Now showing 1 - 8 of 8
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Droplet removal from PVD-coated micro-milling tools with the immersed tumbling process

2017 , Uhlmann, E. , Kuche, Y. , Oberschmidt, D. , Polte, J.

The physical vapour deposition (PVD) process is widely used for the coating of cutting tools. The increased hardness and temperature stability permitted a higher cutting speed and longer tool life in comparison to uncoated tools. Within the PVD-process droplets of the target can be deposited on the coated surface. The consequence is an inhomogeneous surface of the cutting tools with an increased surface roughness. In this study, the immersed tumbling process is used for the droplet removal of micro-milling tools. The results show the functionality of the process for the droplet removal depending of the lapping media and process parameters in connection with the amount and size of the droplets.

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Influence of cutting edge preparation on the performance of micro milling tools

2016 , Uhlmann, E. , Oberschmidt, D. , Löwenstein, A. , Kuche, Y.

A main reason for premature tool failure in micro milling is the irregular wear behavior of the cutting tools. An approach to improve the tool wear behavior is a defined cutting edge preparation using immersed tumbling. A particular challenge is the cutting edge preparation of micro milling tools with small diameters D ⤠0.5 mm. High loads within the preparation process can lead to outbreaks of the cutting edge and tool breakage. Furthermore, the influence of changed cutting edge geometry regarding the process behavior has to be more examined for these tool diameters. In this paper, micro milling tools with a diameter D = 0.2 mm will be prepared and the influence on the cutting process will be presented and discussed. The experiments will show a better wear behavior for the prepared tools and an improved surface roughness on the machined workpiece.

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Cutting edge preparation of micro milling tools

2014 , Uhlmann, E. , Oberschmidt, D. , Kuche, Y. , Löwenstein, A.

Micro milling is commonly used industrially for the production of precision components. Premature tool wear is usually the reason for a short tool life of cemented carbide end mills. An approach to improve the tool wear behavior is the defined cutting edge preparation. In this contribution, experimental investigations on the formation of cutting edge geometry during immersed tumbling of micro milling tools are presented and discussed. It could be shown that it is possible to prepare end mills with a diameter D = 1 mm and to generate edge radii of 4.0 m r 31.2 m. Investigations about the correlations between the cutting edge geometry and the tool wear behavior in micro milling operations showed decreased flank and crater wear as a result of an appropriate cutting edge preparation.

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Wear behaviour of diamond coated micro-milling tools during micro machining

2017 , Uhlmann, E. , Kuche, Y. , Oberschmidt, D. , Polte, J.

Graphite electrodes are used in the die sinking process for manufacturing of micro structured tools in the die and mould fabrication. They are machined using the micro-milling process. During the cutting process graphite grains have strong abrasive effects on the cutting edges and lead to high tool wear. Consequences are short path length lc and geometrical errors. One approach to reduce tool wear is the tool coating with diamond. The diamond coating changes the cutting edge micro geometry which has influences on the process behaviour. In this paper, the wear behaviour of micro-milling tools with diameter D = 0.5 mm and different micro geometries is analysed and discussed. The results show better wear behaviour for prepared and coated tools.

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Geometric deviations in the production of micro-milling tools and their influence on the cutting process

2016 , Uhlmann, E. , Oberschmidt, D. , Kuche, Y. , Polte, M.

For micro-milling tools with decreasing diameter D < 0.5 mm the requirements for the manufacturing rise up and the risk of geometrical deviations of the cutting edges increase. In this investigation industrial produced micro-milling tools with a diameter of D = 0.2 mm made of cemented carbide were analysed. Micro-milling tools with variable macro geometry were selected and used for the machining of mould steel. The influence of the geometrical deviations on the wear behaviour and the surface roughness of the machined steel were examined. It is shown that the variable tool geometry lead to wear of the minor cutting edges S'. Furthermore, an influence on the surface roughness of the machined workpiece is determined.

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Verfahren zur automatisierten Reinigung

2014 , Uhlmann, E. , Oberschmidt, D. , Kuche, Y.

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Effects of different cutting edge preparation methods on micro milling performance

2016 , Uhlmann, E. , Oberschmidt, D. , Kuche, Y. , Löwenstein, A. , Winker, I.

In micro milling, which is mostly used in mold and die making, process reliability and predictability of tool failure are important. Particularly in precision and micro machining, tool breakage is hardly detectable and the requirements on accuracy are very high. Immersed tumbling is an appropriate process for the defined cutting edge preparation of micro milling tools. Its effects like increasing tool wear performance and tool life has been evaluated. In this paper, different cutting edge preparation processes showed that in cutting tests different effects occur regarding tool wear, process forces and surface quality. Immersed tumbling leads to the lowest active force Fa, but magnet finishing leads still do a slightly better surface quality.

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Automatisierte Qualitätskontrolle

2015 , Uhlmann, E. , Oberschmidt, D. , Löwenstein, A. , Kuche, Y. , Wiemann, S.

Inhalt eines Forschungsprojektes der Firma OTEC Präzisionsfinish GmbH und des Fraunhofer-Instituts für Produktionsanlagen und Konstruktionstechnik IPK ist die Entwicklung eines Maschinenprototypen zur Feinbearbeitung mit automatisierter Qualitätskontrolle durch integrierte optische Messtechnik und Messsoftware. Im Rahmen des durch das Zentrale Innovationsprogramm Mittelstand (ZIM) vom Bundesministerium für Wirtschaft und Energie (BMWi) geförderten Projektes wurde dazu eine kompakte, für die Automatisierung und Integration von Messtechnik ausgelegte Maschine entwickelt. Mithilfe dieser Maschine können Werkstücke, wie etwa Nockenwellen oder Zerspanwerkzeuge, mit dem Verfahren Tauchgleitläppen bearbeitet und definierte Kantenradien erzeugt sowie in einem automatisierten Prozess gemessen werden. This paper presents a machine prototype for the finishing of edges and surfaces of work pieces. The prototype has an integrated optical measurement device, which can be used for the control of the process results and possibly automated remachining. The machine is used for the preparation of milling tools. Process parameters and their effects are analyzed and an approach for the automated setting of the process parameters is shown.