamping has been established as a key technology for manufacturing safety-related car body components with high strength-to-weight ratio. During the forming operation, however, hot stamping tools are highly stressed by cyclic thermo-mechanical loads, which encourage the formation of severe wear and high friction at the blank-die interface. Against this background, an innovative surface engineering technology named laser implantation has been investigated for improving the formability of the parts and the efficiency of the hot stamping process. The laser implantation process is based on the generation of highly wear resistant microfeatures on tool surfaces by embedding hard ceramic particles via pulsed laser radiation. As a consequence, the contact area of the tool and thus the tribological and thermal interactions at the blank-die interface are locally influenced. In previous studies, the improved tribological performance of the modified tool surfaces has already been proven. However, the thermal interactions between tool and workpiece have not been analyzed, which in turn have a significant impact on the resulting part properties. In this regard, quenching tests have been carried out under hot stamping conditions by using conventional as well as laser-implanted tooling systems. Based on these results, Vickers hardness test and optical measurements have been performed on the quenched blanks, to qualify the mechanical properties and clarify the cause-effect relations.<br
Keywords: hot stamping; laser implantation; friction; wear; quenching

Investigation on the Tribological Behavior of Tool-sided Tailored Surfaces for Controlling the Material Flow in Sheet-Bulk Metal Forming - Henneberg, Johannes; Lucas, H.; Denkena, B.; Merklein, Marion (AIP Conference Proceedings, 2019)
The increasing demand for closely tolerated and highly integrated functional components motivates the development of the innovative process class sheet-bulk metal forming (SBMF). SBMF is defined as the application of bulk forming operations on sheet metal to produce parts with integrated functional elements. Due to varying tribological loads, caused by the local forming of functional elements and the resulting complex material flow, the geometrical accuracy of the produced parts can be limited. A local increase or decrease of friction by modified surfaces also called tailored surfaces which control the material flow are an approach to improve the geometrical accuracy of the part. These tailored surfaces should be applied tool-sided to guarantee a short process chain. Consequently, the aim of this study is to analyze the potential of modified tool surfaces for a usage as tailored surfaces in SBMF processes. The tribological behavior of tailored tool surfaces is investigated to provide a basis for the selection of tailored surfaces. Different grinding and blasting strategies, as well as lubrication pockets are chosen as surface modifications and applied on the tool steel 1.3344 with a hardness of 61 ± 2 HRC. Lapped tools are chosen as a reference for the modified surfaces, since lapping is a widespread finishing process for forming tools. First of all, the topographies of the modified surfaces are characterized using optical and tactile measurements. Afterwards the tribological behavior of the surfaces is investigated using a modified ring compression test with specimens made of 1.0338. The resulting friction factors are correlated with the topography characteristics of the tailored surfaces to identify functional interrelations. Finally, the tailored surfaces are evaluated regarding their eligibility to adapt the friction and control the material flow in SBMF-processes.
CRIS-Team Scopus Importer:2019-07-23

Investigation on the wear behavior of coatings for lubricant-free deep drawing processes with a novel application-oriented test rig - Henneberg, Johannes; Merklein, Marion (Defect and Diffusion Forum, 2020)
Lubricant-free deep drawing is motivated by the avoidance of using environmentally harmful lubricants as well as the potential for shortening the process chain by eliminating lubricant application and component cleaning. Central challenges of dry deep drawing are a significant increase in friction as well as in adhesive tool wear due to a lack of a separating lubricant layer between tool and workpiece. An approach to meet these challenges is the modification of the tools through diamond-like coatings. Based on findings from laboratory tests, a-C:H and ta-C coatings were selected and their effectiveness in overcoming these challenges was demonstrated in single stroke tests in previous research. In order to use the process-specific advantages of forming technology, high tool life is required. In this context, this research aims at investigating the application behavior of a-C:H and ta-C coatings during lubricant-free deep drawing of a high number of components made of the aluminum alloy AA5182. For this purpose, a new wear test rig is applied, which enables the time and material efficient production of high quantities. Numerical methods are utilized to identify the drawing die radius as well as the blank holder as the highest loaded areas. Based on these findings, the wear of the coatings as well as that of an uncoated tool as a reference is analyzed in these areas by optical and tactile measurements. In addition, the influence of tool wear on the component surface quality is determined. It is proven that the ta-C coating increases the tool life from 10 components in uncoated condition up to 3,000 components.
CRIS-Team Scopus Importer:2020-11-27
Keywords: Coating; Sheet metal; Tribology

Investigation on tool properties for the production of components with micro textured surfaces - Reck, Manuel; Merklein, Marion (IOP Conference Series: Materials Science and Engineering, 2022)

Investigations and approaches on material flow of non-uniform arranged cavities in sheet bulk metal forming processes - Gröbel, Daniel; Koch, Johannes Peter Karl; Vierzigmann, Ulrich; Engel, Ulf; Merklein, Marion (Procedia Engineering, 2014)
LFT Import::2019-07-29 (2050)
Keywords: Flow-control; Process simulation; Sheet-bulk metal forming; Tribology

Investigations of batch fluctuation regarding tribological conditions in series production of car body parts - Hansen, B.; Wagner, P.; Purr, S.; Merklein, Marion (International Journal of Material Forming, 2021)
Fluctuations of material properties are one reason for the occurrence of cracks and waviness in series production of car body parts. Especially fluctuating tribological conditions have an effect on the friction behavior and thus on the material flow. So far fluctuating material properties are not considered in the standard FE-simulation and consequently not in the tool design. In order to enhance the accuracy of the simulation result and thus improve the tool design regarding a robust process, the appearance of batch fluctuations has to be consistently understood. Therefore, the impact of varying lubricant quantities and roughness have been investigated. Several batches have been analyzed to identify the main influencing parameter regarding the friction behavior. Flat strip-drawing tests have been performed to determine the friction coefficient. The investigations have been performed by using material from the series production, as delivered. Since the amount of lubricant turns out to be the main influencing factor, the characteristics and appearance of the lubricant distribution has been analyzed in a further step. The analysis has shown that the distribution of the lubricant changes within one coil over the coil width and length. In addition, the time of storage has been identified as one main influencing factor on the homogeneity of the lubricant distribution over the coil width. Based on these findings, a method has been developed to map the series production conditions regarding the friction conditions in the simulation. Hence, simulations were performed using a side frame blank with different friction conditions, to investigate the impact on the forming result. The results reveal that by considering realistically existing tribological conditions, more scrap is to be expected compared to the conventional simulation. This leads to the conclusion that previous simulation results are too optimistic. Consequently, the introduced method offers the potential to optimize the tool design by considering fluctuating tribological conditions already in the process of development. Thus, it is possible to reduce scrap and increase productivity.
CRIS-Team Scopus Importer:2021-01-22
Keywords: Friction; Material; Tribology

Investigations of ductile damage during the process chains of toothed functional components manufactured by sheet-bulk metal forming - Isik, Kerim; Gerstein, Gregory; Schneider, Thomas; Schulte, Robert Karl; Rosenbusch, Daniel; Clausmeyer, Till; Nuernberger, Florian; Vucetic, Milan; Koch, Sergej; Huebner, Sven; Behrens, Bernd-Arno; Tekkaya, A. Erman; et al. (Production Engineering, 2016)
Sheet-bulk metal forming processes combine conventional sheet forming processes with bulk forming of sheet semi-finished parts. In these processes the sheets undergo complex forming histories. Due to in- and out-of-plane material flow and large accumulated plastic strains, the conventional failure prediction methods for sheet metal forming such as forming limit curve fall short. As a remedy, damage models can be applied to model damage evolution during those processes. In this study, damage evolution during the production of two different toothed components from DC04 steel is investigated. In both setups, a deep drawn cup is upset to form a circumferential gearing. However, the two final products have different dimensions and forming histories. Due to combined deep drawing and upsetting processes, the material flow on the cup walls is three-dimensional and non-proportional. In this study, the numerical and experimental investigations for those parts are presented and compared. Damage evolution in the process chains is simulated with a Lemaitre damage criterion. Microstructural analysis by scanning electron microscopy is performed in the regions with high mechanical loading. It is observed that the evolution of voids in terms of void volume fraction is strongly dependent on the deformation path. The comparison of simulation results with microstructural data shows that the void volume fraction decreases in the upsetting stage after an initial increase in the drawing stage. Moreover, the concurrent numerical and microstructural analysis provides evidence that the void volume fraction decreases during compression in sheet-bulk metal forming.
LFT Import::2019-07-29 (2147)
Keywords: FE simulation; Lemaitre damage model; Sheet-bulk metal forming

