Prof. Dr. Marion Merklein

Chair of Manufacturing Technology

Research projects

  • Mechanical engineering with a focus on forming, joining by forming, material characterization and modeling, additive manufacturing and digitalization of production processes.
  • Hybrid additive manufacturing (AM and forming) for design of high strength, but light implants.
  •  As industrial areas automobile industry, transportation systems, construction work and bioengineering are of interest.

  • „Grundlegende Untersuchungen zur Herstellung von Funktionsbauteilen vom Band“

    (Third Party Funds Single)

    Term: 1. January 2022 - 31. December 2023
    Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)

    The applicationof bulk forming processes to sheet metal, also known as sheet-bulk metalforming, extends the existing forming limits of established sheet and bulkforming processes. This enables the resource-efficient production offunctionally integrated lightweight components. In previous research, sheet-bulkmetal forming of pre-cut blanks was investigated. By using coil assemi-finished products, the advantages of manufacturing from coil in terms ofsimplified component handling and as a result higher output quantity arecombined with the advantages of sheet-bulk metal forming in terms of extendedforming limits.

    The usage ofcoils, however, results in an anisotropic material flow and consequently an unequalshape of the formed components. This worsens the component application behaviorand is especially a challenge for cyclically symmetrical parts. In additionasymmetrical tool loads, critical for fatigue, occur. Considering this, theobjective is to elaborate a process understanding for extrusion of gears fromcoil. It should be investigated how the anisotropic material flow affects the formingof the individual functional elements of cyclically symmetrical components andthe tool loads.

    In order to increasethe application potential of extrusion of gears from coil, another objective isto provide measures to reduce the anisotropic material flow and to improve thegeometrical accuracy of formed parts. For this purpose, different approaches formaterial flow control, such as adjusting the coil width, feed width, toolgeometry and local adaptation of friction should be analyzed for cyclicallysymmetrical parts. In addition to the effectiveness, the wear-behavior of the measureshas to be investigated in tool life tests.

  • In-situ characterization of a locally carburized complex phase steel for manufacturing of tailored semi-finished products

    (Third Party Funds Single)

    Term: 1. October 2021 - 30. September 2024
    Funding source: Deutsche Forschungsgemeinschaft (DFG)
    Hot stamping of ultra-high-strength steels has developed to a state of the art process for manufacturing safety-relevant car body parts with respect to lightweight design. Further improvement of passenger safety can be achieved by locally adapting the mechanical properties. In terms of process design, the development of the microstructure throughout the process stages is significant. Laser-ultrasonics enables the in-situ determination of microstructural changes, such as grain growth or phase transformation. In recent years, this measurement method was already applied for the investigation of processes like rolling but is unknown in the context of hot stamping. The aim of this project is the in-situ characterization of a locally carburized complex phase steel on the basis of grain growth and phase transformation obtained by laser-ultrasonics. Through fundamental scientific investigations of the influencing factors on microstructure and mechanical properties, a process window for local carburization at temperatures above 950 °C will be identified. Furthermore, the prediction accuracy of numerical simulation should be improved by considering the data from in-situ characterization. Based on the identified process window the warm forming behavior of the carburized and non-carburized complex phase steel will be investigated. Besides temperature and strain rate, the modeling of the flow behavior is carried out with respect to further influencing factors such as the carburization parameters. Moreover, the transferability of measurement data obtained by laser-ultrasonics to model the phase transformation in numerical simulation is analyzed. Through experimental investigations, the numerical material models will be validated and verified.
  • Reduction of local tool stresses in cold forging tools

    (Third Party Funds Single)

    Term: 1. July 2021 - 31. December 2023
    Funding source: Bayerische Forschungsstiftung

    Part geometry is a major influence on the formation of local stress in cold forging tools. Non-constant asymmetrical cross-sections result in axial and tangential stress concentrations. This challenge can be seen in the processes of the industrial partners, where fatigue failure occurs in local elements. In order to counteract fatigue and improve process economics, the formation of local tool stresses is to be analysed using a model process. Using the process the influence of functional elements and changes in cross-section on the stress state of the die is researched. With an understanding of the mechanisms of the stress formation, adapted tool concepts will be developed, which enable a suitable improvement of the stress state depending on the part and tool geometry. To evaluate the effectiveness of the new tool designs, they will be implemented in the processes of the industrial partners. That way, the effect on tool life can be analysed for different die materials. These are usually cold working steels or cemented carbides, which react very sensibly to tensile stresses. Finally, the new tool concepts will be evaluated using the developed process understanding and the experimental results regarding the tool life.

