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Item type:Publication, Access status: without files , Sensorvergleich zur ML-Verschleiß-prognose beim Drehen : Bewertung der Informationsqualität verschiedener Sensoren zur Vorhersage des Werkzeugverschleißes beim Längsdrehen unter Einsatz von Maschinellem Lernen(2026-05-25); ; Suitable sensors are required for data-driven wear predictions. The objective was to quantify the predictive power of five sensors for predicting the wear mark width VBmax using deep learning models for the turning process. The models based on the cutting force components achieved the highest prediction accuracy (MAE = 9.68 µm, R<sup>2</sup> = 0.93). Acoustic emission, temperature, and tool vibrations were in a close mid-range with MAE ~ 15 µm. The workpiece surface exhibited the lowest information content with an MAE of 23.47 µm.Publicationtype: Journal Article53 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Influence of spatial engagement conditions on workpiece temperature in grinding of unidirectional CFRP(2025-10); ; Carbon Fibre Reinforced Polymers (CFRP) are favoured for their high strength to weight ratio, excellent directional mechanical and thermal properties, and the ability to be optimized in the direction of stress or heat flow. These properties make it ideal for power transmission applications. Heating of the machined surface during grinding can lead to reduced workpiece quality, particularly if the glass transition temperature of the matrix is exceeded. The selection of tool-material, process parameters and cooling strategy significantly influences heat flow from the region of tool-workpiece interaction and changes in the workpiece temperature. Machining unidirectional CFRP is challenging due to its anisotropic behaviour, resulting in different machining temperatures for identical parameters with different fibre orientations. A universal process-independent model describing the spatial engagement conditions during oblique cutting of unidirectional CFRP was used. The model introduces the spatial fibre cutting angle θ0 and the spatial engagement angle φ0. Using this description, an experimental setup for investigating the workpiece surface temperature of CFRP for all possible engagement conditions was developed. In this paper, the machining temperature is determined for all possible spatial engagement conditions during the machining of CFRP using thermographic camera. Furthermore, the influence of the cutting material in the cases of corundum and diamond is analysed as well as the influence of the cutting speed.Publicationtype: Journal Article33 15 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , The Enabled Worker Combining Smart Hand Tools, Active Exoskeletons and Digital Assistance Systems in the Production of the Future(De Gruyter, 2025-06-21); ; ; ; Manual work processes require high quality, process reliability and ergonomics. The increasing individualization of products further increases these requirements. Smart hand tools, (active) exoskeletons and digital assistance systems can help here. Linking these technologies in terms of sensors, information technology and mechanics can enable a context detection and adaptive process support in order to improve quality, increase process reliability and reduce stress on workers.Publicationtype: Journal Article69 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Modeling Process Forces in CFRP Grinding: Influence of Cutting Materials and Coolant on Process Force Behavior(2025-05); ; Carbon Fibre Reinforced Polymer (CFRP) is favoured for its high strength to weight ratio, excellent directional mechanical and thermal properties, and the ability to be optimized in the direction of stress or heat flow. These properties make it ideal for power transmission applications. Meeting the high-quality requirements in this area requires a precise grinding process and a thorough understanding of cutting forces, which are influenced by different factors e.g. coolant usage, or cutting material. However, machining unidirectional CFRP is challenging due to its anisotropic behaviour, resulting in different machining forces for identical parameters with different fibre orientations. A universal process-independent model was recently developed to describe the engagement conditions during oblique cutting of unidirectional CFRP by introducing the spatial fibre cutting angle θ0 and the spatial engagement angle φ0. Using this description, an universal mechanistic machining force model for grinding of CFRP was developed. In the paper, an extension of the model of oblique cutting for grinding is extended and experimentally verified, taking into account additional parameters e.g. coolant and cutting material. Therefore, the process forces were measured as a function of the spatial fibre cutting angles for different cutting materials, both with and without the use of coolant.Publicationtype: Conference Paper33 46 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Model based assessment of maximal surface temperatures and heat flow in edge trimming of UD CFRP with tools of different type(Elsevier, 2025-04-04); ; ; ; Excessive heating during edge trimming of CFRP components leads to matrix degradation impairing their quality. The thermal response of unidirectional CFRP when machining with different tool types is studied: PCD cutters, coated carbide routers, and diamond grinding pins. Temperature and torque were measured at various fibre orientation angles Φ and cutting conditions. Based on an analytical model, key thermal parameters were identified from experimental data. For all tools, temperatures exceeded the matrix glass transition temperature under most conditions. Maximum of temperature changes was observed at Φ = 135°, minimum at Φ = 90° was most pronounced for the cutter, less noticeable for the router, and almost absent for the grinding pin. At Φ = 90°, the thermal contact length and heat flow ratio typically reached maximum values, while the heat flux was at its lowest. Regarding cutting conditions for both the cutter and router, an increase in cutting speed led to higher equivalent heat flux, heat flow, and temperature change. In contrast, for grinding pins, temperature change increased at the lower cutting speed or feed rate. In grinding, heat flow, equivalent heat flux and thermal contact length were primarily influenced by the fibre orientation symmetry angle, whereas heat flow and equivalent heat flux were nearly independent of the cutting conditions. Thus, the tool types exhibit different thermal parameters and patterns of their dependencies on the machining conditions, which are differentiated by the model and can be explained by pulsed point, pulsed linear or continuous surface contact of individual cutting edges.Publicationtype: Journal Article37 30 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Control loop based dimensional error compensation for milling of near-net-shaped, thin-walled structures(Springer, 2025); ; ; ; Additive manufacturing has the potential to save resources in the pro-duction of lightweight aerospace structural components made of Ti-6Al-4V. Cur-rently, these components are milled out of plate-material, resulting in up to 95% of the material being converted into