Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

Filters
Reset filters

Settings
Now showing 1 - 8 of 8
No Thumbnail Available
Publication

Residual stress assessment during cutting tool lifetime of CVD-diamond coated indexable inserts

2022 , Uhlmann, E. , Hinzmann, Daniel

Insufficient coating adhesion limits reproducibility regarding tool lifetime as well as workpiece quality during the application of CVD-diamond coated cutting tools. Depending on the combination of tungsten carbide substrate material, coating thickness as well as coating morphology, individual residual stress conditions exist within CVD-diamond coated cutting tool specifications. The application of these tools is accompanied by coating delamination as primary cutting tool failure. The tool lifetime of the respective cutting tool composition depends on the corresponding residual stress condition until crack development within the CVD-diamond coating initiates tool failure. During external cylindrical turning of hypereutectic aluminium silicon alloy AlSi17Cu4Mg-T6 the residual stress condition of a CVD-diamond coated cutting tool is assessed along the cutting edge, the rake face as well as flank face throughout the respective tool lifetime. Consequently, the progression of the residual stress condition until cutting tool failure regarding coating delamination is observed. During the tool lifetime of the investigated CVD-diamond cutting tools, compressive residual stress ∆σR,c shifts to tensile residual stress ∆σR,t underneath the cutting edge corner. The approximated residual stress difference of ∆σR ≈ 5 GPa indicates stress peak relaxation processes, such as crack initiation, within the CVD-diamond coating.

View
No Thumbnail Available
Publication

Ecological and functional optimization of the pretreatment process for plasma based coatings of cutting tools

2019 , Uhlmann, E. , Riemer, H. , An, S. , Fröhlich, M. , Paschke, H. , Petersen, M.

Increasing demands in machining of high-tech materials and dry machining lead to higher thermal and mechanical loads on cutting tools. In response to these challenges, enhanced coating solutions are applied to increase performance and life of cutting tools. However, during the production process the cemented carbide substrates are contaminated with grinding oils and residues of organic material. For the subsequent physical vapor deposition (PVD) coating process an intensive and high-quality cleaning process is necessary. In this contribution, plasma electrolytic polishing (PEP) is used as a novel alternative to conventional ecologically harmful cleaning baths. Apart from the ecological advantage, the surface of the substrate can be optimized with regard to the coating adhesion. To examine the performance of the different cleaning processes, machining tests were performed at the IWF to evaluate the layer adhesion and tool life of the tools.

View
No Thumbnail Available
Publication

Flexible clamping jaws for circular sections

1994 , Spur, G. , Bahrke, U.

Today the three-jaw chuck is the most commonly used clamping system in turning machines. In order to avoid damage of the work piece by clamping, the surface pressure between the clamping jaw and the work piece should be very homogeneous in the clamping surface. The aim is to develop flexible clamping jaws for circular sections that are able to self adapt the clamping surface over a wide range of work piece diameters. The adaptation to various work piece diameters and geometries should not lead to a reduction of another very important function of a clamping jaw - the exact positioning of the work piece in the chuck.

View
No Thumbnail Available
Publication

Micro-texture dependent temperature distribution of CVD diamond thick film cutting tools during turning of Ti-6Al-4V

2022 , Uhlmann, Eckart , Schröter, D. , Gärtner, Eric

Machining titanium alloys such as Ti-6Al-4V results in a high thermomechanical load on cutting tools and consequently short tool lifes. With respect to a necessary reduction of the resulting cutting tool temperatures, ultrashort pulse (USP) laser fabricated micro-textured rake faces offer direct supply of cooling lubricant into the cutting zone and lead to a reduced heat induction. As a result, micro-textured CVD diamond thick film cutting tools are also capable of machining high-performance materials due to reduced contact temperatures. In the scope of the research, the resulting temperature distribution for micro-textured rake faces will be compared under both dry and wet process conditions. Measurements show a reduction of the resulting cutting tool temperatures of Δϑt = 27.9 % using micro-textured cutting tools compared to non-textured cutting tools. A validated simulation provides valuable information about the contact temperatures enabling a specific development of the micro-texture geometry. As a result, a reduction of the contact temperature between chip and rake face by ΔϑT = 24.7 % was possible.

View
No Thumbnail Available
Publication

Trockenbearbeitung von Grauguß mit hohen Schnittgeschwindigkeiten

1995 , Spur, G. , Lachmund, U.

Die Trockenbearbeitung metallischer Werkstoffe gewinnt durch das zunehmende Umweltbewußtsein auch in der spanenden Fertigung immer mehr an Bedeutung. Die vorliegenden Untersuchungen beschäftigen sich mit dem Hochgeschwindigkeitsdrehen von Grauguß mit keramischen und hocharten polykristalfinen Schneidstoffen, Zur Anwendung kamen die keramischen Schneidstoffe Aluminiumoxid und Siliciumnitrid sowie kubisches Bornitrid (CBN). Der Schnittgeschwindigkeitsbereich betrug von vc = 1000 bis 1700 m/min. Dabei konnte gezeigt werden, daß sich der keramische Schneidstoff Siliziumnitrid und der hochharte polykristalline Schneidstoff CBN zur Bearbeitung von Grauguß mit hohen Schnittgeschwindigkeiten gut eignen. Die besten Ergebnisse hinsichtlich des Verschleißverhaltens und der Fertigungsqualität sind mit CBN erreicht worden.

View
No Thumbnail Available
Publication

Closed-loop control in power operated thee-jaw chucks

1994 , Spur, G. , Stelzer, C.

View
No Thumbnail Available
Publication

Prediction of temperature distribution in diamond cutting tools during machining Ti-6Al-4V

2021 , Uhlmann, Eckart , Schröter, D. , Wohlfahrt, V. H.

The high thermal conductivity and wear resistance of CVD diamond provide potential for the machining of Ti-6Al-4V. By predicting thermomechanical loads, simulations can provide information about the usability of these cutting materials. However, the occurring shear chip formation within the cutting process leads to unsteady contact conditions. Therefore, a computationally intensive long-term transient simulation is necessary for precise prediction of tool temperatures. In this respect, a user-subroutine has been developed, allowing a high-resolution long-term simulation with acceptable computing time. By experimental investigations and validation of simulated results, a modelling of temperature distribution within the cutting tool is possible, providing valuable information regarding the contact temperatures.

View
No Thumbnail Available
Publication

Feindrehen von Gußeisen mit hohen Schnittgeschwindigkeiten

1995 , Spur, G. , Becker, K. , Lachmund, U.

In the past years, rising requirements on productivity and quality have lad to high cutting speed. Especially superhard non-metallic cutting materials brought progress in this field. This study deals with high speed finishing of lamellar gray cast iron with ceramic cutting materials and cubic boron nitride. The results show that the application of high cutting speeds loads to a considerable reduction of processing times. Regarding the tool life the application of cubic boron nitrid, especially with cutting speedover Vc =1000m/min, yielded the best results. High surface qualities can be reached up to a cutting speed level of Vc=2000m/min.

View