  • Enhancement of joinability and joint characteristics in mechanical joining processes by tailor heat-treated aluminium semi-finished products

    (Third Party Funds Single)

    Term: 1. April 2021 - 31. March 2023
    Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
    The increasing demands on the automotive industry to reduce the vehicle weight and simultaneously increase the crash safety require new design approaches. A material mix of steel and aluminum with increased strengths provides a possible solution for both problems. However, a material mix is also associated with new challenges for joining technology. In this context the use of mechanical joining processes has been intensively investigated in recent years. However, as it is known from the state of the art, the joining of high-strength materials is not yet unlimited possible. Therefore, the aim of the research project is the enhancement of joinability and the resulting bonding strength of high-strength dissimilar materials by the use of a local short-term heat treatment. The softening effect that occurs during the short-term heat treatment of aluminum alloys of the 7000 series can be used to improve the material flow of the high-strength aluminum material located on the punch side. Based on fundamental scientific investigations, the influence of tailor heat-treated blanks on the joining process and on the bonding strength of the joining point will be analyzed. This represents a new field of application for tailor heat-treated semi-finished products, which until now have only been used to expand the forming limits in part manufacturing. By analyzing the complex material flow in the shear-clinching process, a holistic process understanding will be established. Taking into account the interactions involved, an ideal strength distribution in the joining zone should be determined based on numerical models of the short-term heat treatment and the shear-clinching process. By means of experimental investigations the numerical results should be validated and the mechanical properties and the joint strength should be identified.
  • Friction reduction in lubricated tribological contacts by micro textured surfaces

    (Third Party Funds Single)

    Term: 1. January 2021 - 31. December 2022
    Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
    The modification of component surfaces in lubricated tribological systems can improve the tribological behavior and reduce friction losses. This can be achieved by tribological layers or by discrete microtextures applied to the component surface. With regard to larger quantities, these microtextures have to be realized by forming processes such as micro coining, which can be integrated into conventional manufacturing processes. Up to now, basic knowledge is missing in order to understand the manufacturing challenges in combined forming processes during component production. In addition, a deeper understanding of the effects as well as the optimal design of surface microtextures in lubricated tribological contacts is lacking.The aim of the research project is to gain basic scientific knowledge with regard to the effect of surface microtextures in EHL contacts, as well as their manufacturability using forming processes. In cooperation with industrial partners, the obtained basic knowledge is transferred to industrial applications. A more realistic determination of the effects of microtextures in rolling-sliding contacts is achieved by the expansion of a TEHL simulation model by the influence of thin layers, roughness and solid-solid contact as well as dynamic operating conditions. Exemplary for the cam/tappet-contact, over the cup surface locally optimized microtextures are derived, taking into account the manufacturing limitations. Latter are investigated for an extrusion-coining process, in which a more homogeneous and precise texture shaping on the component by an inverse texture optimization is strived. In addition, a combined process including deep drawing, ironing and coining which has a lower material flow in the coining area is compared with the extrusion process. The objective is to identify process-specific influencing variables on the texture shape. In addition, the wear behavior of the coining punches is examined using a wear test-rig. The overriding objective of the study is to gain knowledge on the achievable accuracy of the texture geometry as well as on the application behavior of the tools based on numerical models and simplified bench tests. The analysis of the application behavior of the components in terms of friction and wear in a complete test chain from model, over component, to aggregate testing-rigs serves to validate the numerical design. Finally, the obtained knowledge about suitable and simultaneously technically feasible microtextures is validated for different application cases using experimental setups.
  • Development of a forming process to manufacture near-net-shape functional components with a gradient in sheet thickness

    (Third Party Funds Group – Sub project)