Investigations on austenitization parameters influencing wear behavior within hot stamping - Merklein, Marion; Wieland, Michael (Procedia Engineering, 2014)
LFT Import::2019-07-29 (2049)
Keywords: Alsi; Austenitization; Hot stamping; Wear

Investigations on different strategies for influencing the microstructural properties with respect to partial hot stamping - Stöhr, Thomas; Lechler, Jürgen; Merklein, Marion (Proceedings 2nd International Conference Hot Sheet Metal Forming of High-Performance Steel - CHS², 2009)
LFT Import::2019-08-05 (215)

Investigations on Double Sheet Hydroforming with Counterpressure - Cojutti, Massimo; Merklein, Marion; Geiger, Manfred (2nd International Conference on New Forming Technology, 2007)
LFT Import::2019-08-05 (1451)

Investigations on foaming AFS-tailored blanks - Dörfler, Stephan Manuel; Otto, Andreas (Cellular Metals and Polymers, 2005)
LFT Import::2019-07-16 (1122)

Investigations on Formability and Tribology of Magnesium Sheets with Regard to Warm Forming processes - Geiger, Manfred; Merklein, Marion; Hecht, Joachim; Stich, A. (Proceedings of the 7th International Conference on Magnesium Alloys and their Applications, Nov 6-9, Dresden, Germany, 2006)
LFT Import::2019-08-05 (1337)

Investigations on Formability and Tribology with Regard to Warm Forming of Magnesium Sheets - Geiger, Manfred; Merklein, Marion; Hecht, Joachim (Production Engineering. Annals of the German Academic Society for Production Engineering, 2006)
LFT Import::2019-08-05 (1305)

Investigations on Forming Limits within Hot Stamping - Geiger, Manfred; Arbak, Murat; Engel, Ulf (Production Engineering, 2008)
LFT Import::2019-07-29 (1535)

Investigations on load spectrum and adhesive wear development in hot stamping operations - Wieland, Michael; Neubauer, Franziska; Andreas, Kolja; Merklein, Marion (The "A" Coatings Conference Proceedings, 2016)
LFT Import::2019-08-05 (2166)

Investigations on orbital forming of sheet metals to manufacture tailored blanks with a defined sheet thickness variation - Plettke, Raoul; Opel, Simon (Advanced Materials Research, 2013)
Orbital forming is an incremental bulk cold forming process with many advantages. It can produce net-shape or near-net-shape parts that have superior mechanical properties due to work hardening compared to manufacturing with cutting processes or hot forming. In this work the orbital forming process is employed in a closed-die configuration. A rising of the material thickness in the outer areas of a circular sheet metal blank is enabled by preventing the lateral material flow. The main effects and subsequently the effects of the interaction of parameters were investigated by a two-step design of experiments. A screening plan was used to identify the statistically relevant parameters. The effects were then studied in a subsequent central-composite design of experiments. With the measured data a nonlinear response-surface model was parameterized to describe the dependency of the mould filling on the investigated process parameters. This model was validated experimentally and showed a good agreement to reality. Additionally a new concept for the tool system was developed and investigated. The form-defining cavity can be changed from the upper punch to the counterpunch. © (2013) Trans Tech Publications, Switzerland.
LFT Import::2019-07-29 (1883)
Keywords: Cold forming; Orbital forming; Steel

Investigations on Parameters Influencing Thermal and Frictional Properties within Hot Stamping - Merklein, Marion; Stöhr, Thomas; Svec, Thomas; Wieland, Michael (Journal of Heat Treatment and Materials, 2011)
LFT Import::2019-07-29 (1772)
Keywords: Abrasive wear; Adhesive wear; Heat tnmsler; Hot stamping; Jriclion

Investigations on Residual Stress Generation in Extruded Steel Components - Jobst, Andreas; Kiener, Christoph; Merklein, Marion (9th Congress of the German Academic Association for Production Technology (WGP), 2019)
During the forming of components, inhomogeneous stress conditions lead to residual stresses, which influence the operating behaviour of the manufactured part. Compressive residual stresses generally have a positive effect, while tensile residual stresses reduce the fatigue strength and facilitate crack initiation. Full forward extrusion has been established as an industrial manufacturing technique, where cylindrical billets are formed in the die and ejected in opposite direction. In order to influence the residual stresses state, it is essential to know about its formation. A basic understanding is created by separate investigation of the forming and the ejection step. In the context of this paper, singlephase ferritic stainless steel X6Cr17 and ferritic-austenitic duplex steel X2CrNi- MoN22-5-3 are used. The quantification of the residual stresses states is carried out by X-ray diffractometry, for which a measurement method for duplex steel is validated. The influence of forming and ejection is determined separately by manufacturing components with and without an ejection operation.<br
Keywords: Residual Stress; Forward Extrusion; Stainless Steel

Investigations on residual stress generation in full-forward-extrusion - Landkammer, Philipp; Jobst, Andreas; Kiener, Christoph; Steinmann, Paul; Merklein, Marion (Production Engineering, 2019)
Within cold-forming processes, the influence of forming induced residual stresses is a critical issue regarding the life-time behaviour of the formed components. However, a targeted use of forming-induced residual stresses is also capable to improve the components properties. The rotation-symmetrical full-forward extrusion is used as a reference process to investigate the generation of residual stresses within manufacturing. A novel and generally applicable computational evaluation procedure is introduced, which achieves to compute and visualize the evolution of the residual stress state during the entire forming operation. Simulative results are compared with their experimental counterparts. The near-surface residual stresses in the formed component are evaluated in axial and tangential direction by X-ray diffraction. Indentation tests are used to determine the micro-hardness inside the components and optical instruments quantify geometrical difference
Keywords: Residual stresses· Full-forward-extrusion· Experimental validation· Advanced post processing

Investigations on Seam Quality in Laser Beam Welding of Contaminated, Zinc Coated Sheets - Blankl, Andreas; Geiger, Manfred (Sheet Metal 2005, Proceedings of the 11th International Conference on Sheet Metal, 2005)
The customers' demand for high quality and low cost products with rising functionality forces the enterprises to cost savings. In production these cost savings can be accomplished by simplification or omission of handling operations in the process chain. In laser beam welding of stamped sheet metals a previous cleaning of the sheets is usually necessary to guarantee a sufficient seam quality at a lap joint. Due to the recent trend towards low use of lubricants in forming operations the question arises, whether this process could be avoided in order to lower the production costs. The disadvantage of this measure would be a degradation of the seam quality. This reduction shows up in a falling strength of the weld due to inclusions and pore formation. This paper deals with the impact of different types of contaminations on the quality of laser welding. Therefore several liquid (oils) and solid (metallic and non-metallic) contaminants are examined. Zinc coated sheets are investigated too, because a zinc contamination arises with these sheets in the welding operation. The zinc coating evaporates because of the high temperature and this leads to a high porosity in the welding seam. In both cases also the height of the gap between the two sheets is varied in order to investigate its influence on the weld. To reduce the effort of the investigations, but not the accuracy of the results, the laboratory trials were supported by the methods of design of experiments. After the welding operation, the quality of the welding seam is evaluated by means of its mechanical properties and tightness. The results of the investigations are discussed and the developed solution strategies are presented.
LFT Import::2019-08-05 (1138)
Keywords: Lubrication; Nd:YAG laser; Welding

Investigations on sheet metal forming of hybrid parts in different stress states - Hafenecker, Jan; Merklein, Marion (Production Engineering, 2022)
Conventional processes are being pushed to their limits by growing demands in terms of sustainability and diversity of variants. Hybrid components, which are produced by a combination of two or more manufacturing processes, are a suitable way of meeting these challenges. The combination of sheet metal forming processes with additive manufacturing offers the potential to link personalized components with standardized parts. Knowing that the additively manufactured components influence the forming process, it is essential to understand the interactions in detail. Therefore, this work will compare the influence of several additively manufactured elements (AME) for deep drawing with two different punch geometries. The approach used combines experimental and numerical investigations to improve process insight in relation to sheet metal forming of hybrid components. The results show that the AMEs amplify existing stresses and strains in dependence of the present load. Sections subjected to low loads, as it is found in the bottom of the cup manufactured with a cylindrical punch, are hardly affected, whereas stronger loaded areas, e.g. the center of the parts manufactured with a hemispherical punch, are affected all the more.<br
Keywords: Additive manufacturing; Powder bed fusion; Hybrid; Sheet metal forming; FEM; 316L

