Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Laser Surface Texturing of Ti6Al4V Alloy for the Reduction of Peri-implantitis
    (Fraunhofer Verlag, 2023)
    Souza Schweitzer, Luiz Guilherme De
    Within the scope of the present work, a novel laser texturing processing to optimize the surface characteristics of dental titanium implants is developed. The treatment with ultrashort pulsed laser for the surface texturing shows promising results to prevent implant-associated infections on dental implants. On the one hand, this is achieved by reducing the biofilm formation of the pioneer bacteria Streptococcus. The reduction of biofilm formation on the surface avoids the proliferation of pathogen bacteria responsible for the peri-implantitis disease. On the other hand, the host tissue integration is achieved through the adhesion of human MSCs, allowing the maintenance of biocompatibility. The investigation of both aspects within the same framework conditions comprises a method to assess the technology developed to prevent the occurrence of peri-implantitis cases without compromising the biocompatibility of the implant.
  • Publication
    Injection mould measurement system for increasing manufacturing control and production quality
    ( 2023)
    Uhlmann, Eckart
    ;
    Trabasso, Luís Gonzaga
    ;
    Bolz, Robert
    ;
    Souza Schweitzer, Luiz Guilherme De
    ;
    Hein, Christoph
    ;
    Souza, Diego de
    Tool and mould making is one of the most important sectors of industrial manufacturing. Currently, over a third of polymer products are manufactured by injection moulding or stamping. These processes are complex, as the melted or heated polymers are subject to thermomechanical changes. Since injection moulding and stamping are mostly used for mass production, process repeatability and quality of the final product are very important. Improper adjustments of process variables lead to various defects in the final product along with high amount of waste and rejects. The need for measurement and control of the process is mandatory. Frequently, the tool is not operated by the owner of the mold or the end user of the plastic components, respectively, but by an injection molding service provider within the supply chain. Consequently, it is impossible for the tool owner to trace the quality of parts regarding the parameters applied for processing. This is crucial information to connect parts outside the tolerances to the respective process characteristics. The increase of quality in the production is achievable through correlating the processing parameters applied with the produced components. Therefore, the aim of the research herein is to develop an autonomous sensor system for monitoring injection moulding and stamping processes. The system comprises an external component of the tool in order to record and document the parameters applied such as tool temperature, pressure, number of machined parts and geolocation among others. In conjunction with a connected laser marking system for injection moulding, the unique identification of the components and the unchangeable connection of the production parameters with an individual component is enabled. The direct technological added value is given by the fact that the customer is able to monitor the production at any time, any place, comparing the actual production with the agreed and specified conditions. Furthermore, this information enables the creation of new business models for the tool owner. Even though this work is at initial stages, the preliminary results detailed herein are rather encouraging.
  • Publication
    Application of laser doppler vibrometry to characterize the laser drilling process
    ( 2023)
    Uhlmann, Eckart
    ;
    Hein, Christoph
    ;
    Souza Schweitzer, Luiz Guilherme De
    Laser drilling is being used more and more frequently in many industries, such as the aerospace, medical and electronics industries, to produce precision bores. A wide range of technically difficult-to-machine materials are applied. Laser drilling has already been intensively researched in order to investigate the basic mechanisms of the drilling process and the influences of various machining parameters on the quality of the holes. These findings have explicitly led to more successful machining processes of various technical components and industries. Despite all the advantages, there are some limitations of the laser drilling process and thereby a demand for innovative solutions to increase productivity. This paper presents a novel approach to the characterisation of the laser drilling process through the analysis of the acoustic signal characteristics. The objective is to apply a new generation of optical microphones to detect key aspects of the laser drilling process. This enables the development of new strategies to optimize the laser processing parameters, increasing repeatability and productivity for industrial applications.
