Dipl.-Ing. Christopher Ehrmann

  • 4800 Cao An Road, Jiading District
    Shanghai 201804
    P.R. China

Dipl.-Ing. Christopher Ehrmann

Areas of Research:

  • Mechatronic subsystems for machine tools
  • Diagnosis and prognosis of rack & pinion drives


[ 1 ] Ehrmann, C. & Herder, S. (2013), "Integrated Diagnostic and Preload Control for Ball Screw Drives by Means of Self-Sensing Actuators". Advanced Materials Research, eds. M. Merklein, pp. 271-277.
Piezoelectric ceramics can be used as sensors, as well as actors. The concept of a selfsensing actuator tries to use both modes of operation in one device, allowing the economic integration of mechatronic systems. Possible fields of application are ball screws of machine tools, where wear-induced degradation of the preload can be compensated. Furthermore, the signal processing part of such a system can be used to gather information related to the condition of the ball screw. Both excitation signal generation and filtering of the measured signal have to offer high flexibility and signal fidelity. In this article the concept of a power amplifier and its corresponding signal processing system are presented.

[ 2 ] Ehrmann, C.; Isabey, P. & Fleischer, J. (2016), "Condition Monitoring of Rack and Pinion Drive Systems: Necessity and Challenges in Production Environments". Procedia CIRP, eds. Seliger, G.; Kohl, H. & Mallon, J., pp. 197-201.
Rack and pinion drives are linear actuators commonly found in feed axes of machine tools and handling systems. Despite their use in demanding production environments and the possibility of failure due to foreseen or unforeseen cause, as of this writing, no condition monitoring systems are used in such applications. This paper shows the prospects of condition monitoring of rack and pinion drive systems concerning predictability of faults and saving of resources. Additionally the current state of the art of science and technology in this field and the challenges of condition monitoring of such drive systems under the circumstances of production environments are outlined. The publication concludes the need for action and gives an outlook on ongoing developments in condition monitoring of rack and pinion drives.

[ 3 ] Gönnheimer, P.; Kimmig, A.; Mandel, C.; Stürmlinger, T.; Yang, S.; Schade, F.; Ehrmann, C.; Klee, B.; Behrendt, M.; Schlechtendahl, J.; Fischer, M.; Trautmann, K.; Fleischer, J.; Lanza, G.; Ovtcharova, J.; Becker, J. & Albers, A. (2019), "Methodical approach for the development of a platform for the configuration and operation of turnkey production systems". Procedia CIRP, eds. Putnik, G., pp. 880-885. 10.1016/j.procir.2019.04.260
Shorter product lifecycles lead not only to faster time-to-market for products but also to the need for just as fast available associated production systems. These shorter product lifecycles, as well as the increasing individualization of products, also result in further decreasing production lot sizes. Young companies in China in particular are characterized by a very high speed of innovation but may not have the necessary manufacturing knowledge or capacities to bring their developed products to the market with a scalable production. For this reason, there is a great need to quickly set up and commission turnkey production systems or to reconfigure existing production systems for new production tasks in the shortest possible time. This paper describes the design and architecture of a cloud platform with the aim to support a manufacturer independent design process for turnkey production systems. This process ranges from the product to be manufactured to the operation of the production system. Firstly, the structure and methodology used to link the various objectives are discussed. The system for recording and structuring product and production system data to create reusable modules from components and machines is described. Subsequently, the use of standardized modules is developed to support reconfiguration of the production system during operation. In addition, the digital business models tailored to the production system are proposed to the platform user for commissioning and operation of the plant. A case study is conducted to validate the proposed methodology.

[ 4 ] Barton, D.; Gönnheimer, P.; Schade, F.; Ehrmann, C.; Becker, J. & Fleischer, J. (2019), "Modular smart controller for Industry 4.0 functions in machine tools". Procedia CIRP, eds. Butala, P.; Govekar, E. & Vrabič, R., pp. 1331-1336. 10.1016/j.procir.2019.04.022
In machine tools, Industry 4.0 functions can increase availability through predictive maintenance, while other functions improve productivity and workpiece quality through process supervision and optimisation. Many of these functions rely on data communication between systems from different suppliers. Requirements regarding latency and computing vary widely depending on the application. Based on an analysis of these requirements, a smart controller for the implementation of Industry 4.0 is designed, using a hypervisor to allow for the integration of soft real-time and best-effort applications.

