Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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Investigation of wear resistance of coated PcBN turning tools for hard machining

2018 , Uhlmann, E. , Riemer, H. , Schröter, D. , Henze, S. , Sammler, F. , Barthelmä, F. , Frank, H.

The machining of steels with a hardness of 50 HRC and above was in the past primarily only possible with grinding processes. Since the application of cutting inserts made of polycrystalline cubic boron nitride (PcBN), hard turning as a production process with higher material removal rates has established as an economic alternative or supplement to grinding. The increasing number of materials with difficult machining characteristics requires a further development of cutting tools. Physical Vapor Deposition (PVD) coatings lead to an increase of wear resistance, but have thus for not been studied on PcBN substrates. In this contribution, different hard coatings were deposited on PcBN cutting inserts. To identify wear resistance of the coating systems tribological investigations and cutting tests were performed. Furthermore, simulations for evaluation of the coatings as a thermal barrier have been carried out. For the verification of the simulation results, temperature measurements in the cutting process were performed. Based on these investigations the wear behavior of the different coating systems has been analyzed.

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Machining of Carbon and Glass Fibre Reinforced Composites

2016 , Uhlmann, E. , Sammler, F. , Richarz, S. , Reucher, G. , Hufschmied, R. , Frank, A. , Stawiszynski, B. , Protz, F.

The combination of carbon and glass fibres in new reinforced composite components makes the machining of these promising materials challenging. The abrasive carbon and glass fibres cause tool wear and cutting edge rounding which results in higher process forces and insufficient workpiece quality. At the IWF, innovative process strategies for the machining of these materials have been developed, combining these with new cutting tool geometries. Furthermore, the classification of workpiece quality for reinforced plastic components has not been sufficiently addressed thus far and is also a focus of the work being undertaken. In order to adequately describe the workpiece quality, fibre pull-out and fibre protrusion must both be analysed. Using the example of a carbon and glass fibre composite material, the dependency of these characteristic quality parameters on process and tool parameters shall be analysed. The work described here compares an axial drilling with an helical milling process from both a technological (workpiece quality) and an economical (processing time) point of view.

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Bearbeitung und Einfluss der Schneidkantenmikrogeometrie von Hartmetallwerkzeugen im Fräsprozess

2012 , Uhlmann, E. , Gebhard, S. , Sammler, F. , Kropidlowski, K.

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Substitution of Coolant by Using a Closed Internally Cooled Milling Tool

2017 , Uhlmann, E. , Riemer, H. , Schröter, D. , Sammler, F. , Richarz, S.

The saving of raw materials plays a major role in industry and is becoming increasingly important. In the field of cutting technology, the aim is to maximise practices such as the substitution of coolant and the steady increase of tool life in order to make an effective contribution towards environmental protection. Concerning the saving of coolant and to enhance the performance in dry machining a milling tool with a closed internally cooled system was developed. Heatpipes are applied which ensure improved heat dissipation from the cutting edge because of their excellent thermal conductivity. The dissipated heat is subsequently delivered to the surroundings via a heat sink. This contribution describes how the performance of a standard tool can be enhanced by the integration of a closed internally cooled system. Simulations of the heat distribution in the tool have been conducted to design and optimise the prototype. Hence, milling tests on duplex steel and temperature measurements in the cutting process have been carried out to verify and further optimise these simulation results.

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Machining of carbon fibre reinforced plastics

2014 , Uhlmann, E. , Sammler, F. , Richarz, S. , Heitmüller, F. , Bilz, M.

The implementation of carbon fiber reinforced plastics (CFRPs) in the aeronautical industry has increased dramatically in recent years due to their favourable combination of low weight and high strength as well as the adaptability of their material properties. In order to economically and reproducibly machine these materials with high part qualities, improvements in machining strategies must be made. The focus of this paper lies on innovative technologies for the machining of CFRPs whereby CVD diamond coated tools and milling tools for the improvement of milling processes have been designed. Furthermore, water jet cutting, CO2 jet cutting and grinding of CFRPs has been investigated. The quality of the machined workpieces is also an issue which requires addressing, particularly in relation to the fraying of machined edges. An innovative quantitative method for the evaluation of the workpiece quality of CFRP is presented.

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Hard Turning of Hot Work and Cold Work Steels with HiPIMS and DCMS TiAlN Coated Carbide Inserts

2016 , Uhlmann, E. , Stawiszynski, B. , Leyens, C. , Heinze, S. , Sammler, F.

Hard machining has grown in importance in recent years, due to the possibility of substituting cost and time intensive grinding processes, but also due to the development of heat and wear resistant cutting materials. Cemented carbide tools offer different substrate compositions, micro and macro geometries and the possibility to deposit a wide range of coatings. By the application of the High Power Impulse Magnetron Sputtering (HiPIMS) coating technology hard, dense and adhesive layers can be deposited. However, the impacting factors on the wear resistance of these coatings has thus far not been studied adequately. In this contribution cemented carbide cutting inserts in combination with different HiPIMS and Direct Current Magnetron Sputtering (DCMS) TiAlN films are studied with regards to their wear behavior in the machining of hardened steels.

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Werkzeugauslegung zur Bearbeitung von Leichtbauwerkstoffen

2012 , Uhlmann, E. , Reimers, W. , Sammler, F. , Meixner, M.

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