Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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Nachhaltige Reinigung und Präparation

2024 , Uhlmann, Eckart , Polte, Julian , Burgdorf, Philipp , Reder, Waldemar

In der Fertigungstechnik lautet aktuell die Devise, innovative Wege für mehr Nachhaltigkeit zu entdecken. Für industrielle Reinigungsprozesse ist das CO2-Strahlen auf dem Vormarsch - im Beitrag wird beschrieben, warum.

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Semi-automatic process control for efficient refurbishment of turbine blades

2023-06-16 , Uhlmann, Eckart , Polte, Julian , Mühlich, Christopher , Mönchinger, Stephan , Ebrahimi, Puya

The refurbishment of turbine blades requires the precise removal of damaged surface coatings. In manufacturing companies, this usually involves time-consuming activities such as detecting residual coatings and adapting process settings to varying turbine blade geometries. The use of automated systems therefore opens up opportunities to improve the efficiency of turbine blade refurbishment processes by replacing manual tasks. This paper presents an conceptual approach for a semi-automatic decoating process of turbine blades that integrates abrasive blasting technology into a closed loop process control system. The experimental setup consists of a robot for guiding the turbine blade in a blast machine and a nozzle system for local removal of residual coatings using abrasive material. Based on image processing the residual coatings of a turbine blade are labeled by a neural network and mapped to a 3D model of the turbine blade, which is used by a software control system to coordinate the decoating process. Using a prototype setup this paper investigates the applicability of the proposed approach and evaluates its feasibility.

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Smarte Überwachung elektrischer Großantriebe

2023 , Geisert, Claudio , Polte, Julian , Uhlmann, Eckart , Rauch, Hartmut , Brach, Karsten

Die Nutzung von Digitalisierungstechnologien im Kontext von Industrie 4.0 bietet insbesondere für den gesamten Bereich der Wartung und Instandhaltung von elektrischen Großantrieben großes Potenzial zur Schaffung innovativer Serviceangebote. Durch erweiterte Sensorik im elektrischen Antrieb und Intelligenz in der Verarbeitung und Analyse von Daten im Betrieb von Anlagen, kann eine vorausschauende Instandhaltungsstrategie eingeführt werden, die eine höhere Verfügbarkeit der Anlagen ermöglicht und gleichzeitig den Aufwand für Instandhaltungseinsätze reduziert. Um diese Potenziale im Servicegeschäft elektrischer Großantriebe zu erschließen, wird in diesem Beitrag ein hypothesengetriebener Ansatz zur Zustandsüberwachung beschrieben.

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DEM simulation of centrifugal disc finishing using smoothed particle hydrodynamics

2023 , Uhlmann, Eckart , Polte, Julian , Kuche, Yves , Hocke, T.

Centrifugal disc finishing is a widely used technology forserial post-processing of small components made of various materials. During the process, the workpieces are completely surrounded by dry or moist abrasive media, making it difficult to obtain precise information about particle contacts or the movement of the workpieces. Numerical analysis through the discrete element method (DEM) has the potential to improve the understanding of the process, but the accurate representation of moist particles with varying contact conditions remains a challenge. This paper compares different contact models using the ROCKY DEM software, including the liquid-bridge model and the smoothed particle hydrodynamics (SPH) model. The analysis indicates that, compared to other models, SPH demonstrates clear advantages in representing process water flow and is better suited for cases with higher water content in the medium.

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A Comparative Evaluation of Powder Characteristics of Recycled Material from Bronze Grinding Chips for Additive Manufacturing

2024 , Uhlmann, Eckart , Polte, Julian , Fasselt, Janek Maria , Müller, Vinzenz , Klötzer-Freese, Christian , Kleba-Ehrhardt, Rafael , Biegler, Max , Rethmeier, Michael

In the manufacturing process of ship propellers, large quantities of grinding chips are generated. These grinding chips result from the finishing of the blade surfaces after the primary casting process of the propeller. The aim of this study was to investigate and compare different preparation processes used to produce chip powders with sufficient powder quality for the additive manufacturing process of directed energy deposition. The preparation of the samples was performed through different sieving, milling and re-melting processes. For the characterization of the prepared samples, powder analysis according to relevant industry standards was carried out. It was found that the re-melting processes result in superior powder quality for additive manufacturing in terms of particle size, morphology, and flowability. For some characteristics, the powder exhibits even better properties than those of commercial powders. Furthermore, the powder properties of the milled samples demonstrate a promising potential for use in additive manufacturing.

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Surface modification of tungsten carbide cobalt tool electrodes by heat treatment under nitrogen atmosphere for electro-discharge drilling

2023 , Uhlmann, Eckart , Camin, B. , Polte, Julian , Polte, Mitchel , Streckenbach, J. , Dinh, N.C.