Investigations on Surface and Process Parameters Influencing the Friction Behavior in Hot Sheet Metal Forming - Bachmann, M.; Zöller, Fabian; Ademaj, A. (Proc. 4th Int. Conf. Hot Sheet Metal Forming of High-Performance Steel, 2013)
LFT Import::2019-08-05 (1904)

Investigations on TaC Localized Dispersed X38CrMoV5-3 Surfaces with Regard to the Manufacturing of Wear Resistant Protruded Surface Textures - Spranger, Felix; Schirdewahn, Stephan; de Oliveira Lopes, Marcelo; Merklein, Marion; Hilgenberg, Kai (Lasers in Manufacturing and Materials Processing, 2019)
Purpose: The potential of lowered surface features as well as the application of wear resistant coatings have been known for many years to improve the tribological behavior of forming tools. More recent studies also discuss the capability of protruded microfeatures for adjusting the tribological behavior between contacting surfaces. The demand for a high wear resistance of such structures as well as their economical and reliable production, however, often limits the industrial application. The laser implantation process can overcome these limitations. In contrast to conventional cw-laser dispersing processes, where the formation of uniform metal matrix composite layers is intended, this surface engineering technique aims to improve the tribological behavior of contacting surfaces by a localized dispersing of pre-placed hard ceramic particles. This enables the formation of deterministic textures composed of separated wear resistant dome- or ring-shaped microstructures (implants). Since TaC shows very promising material properties for improving the wear resistance of tools exposed to severe operating conditions, this paper analyzes its suitability for pulsed laser implantation on X38CrMoV5-3 tool steel for the first time. Methods: In the experiments, the influence of the particles and the laser parameters (pulse power, pulse duration and focal diameter) on the material properties of the localized dispersed zones was studied by optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. The composite’s (micro-) hardness was measured and calculated by using a rule of mixture. Additionally, the influence of the laser parameters and the TaC particles on the geometrical properties of the implants was studied by optical microscopy and white light interferometry. Results: The results showed that defect-free implants with hardness values of 900 HV1 can be obtained at the focal spot, since a localized dispersing of the TaC particles is possible using a pulsed millisecond laser. However, in dependence of the laser intensity, also a partial dissolution of the initial particles occurs. This leads to the precipitation of new dendritic TaC nanoparticles and to varying contents of retained austenite in the matrix. Both effects have a strong influence on the implant hardness and must be considert by the rule of mixture. Regarding the geometrical response it was pointed out that protruded microfeatures with heights up to 10 μm can be created. In comparison to laser remelted zones, the implanted zones showed significantly altered weld pool profiles due to the influence of the particles on the melt convection. A transition of the implant shape from predominantly dome-shaped to predominantly ring-shaped was observed for intensities >1.7∙106 W/cm2 due to the onset of the keyhole effect. Conclusions: In conclusion, TaC particles seem to be very suitable for laser implantation on hot-work tool steels. The implants can be used for textures, where flat structures are needed. Since the TaC particles can be dispersed in the LIZ, it may be possible to reduce abrasive and adhesive wear due to the promising material properties of this hard phase and the improved hardness of the implants.
CRIS-Team Scopus Importer:2019-12-27
Keywords: Hot-work tool steel; Laser implantation; Localized laser dispersing; Surface texturing; TaC; Tantalum carbide; X38CrMoV5-3

Investigations on the Flow Behavior of Boron-Manganese Steels at elevated strain rates - Stöhr, Thomas; Merklein, Marion (Proceedings 3rd International Conference on Hot Sheet Metal Forming of High-Performance Steel, 2011)
LFT Import::2019-08-05 (1736)

Investigations on the Mechanical Properties and Formability of Friction Stir Welded and Laser Welded Aluminium Tailored Blanks - Staud, Detlev; Merklein, Marion; Fratini, L.; Buffa, G. (5th Laser Assisted Net Shape Engineering LANE, 2007)
LFT Import::2019-08-05 (1440)

Investigations on the Mechanical Properties and Formability of Friction Stir Welded Tailored Blanks - Buffa, G.; Fratini, L.; Merklein, Marion; Staud, Detlev (Proceedings of the 12th International Conference on Sheet Metal (SheMet), 2007)
Tight competition characterizing automotive industries in the last decades has determined a strong research effort aimed to improve utilized processes and materials in sheet stamping. As far as the latter are regarded light weight alloys, high strength steels and tailored blanks have been increasingly utilized with the aim to reduce parts weight and fuel consumptions. In the paper the mechanical properties and formability of tailored welded blanks made of a precipitation hardenable aluminum alloy but with different sheet thicknesses, have been investigated: both laser welding and friction stir welding have been developed to obtain the tailored blanks. For both welding operations a wide range of the thickness ratios has been considered. The formability of the obtained blanks has been characterized through tensile tests and cup deep drawing tests, in order to show the formability in dependency of the stress condition; what is more mechanical and metallurgical investigations have been made on the welded joints.
LFT Import::2019-08-05 (1394)
Keywords: Friction stir welding; Laser welding; Tailored blank

Investigations on the thermal behavior of ultra high strength boron manganese steels within hot stamping - Merklein, Marion; Lechler, Jürgen; Stöhr, Thomas (International Journal of Material Forming, 2009)
LFT Import::2019-07-29 (221)

Investigations on Three-Roll Bending of Plain Tubular Components - Merklein, Marion; Hagenah, Hinnerk; Cojutti, Massimo (Key Engineering Materials, 2009)
Bent metal tubes find a widespread application in many industrial sectors. Among different bending processes developed for the manufacturing of these components, three-roll bending is characterized by a high flexibility, as only one toolkit per tube diameter is necessary to form the required bending radius. In this type of forming process the part geometry is obtained by means of a relative movement of the die (setting roll) towards the fixed tools (bending and holding roll) with simultaneous feeding of the tube. This study describes the FE-model developed for the three-roll bending and presents first results of numerical investigations conducted on steel tubes made of carbon steel St37. By the FE-analysis great attention is paid on the modeling of the stiffness of the tool, on the description of the kinematics of the setting roll as well as on the characterization of the material behavior for the simulation. The results of the numerical investigations are compared with experiments conducted with a CNC-bending machine available at the Chair of Manufacturing Technology of the University of Erlangen. As a main criterion for the validation of the FE-model the radius of the tube at the extrados and the bending angle are chosen. The geometry of the part is measured by means of both optical and tactile measuring devices.© (2009) Trans Tech Publications, Switzerland.
LFT Import::2019-07-29 (916)
Keywords: FE-analysis; Three-roll bending; Tube bending

Investigations towards extended stability in laser brazing - Grimm, A.; Schmidt, Michael; Dietrich, Simon; Hoffmann, Peter; Geiger, Manfred (Laser Assisted Net Shape Engineering 5 - Proceedings of the LANE 2007, 2007)
LFT Import::2019-08-05 (1448)

Irradiation planning for automated treatment of psoriasis with a high-power excimer laser - Klämpfl, Florian; Schmidt, Michael; Hagenah, Hinnerk; Görtler, A.; Wolfsgruber, F.; Lampalzer, R.; Kaudewitz, P. (Photonics West 2006: Integrated Optoelectronic Devices, 2006)
American and European statistics have shown that 1-2 per cent of the human population is affected by the skin disease psoriasis. Recent research reports promising treatment results when irradiating skin areas affected by psoriasis with high powered excimer lasers with a wavelength of 308 nm. In order to apply the necessary high energy dose without hurting healthy parts of the skin new approaches regarding the system technology must be considered. The aim of the current research project is the development of a sensor-based, automated laser treatment system for psoriasis. In this paper we present the algorithms used to cope with the difficulties of irradiating irregularly shaped areas on curved surfaces with a predefined energy level using a pulsed laser. Patients prefer the treatment to take as little time as possible. This also helps to reduce costs. Thus the distribution of laser pulses on the surface to achieve the given energy level on every point of the surface has to be calculated within a limited time frame. The remainder of the paper will describe in detail an efficient method to plan and optimize the laser pulse distribution. Towards the end. some first results will be presented.
LFT Import::2019-08-05 (1257)
Keywords: Automated irradiation; Excimer laser; Optimization; Planning; Psoriasis

