| 1. |
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| 2. |
- Can, Antionette
(creator_code:cre_t)
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Polycrystalline cubic boron nitride material
- 2023
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Patent (other academic/artistic)abstract
- This disclosure relates to a polycrystalline cubic boron nitride, PCBN, material that includes a binder matrix material containing nitride compounds. The nitride compounds are selected from HfN, VN, and/or NbN.
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| 3. |
- Turkevych, Dmytro, et al.
(author)
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HP-HT sintering, microstructure, and properties of B6O- and TiC-containing composites based on cBN
- 2015
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In: Journal of Superhard Materials. - 1934-9408. ; 37:3, s. 143-154
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Journal article (peer-reviewed)abstract
- The article presents a study of the potential for the use of B6O superhard boron suboxide as a binder in composite materials with a low cBN content. Superhard B6O is characterized by higher mechanical properties than TiC widely used in commercial materials today. Composites containing 60 vol % cBN and different binder compositions that included B6O and TiC have been sintered in a toroid-type high-pressure apparatus at a pressure of 7.7 GPa in a temperature range from 1500 to 2000 A degrees C. The microstructure, phase and elemental composition of the sintered materials have been examined via electron microscopy and X-ray diffraction analysis. Mechanical properties have been analyzed via indentation techniques. The performance of the cutting tools produced from the sintered composites has been evaluated in turning hardened cold work tool steel.
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| 4. |
- Agmell, Mathias, et al.
(author)
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Development of a simulation model to study tool loads in pcBN when machining AISI 316L
- 2018
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In: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 96:5-8, s. 2853-2865
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Journal article (peer-reviewed)abstract
- This paper presents the development of a FE-simulation model to predict the mechanical stresses and thermal loads that a cutting tool of polycrystalline cubic boron nitride (pcBN) is subjected to, when machining AISI 316L. The serrated chip formation of AISI 316L has a major impact on the periodic loads acting on the cutting tool. Therefore, it is vital to correctly model this serrated chip formation. One of the major difficulties with FE-simulations of metal cutting is that the extreme deformations in the workpiece material, often leads to a highly distorted mesh. This paper uses the Coupled Eulerian-Lagrangian (CEL) formulation in Abaqus/Explicit, where the workpiece is modelled with the Eulerian formulation and the cutting tool by the Lagrangian one. This CEL formulation enables to completely avoid mesh distortion. To capture the chip serration process, the workpiece material is described with the Johnson-Cook damage model. The FE-simulation results are validated via comparison of the modelled cutting forces, chip serration frequency, and contact length against experimental ones.
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| 5. |
- Agmell, Mathias, et al.
(author)
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Investigation of mechanical and thermal loads in pcBN tooling during machining of Inconel 718
- 2020
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In: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 107, s. 1451-1462
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Journal article (peer-reviewed)abstract
- This study investigates machining superalloy Inconel 718 with polycrystalline cubic boron nitride (pcBN) tooling both numerically and experimentally. Particular attention is given to mechanical and thermal stresses in the cutting tool arising from segmented chip formation and associated forces and temperatures. The temperature dependence of the mechanical properties of pcBN has been investigated and incorporated into a numerical model. In order to capture the dynamic loads due to a serrated chip formation, the Johnson–Cook damage model has been used. The extreme deformations during a machining process often results in a numerical difficulties due to a distorted elements. This paper uses the coupled Eulerian–Lagrangian (CEL) formulation in Abaqus/Explicit, where the workpiece is modelled with the Eulerian formulation and the cutting tool by the Lagrangian one. This CEL formulation enables to completely avoid mesh distortion. The finite element simulation results are validated via comparison of the modelled static and dynamic cutting forces and thermal loads induced into the cutting tool. The numerical model predicts a temperature of 1100–1200 ∘C at the cutting interface, which is in line with experimental determined data. The principal stresses at the rake up to 300 MPa are recorded, whereas higher level of stresses up to 450 MPa are found in the notch region of the tool, well correlated with experimental observation.
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| 6. |
- Agmell, Mathias, et al.