  • Publication
    Surface optimization of dental implants with laser surface texturing and silver coating
    ( 2022)
    Uhlmann, Eckart
    ;
    Brehmer, Annika
    ;
    Schneider, Peter
    ;
    Hein, Christoph
    ;
    Souza Schweitzer, Luiz Guilherme De
    The risk of bacterial inflammation at the interface between implant and tissue exists following the implantation of a dental prosthesis. Nearly half of implants are at risk of colonisation by pathogenic bacteria, which is associated with the occurrence of peri-implant mucositis. This disease can develop into peri-implantitis and thereby trigger a severe inflammatory process. The occurrence of peri-implantitis includes different phases. The initial attachment of microorganisms is only possible by pioneer bacteria, such as the gram-positive streptococci. Since the pathogenic cannot form a biofilm unless attached to a surface, the attachment of the pioneer bacteria is crucial for the onset of peri-implantitis. Due to the flexibility and contact free process, laser material processing is used for the surface structuring of several materials. In the biomedical field, laser-based surface texturing enables the production of implants with improved biological reaction surfaces to positively influence protein adsorption and cell adhesion. This paper presents laser texturing and silver coating to reduce initial biofilm formation on Ti6Al4V. The laser processing includes the manufacturing of LIPSS (Laser Induced Periodic Surface Structures), which enables the functionalisation of the surface. Furthermore, the surfaces are coated with silver to act as an inhibitor of biofilm formation. The implant material undergoes an in vitro culture of the microorganism Streptococcus salivarius in order to determine the biofilm formation applying both techniques. The analysis was realized by fluorescence microscopy with the application of 4', 6-diamidino-2-phenylindole (DAPI) on the adhered biofilm. Results show that the surface modification plays a major role in the inhibition of biofilm formation.
  • Publication
    Steuerung von Laser-induzierten periodischen Oberflächenstrukturen
    ( 2021)
    Uhlmann, Eckart
    ;
    Souza Schweitzer, Luiz Guilherme De
    ;
    Schneider, Peter
    ;
    Michel, Andre
    ;
    Hein, Christoph
    Laser-induzierte periodische Oberflächenstrukturen (LIPSS) weisen ein hohes Potenzial für Anwendungen in den Bereichen der Oberflächenfunktionalisierung auf. Die Steuerung der Richtung dieser Nanostrukturen kann nur durch Änderung der Laserpolarisation erfolgen. Auf dem Markt gibt es kein System zur automatischen Änderung der LIPSS-Orientierung. Für den industriellen Einsatz ist dies vom Vorteil, um Inhomogenität im Strukturverlauf zu vermeiden. In diesem Beitrag wird eine Systemlösung vorgestellt, indem die Steuerung der Richtung von Nanotexturen ermöglicht wird.
  • Publication
    Preclinical In Vitro Assessment of Submicron-Scale Laser Surface Texturing on Ti6Al4V
    ( 2020)
    Souza Schweitzer, Luiz Guilherme De
    ;
    Cunha, Alexandre
    ;
    Pereira, Thiago
    ;
    Mika, Kerstin
    ;
    Rego, Ana Maria P. L. R. Botelho Do
    ;
    Ferraria, Ana Maria
    ;
    Kieburg, Heinz
    ;
    Geißler, Sven
    ;
    Uhlmann, Eckart
    ;
    Schoon, Janosch
    Loosening of orthodontic and orthopedic implants is a critical and common clinical problem. To minimize the numbers of revision surgeries due to peri-implant inflammation or insufficient osseointegration, developments of new implant manufacturing strategies are indicated. Ultrafast laser surface texturing is a promising contact-free technology to modify the physicochemical properties of surfaces toward an anti-infectious functionalization. This work aims to texture Ti6Al4V surfaces with ultraviolet (UV) and green (GR) radiation for the manufacturing of laser-induced periodic surface structures (LIPSS). The assessment of these surface modifications addresses key aspects of topography, morphology and chemical composition. Human primary mesenchymal stromal cells (hMSCs) were cultured on laser-textured and polished Ti6Al4V to characterize the surfaces in terms of their in vitro biocompatibility, cytotoxicity, and metal release. The outcomes of the in vitro experiment show the successful culture of hMSCs on textured Ti6Al4V surfaces developed within this work. Cells cultured on LIPSS surfaces were not compromised in terms of their viability if compared to polished surfaces. Yet, the hMSC culture on UV-LIPSS show significantly lower lactate dehydrogenase and titanium release into the supernatant compared to polished. Thus, the presented surface modification can be a promising approach for future applications in orthodontics and orthopedics.