Journal: Procedia CIRP

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Elsevier

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ISSN

2212-8271

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2012 - 2019802020 - 202540
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Publications 1 - 10 of 120
  • Development and Application of an Eco-design Tool for Machine Tools
    Item type: Conference Paper
    Züst, Simon; Züst, Rainer; Schudeleit, Timo; et al. (2016)
    Procedia CIRP ~ The 23rd CIRP Conference on Life Cycle Engineering
    Improving the energy efficiency of machine tools is one of the challenges regarding the European energy saving goals. This work presents a new tool, enabling an effective quantification of a machine tool's (MT) energy consumption during all life phases. Scope of the presented tool is the fast and efficient estimation of a MT's cumulated energy demand and the systematic derivation of improvement measures regarding ecological performance. This work will present a framework, as well as the required calculations for this task. Using model and rule-based procedures, only a minimal set of input parameters is required to identify the hot-spots regarding energy consumption and improvement potential. Applications of this tool as well as a systematic approach to derive measures to increase the energy efficiency based on the output of the tool are presented on practice-oriented examples from industry.
  • Geometric-kinematic model for wear simulation of diamond-impregnated segments in concrete core drilling
    Item type: Conference Paper
    Marra Araujo, Lucas; Borges Esteves, Paulo; Fabbro, Stefan; et al. (2023)
    Procedia CIRP ~ 19th CIRP Conference on Modeling of Machining Operations
    The main concerns during the development of new diamond-impregnated segments in concrete core drilling are the tool lifetime and its capacity to self-sharpen, since tool sharpening is, most of the time, not acceptable under the conditions on the construction site. However, development only based on experiments can be very costly, considering that the amount of material and workforce are quite demanding. One of the solutions to overcome these issues is the development of a geometric-kinematic model to simulate the wear of diamonds in the segments due to the core drilling process. The main purpose of the model is to simulate the reinforced concrete core drilling, providing an estimation of the diamond wear states proportion for the segment diamond layer. This can allow an evaluation of the geometric characteristics impact of diamond-impregnated segments (diamond size, geometry, pattern, etc.) and of drilling parameters on the tool self-sharpening capacity. A specialized kinematic model, process force model and diamond wear model are the main ingredients. For the model validation, diamond wear states characterization after core drilling tests are carried out. The wear simulation delivers a tendency of a diamond layer design in specific process conditions, providing orthogonal worn/fractured profile, number of active diamonds and number of diamond pull-outs.
  • Semi-Automated Design Workflow for Bolt Clamping Interfaces to Post-Process Additive Manufactured Parts
    Item type: Conference Paper
    Beutler, Patrick; Ferchow, Julian; Schlüssel, Marcel; et al. (2023)
    Procedia CIRP ~ The 33rd CIRP Design Conference
    Metal additive manufacturing (AM) enables the production of complex and individualized designs. However, most AM parts require postprocessing with subtractive manufacturing processes, which can account for a significant percentage of the total manufacturing cost of an AM part. Positioning and clamping of complex AM parts within post-processing machines often lead to increased prestresses and reduced tool accessibility. One concept to address this problem is the integration of clamping interfaces in the part. But this leads to the new design challenge of optimal and material-saving placement of clamping interfaces on the part. To overcome this challenge new design tools are desired that facilitate this work and automatically generate the design of clamping interfaces. A recently developed clamping system uses bolts that are directly printed onto parts as clamping interfaces. These printed bolts and the clamping jaws of the system enable a unique spatial positioning and rigid clamping of AM parts for post-processing. This work introduces a design workflow that supports the positioning of bolts using a knowledge-based engineering (KBE) approach. The workflow thus allows the user to easily find a feasible clamping configuration and automatically generates the geometries of the bolt-shaped clamping interfaces. As input, the workflow uses the part geometry and an AM build direction. During the workflow, the user can modify the position of the clamping system relative to the part and find feasible positions for bolts. The bolt geometries are then generated automatically, and the part can be exported. This paper describes the workflow in detail and provides a vision for future developments of the tool and its potential for the AM process chain.
  • Building Blocks for Volume-oriented Changeability of Assets in Production Plants
    Item type: Conference Paper
    Rippel, Manuel; Schmiester, Johannes; Wandfluh, Matthias; et al. (2016)
    Procedia CIRP ~ Research and Innovation in Manufacturing: Key Enabling Technologies for the Factories of the Future - Proceedings of the 48th CIRP Conference on Manufacturing Systems
    Demand volatility and uncertainty in the business environment lead to an increasing relevance of volume-oriented changeability (VoC) for manufacturing companies. Strategic investment decisions are often based on forecasts and predictions, which more frequently fail to materialize due to obsolete assumptions or unpredictable events with extreme impact. If the production output fluctuates, fixed costs of production plants emerging from these investments result in high variance of unit costs, which has an impact on operational performance. Despite these demand and investment risks, managers on the strategic level must make capacity decisions without endangering the plant's performance both in growth and decline phases. Therefore, the paper conceptualizes building blocks for strategizing VoC of assets in production plants. These building blocks systemize capacity strategies for economical and dynamical up- and downscaling of production output. The paper depicts the impact on financial targets and analyzes contextual requirements and interdependencies with the organizational concept. By means of this decision support concept, managers of the production plant can select and combine interdisciplinary measures for developing an asset management strategy in the face of demand volatility and uncertainty.