.: Is Magneto Inductive Testing a Satisfactory Substitute For Destructive Tensile Test of Steel Sheet and Plate?. - Lutz, Barbara; Engel, Ulf; Schwind, Michael (Proc.6th Europ. Conf. on Nondestructive Testing ECNDT'94, Vol. 2, 1994)
None
LFT Import::2019-08-05 (1985)

Ist die LED ein Laser? Eine kritische Betrachtung der europäischen Regelungen zum Laserschutz - Eßer, Gerd; Klettke, O. (Europäischer Laser-Markt, 2006)
LFT Import::2019-07-16 (1282)

Joinability of the High-strength Aluminium Alloy AA7075 in Shear-clinching Processes - Wiesenmayer, Sebastian; Merklein, Marion (2nd International Conference on Advanced Joining Processes AJP 2021, 2021)

Joining by forming technologies: current solutions and future trends - Buffa, Gianluca; Fratini, Livan; La Commare, Umberto; Römisch, David; Wiesenmayer, Sebastian; Wituschek, Simon; Merklein, Marion (International Journal of Material Forming, 2022)
The progressively more demanding needs of emissions and costs reduction in the transportation industry are pushing engineers towards the use of increasingly lightweight structures. This goal can be achieved only if dissimilar and/or new materials, including polymers and composites, are joined together to create complex structures. Conventional fusion welding processes have often been proven inadequate to this task because of the high heat input reducing the joint mechanical properties or even making the joining process impossible. Joining by forming technologies take advantage on the plastic deformation to create sound joints out of even very dissimilar materials. Over the last 25 years, several new processes, with increasing potential in effectively joining virtually every structural material, have been invented and developed. In the paper, a comprehensive overview of the most utilized joining by forming processes is given. For each process, an analysis of the current research trends and hot topics is provided, highlighting strengths and weaknesses for industrial application
Keywords: Light alloy; Joining; Welding; Solid state; Clinching; Riveting

Joining of CFRT/Steel Hybrid Parts via Direct Pressing of Cold Formed Non-Rotational Symmetric Pin Structures - Popp, Julian; Römisch, David; Merklein, Marion; Drummer, Dietmar (Applied Sciences, 2022)
In this study, quasi-unidirectional continuous fiber reinforced thermoplastics (CFRTs) are joined with metal sheets via cold formed cylindrical, elliptical and polygonal pin structures which are directly pressed into the CFRT component after local infrared heating. In comparison to already available studies, the unique novelty is the use of non-rotational symmetric pin structures for the CFRT/metal hybrid joining. Thus, a variation in the fiber orientation in the CFRT component as well as a variation in the non-rotational symmetric pins’ orientation in relation to the sample orientation is conducted. The created samples are consequently mechanically tested via single lap shear experiments in a quasi-static state. Finally, the failure behavior of the single lap shear samples is investigated with the help of microscopic images and detailed photographs. In the single lap shear tests, it could be shown that non-rotational symmetric pin structures lead to an increase in maximum testing forces of up to 74% when compared to cylindrical pins. However, when normalized to the pin foot print related joint strength, only one polygonal pin variation showed increased joint strength in comparison to cylindrical pin structures. The investigation of the failure behavior showed two distinct failure modes. The first failure mode was failure of the CFRT component due to an exceedance of the maximum bearing strength of the pin-hole leading to significant damage in the CFRT component. The second failure mode was pin-deflection due to the applied testing load and a subsequent pin extraction from the CFRT component resulting in significantly less visible damage in the CFRT component. Generally, CFRT failure is more likely with a fiber orientation of 0° in relation to the load direction while pin extraction typically occurs with a fiber orientation of 90°. It is assumed that for future investigations, pin structures with an undercutting shape that creates an interlocking joint could counteract the tendency for pin-extraction and consequently lead to increased maximum joint strengths.
Keywords: joining of CFRT/metal; hybrid technology; mechanical properties; pin geometry; continuous fiber reinforced thermoplastics

Joining of CFRT-steel hybrid parts via hole-forming and subsequent pin caulking - Römisch, David; Popp, Julian; Drummer, Dietmar; Merklein, Marion (Production Engineering, 2021)
In times of increasing global warming, the awareness of the necessity for significant CO2 reduction is growing. Especially in the transport and aerospace sector, lightweight construction has potential to achieve emission reduction goals by reducing the overall vehicle weight. Thereby, adding lightweight fibre-reinforced composites to materials such as steel and aluminium is used to achieve weight savings. Furthermore, continuous-fibre-reinforced thermoplastics (CFRTs) begin to replace more traditional thermoset thermoplastics due to their easier bulk production and uncomplicated storage. Hybrid parts often consist of a CFRT and a higher strength metal component. Here, the joining process poses the main challenge, due to different chemical and physical properties of the components. In the current state of the art, riveted and bolted joints are commonly used, leading to increased weight due to auxiliary elements and requiring precise bolt holes often destroying load-bearing fibres. Joining with cold formed pin structures is an innovative and versatile joining process, which avoids the need for auxiliary elements. These pins are subsequently inserted in warm formed holes in the CFRT component and then caulked to create a form-fitting hybrid joint. To obtain a fundamental understanding of this joining process, hole-forming and pin-caulking, are investigated in this study. First, the hole-forming with IR-radiation is investigated with regard to suitable process parameters and resulting fibre morphology. The formed holes are consequently mechanically characterized. Second, the caulking-process is investigated by iteratively upsetting a pin and subsequently measuring the geometry. Based on these findings two different suitable caulking degrees are defined and samples for mechanical as well as microscopic investigations are manufactured. The created joints are first investigated via micro-sections and reflected light microscopy to identify possible damage in the CFRT component, which can result from the pin caulking process. Second, a mechanical characterisation under shear load as well as pin extraction loads normal to the sample surface is conducted and the normal load tests are compared with the bearing strength of CFRT samples.
CRIS-Team WoS Importer:2021-12-31

Joining of DC04 and AA5182 in a butt joint configuration by laser assisted friction stir welding - Giera, Artur; Merklein, Marion; Geiger, Manfred (5th Laser Assisted Net Shape Engineering LANE, 2007)
LFT Import::2019-08-05 (1435)

Joining of hybrid semi-finished products from sheet metal by orbital forming - Hetzel, Andreas; Lechner, Michael; Merklein, Marion (Proceedings of the Institution of Mechanical Engineers Part L-Journal of Materials-Design and Applications, 2021)
Contrary demands like a reduction of carbon dioxide emissions and an increase in functionality are facing the manufacturing industry with growing challenges. When processing functional components, like synchronizer rings, conventional process chains, like shearing and subsequent joining, are reaching their limits due to an increased complexity of the components and a lack in efficiency, referring to the long process time. To meet these challenges, the strategy of lightweight construction combines the application of lightweight materials with efficient manufacturing processes and an innovative product design. One possibility within lightweight construction is the utilization of load-adapted hybrid components, featuring different material strength classes. In previous research, the process of orbital forming is used to manufacture semi-finished products with a varying thickness profile due to the specific radial material flow. This material flow should now be used to realize a permanent joint between materials of two different strength levels. Therefore, the process of orbital forming is modified to manufacture hybrid semi-finished products from a dual-phase steel DP600 and a naturally rigid aluminum alloy EN AW 5754, both with an initial thickness of 2.0 mm. Different joint geometries are cut by laser into a steel ring and the part is coaxially positioned around a basic aluminum disc inside a die and subsequently formed. The joint is investigated regarding the geometrical and mechanical properties, comparing a radial cross-section and the micro hardness distribution. In order to reveal the potential of orbital forming for a combined forming and joining operation, the axial as well as the peeling strength of the multi-material components are investigated and evaluated.<br
Keywords: Sheet-bulk metal forming; orbital forming; joining by forming; hybrid semi-finished products; lightweight design