    Overall project: Manufacturing of complex functional components with variants by using a new sheet metal forming process - Sheet-Bulk Metal Forming
    Term: 1. January 2021 - 31. December 2022
    Funding source: Deutsche Forschungsgemeinschaft (DFG)
    Within the TCRC, the process of orbital forming was investigated fundamentally and the technolog-ical potential was shown. The process understanding referring to the possibility of controlled material flow forms the basis for the present transfer project. A high complexity as well as a long process dura-tion are unsolved challenges today. The system specific dependency of a tumbling plate results in an additional restriction of a maximum tumbling angle of Θmax = 1°, which severely limits the forming ca-pacity.The aim of the submitted transfer project is the substitution of the conventional orbital forming process by an iterative combination of tilting and turning. The overall objective is to extend the process limits known from fundamental research by using an adapted process. On the one hand, the essential find-ings of fundamental research regarding the control of the material flow should be applied. On the other hand, the formability and efficiency of the process should be improved. A basic advantage of the new process is the ability to use a conventional press, thus significantly reducing the process time and removing the restriction of a maximum tumbling angle of Θmax = 1°. An increase of the tumbling angle offers the potential of a reduced contact area, realizing an increased forming capacity.Challenges of the innovative manufacturing process can be derived from the modified process charac-teristics and forming kinematics. Besides the analysis of the tilting process, the number of forming steps required to achieve the desired form filling should be evaluated. In addition, the maximum tilt angle and the resulting influence on the functional components must be evaluated. In order to in-crease the load capacity, the hardening behaviour of strongly hardened high performance steels dur-ing the forming process should be analysed to verify the omission of a subsequent hardening process. The target parameters should be optimized by an investigation and application of comprehensive pro-cess strategies.The process characteristics to be investigated can be reproduced by using the current orbital forming process setup, allowing the characteristic tilting kinematic. Thus, the new process can be investigated fundamentally and at the same time, the effort for the production of the new tool concept can be pre-vented. Therefore, the development of a suitable method to ensure the applicability is required. Due to the expected change of the material flow components caused by the modified process kinematics, a material flow control is essential. A numerical simulation is used for the analysis of the material flow. The influence of the process parameters on the actual process should be investigated by evaluating reference parts produced with the adapted process. Due to the mentioned disadvantages of the cur-rent orbital forming process setup, the results of the adapted process transferred to a flexible tool con-cept for the use on a conventional press.
  • Laser implantation of press hardening tools to influence the tribological and thermal properties for the process application

    (Third Party Funds Single)

    Term: 1. November 2020 - 31. October 2022
    Funding source: Deutsche Forschungsgemeinschaft (DFG)
    Major development goals of the automotive industry are to increase the passenger safety as well as to reduce the fuel consumption and to achieve emission regulations. Hence, hot stamping has been established as a suitable and resource efficient process to manufacture high-strength and lightweight body-in-white components. However, the production is limited by friction and wear due to high thermo-mechanical tool stresses and the lack of lubricants. The overall aim of this research project is to modify the tool surface by using a laser implantation process in order to influence the thermal, mechanical and tribological interactions in the contact zones. Within the first project phase, tribological highly stressed tool areas as well as requirements for the implant geometry were identified by means of numerical models. Furthermore, suitable hard ceramic particles were determined and their interactions with different laser parameters were analyzed. Tribological experiments have shown that laser-implanted tools exhibit a high wear resistance and decreasing friction forces due to the limitation of the contact area and the reduced chemical affinity between tool and workpiece. By modifying an industry-related tool geometry, it was finally proven that an increased part quality and an improved forming behavior was achieved. However, based on the numerical results, maximum tool loads were located in geometrical complex areas which could not be laser-implanted due to the lack of implantation strategies and the unknown cause-effect relations between the tool and the workpiece. Thus, it is expected that structuring these highly stressed tool areas will significantly improve the tribological behavior. In a second project phase, further investigations with regard to varying tool stresses must be initiated in order to identify the interactions between surface properties, friction and wear behavior. In this context, suitable implants made out of hard phase compositions and tailored structuring patterns will be created for specific load cases. Afterwards, they will be tested in industrially relevant experiments to verify their effectiveness. This approach provides a deeper understanding regarding the interactions between hard ceramic particles and the arrangement of the implants in highly stressed tool areas.
  • Resource-minimized production through hybrid and highly networked processes

    (Third Party Funds Single)

    Term: 1. November 2020 - 31. October 2023
    Funding source: Bundesministerium für Wirtschaft und Technologie (BMWi)
  • Hydroforming of high-strength aluminium alloys

    (Third Party Funds Single)

    Term: 1. October 2020 - 30. September 2022
    Funding source: Bundesministerium für Wirtschaft und Technologie (BMWi), AIF Arbeitsgemeinschaft industrieller Forschungsvereinigungen
  • Kerbwalzen und Wechselbiegen - Grundlegende Untersuchungen zur Herstellung von Fließgut mit geringem Aspektverhältnis ausgehend von Bandmaterial

    (Third Party Funds Single)

    Term: 1. April 2020 - 31. March 2022
    Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)

    Inorder to increase the productivity of the production process of steel wires,the process chain of notch rolling and cyclic bending is fundamentallyanalyzed. During notch rolling, notches are formed on both sides of a sheetmetal strip, in whose areas the material fatigues and forms cracks during thesubsequent fulling process. The numerical and experimental implementation ofboth process steps enables the identification of relevant influencingparameters and their interactions. Parameters taken into account are, amongothers, the notch radius, notch angle and web thickness in notch rolling, andthe bending angle and number of cycles to breakage or to the desired residualweb thickness in cyclic bending. Numerical and experimental studies of ductiledamage are required to evaluate material separation.