The requirements for high-precision components for tool and mould-making, automotive and aerospace industries are constantly increasing. Due to the strong mechanical properties of the used materials, such as tool steels and nickel-based alloys, conventional cutting processes are not always suitable. Instead, electrical discharge machining is used for cutting electrically conductive materials. One challenge even today is debris formation, causing arcs and short-circuits in the lateral working gap. This applies particularly to electro-discharge drilling with high aspect ratios and increased difficulties of debris removal. This leads to increased process instability, tool wear and conicity as well as decreased material removal rates. To reduce the effects of arcing and short-circuits in the lateral working gap, tungsten carbide-cobalt tool electrodes with an outer diameter of dO = 1.5 mm were heat-treated to increase the electrical resistivity of the electrode's surface. For this purpose, two different ambient atmospheres were selected, a nitrogen atmosphere and vacuum in comparison. Subsequently, the modified tool electrodes were used to produce boreholes in tool steel of the type Elmax Superclean with a depth of et = 6.75 mm by electrodischarge drilling. The surface modification in the nitrogen atmosphere led to a slightly higher material removal rate and a decrease in the linear tool wear of the tool electrode by up to 6.67 % compared to an untreated reference electrode.

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Prediction of Quality in Thermographic Spray Spot Applications with Machine Learning Algorithms

2023 , Uhlmann, Eckart , Polte, Julian , Koutrakis, Nikolaos-Stefanos , Pyka, Lasse Stephan , Ider, Müslüm , Thomas, Georg , Rupprecht, Christian

Due to the high number of influences in production applications, quality fluctuation and deviating results in thermal spray applications are a challenging issue in manufacturing processes. This paper presents a concept for an adaptive process control based on different machine learning algorithms that are utilized to correlate input parameters with output results in thermal spray processes. For that purpose, a test environment was developed, incorporating different application scenarios with various input parameters. During the experiments, a series of measurements was performed, that is used to describe and evaluate the process. The extracted data of the conducted experiments are transformed into features and serve as the data input for the development of machine learning models based on various algorithms. These algorithms offer a prediction of the peak position, which describes the deviation of the programmed application spot, thus offering a quality prediction by utilizing solely the input process parameters. This work provides an approach based on the compared algorithms, that can be applied to create an adaptive process control, by adjusting the input parameters during the thermal spray application process.

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Schneestrahltechnologie im Refurbishment-Prozess

2024 , Polte, Julian , Burgdorf, Philipp , Uhlmann, Eckart

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Precise cutting of cemented carbide with nanopolycrystalline diamond in ductile regime

2023 , Uhlmann, Eckart , Polte, Mitchel , Hocke, Toni , Polte, Casey , Polte, Julian

Today's demands on technical applications require the precise machining of high-performance materials. Cemented carbide is used as a wear-resistant material in a wide range of industrial applications, e.g. tool and mould making, mobility and medical engineering. Due to the brittle material characteristics and the resulting high hardness and wear resistance, the machining of the cemented carbide is severely limited. Long machining times and high tool wear are remaining challenges at state of the art. A novel approach for the machining of cemented carbide is the application of binderless nanopolycrystalline diamond (NPD) as cutting material for precise turning. Based on investigated fundamental cutting phenomena, within the scope of this work, the application of the novel cutting material was further investigated by comprehensive turning experiments. Turning tests were carried out with cemented carbide samples with a tungsten carbide content of CC = 88 %, a cobalt content of CCo = 12 % and a grain size of dg = 0.5 μm. Prior to the turning tests, the brittle-ductile transition as well as the minimum chip thickness were determined by dedicated spiral cutting tests as a function of the feed. In subsequent turning tests, the influence of the cutting speed, feed velocity and depth of cut were investigated. Process forces were evaluated and specimens were analysed regarding surface roughness and topography. In the course of the investigations, it could be shown that a dedicated set of process parameters enable cutting in ductile regime with great chip formation. Thus, the great potential of the novel cutting material NPD in turning of cemented carbide could be demonstrated.

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Distributed real-time production control for resilient manufacturing systems

2023 , Uhlmann, Eckart , Polte, Julian , Mühlich, Christopher

To enable resilient manufacturing, production control systems must be able to adapt quickly and flexibly to unexpected changes. Motivated by Industrie 4.0, multi-agent systems offer a promising approach to meet these requirements. This paper presents a method for distributed production control that enables production entities to make optimal decisions regarding capacity utilization and the compliance of delivery dates in real-time despite disruptive events. Based on a multi-agent Markov Decision Process, production entities are modeled as autonomous software agents that can solve Flexible Job-Shop Problems through message passing. The performance of the proposed method is evaluated in a simulated production environment.

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