Joining of multi-material structures using a versatile self-piercing riveting process - Kappes, Fabian; Wituschek, Simon; Bobbert, Mathias; Lechner, Michael; Meschut, Gerson (Production Engineering, 2022)
Due to the increasing use of multi-material constructions and the resulting material incompatibilities, mechanical joining technologies are gaining in importance. The reasons for this are the variety of joining possibilities as well as high load-bearing capacities. However, the currently rigid tooling systems cannot react to changing boundary conditions, such as changed sheet thicknesses or strength. For this reason, a large number of specialised joining processes have been developed to expand the range of applications. Using a versatile self-piercing riveting process, multi-material structures are joined in this paper. In this process, a modified tool actuator technology is combined with multi-range capable auxiliary joining parts. The multi-range capability of the rivets is achieved by forming the rivet head onto the respective thickness of the joining part combination without creating a tooling set-up effort. The joints are investigated both experimentally on the basis of joint formation and load-bearing cpacity tests as well as by means of numerical simulation. It turned out that all the joints examined could be manufactured according to the defined standards. The load-bearing capacities of the joints are comparable to those of conventionally joined joints. In some cases the joint fails prematurely, which is why lower energy absorptions are obtained. However, the maximum forces achieved are higher than those of conventional joints. Especially in the case of high-strength materials arranged on the die side, the interlock formation is low. In addition, the use of die-sided sheets requires a large deformation of the rivet head protrusion, which leads to an increase in stress and, as a result, to damage if the rivet head. However, a negative influence on the joint load-bearing capacity could be excluded.<br
CRIS-Team WoS Importer:2022-08-19

Joining of steel/CFRT-hybrid parts via non-rotational symmetric cold formed pin structures - Popp, Julian; Drummer, Dietmar (Hybrid 2022, 2022)
Hybrid parts, consisting of a steel and continuous fiber reinforced thermoplastic (CFRT) component offer new possibilities such as the combination of good weight related mechanical properties and high temperature resistance that can exceed the potential of single material parts. This study investigates the direct pin pressing process with single cold formed, non-rotational symmetric pins into a quasi-unidirectional CFRT component. In the current state of the art, primarily rotational symmetric cross sections of the pins are investigated although non-rotational symmetric cross sections could offer potential in means of material and load appropriate joining and introduction of forces into the reinforcing fibers: Depending on the failure mode of the joint, the orientation of the non symmetric pin strucuture is expected to influence the joint characteristic. Consequently, in the scope of this study, three different geometries are investigated: As a baseline geometry, a cylindrical pin with a diameter of 1 mm is used, which is utilized to compare the results of the non-rotational symmetric pins. The second geometry is an oval shaped pin with an aspect ratio of 1:2 and length of the short side of 1 mm aiming at a more gently fiber displacement in the quasi unidirectional composite and also increased bending resistance of the pin structure. The third geometry is a polygon, which is based on a triangular shape with rounded corners and sides and an in-circle diameter of 1 mm aiming at an increased, load direction dependent, joint strength. Thereby, the fiber component is a custom-manufactured quasi-unidirectional CFRT glass fiber/polypropylene composite with a fiber volume content of approximately 45 %. In a first step, the joints are characterized via imaging methods in order to create a thorough understanding of the geometries’ influence on fiber displacement mechanisms. Thereby the structures are joined with the CFRT in different orientations in relation to the fiber direction in order to create a thorough understanding about the anisotropic fiber displacement. In a second step, the joints are characterized in quasi-static single lap shear tests in 0° and 90° to the fiber orientation in order to determine the mechanical performance and the results of the different geometry types. Besides the fiber orientation, the orientation of the non-symmetric pin structures is also varied in relation to the load direction resulting in a total of six tested combinations.

Join sheet Metal with cold-Extruded Pins - Römisch, David (Assembly, 2024)
Lightweight structures and multi-material assemblies are of great interest to the automotive industry. However, joining dissimilar materials poses a challenge. Conventional joining methods, such as welding, bonding, screwdriving and riveting, have limited effectiveness due to differences in stiffness, chemical compatibility and thermal expansion. A new mechanical joining method, using pin structures formed in one of the parts, has shown promise for assembling dissimilar materials.
CRIS-Team Scopus Importer:2024-12-13

Justieren vormontierter Systeme mit dem Nd:YAG-Laser unter Einsatz von Aktoren - Huber, Alexander (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2001)
The manufacture and assembly of microtechnical assemblies place the highest demands on the positional tolerances of the microcomponents used. Alignment with the laser is an innovative process to adjust position-sensitive components with high precision and without contact in the pre-assembled state. The book provides information on how localized plastic deformations that change the position of the component to be adjusted can be generated by targeted laser irradiation. Through the use of special actuators, which are inserted between the unit to be adjusted and a carrier, shifts in the sub-micrometer range and angles in the sub-millirad range can be achieved via a contro

Kaltfließpressen von gerad- und schrägverzahnten Zahnrädern - Kiener, Christoph (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2020)
For gear manufacturing, cutting processes are used as standard due to the achievable manufacturing accuracy. Considering economic and ecological aspects, cold forging offers an alternative due to shorter production cycles and increased material efficiency. In addition, cold forged gears are more loadable in operation due to process-related hardening and a fiber-like microstructure. One variant of forward extrusion for the production of gears is the so-called Samanta-process. The decisive advantage of this process compared to conventional transverse and forward extrusion is that no ejection process is required. In addition to a positive effect on the achievable quantity output, an influence on the component accuracy is avoided during the ejection of the formed components out of the tool system. To apply the Samanta-process in industry, the achievable gearing quality and tool life have to be increased. Therefore, this work focuses on the determination of functional relationships between gear parameters and process variables in order to generate a fundamental process understanding for cold forging of gears in the Samanta-process. The research of methods for the beneficial influencing of the process result in order to derive practice-relevant recommendations for process design is also a key aspect of this wor

Kennwertermittlung für Streck-Biege-Beanspruchungen - Merklein, Marion; Hezler, Christian; Kopp, C.; Hecht, J.; Schaller, L. (Proceedings Tagung Werkstoffprüfung, 2010)
LFT Import::2019-08-05 (719)

Keramik als Werkzeugstoff in der Kaltmassivumformung - Arbak, Murat; Putz, Alexander; Engel, Ulf; Geiger, Manfred (Technik in Bayern, 2006)
LFT Import::2019-07-16 (1349)

Know-how for better Cold Forming: New Documents of the International Cold Forging Group (ICFG) - Tekkaya, A.E.; Putz, Alexander (Wire, 2002)
LFT Import::2019-07-16 (1670)

Knowledge Based Approach for Intelligent Design of Manufacturing Processes - Menzel, Thomas; Hagenah, Hinnerk (Proceedings of the EIS'2000. Second ICSC Symposium on Engineering of Intelligent Systems, 2000)
LFT Import::2019-08-05 (807)

Knowledge based automated process design using finite element intermediate states - Hagenah, Hinnerk; Kohlbauer, Rainer; Geiger, Manfred (Proceedings of the 4th CIRP International Seminar on Intelligent Computation in Manufacturing Engineering. ICME' 2004. Sorrento, Italy, 2004)
LFT Import::2019-08-05 (1038)

Knowledge based process design for optimisation of laser sintering technique for rapid tooling - Menzel, Thomas; Niebling, F.; Kach, Andreas (2nd International Conference on Production of Dies and Molds, Turkey, 2001)
LFT Import::2019-08-05 (895)

Knowledge Management and Environmental Aspects in Integrated Forming Process - Cser, Adrienn Orsolya; Geiger, Manfred; Celeghini, Martino (Advanced Technology of Plasticity, Proceedings of the 7th ICTP, 2002)
LFT Import::2019-08-05 (1709)

Kombination der Laser-Bearbeitung mit herkömmlichen Fertigungsverfahren - Geiger, Manfred; Nuss, Rudolf; Müller, Roland (Werkstatt und Betrieb, 1988)
LFT Import::2019-07-15 (283)

Kombiniertes 3D-Laserstrahlschneiden und -schweißen - ein neues Verfahren für die Karosseriefertigung - Geiger, Manfred; Hoffmann, Peter; Biermann, Stefan (Opto-Elektronik-Magazin, 1989)
LFT Import::2019-07-15 (432)

Kombiniertes Laserstrahlschneiden und -schweißen von Blechformteilen - Rief, Alfons; Nuss, Rudolf; Geiger, Manfred (Laser/Optoelektronik in der Technik, 1989)
LFT Import::2019-07-15 (440)