[ 5 ] Gönnheimer, P.; Kimmig, A.; Ehrmann, C.; Schlechtendahl, J.; Güth, J. & Fleischer, J. (2019), "Concept for the Configuration of Turnkey Production Systems". Procedia CIRP, eds. Dietrich, F. & Krenkel, N., pp. 234-238. 10.1016/j.procir.2020.01.047
Shorter product lifecycles and increasing individualization of products lead to the necessity for a reoccurring process, which includes the selection and configuration of production systems to provide a system that produces the product. Especially in fast developing countries like China, the offer for this knowledge can hardly supply the demand. In order to solve this, this paper presents a systematic approach in the form of a multi-stage process. In the first stage, a configuration logic maps product requirements with the properties and specifications of production machines together with equipment and matches them using a uniform data information model for both products and production modules. In the second stage, the turnkey production system is set up, commissioned and operated based on the Industrie 4.0 administration shell. The presented approach has been prototypically implemented on an online platform and demonstrated on a real production system using a new product that has been integrated into production.

[ 6 ] Song, K.; Wang, Y.; Xu, H.; Müller-Welt, P.; Stuermlinger, T.; Bause, K.; Ehrmann, C.; Weinmann, H. W.; Schaefer, J.; Fleischer, J.; Zhu, K.; Weihard, f.; Trostmann, M.; Schwartze, M. & Albers, a. (2021), "Assembly techniques for proton exchange membrane fuel cell stack: A literature review", 10.1016/j.rser.2021.111777
The assembly of proton exchange membrane fuel cell (PEMFC) is a complex process. The joint action of the assembly load and the working temperature causes an uneven stress distribution among the components and produces a certain degree of deformation. In addition, the assembly process is often related to load transfer, material transfer, energy exchange, multi-phase flow and electrochemical reaction. At present, the manufacturing cost of fuel cells is extremely high, and assembly cost accounts for a large proportion. Assembly techniques with low efficiency and accuracy further increase manufacturing costs. Therefore, there is an urgent need for further research on stack assembly theory and techniques to improve stack assembly efficiency and reduce costs. Based on a survey of the literature, the research status of assembly load, assembly load optimisation, assembly mechanism, and automatic assembly are summarised. Based on comprehensive analyses, this review proposes the development trends of assembly key techniques for fuel cell stacks, and provides a helpful reference for researchers and producers. In the future, the research of assembly technique should pay more attention to the assembly load of fuel cell under on-line conditions and the joint influence of assembly load and other stresses. The assembly mechanism should be designed according to the application scenario of fuel cell and be more convenient to dynamically adjust the assembly load. The review also points out that automation is the development direction of assembly technique. The design, manufacture and assembly of fuel cells need to be better coordinated.

[ 7 ] Gönnheimer, P.; Ehrmann, C.; Wu, Y.; Kimmig, A. & Fleischer, J. (2021), "Konzeption und Entwicklung eines Produktionsanlagenkonfigurators im Rahmen einer deutsch-chinesischen Industrie 4.0 Fabrikautomatisierungsplattform", Zeitschrift für wirtschaftlichen Fabrikbetrieb (ZWF), vol. 116, no. 11, pp. 836-840. 10.1515/zwf-2021-0193
Kürzere Produktlebenszyklen und der fortschreitende Trend zur Individualisierung von Produktionsgütern mit immer kleineren Losgrößen führen zu der Notwendigkeit eines wiederkehrenden Prozesses, der die Auswahl und Konfiguration von Produktionssystemen beinhaltet. Produktionssysteme werden dabei auf Basis der Produktanforderungen aus einer großen Zahl komplexer Einzelmaschinen und Komponenten zusammengestellt, was zu einem hohen Integrationsaufwand führt. In diesem Beitrag wird daher ein Ansatz zur nutzerindividuellen, modellbasierten Auswahl von Maschinen und Anlagen vorgestellt, der im Rahmen eines deutsch-chinesischen Industrie 4.0 Forschungsprojektes entwickelt wurde.