chips that can only be downcycled. However, machining near-net-shape parts poses new challenges. For example, commonly used methods such as the “waterline”-path approach, which uses the residual stiff-ness of the plate-material to reduce the deflection of the thin-walls due to process forces, can no longer be applied. In this paper, a dimensional error compensation method is presented, that measures the deflection of the workpiece during helical end mill finishing using eddy current sensors. The sensor values are used within a control loop to adjust the toolpaths width of cut and inclination in real time to minimize dimensional error. Next to adjusting for different compliant states of the workpiece, this method adjusts for increasing tool wear states, that produce higher process forces and thereby larger dimensional errors. The presented compensation is compared to a conventional machining approach to demonstrate its capability to enable finishing of near-net-shape parts within tight tolerances while maintaining high material removal rates.Publicationtype: Conference Paper48 26 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , The role of material properties in modeling maximal surface temperatures and heat distribution in milling of UD CFRP(Elsevier, 2025); ; ; ; In order to meet the precision requirements for components made of carbon fibre reinforced plastics (CFRP), the edges are often trimmed by milling. However, this can lead to detrimental thermal damage to the machined surface. The aim of the study was to investigate in detail the maximum temperatures and characteristic thermal parameters for various unidirectional CFRP materials under different cutting conditions. During upcut milling using a PCD cutter an infrared camera, thermocouples and a dynamometer were employed to monitor temperatures and the cutting power. An analytical heat flow model suitable for arbitrary fibre orientation angles was used to determine, based on thermal material properties, the temperature change at the machined surface and the heat flow parameters from experiments. Material influence on the cutting power was considered by its specific elastic energy at fracture depending on the volume content and mechanical properties of the fibres. At the machined surface, the resin glass transition temperatures were frequently exceeded, and the highest temperature changes were observed at a fibre orientation angle of Φ = 135◦. In most cases, higher cutting speeds were accompanied by greater temperature changes. Phenomenological models of the thermal parameters of the machining process were developed, which take into account both the thermal and mechanical CFRP properties and show a good correlation with the experimental results. They provide benefits in order to predict the temperature fields for materials with differing properties and under varying cutting conditions.Publicationtype: Review Article41 11 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Modeling of temperature fields in milling of unidirectionally reinforced CFRP depending on the fibre orientation angle and the effective width of cut(Elsevier, 2025); ; ; ; CFRP parts are conventionally used within various industries; however, during machining these components, the generated heat is a very relevant limiting factor. Exceeding the glass transition temperature can lead to workpiece degradation, reduced strength, and shorter lifetime. During up-cut milling of unidirectional (UD) CFRP with PCD cutters, the temperature was measured using thermocouples and a thermographic camera, while the cutting torque was measured with a rotating dynamometer. The maximum temperature increase at the machined surface, the heat flow from the machining zone into the material, and the ratio of heat flow to cutting power were simulated. An analytical model developed earlier for the temperature field in machining orthotropic composites with arbitrary fibre orientation was used. The results indicate that cutting power, heat flow, and the ratio of heat flow to cutting power exhibit approximate symmetry relative to the fibre orientation angle Φ = 90°. Introducing the concept of the fibre orientation symmetry angle is useful. Unexpected fractures of larger segments of remaining UD CFRP material occur at all feeds at higher fibre orientation and engagement angles within a small range of fibre cutting angles near 45°, significantly reducing the nominal width of cut and impairing results. The effective width of cut was evaluated based on the drop in cutting torque, measured at various fibre orientation angles, cutting speeds, feeds, and nominal widths of cut. The highest maximum temperature increase consistently occurs at Φ = 135°. As an overall effect, higher cutting speeds lead to increased cutting power, heat flow, and maximum temperature at the machined surface, but result in a smaller depth of the heat-affected zone. The simulations conclude that a higher fibre orientation symmetry angle leads to a higher equivalent heat flux, shorter thermal contact length, and reduced heat flow, and vice versa. In the future, the influence of different tools and composite materials needs to be investigated.Publicationtype: Conference Paper52 14 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Surface quality during grinding of CFRPSurface Quality during Grinding of CFRP. The use of carbon fibre-reinforced polymers in high-performance electric motors enables higher levels of efficiency and system rigidity. The demands on the surface quality of the individual components are so high that they can only be achieved by grinding processes. This paper investigates the influence of fibre orientation and abrasive grain size on the surface roughness during side-face grinding of CFRP.Publicationtype: Journal Article34 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Cutting carbon footprint with smart tool management and cemented carbide (WC-Co) upcycling(Institutionelles Repositorium der Leibniz Universität Hannover, 2024-07); ; ; During the production of a small to medium-sized aircraft, approximately 250,000 rivet holes are required. These must be manufactured according to strict aviation specific technical, quality, and safety standards. High-quality cemented carbide (WC-Co) drilling tools are used to ensure the necessary precision and durability. However, the high energy requirement for production, especially for sintering the WC-Co blanks, and grinding the final tool geometry negatively impacts the carbon footprint of aircraft production. This study aims to analyse the environmental impact of each step in the WC-Co tool production chain and proposes innovative methods to upcycle worn tools without the need of conventional recycling processes. To reduce the climate impact, a novel smart digital tool management system is introduced containing digital twins of the individual tools. This system is complemented with three new methods of upcycling WC-Co drilling tools: regrinding worn tools to smaller diameters, applying a PVD-coating to compensate for diameter deviations, and de- and recoating diamond coatings on WC-Co tools. Preliminary results in modelling the climate impact show that these strategies can reduce the carbon footprint by up to 53 %.Publicationtype: Conference Paper67