  • Height prediction in Directed Metal Deposition with Artificial Neural Networks
    Item type: Conference Paper
    Knüttel, Daniel; Baraldo, Stefano; Valente, Anna; et al. (2022)
    Procedia CIRP ~ 21st CIRP Conference on Electro Physical and Chemical Machining, ISEM XXI
    Directed Metal Deposition (DMD) is a promising metal additive manufacturing technology, where parts are manufactured by fusing injected metal powder particles with a laser beam moving along a predefined trajectory. A toolpath typically includes sections as curves or edges, where machine axes need to decelerate and accelerate accordingly. As a result, the locally applied laser energy and powder density vary during the deposition process, leading to local over-deposition and over-heating. These deviations are additionally influenced by the toolpath geometry and process duration: previous depositions can influence close toolpath segments, in terms of time and space, resulting in local heat accumulations and develop profiles and microstructures that are different from the ones generated in other segments deposited with the same parameters due to geometry- and temperature dependent catchment profiles. To prevent these phenomena, lightweight and scalable models are required to predict the process behaviour for variable toolpaths. In this work, an artificial intelligence-based approach is presented to handle the process complexity and the multitude of toolpath variations for Inconel 718. Artificial neural networks (ANN) are used to predict the height of the deposition considering the previously defined toolpath. Training data have been generated by printing a randomized toolpath containing multiple curvatures and geometries. Based on the trained models, significant local geometric deviations are successfully predicted for the complete toolpath and could be anticipated by adapting process parameters accordingly
  • High aspect ratio microstructuring of copper surfaces by means of ultrashort pulse laser ablation
    Item type: Conference Paper
    Büttner, Henning; Hajri, Melik; Roth, Raoul; et al. (2018)
    Procedia CIRP ~ 19th CIRP Conference on Electro Physical and Chemical Machining
    Laser beam machining (LBM) is capable of almost force-free 2D and 3D machining of any kind of material without tool wear. This process is defined by many parameters, such as pulse energy, frequency, scanning velocity and number of scanning repetitions. Modern laser machines provide high energy at shorter pulse durations and have more precise positioning systems than machines of the past. These can easily fulfil today's continuous changing product requirements. For an overall understanding, an extensive amount of experimentation is required to display the interaction laws and dependencies between process parameters, as well as the resulting shapes and quality of the machined surface. By using an ultrashort pulse (USP) laser, a wide range of customer oriented applications in micrometer scale can be addressed, which leads to precise ablation with minimal thermal damage. This paper provides knowledge on the machining of copper micro features with high aspect ratio and a 532 nm wavelength laser beam. Aspect ratios up to 17 and slot widths smaller than 20 μm were performed with a beam radius ω0 smaller than 5 μm and pulse duration smaller than 12 ps. For desired slot geometries, necessary process parameters were developed and their physical limits are shown and discussed. The limits of minimum structure size have been analysed by observing the remaining material between slots at decreasing distances. Material debris deposits on the non-machined surface, as well as chemical changes of copper, were analysed using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). Special attention was given to the taper angle, which arises due to the Gaussian distribution of energy in the laser beam.
  • Design of a Test Stand for Lifetime Assessment of Flat Belts in Power Transmission
    Item type: Conference Paper
    Urundolil Kumaran, Varun; Zogg, Markus; Weiss, Lukas; et al. (2020)
    Procedia CIRP ~ Enhancing Design Through the 4th Industrial Revolution Thinking
    Flat belts are machine elements used for the power transmission between rotating elements. Compared to chain or gear drives, belt drives express advantages such as low-noise, and shock- and vibration-damping characteristics. Additionally, the simple, low maintenance and cost effective setup as well as high energy efficiency up to 98 % make them an attractive choice. Since they transfer power based on friction, they are subject to wear and consequently are expendable parts. Hence, there is a demand to increase the service lifetime of power transmission flat belts to decrease cost and downtime due to belt failure. This requires a deeper understanding on the fundamental transmission mechanics of flat belts as well as the failure mechanism limiting their lifetime. Experimental investigation is key in achieving both goals. Existing test stands are not able to replicate high performance applications and accelerating the lifetime assessment of flat belts due to limited capabilities in belt force and speed. Therefore, in this work an innovative test stand was designed and build, with a maximum belt tension of 1500 N and a maximum belt speed of 50 m/s, enabling the transfer of 75 kW. The design of the test stand was governed by modularity regarding multiple aspects. First, a variety and range of reproducible adjustable parameters were required. Second, the test stand had to be flexible regarding the emulation of possible drive configurations. Lastly, auxiliary instrumentation had to be accommodated by the test stand and its data acquisition system. The solution concepts for specific components were evaluated using morphological analysis.