Konstitutives Reibgesetz zur Beschreibung und Optimierung von Tailored Surfaces - Henneberg, Johannes; Beyer, Florian; Willner, Kai; Merklein, Marion (23. Umformtechnisches Kolloquium Hannover: Aktuelle Entwicklungen im Bereich der Umformtechnik, 2020)

Konzepte zur laserstrahlunterstützten, strukturierten Metallisierung von 3-D - Geiger, Manfred; Pucher, Hans-Jörg; Glasmacher, Matthias; Hutfless, Joachim; Kickelhain, J. (Berichtsband zum 1. Int. Kongreß MID 94 - Molded Interconnect Devices, 1994)
LFT Import::2019-08-05 (602)

Konzeption biomechanischer digitaler Senioren-Menschmodelle zur Anwendung in der altersgerechten Produktentwicklung - Miehling, Jörg; Geißler, Bastian; Wartzack, Sandro (Stuttgarter Symposium für Produktentwicklung (SSP) 2013, 2013)
Aufgrund des demographischen Wandels wird die Entwicklung von Produkten, die auch von älteren Menschen nutzbar sind, immer wichtiger. Heutzutage sollen Produkte zunehmend nach dem Grundsatz der virtuellen Produktentwicklung, nämlich möglichst ohne physische Prototypen, entwickelt werden. Dieser Ansatz soll helfen die Kosten und den Zeitbedarf, die in der Entwicklung und Herstellung anfallen, zu reduzieren sowie die Qualität der Endprodukte zu erhöhen. In der menschzentrierten Produktentwicklung kommen dafür biomechanische digitale Menschmodelle zum Einsatz, welche jedoch meist nur einen Durchschnittsmenschen abbilden. Dieser Beitrag zeigt eine Methodik um die Parameter, die zur Anpassung der muskuloskeletalen Modelle an unterschiedliche Alters- und Leistungsklassen notwendig sind, abzuleiten, damit diese schließlich zur Entwicklung altersgerechter Produkte herangezogen werden können. Der Konzeptionsprozess umfasst die Modifikation von Anthropometrie, Muskelkräften, Beweglichkeit und Bewegungsgeschwindigkeit basierend auf Literaturwerten oder auch Messungen an realen Versuchspersonen.
UnivIS-Import:2015-04-16:Pub.2013.tech.FT.FT-KLMEFK.konzep
Keywords: Altersgerechte Produktentwicklung; Virtuelle Methoden; Digitale Menschmodelle; Biomechanik

Konzept zur Beherrschung der Prozessschwankungen im Presswerk - Neumann, Anja (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2013)
The increasing complexity of design, crash and weight requirements of body parts in the automotive industry leads to smaller process windows which guarantee produced parts of good quality. As a result, minimal fluctuations of the influencing parameters lead to failure of the parts. The aim of the study was the development of a concept which enables an automatically reaction on the fluctuations of the process parameters of the deep drawing operation in the press shop in order to get best quality parts. For this purpose appropriate measurement techniques were identified and further qualified to record the significant influencing parameters in series production. Based on the for series production developed and subsequently integrated metrological total system, the influencing parameters of each stroke could be recorded over numerous pressing jobs of the series part and analyzed. This approach allowed a study of the cause-effect correlation of the time-dependent influencing parameters and the definition of potential control and actuating variables of the process for the realization of an automatic control loo

Kräfte-und Belastungsermittlung: Bei der Handhabung von Statorblechpaketen in der Fertigung von Elektromotoren - Schneider, Michael; Zahner, Michael; Franke, Jörg (Zeitschrift für wirtschaftlichen Fabrikbetrieb, 2015)
Due to the proven low shear stress and its favorable allocation in the contact area between the individual sheets, the adhesive bonding process or baked enamel process represent packaging technologies with good electromechanical properties. For each individual application, it remains to weigh whether the lower eddy current losses justify the higher energy and time which is needed by using adhesive bonding or baked enamel. From a purely mechanical point of view, there are no concerns about the rigidity of the lamination stack during the handling process.
CRIS-Team Scopus Importer:2023-03-07

Kristallisation amorpher SI-Schichten für die Displayherstellung - Urmoneit, U.; Eßer, Gerd; Christiansen, S. (Laser in der Elektronikproduktion und Feinwerktechnik LEF 2002, 2002)
LFT Import::2019-08-05 (1714)

Kumulatives Walzplattieren : Bewertung der Umformeigenschaften mehrlagiger Blechwerkstoffe der ausscheidungshärtbaren Legierung AA6014 - Herrmann, Jürgen (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2020)
Accumulative Roll Bonding is a well-known process for the production of semi-finished sheet material with an ultra-fine grained microstructure. Against the background of lightweight design, the increase in strength that can be achieved is a significant advantage. The industrial implementation of the process is prevented by a lack of knowledge of the material behavior of the high-strength, multi-layered sheet material in forming processes. The aim of this work is the evaluation of the forming properties of the ultra-fine grained aluminum alloy AA6014. For this purpose, the resulting material properties are examined depending on the parameters of the Accumulative Roll Bonding process. The focus is on a new approach to tempering the working rolls in the rolling process. The forming properties as well as the forming limits are analyzed based on the processes of deep drawing and bending. Finally, the well-known approach of Tailor Heat Treated Blanks technology to enhance the formability as a result of a local short-term heat treatment is transferred to the multi-layered, high-strength aluminum alloy AA6014. On the basis of the results of this work, the performance of the investigated materials for use in metal forming technology is demonstrated. Increasing the potential for lightweight construction by significantly increasing the specific strength of semi-finished sheet material can make a contribution to meeting the high requirements for future mobility concept

Laminated Object Manufacturing of Metal Foil - Process Chain and System Technology - Prechtl, Martin; Otto, Andreas; Geiger, Manfred (Advanced Manufacturing Systems and Technology: Proceedings of the 7th International Conference, 2005)
Laminated Object Manufacturing of metal foil as an automated two-step procedure is a novel technology for additive manufacturing of massive three-dimensional parts. It enables for example the production of technical tools like moulds. The great advantage hereby is the high accuracy in combination with a high stability of the resulting tools. A laser system for the automated stacking of metal foil contours has been developed. The stacking procedure is realised by a combination of layer fixing and contour generation with a laser beam. But the stability of the produced foil stack is insufficient for most kind of application. Therefore a second step to enhance the mechanical properties of the part is necessary. This can for example be realised by high temperature brazing or diffusion welding. In this paper the laser system for the automated stacking of metal foil contours is described as well as the required preparation of the layer data. Further on some results of investigations on the sub-processes layer fixing, counter generation and final joining are shown.
LFT Import::2019-08-05 (1127)
Keywords: Diffusion welding; Laser material processing; Rapid tooling

Laminated Tool System for Press Brakes. - Franke, Volker; Greska, Wolfgang; Geiger, Manfred (Manufacturing Systems, 1995)
LFT Import::2019-07-15 (516)

Langes Leben für Werkzeuge - Arbak, Murat; Wagner, Kay (Zukunft im Brennpunkt, 2006)
LFT Import::2019-07-16 (1350)

Laser-adjustable actuators for high accuracy positioning of micro components - Schmidt, Michael; Dirscherl, Manfred; Eßer, Gerd (Proceedings of SPIE. Fourth International Symposium on Laser Precision Microfabrication, 2003)
High-precision adjustment of smallest optical and electronic components is increasingly recognized as one of the key issues facing micromachining technology. As even narrow production tolerances for all individual parts are often not sufficient to match the tightly specified positioning accuracies of the complete assembly, in situ adjustment techniques are gaining more and more attention. Together with research partners from industry and science, the BLZ is developing a contact-free, laser-based adjustment method which allows high-accuracy adjustment of components mounted on specifically designed actuators. The underlying mechanisms do not depend on thermal effects but on selective laser ablation of prestressed layers of actuator substrate. This way, slightest deformations or modifications of particular mechanical properties can be initiated. The method promises to be more accurate and less time consuming than thermally induced laser bending.
LFT Import::2019-08-05 (986)
Keywords: Actuators; Laser ablation; Laser bending; Micro-adjustment

Laser Adjustment of Pre-assembled Systems using Actuators - Geiger, Manfred; Huber, Alexander (Production Engineering, Annals of the WGP, 2001)
LFT Import::2019-08-05 (921)

