| 1. |
- Agic, Adnan, 1967-, et al.
(författare)
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Influence of radial depth of cut on entry conditions and dynamics in face milling application
- 2017
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Ingår i: Journal of Superhard Materials. - New York : Allerton Press. - 1063-4576 .- 1934-9408. ; 39:4, s. 259-270
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Tidskriftsartikel (refereegranskat)abstract
- The choice of milling cutter geometry and appropriate cutting data for certain milling application is of vital importance for successful machining results. Unfavorable selection of cutting conditions might give rise to high load impacts that cause severe cutting edge damage. Under some circumstances the radial depth of cut in combination with milling cutter geometry might give unfavorable entry conditions in terms of cutting forces and vibration amplitudes. This phenomenon is originated from the geometrical features that affect the rise time of the cutting edge engagement into workpiece at different radial depths of cut. As the radial depth of cut is often an important parameter, particularly when machining difficult-to-cut materials, it is important to explore the driving mechanism behind vibrations generation. In this study, acceleration of the workpiece is measured for different radial depths of cut and cutting edge geometries. The influence of the radial depth of cut on the dynamical behavior is evaluated in time and frequency domains. The results for different radial depths of cut and cutting geometries are quantified using the root mean square value of acceleration. The outcome of this research study can be used both for the better cutting data recommendations and improved tool design.
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| 2. |
- Hoier, Philipp, 1988, et al.
(författare)
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Characterization of tool wear when machining Alloy 718 with high-pressure cooling using conventional and surface-modified WC–Co tools
- 2017
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Ingår i: Journal of Superhard Materials. - : Allerton Press. - 1063-4576 .- 1934-9408. ; 39:3, s. 178-185
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Tidskriftsartikel (refereegranskat)abstract
- Coolant supplied by high pressure into the cutting zone has shown to lower thermal loads on the tool when machining difficult-to-cut materials as the Alloy 718. In this study, we investigate how the combination of high-pressure cooling and tool–surface modifications can lead to further improvements regarding tool life. The general approach is to enhance the coolant–tool interaction by increasing the contact area. Therefore, we machined cooling features into flank and rake faces of commercially available cemented tungsten carbide inserts. In this way, the surface area was increased by ~ 12%. After the cutting tests, the tools were analyzed by scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Compared with conventional tools, the tool modifications reduced the flank wear by 45% for the investigated cutting parameters. Furthermore, we were able to significantly increase the cutting speed and feed rate without failure of the tool. The investigated surface modifications have great potential to enhance the productivity of metal cutting processes.
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| 3. |
- Markocsan, Nicolaie, 1967-, et al.
(författare)
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MAX-phase coatings produced by thermal spraying
- 2017
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Ingår i: Journal of Superhard Materials. - : Allerton Press. - 1063-4576 .- 1934-9408. ; 39:5, s. 355-364
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a comparative study on the Ti2AlC coatings produced by different thermal spray methods, as Ti2AlC is one of the most studied materials from the MAX-phase family. Microstructural analysis of coatings produced by High Velocity Air Fuel (HVAF), Cold Spray and High Velocity Oxygen Fuel (HVOF) has been carried out by means of the scanning electron microscopy equipped with an energy dispersive spectrometer (EDS). The volume fraction of porosity was determined using the ASTM standard E562. The phase characterization of the as-received powder and as-sprayed coatings was conducted using the X-ray diffraction with CrKα radiation. Impact of the spray parameters on the porosity and the mechanical properties of the coatings are discussed. The results show that the spraying temperature and velocity play a crucial role in coatings characteristics. © 2017, Allerton Press, Inc.
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| 4. |
- Bushlya, Volodymyr, et al.
(författare)
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Tool wear and tool life of PCBN, binderless cBN and wBN-cBN tools in continuous finish hard turning of cold work tool steel
- 2014
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Ingår i: Journal of Superhard Materials. - 1934-9408. ; 36:1, s. 49-60
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents the results of comparative study of performance of cutting tools made of ceramic-bound, binderless cBN, and wBN-cBN tool materials. The tool performance was assessed by tool wear-resistance, values of cutting forces, parameters of machined surface quality, and the state of sub-surface layer generated in continuous turning of hardened cold work tool steel. The tests were carried out under conditions of high speed machining (v (c) = 120-180 m/min) both with and without a coolant. The best tool performance by the above-mentioned criteria is provided by a low-cBN material with ceramic binder.
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| 5. |
- Chen, L., et al.