  • Development of Process Chain for Micro-Injection Molding
    Item type: Conference Paper
    Büttner, Henning; Maradia, Umang; Suarez, Manuel; et al. (2020)
    Procedia CIRP ~ 20th CIRP Conference on Electro Physical and Chemical Machining
    In today’s continuously growing demand for components with increasingly smaller dimensions and features, micro-manufacturing is gaining more significance. For the mass production of plastic components with micro-features, injection molding is particularly suitable and still customary in order to keep target costs. Due to high requirements regarding lifetime and resistance to wear, the molds are made of hardened steel. The shaping of these molds involves electrical discharge machining (EDM). This process allows the generation of micro-structures in micrometer range having small inner radii, high dimensional accuracy and extreme aspect ratio independent of the workpiece hardness. As a work tool for EDM, electrodes made of pure copper (Cu) and tungsten reinforced copper (WCu) are commonly used. The shaping of the electrodes is conducted by micro-milling. For an overall understanding of this process chain, the interaction between micro-milling, micro-EDM, and micro-injection molding must be evaluated. This paper provides knowledge on the limits of each process with regard to burr formation, form accuracy, structure size and aspect ratio. Many factors throughout the process chain affect the size of an attainable micro-feature of a final product. The proper selection of the electrode material is a key factor in the process chain. As the feature size of the electrode defines the dimension of the final product shape, the smallest possible structures have to be found during micro-milling. The dimension of the eroded cavity is defined by the feature size of the electrode in combination with the lateral working gap. Eroded cavities with small inner corner radii and steep flanks can be generated when applying flawless and burr-free electrodes. However, using electrodes in inadequate conditions can lead to worse outcomes. The quality and reliability of the final product are determined to a great extent by the design of the injection molding process. Due to the arising vacuum when evacuating the remaining air in the mold, the inflowing melt is being distributed equally. It must be guaranteed that during injection molding, the mold is thermally-controlled. This prevents premature solidification. Through a combination of these two strategies, a form filling rate in micro-cavities up to 100 % is carried out. By deriving an impeccably adapted process chain, a precise micro-molding can be performed. This leads to the capability of manufacturing bars on a final plastic part with a width and height as low as 55 x 100 µm, and a length of 2 mm.
  • 21st CIRP Conference on Electro Physical and Chemical Machining, ISEM XXI
    Item type: Conference Proceedings
    (2022)
    Procedia CIRP
  • Limits of die-sinking EDM for micro structuring in W300 steel with pure copper electrodes
    Item type: Conference Paper
    Büttner, Henning; Roth, Raoul; Wegener, Konrad (2018)
    Procedia CIRP ~ 8th CIRP Conference on High Performance Cutting (HPC 2018)
    Electrical discharge machining (EDM) is capable of almost force-free 2D and 3D machining of any kind of conductive material. The micro die-sinking EDM process described in this paper uses electrodes with features in the micrometer scale as a working tool. The ability to machine micro features is desirable for many applications, which range from miniaturization to functionalization of large surfaces. To achieve the desired workpiecès final shape, the working gap and the tool wear behavior must be known and minimized or compensated if possible. For an overall understanding, the interaction between process parameters, such as pulse and pause duration, as well as discharge current with resulting gap sizes, wear formation and work piece shape must be displayed. Besides the optimization of the micro-EDM process itself, the entire process chain must be discussed, including the shaping of the electrodes. This paper provides knowledge on micro structuring copper electrodes using wire-EDM. It also includes information about their subsequent use in micro die-sinking EDM when machining large areas with high aspect ratio micro structures in W300 steel of Böhler Edelstahl. On electrodes, micro ribs with heights of 350 µm, widths of 70 µm and pitch distances of 320 µm could be reached. For micro die-sinking, a relative frontal length wear as low as 19% was determined. The limits of minimum structure sizes in W300 have been investigated, and rib widths down to 31 µm, as well as pillar edge lengths down to 80 µm, have been achieved. Surface quality and changes of the chemical surface compounds of W300 were analyzed using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). Deposit of copper material from the electrode was identified and a proliferation of carbon was detected on the workpiece.
Publications 1 - 10 of 120