Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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High-Performance Electro-Discharge Drilling with a Novel Type of Oxidized Tool Electrode

2022 , Uhlmann, Eckart , Polte, Julian , Streckenbach, Jan , Dinh, Ngoc Chuong , Yabroudi, Sami , Polte, Mitchel , Börnstein, Julian

Electro-discharge drilling is a key technology for manufacturing sophisticated nozzles in a broad range of automotive and aerospace applications. The formation of debris in the working gap leads to arcs and short circuits on the lateral surface when state-of-the-art tool electrodes are used. As a result, limited drilling depth, increased linear tool wear, and the conicity of boreholes are still challenges. In this work, a new approach for the passivation of the lateral surface of copper tool electrodes by oxidation is shown. The comparison with state-of-the-art tool electrodes showed a reduction in the erosion duration by 48% for machining hardened steel. Promising improvements could be achieved by the thermal oxidation of the tool electrodes with the aim of increasing the electrical resistivity of the lateral surface of the tool electrode. However, due to the loss of strength, the high oxide layer thickness, and the partial delamination of the oxide layer, further comprehensive investigations on the influence of the oxidation temperature need to be conducted. Future adjustments with lower oxidation temperatures will be carried out.

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Influence of cutting edge micro-geometry in micro-milling of copper alloys with reduced lead content

2018 , Uhlmann, Eckart , Kuche, Yves , Polte, Julian , Polte, Mitchel

Especially copper-zinc alloys (CuZn) with good machining properties are used for electrical components and fittings. By using copper alloys with lead content of 1 % < Pb < 3 % an improved chip breakage can be achieved. Legal regulations require the reduction of lead and demand further knowledge about the effect of the material properties in interaction with the used micro-milling tools. In this contribution the cutting conditions of copper as well as four copper alloys were examined. The results show considerable differences in the resultant surface roughness and burr formation. Furthermore, the influence of two different tool geometries and variied cutting edge micro-geometries were investigated while machining CuZn21Si3P. Thereby, tools with increased cutting edge radii rv showed increased active forces Fa, burr height h0 and decreased surface roughness.

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Modeling of the wet immersed tumbling process with the Discrete Element Method (DEM)

2021 , Uhlmann, Eckart , Fürstenau, J.-P. , Kuche, Yves , Yabroudi, Sami , Polte, Julian , Polte, Mitchel

Immersed tumbling is an industrially established process for finishing of components made of metal, ceramic or plastic. In this process, the components are completely surrounded by a wet, abrasive medium, which allows burrs to be removed and surfaces to be polished. In order to gain specific insights into the influence and flow properties of the abrasive media used in this process, numerical approaches using the Discrete Element Method (DEM) with the Rocky DEM software are presented within these investigations. A complete process simulation could be realised by means of a digital machine tool. The immersed tumbling process with cone-shaped polymer abrasive media is implemented by use of a liquid bridge model. The results were validated by experiments with an industrially used immersed tumbling machine tool and for the first time allow sound statements about the contact conditions and interactions of the abrasive media with the workpiece.

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Verschleißverhalten neuartiger Mikrofräswerkzeuge mit Schneiden aus CBN bei der Hartzerspanung

2018 , Uhlmann, Eckart , Polte, Julian , Polte, Mitchel , Kuche, Yves , Wiesner, Hagen Maximilian

In der Mikroproduktionstechnik bei der Zerspanung mit geometrisch bestimmter Schneide und Werkzeugdurchmessern von D < 1mm stellt der Werkzeugverschleiß einen entscheidenden Faktor für die Entstehung hoher Fertigungskosten dar. Ein großes Anwendungsfeld der Mikrozerspanung ist die Fertigung hochpräziser Spritzgusswerkzeuge für die Serienfertigung von Präzisionskunststoffteilen. Gefordert werden dabei hohe geometrische Genauigkeiten und niedrige Oberflächenrauheitskennwerte. Um diese Anforderungen zu erfüllen, ist eine stetige Forschungsarbeit notwendig. Ein Ansatzpunkt zur Optimierung der Fertigungsprozesse ist der Einsatz neuartiger Schneidstoffe und Werkzeuggeometrien.

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PKD-Glattdrückwerkzeuge für den Werkzeug- und Formenbau

2018 , Uhlmann, Eckart , Polte, Mitchel , Polte, Julian , Guhde, Sebastian , Kuche, Yves , Kappel, Thomas

Es wurden Glattdrückwerkzeuge mit Sphärenkopf aus polykristallinem Diamant der Firma Baublies AG, Rennigen, genutzt. Das Werkzeugkonzept orientiert sich dabei an den aktuellen Herausforderungen beim Werkzeug- und Formenbau sowie an handelsüblichen Zerspanwerkzeugen. In diesem Beitrag sind das Werkzeugkonzept, der Versuchsaufbau und die ersten Ergebnisse zur Kraftmessung dargestellt. Darüber hinaus werden die erreichbare Härtekennwerte und die Rauheitskennwerte in Abhängigkeit verschiedener Prozessparameter sowie zu den Ausgangswerten verglichen.

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