(författare)
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Nano-Scratching resistance of high-chromium white cast iron and its correlation with wear of cBN tool in machining
- 2017
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Ingår i: Journal of Superhard Materials. - 1063-4576. ; 39:5, s. 365-372
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a nano-scratch testing approach was used to measure and evaluate the abrasion wear resistance of high-chromium white cast irons in order to understand the wear mechanism in the interaction between the high-chromium white cast iron and the cBN cutting tool during the machining process. Scratch testing was performed on a nanoindentation instrument using a diamond indenter as the scratch tool. Linear multi-pass scratches in the same path were made on pre-worn surfaces of test materials. The correlation of the scratching resistance and tool wear measured from the machining is presented by the flank wear and maximum scratch depth. The appearance of the cutting edge on a cBN tool suggests that the abrasion wear is mainly related with a combined effect of the carbides and the matrix during machining the high-chromium white cast iron.
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| 6. |
- Dub, S. N., et al.
(författare)
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Theoretical shear strength and the onset of plasticity in nanodeformation of cubic boron nitride
- 2017
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Ingår i: Journal of Superhard Materials. - 1063-4576. ; 39:2, s. 88-98
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Tidskriftsartikel (refereegranskat)abstract
- The nanoindentation in the continuous stiffness measurement mode was used to investigate the onset of plasticity at the nanodeformation of cubic boron nitride (cBN). This technique allows us to reveal an elastic-plastic transition in the contact and to measure the yield strength of cBN at the nanoscale. An abrupt elastoplastic transition (a pop-in) was observed in the (111) cBN single crystal as a result of a homogeneous or heterogeneous nucleation of dislocations in the previously dislocations-free region under the contact. The analysis of the data obtained at the homogeneous nucleation of dislocations in the contact region made it possible to experimentally estimate the theoretical shear strength of cBN and its ideal (elastic) hardness. In a sample of the fine-grained cBN with a nanotwinned substructure a smooth elastoplastic transition was observed in consequence of the propagation and multiplication of already existing dislocations in the contact region.
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| 7. |
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| 8. |
- Johansson, D., et al.
(författare)
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Sensitivity of Colding tool life equation on the dimensions of experimental dataset
- 2017
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Ingår i: Journal of Superhard Materials. - 1063-4576. ; 39:4, s. 271-281
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Tidskriftsartikel (refereegranskat)abstract
- In this work, 22 sets of cutting data and tool life for longitudinal turning of steel are analyzed using the Colding equation. When modeling tool life with a limited number of tool performance data points, the model error may be low for these points. Evaluating the model for test points not used when computing the model coefficients may give larger errors for these points. This work proves that the Colding model also provides sufficient precision when modelling data points not being used to create the model, and is therefore a well-functioning instrument for tool life modelling. The results also prove that for the selected data, the precision of the model can be greatly improved when the dimension of the data set is increased from 5 to 10 data points. Above 13 data points the precision improvements are negligible.
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| 9. |
- Kolabylina, T., et al.
(författare)
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Superhard pcBN tool materials with Ti3SiC2 MAX-phase binder : Structure, properties, application
- 2017
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Ingår i: Journal of Superhard Materials. - 1063-4576. ; 39:3, s. 155-165
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Tidskriftsartikel (refereegranskat)abstract
- Superhard cutting tool materials were sintered in cBN–(Ti3SiC2–TiC) system via high pressure–high temperature method. Sintering was performed under the pressure 8 GPa in the 1400–2400°C temperature range. The initial mixtures of three compositions were chosen with 90, 80 and 60 vol % cBN. The mixtures were prepared by mixing cBN (1–3 μm) and Ti3SiC2–TiC (< 2 μm). It was found, that upon sintering, the compositions of the obtained samples differed from the initial mixtures in all cases as a result of chemical reactions. Microstructure observations, phase composition estimation, and mechanical properties of the obtained tool materials were carried out. The results indicate that both the varying cBN content and the applied sintering conditions have a direct effect on the structure, properties, and kinetics of reactions.
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| 10. |
- Kryzhanivskyy, V., et al.
(författare)
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Influence of tool material and tool wear on tool temperature in hard turning reconstructed via inverse problem solution
- 2017
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Ingår i: Journal of Superhard Materials. - 1063-4576. ; 39:3, s. 192-202
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Tidskriftsartikel (refereegranskat)abstract
- In this work the cutting tool temperature distribution that develops during turning of hardened cold-work tool steel is modeled on the basis of experimental data. The data obtained from a series of thermocouples, placed on a PCBN insert, into an anvil, and into a toolholder, were used as the input for the model. An inverse problem was solved, where the heat fluxes were computed. The temperature distribution was modeled for the case of new tools, as well as for the case of its development in the course of a tool wear. The reconstructed temperature distributions were in good agreement with the measured data. The heat flux through rake face was found to be reducing with the decrease of thermal conductivity of the tool material.
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