Laser Adjustment Using Actuators - Hagenah, Hinnerk; Geiger, Manfred (60 Excellent Inventions in Metal Forming, 2015)
After the identification and classification of laser forming mechanism the potentials of this technology in the field of adjustment was discovered. In order to use the possibilities in the field of micro systems technology the idea of specifically designed, task specific actuators was born and researched. The detected challenge of actuator design has been addressed with suitable algorithms models. The paper gives an overview of the possibilities and explains how the design challenge has been overcome.
LFT Import::2019-08-05 (2094)

Laser alignments as a tool for precision assembly of micro opticals products - Eßer, Gerd (54th CIRP General Assembly, 2004)
LFT Import::2019-08-05 (1118)

Laser and forming technology - an idea and the way of implementation - Geiger, Manfred; Merklein, Marion; Pitz, Matthias (Journal of Materials Processing Technology, 2004)
This paper will give a survey of some of the actual research activities at the Chair of Manufacturing Technology in Erlangen concerning laser and forming technology. In detail the paper will deal with two main focuses of development: laser forming of aluminum alloys and laser-assisted forming of high strength steels. Laser forming is a technology often used for small series productions and for adjustment of small electronic components. In contrast to laser forming, which is a forming technology that is common for over 20 years, laser-assisted forming is an example of a new production technology that is able to enhance the forming limits of high strength steels. © 2004 Elsevier B.V. All rights reserved.
LFT Import::2019-07-16 (1028)
Keywords: Laser forming; Laser-assisted forming; Mechanical properties; Microstructure

Laser Application in Automotive Industry - Geiger, Manfred; Hoffmann, Peter; Deinzer, Günter (Proceedings of the 9th Int. Colloquium -Advanced Manufacturing and Repair Technologies in Vehicle Industries-, Balatonfüred (1992), 1992)
LFT Import::2019-08-05 (473)

Laser Applications in the Automotive Industry - Geiger, Manfred; Hoffmann, Peter; Deinzer, Günter (Laser Applications in the Automotive Industries, Proc. 25th Int. Symp. on Automotive Technology and Automation (ISATA) (1992), Croydon, England : Automotive Automation Ltd, 1992)
LFT Import::2019-08-05 (474)

Laser assisted bending of complex-phase steel - Geiger, Manfred; Merklein, Marion; Otto, Andreas (Production Engineering - Annals of the WGP, 2004)
LFT Import::2019-08-07 (1027)

Laser assisted bending of martensite-phase steel - Pitz, Matthias; Geiger, Manfred; Merklein, Marion; Otto, Andreas (Sheet Metal 2003, Proceedings of the 9th International Conference on Sheet Metal, 2003)
LFT Import::2019-08-05 (965)

Laser assisted fabrication of electronic circuits using the ADDIMID process - Eßer, Gerd; Jahrsdörfer, Bernd; Urmoneit, U. (Proceedings of the LASE 2001 confernce on Laser Applications in Microelectronic and Optoelectronic Manufacturing, 2001)
LFT Import::2019-08-05 (878)

Laser assisted fabrication of highly precise 2D fiber collimator arrays - Eßer, Gerd; Stark, Markus; Lamott, A.; Schmidt, Michael (Proceedings of EUSPEN-Konferenz, 2004)
LFT Import::2019-08-05 (1117)

Laser assisted fabrication of micro-optical components - Schmidt, Michael; Eßer, Gerd; Dirscherl, Manfred (Congress Proceedings ICALEO 2003, 22nd International Congress on Application of Laser & Electro-optics, 2003)
The role of optics in micro systems is continuously growing. Future systems will use electrical and optical data paths in parallel for a higher performance. Two dimensional silicon-based systems for optical data processing like power splitters or optical switches are already widespread. To expand the architecture of micro-optical systems into the third dimension a suitable joining technology is needed. Conventional laser welding can be used for this task but often causes cracks due to the high temperature gradients. In this contribution a solution for this problem is presented with laser pre- and post heating. Thus high input / output counts in a small volume can be achieved that generate or manipulate optical data. For a long distance transmission, optical fibers have to be coupled to the micro optical components. Therefore the fibers are often fixed in V-grooves by gluing. To replace this temperature sensitive technology by significantly more reliable alternatives, we will present two laser based methods: laser beam soldering and laser beam welding (clamping). For short interconnects between or within functional units, integrated signal transmission with polymer planar waveguides can simplify the system. Therefore we will finally report on some new results based on laser direct writing. This technology allows the realisation of arbitrary formed waveguides in optical polymers based on UV induced refractive index changes.
LFT Import::2019-08-05 (995)
Keywords: Laser direct writing; Laser welding; Optical fibers; Silicon; Waveguides

Laser-assisted Friction Stir Welding of Dissimilar Steel and Aluminium Alloys - Giera, Artur; Merklein, Marion; Baumeister, P. (2nd International Conference on New Forming Technology ICNFT, 2007)
LFT Import::2019-08-05 (1433)

Laser assisted Friction Stir Welding of drawable steel-aluminium tailored hybrids - Merklein, Marion; Giera, Artur (The 11th International conference on Material Forming, 2008)
Steel aluminium Tailor Welded Hybrids are still mentioned to be difficult to be joint as intermetallic phases appear during melting welding techniques. These phases are the reason for failure of the joint during loading or forming. As conventional friction stir welding, a solid phase welding technology, is not feasible to join steel and aluminium, laser assistance for preheating the steel sheet is adapted in order to enhance the weldability as well as the welding feed and to reduce the wear at the tool. Tensile tests are performed to achieve mechanical properties of joints, which were welded by systematic variation of process parameters. Finally deep drawing tests are conducted to demonstrate the formability of laser assisted friction stir welded steel aluminium joints. © Springer/ESAFORM 2008.
LFT Import::2019-08-05 (1510)
Keywords: Cup Deep Drawing; Laser Assisted Friction Stir Welding; Mechanical Characteristics; Microstructure; Steel-Aluminium Tailored Hybrid

Laser assisted generation of electronic circuits on tailored thermoplastics - Eßer, Gerd; Geiger, Manfred (First International Symposium on High-Power Laser Macroprocessing Proceedings of the SPIE, 2003)
LFT Import::2019-08-05 (977)

Laser-assisted Property Gradients in Multi-layered Aluminum - Böhm, Wolfgang; Merklein, Marion (Physics Procedia, 2014)
The Accumulative Roll Bonding (ARB) process enables manufacturing of multi-layered aluminum sheet metals with outstanding mechanical properties. However, a significant increase in strength is accompanied by a reduced ductility. Besides, delamination effects can occur during forming operations. Therefore, property gradients will be applied by short-term laser heat treatment according to the Tailored Heat Treated Blanks technology to enhance the formability and to enable the production of components. These gradients can be realized across the plane and in thickness direction of a blank. In this paper, property gradients in thickness direction are applied to multi-layered aluminum sheet metal with nanocrystalline grain structure produced in the ARB process. Furthermore, the effect of different process parameters on the shape of the heat affected zone is presented. The property gradients are characterized using micro hardness tests. Finally, the enhancement of the formability is proven using air bending tests.
EAM Import::2019-03-12

Laser Assisted Rapid Prototyping - Processes, Applications and Developments in the Field of Additive Processes - Geiger, Manfred; Prechtl, Martin; Niebling, Frank; Otto, Andreas (Proceedings of the 4th International Conference on Industrial Tools (ICIT 2003), 2003)
LFT Import::2019-08-05 (933)

Laser assisted techniques for patterning of conductive tracks on molded interconnect devices - Eßer, Gerd; Dietel, C.; Roth, Stephan; Glasmacher, Matthias; Renner, G.; Kickelhain, J. (Proceedings of the Pan Pacific Microelectronics Symposium, 1998)
LFT Import::2019-08-05 (1375)

Laser assisted tooling in metal forming - Kreis, Oliver; Geiger, Manfred; Vahl, Meik (Proceedings of the 2nd International Conference on Industrial Tools (ICIT), 1999)
This article describes several applications of laser technology for tooling. Laminated tools and laser sintering as technologies for rapid tooling are presented. In the field of laser beam surface treatment, the technologies laser ablating, hardening and microstructuring are discussed. Finally, the integration of cutting and laser beam welding in the tool of a forming press is described.</
Keywords: Rapid Tooling; Laminated Tools; Laser Sintering; Laser Surface Treatment; Hydroforming; Process Integration