  • Hilfsfügeteilfreies Fügen

    (Third Party Funds Group – Sub project)

    Overall project: Methodenentwicklung zur mechanischen Fügbarkeit in wandlungsfähigen Prozessketten
    Term: 1. July 2019 - 30. June 2023
    Funding source: DFG / Sonderforschungsbereich / Transregio (SFB / TRR)
    URL: https://trr285.uni-paderborn.de/
  • Fundamental investigation of ultrasonic-assisted metal forming by compressive and shear stress

    (Third Party Funds Single)

    Term: 1. March 2018 - 30. November 2022
    Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
  • Investigation of residual stress related elementary processes in cold forged components in the manufacturing and operating phase

    (Third Party Funds Single)

    Term: 1. February 2018 - 31. December 2022
    Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)

    Due to the potential of forming induced residual stresses to influence component properties, a deeper understanding of the mechanisms of residual stress generation and stability is required. Therefore, the approach to the research project is structured into the phases of component manufacturing (generation of residual stresses), component operation (residual stress stability) and process design (exploitation of residual stresses). As reference process the forward rod extrusion is used, which is established as standard process in industrial use. Due to the trend towards component materials with higher strength and corrosion resistance, two stainless steels are used in the project. The investigations include parallel experimental and numerical analyses of the process and its synthesis.

    During the first phase, the necessary experimental equipment for component manufacture and testing was set up, material and friction parameters were identified, components were formed under consideration of different parameter variants and their residual stresses were determined by X-ray diffraction. In a complementary approach, macroscopic finite element models with subroutines for an extended post-processing of residual stresses were developed on the simulation side and applied in the context of numerical parameter variations. Furthermore, differential geometric and continuum mechanical relationships of residual stresses were investigated and the material modelling was extended to crystal plasticity. The predictivity of the numerical results was quantified on the basis of experimental results.

    The second phase concentrates on the residual stress stability in component use and the process robustness during component manufacture. The knowledge gained will be used at the end of the second and in the third phase to specifically influence the operating behaviour and to control the cyclic strength.

    The objective in the second phase is the experimental and numerical determination of the mechanical and thermal residual stress stability. As a requirement for the targeted influencing, relevant parameters will be identified. These cause-and-effect relationships are to be plausibilised by means of fundamental physical effects, whereby a recourse is made to effects described in the literature and numerical methods for the derivation of basic model ideas. Based on the experience gained so far, fluctuations of input variables and previously known disturbance variables are to be taken into account in all investigations. A further prerequisite for a systematic investigation of the fundamental mechanisms relevant to residual stresses is an increase in the numerical modeling and prediction accuracy of the deformation-induced residual stresses. In analogy to the generation phase, a constant comparison of simulation and experiment is therefore also carried out in the operating phase in the sense of an assessment of the prognosis quality of the numerical approaches and the plausibility of the experimental laboratory results.

    The Project is part of the DFG priority programm SPP2013 "Targeted Use of Forming Induced Internal Stresses in Metal Components". Within the priority program, the subproject takes part in the expert groups Production technology (thick-walled) and Mechanics and simulation.

  • Investigation of residual stress related elementary processes in cold forged components in the manufacturing and operating phase

    (Third Party Funds Single)

    Term: 1. January 2018 - 31. March 2024
    Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
  • FOR 2271: Prozessorientiertes Toleranzmanagement mit virtuellen Absicherungsmethoden

    (Third Party Funds Group – Overall project)

    Term: 1. June 2016 - 31. December 2019
    Funding source: DFG / Forschergruppe (FOR)
    URL: https://www.for2271.tf.fau.de/

    The comprehension of geometric part deviationsand their manufacturing and assembly related sources as well as the investigationof their effects on the function and quality of technical products builds theframework for the planned research group “process-oriented tolerance managementbased on virtual computer-aided engineering tools”. The aim of this researchgroup is the provision of holistic methods and efficient tools for thecomprehensive management of geometric deviations along the product originationprocess, which are to be validated in a model factory. In doing so, aparticular focus is set on the development of a procedure for the fruitfulcooperation of all departments involved in geometric variations management,from product development, to manufacturing, to assembly and to metrology, whichwill enable companies to quickly specify functional tolerances, which aremanufacturable and measurable, and consequently to save costs and to reduce thetime to market.

