Universität Stuttgart

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Author: search.filters.author.Guenther, ThomasSubject: search.filters.subject.670

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    Mass-producible micro-optical elements by injection compression molding and focused ion beam structured titanium molding tools
    (2020) Ristok, Simon; Roeder, Marcel; Thiele, Simon; Hentschel, Mario; Guenther, Thomas; Zimmermann, André; Herkommer, Alois; Giessen, Harald
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    Direct processing of PVD hard coatings via focused ion beam milling for microinjection molding
    (2023) Ruehl, Holger; Guenther, Thomas; Zimmermann, André
    Hard coatings can be applied onto microstructured molds to influence wear, form filling and demolding behaviors in microinjection molding. As an alternative to this conventional manufacturing procedure, “direct processing” of physical-vapor-deposited (PVD) hard coatings was investigated in this study, by fabricating submicron features directly into the coatings for a subsequent replication via molding. Different diamondlike carbon (DLC) and chromium nitride (CrN) PVD coatings were investigated regarding their suitability for focused ion beam (FIB) milling and microinjection molding using microscope imaging and areal roughness measurements. Each coating type was deposited onto high-gloss polished mold inserts. A specific test pattern containing different submicron features was then FIB-milled into the coatings using varied FIB parameters. The milling results were found to be influenced by the coating morphology and grain microstructure. Using injection–compression molding, the submicron structures were molded onto polycarbonate (PC) and cyclic olefin polymer (COP). The molding results revealed contrasting molding performances for the studied coatings and polymers. For CrN and PC, a sufficient replication fidelity based on AFM measurements was achieved. In contrast, only an insufficient molding result could be obtained for the DLC. No abrasive wear or coating delamination could be found after molding.
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    Open-eco-innovation for SMEs with pan-European key enabling technology centres
    (2020) Civelek, Faruk; Kulkarni, Romit; Fritz, Karl-Peter; Meyer, Tanja; Troulos, Costas; Guenther, Thomas; Zimmermann, André
    The project “key enabling technologies for clean production” (KET4CP), which is supported by the European Commission, has the aim to connect small and medium-sized enterprises (SME) and Technology Centres (TC) for cleaner, greener and more efficient production. Within this context, SMEs and TCs across Europe work together to establish an open-innovation network and to raise awareness in productivity and environmental performance. This article presents how an open European network of TCs opens its innovation process to support SMEs to become cleaner, greener and more efficient. Furthermore, this article shows how the TCs and SMEs become a part of the open-eco-innovation platform in clean production and how successful the open-eco-innovation process of different European countries is. We revealed that a pan-European open innovation process for eco-innovations with TCs for key enabling technologies (KET TCs) and Enterprise Europe Network partners (EEN) is a successful approach for SMEs that want to produce and develop cleaner products. An application example is mentioned, in which TCs from different European countries have contributed to developing a product of a SME for energy harvesting. The SME, together with the TCs, developed a generator that is installed in city-level water supply pipes and so, it is outstanding in its application. This innovative application is also described in this article.
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    Characterization of a PCB based pressure sensor and its joining methods for the metal membrane
    (2021) Schwenck, Adrian; Grözinger, Tobias; Guenther, Thomas; Schumacher, Axel; Schuhmacher, Dietmar; Werum, Kai; Zimmermann, André
    The collection and analysis of industrial Internet of Things (IIoT) data offer numerous opportunities for value creation, particularly in manufacturing industries. For small and medium-sized enterprises (SMEs), many of those opportunities are inaccessible without cooperation across enterprise borders and the sharing of data, personnel, finances, and IT resources. In this study, we suggest so-called data cooperatives as a novel approach to such settings. A data cooperative is understood as a legal unit owned by an ecosystem of cooperating SMEs and founded for supporting the members of the cooperative. In a series of 22 interviews, we developed a concept for cooperative IIoT ecosystems that we evaluated in four workshops, and we are currently implementing an IIoT ecosystem for the coolant management of a manufacturing environment. We discuss our findings and compare our approach with alternatives and its suitability for the manufacturing domain.
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    Injection molding of encapsulated diffractive optical elements
    (2023) Wagner, Stefan; Treptow, Kevin; Weser, Sascha; Drexler, Marc; Sahakalkan, Serhat; Eberhardt, Wolfgang; Guenther, Thomas; Pruss, Christof; Herkommer, Alois; Zimmermann, André
    Microstructuring techniques, such as laser direct writing, enable the integration of microstructures into conventional polymer lens systems and may be used to generate advanced functionality. Hybrid polymer lenses combining multiple functions such as diffraction and refraction in a single component become possible. In this paper, a process chain to enable encapsulated and aligned optical systems with advanced functionality in a cost-efficient way is presented. Within a surface diameter of 30 mm, diffractive optical microstructures are integrated in an optical system based on two conventional polymer lenses. To ensure precise alignment between the lens surfaces and the microstructure, resist-coated ultra-precision-turned brass substrates are structured via laser direct writing, and the resulting master structures with a height of less than 0.002 mm are replicated into metallic nickel plates via electroforming. The functionality of the lens system is demonstrated through the production of a zero refractive element. This approach provides a cost-efficient and highly accurate method for producing complicated optical systems with integrated alignment and advanced functionality.
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    Characterization of hermetically sealed metallic feedthroughs through injection-molded epoxy-molding compounds
    (2021) Haybat, Mehmet; Guenther, Thomas; Kulkarni, Romit; Sahakalkan, Serhat; Grözinger, Tobias; Rothermel, Thilo; Weser, Sascha; Zimmermann, André
    Electronic devices and their associated sensors are exposed to increasing mechanical, thermal and chemical stress in modern applications. In many areas of application, the electronics are completely encapsulated with thermosets in a single process step using injection molding technology, especially with epoxy molding compounds (EMC). The implementation of the connection of complete systems for electrical access through a thermoset encapsulation is of particular importance. In practice, metal pin contacts are used for this purpose, which are encapsulated together with the complete system in a single injection molding process step. However, this procedure contains challenges because the interface between the metallic pins and the plastic represents a weak point for reliability. In order to investigate the reliability of the interface, in this study, metallic pin contacts made of copper-nickel-tin alloy (CuNiSn) and bronze (CuSn6) are encapsulated with standard EMC materials. The metal surfaces made of CuNiSn are further coated with silver (Ag) and tin (Sn). An injection molding tool to produce test specimens is designed and manufactured according to the design rules of EMC processing. The reliability of the metal-plastic interfaces are investigated by means of shear and leak tests. The results of the investigations show that the reliability of the metal-plastic joints can be increased by using different material combinations.
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    Experimental study on surface roughness and residual stress development in loose-abrasive polishing of hardened tool steel
    (2025) Ruehl, Holger; Li, Yuxuan; Guenther, Thomas; Breidenstein, Bernd; Zimmermann, André
    The repeatability and control of the achievable surface integrity in manual loose-abrasive diamond polishing of workpieces is very limited. In this study, first effects of polishing on the surface roughness and on induced near-surface residual stress of hardened tool steel X37CrMoV5-1 using an automatic metallographic grinder polisher have been investigated. The results show different effects of polishing parameters such as grain size, platen speed and forces applied to the workpiece on roughness and residual stress. XRD measurements of the residual stress depth profile showed a reduction in compressive stress which could be explained by the material removal mechanism and direction.