Laser based additive manufacturing in industry and academia - Schmidt, Michael; Merklein, Marion; Bourell, David; Dimitrov, Dimitri; Hausotte, Tino; Wegener, Konrad; Overmeyer, Ludger; Vollertsen, Frank; Levy, Gideon N. (CIRP Annals - Manufacturing Technology, 2017)
Additive manufacturing (AM) is pushing towards industrial applications. But despite good sales of AM machines, there are still several challenges hindering a broad economic use of AM. This keynote paper starts with an overview over laser based additive manufacturing with comments on the main steps necessary to build parts to introduce the complexity of the whole process chain. Then from a manufacturing process oriented viewpoint it identifies these barriers for Laser Beam Melting (LBM) using results of a round robin test inside CIRP and the work of other research groups. It shows how those barriers may be overcome and points out research topics necessary to be addressed in the near future.
Created from Fastlane, Scopus look-up
Keywords: Additive manufacturing; Laser; Production

Laser-based microalignment for fabrication of highly precise 2D fiber collimator arrays - Stark, Markus; Eßer, Gerd; Lamott, A.; Geiger, Manfred (Photon Processing in Microelements and Phonotonics III, 2004)
LFT Import::2019-08-05 (1115)

Laser based micro joining techniques in electronic production - Albert, F.; Jahrsdörfer, Bernd; Mys, I.; Schmidt, Michael (Proceedings of the 2nd International Conference on Laser Technologies in Welding and Materials Processing LTWMP, 2005)
LFT Import::2019-08-05 (1212)

Laser based techniques to adapt the tribological conditions in dry deep drawing - Vorndran, Martin; Häfner, Tom; Rothammer, Benedict; Krachenfels, Kim; Merklein, Marion; Tremmel, Stephan; Schmidt, Michael (International Conference on Advanced Optical Technologies, 2019)
Sheet metal forming is widely used in industry to transform a flat metal sheet to a final shape. However, sheet metal forming requires the use of lubricants to prevent the direct contact between tool and workpiece. These lubricants are often toxic and have to be removed after the forming process. Therefore, the environment and the process chain will profit from the abandonment of lubricants. The use of tool sided coatings is a well-known approach to substitute lubricants and perform dry deep drawing. To achieve satisfying results in deep drawing it is beneficial to tune the tribological conditions. Here, we show laser based techniques to locally adapt the tribological conditions by either reducing the roughness of the surface or by creating structures within the surface. It is e.g. shown that the reduced peak height of coated surfaces can be decreased by a laser process. Furthermore, the resulting tribological conditions are investigated for zinc coated DC04 and AA5162 specimens. In Addition to the tribological behavior the changes of the chemical coating properties are investigated using Raman spectroscopy.<br

Laser-based ultrasonic measurement of the influence of PBF-LB/M-typical thermal cycles on sheet metal components of hybrid parts - Hafenecker, Jan; Rigas, Nikolaos; Merklein, Marion (Production Engineering, 2023)
In order to cope with the upcoming challenges from industrial trends, such as mass customization, hybrid parts made out of sheet metal and additively manufactured components offer a possible approach. Hybrid parts can be used for instance in the field of medical and aerospace industries. The combination of the two technologies forming and additive manufacturing allows to use the advantages of each while at the same time avoiding the disadvantages. During the additive manufacturing process, however, the sheet metal substrates, which are a component of the later part, are subjected to heat input such as substrate heating and laser radiation. Each heat input has a different temperature and duration, which are simulated to detect changes in the material properties. Experiments are performed for 316L and Ti-6Al-4 V, which are both commonly used in additive manufacturing. The investigations aim at proving that the substrate heating has no influence on either material. To investigate the influence of substrate heating during additive manufacturing, tensile tests in heat-treated state as well as laser-based ultrasonic measurements are used to detect changes in mechanical or microstructural properties. However, the heat input of the laser is expected to lead to a phase transformation for the titanium alloy due to the high cooling rate. Therefore, the feasibility of using a laser based ultrasonic measurement system to detect microstructural changes during heat input similar to the laser radiation during laser-based powder bed fusion processes is tested. Based on the results, the substrate heating does not influence the sheet material, despite long holding times. However, the short laser beam-like heat inputs lead to phase transformations for the titanium alloy, which can be detected temperature and time dependent via laser-based ultrasonic measurements.
CRIS-Team Scopus Importer:2023-06-30
Keywords: Additive manufacturing; Hybrid; In-situ; Laser-ultrasonic; Powder bed fusion

Laser Beam Bending of Metallic Foils - Geiger, Manfred; Meyer-Pittroff, Frank (Production Engineering - Annals of the WGP, 2001)
LFT Import::2019-08-05 (910)

Laser Beam Brazing Using the Twin Spot Technology - Hanebuth, Henning; Hoffmann, Peter; Geiger, Manfred (Proceedings of the International Symposium on High Power Lasers and Laser Applications V, 1994)
LFT Import::2019-08-05 (612)

Laser Beam Cutting. - Gropp, Armin; Hutfless, Joachim; Schuberth, Stefan; Geiger, Manfred (Optical and Quantum Electronics, 1995)
LFT Import::2019-07-15 (559)

Laser Beam Cutting of Aluminium Foam Sandwich at Different Material States - Otto, Andreas; Dörfler, Stephan Manuel; Klausecker, Roland (LANE 2004, Proceedings of the 4th International Conference on Laser Assisted Net Shape Engineering, 2004)
LFT Import::2019-08-05 (1080)

Laser Beam Joining of Magnesium Alloys - Klausecker, Roland; Geiger, Manfred; Otto, Andreas; Haberling, C. (LANE 2001, Proceedings of Laser Assisted Net Shape Engineering, 2001)
LFT Import::2019-08-05 (869)

Laser beam joining of optical fibers in silicon-V-grooves - Kaufmann, Stefan; Otto, Andreas; Luz, G. (Laser Applications in Microelectronic and Optoelectronic Manufacturing V, Proceedings of SPIE, 2000)
The increasing use of optical data transmission systems and the development of new optical components require adjustment- insensitive and reliable joining and assembling techniques. The state of the art includes the utilization of silicon submounts with anisotropically etched V-grooves. Several glass fibers are fixed in these V-grooves with adhesive. Adhesive bonds tend towards degradation under the influence of temperature and moisture. For this reason, the alternative joining processes laser beam welding and laser beam soldering are relevant. The goal is a reliable joining of optical fibers in V-grooves without damage to the fibers or the silicon submount. Because of the anomaly of silicon during phase transformation, a positive joining can be realized by laser beam welding. A melt pool is created through the energy of a Nd:YAG-laser pulse. During solidification, the volume of silicon increases and a bump is formed in the center. Experiments have shown that this phenomenon can be used for joining optical fibers in silicon-V-grooves. With suitable parameters the silicon flows half around the fiber during solidification. For each fiber, several welding points are necessary. Another promising joining method is laser beam soldering. In this case, a second silicon sheet with a solder deposit is placed on the fibers which lie in the V-grooves of the metalized silicon submount. The laser heats the upper silicon until the solder melts by heat conduction.
LFT Import::2019-08-05 (784)

Laser Beam Micro Processing of Three-Dimensional Circuit Boards. - Hutfless, Joachim; Glasmacher, Matthias; Pucher, Hans-Jörg; Geisel, Mark (Proc. Int. Symp. for Electromachining (ISEM-XI), 1995)
LFT Import::2019-08-05 (567)

Laser Beam Micro Welding as a new Interconnection Technique - Geiger, Manfred; Glasmacher, Matthias; Hutfless, Joachim; Pucher, Hans-Jörg (Proceedings of 10th European Microelectronics Conference 1995, 1995)
LFT Import::2019-08-05 (540)

Laser beam processing of aluminium foam sandwich - Klausecker, Roland; Otto, Andreas; Geiger, Manfred (Cellular Metals: Manufacture, Properties, Applications, 2003)
LFT Import::2019-07-15 (1000)

Laser Beam Welding of Magnesium Matrix Composites - Geiger, Manfred; Klausecker, Roland; Otto, Andreas (Annals of the German Academic Society for Production Engineering, 2001)
LFT Import::2019-08-05 (866)