    In this regard, the vision of the researchgroup is to enable the close collaboration of product development,manufacturing, assembly and metrology in computer-aided tolerancing, i. e.the joint formulation of functional tolerances, which are manufacturable andmeasurable. By enabling this close collaboration, all manufacturing andassembly related sources of later problems regarding the product function andquality can be considered already during early phases of virtual product andprocess development. As a consequence, tolerances can be specified efficientlyand optimized inspection plans as well as robust manufacturing and operatingwindows can be identified, which allows the development of robust products tobe manufactured and measured at low costs.  

    Since geometric part deviations are inevitableand affect the function and quality of technical products, their managementalong the product origination process is essential for the development offunctioning products, which conform to the quality and usage requirements ofcustomers and are successful on international markets. As a consequence,tolerance management is a fundamental task in product development and reachesvarious fields of industry, from consumer to industrial goods. Due to steadilyincreasing requirements on quality and efficiency, it strongly gains importancenot only with large, but also small and medium-sized enterprises. In thiscontext, the industrial application of the scientific findings of the researchgroup will contribute to the success of the German economy.  

  • Consideration of functionally relevant geometric deviations in the design of metal forming processes for the production of gears by extrusion

    (Third Party Funds Group – Sub project)

    Overall project: FOR 2271: Prozessorientiertes Toleranzmanagement mit virtuellen Absicherungsmethoden
    Term: 1. April 2016 - 31. March 2023
    Funding source: DFG / Forschergruppe (FOR)
  • Additive and formative manufacturing of hybrid parts with locally adapted, tailored properties (B5)

    (Third Party Funds Group – Sub project)

    Overall project: CRC 814 - Additive Manufacturing
    Term: 1. July 2011 - 30. June 2023
    Funding source: DFG / Sonderforschungsbereich (SFB)
    URL: https://www.crc814.research.fau.eu

    Aim of this sub-projectis to investigate the combination of additive manufacturing and formingtechnology for the production of tailored, functionalized and individualizedtitanium hybrid parts, fundamentally. Besides the sheet metal body also theadditively manufactured elements of the hybrid parts will be formed. This leadsto a defined work-hardening of the material and locally adjusted properties. Bythe spatially resolved application of additives in combination with in situalloying during Laser Beam Melting (LBM) a local material modification isintended. This modification is supposed to be adjustable to the demands of theforming operation as well as to the demands of the later use case.

  • Center for Nanoanalysis and Electron Microscopy

    (FAU Funds)

    Term: 1. January 2010 - 3. March 2038
    The Center for Nanoanalysis and Electron Microscopy (CENEM) is a facility featuring cutting-edge instrumentation, techniques and expertise required for microscopic and analytical characterization of materials and devices down to the atomic scale. CENEM focuses on several complementary analysis techniques, which closely work together: Electron Microscopy, X-ray Microscopy, Cryo-TEM, Scattering Methods, Scanning Probes and Atom Probe Microscopy. With the combination of these methods new materials, particles, structures and devices are characterized not only microscopically and analytically on all length scales even down to the atomic scale but also by various in situ investigations and 3D methods. The knowledge gained through the versatile characterization methods is then used to further develop and improve materials and devices.

    CENEM was established in 2010 to provide a forefront research center for the versatile characterization of materials and devices with state-of-the-art instrumentation and expertise and to intensify the interdisciplinary research. The big CENEM network represents the strong collaborations within the University of Erlangen-Nürnberg as well as the collaboration with other universities, dedicated research institutes and industry.

    The support of the core facility CENEM by the German Science Foundation (DFG) and the Cluster of Excellence EXC 315 “Engineering of Advanced Materials” is gratefully acknowledged.

  • TRR 73: Manufacturing of complex functional components with variants by using a new sheet metal forming process - Sheet-Bulk Metal Forming

    (Third Party Funds Group – Overall project)

    Term: 1. January 2009 - 28. February 2024
    Funding source: DFG / Sonderforschungsbereich / Transregio (SFB / TRR)
    URL: http://www.tr-73.de

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