(author)
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Modelling Subsurface Deformation in High Speed Machining of Inconel 718
- 2012
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Conference paper (peer-reviewed)abstract
- Abstract in UndeterminedTraditionally, the development and optimization of the machining process with regards to the sub-surface deformation is done through experimental method which is often expensive and time consume. This paper presents the development of a FE-simulation model to predict the depth of sub-surface deformation induced in the high speed machining of Inconel 718 by use of whisker-reinforced ceramic tool. The effects of cutting parameters and geometry on sub-surface deformation will be simulated by developed FE model. In addition to FE model, the experimental study was made to validate the results of FE model. Characterization of sub-surface deformation produced under different machining parameters and tool conditions was made by EBSD and in the cutting and feed directions.
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| 7. |
- Bjerke, Axel, et al.
(author)
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Machinability improvement by in-operando Tool Protection Layers through designed steel alloying : The case of manganese steel
- 2024
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In: Journal of Materials Processing Technology. - : Elsevier BV. - 0924-0136 .- 1873-4774. ; 330
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Journal article (peer-reviewed)abstract
- Improvements in machinability by alloying of the workpiece often adversely impact the end user properties of a material. For example, the common use of non-metallic inclusions can lead to improved tool life during turning or milling, but often adversely affects weldability, corrosion, and wear resistance. A cutting tool material meets kilometers of workpiece material during a machining operation. Hence elements in small quantities in the workpiece may insignificantly affect the end user properties but may have large effects on tool wear. One such effect is the formation of refractory and wear resistant reaction products between the workpiece and tool. Such reaction products forming on tool surfaces may lead to improved machinability. This paper proposes the use of small amounts of alloying to induce such a Tool Protection Layer. Additionally, the paper develops a computational framework for designed alloying which balances formation of Tool Protection Layers, its in-process retention, and the functional properties of the alloy. The method has been validated for a case of manganese steel. The calculations were validated first by a wide range of diffusion experiments. Then by industrial turning of cast alloys, by comparing one reference and two newly designed alloys based on the alloying concept. The alloy with 0.003 mol fractions of Al resulted in more than 3 times increase in tool life, due to in-operando formation of Al2O3 Tool Protection Layer. The designed manganese steel maintained its functional properties with respect to abrasive wear resistance and retained its ability to work harden.
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| 8. |
- Bjerke, Axel, et al.
(author)
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On chemical interactions between an inclusion engineered stainless steel (316L) and (Ti,Al)N coated tools during turning
- 2023
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In: Wear. - 0043-1648. ; 532-533
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Journal article (peer-reviewed)abstract
- Non-metallic inclusions offer one of the most effective routes for improving the machinability of steels. However, the wear-reducing mechanisms activated by such inclusions are not fully understood. The interactions are notoriously difficult to predict due to the wide variety of steel grades, cutting conditions, and tool materials employed in industry. The interaction between PVD (Ti,Al)N coated cemented carbide tools, non-metallic inclusions, atmospheric oxygen, and the stainless steel 316L in a turning operation is therefore investigated here as a case study. The study includes turning experiments, nanometer resolution microscopy, and thermodynamic calculations. The paper explains how not only too high a contact pressures hinder the formation of protective deposits at the tool edge, but also how too low a contact pressure leads to excessive wear. A range of conditions specified in this paper must therefore be met for the two observed protective non-metallic inclusions Mg1Al2O4 and Al2Ca2Si1O7 to be preferentially deposited on a tool. Hence the coating wear is experimentally investigated, explained, and a thermodynamic calculation method for predicting the protective or degenerative potential of a deposit on the coating is presented.
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| 9. |
- Bjerke, Axel, et al.
(author)
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Onset of the degradation of CVD alpha-Al2O3 coating during turning of Ca-treated steels
- 2021
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In: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 477
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Journal article (peer-reviewed)abstract
- The ability to control the shape, distribution and composition of non-metallic inclusions has had an important impact on many aspects of steel making. One such impact is on the machinability. Ca-treatments have shown to be able to reduce the abrasiveness of oxide inclusions, improve chip-breaking and lead to formation of deposits that reduce tool wear. However, machining Ca-treated steels with Al2O3 coated cemented carbide tools has not been as advantageous as expected. This study investigates the mechanisms behind the anomalous wear of Al2O3 coatings when turning soft Ca-treated steels. Longitudinal turning tests at a range of speeds (vc = 100-600 m/min) show rapid localized degradation of the Al2O3 coating limited to the sliding zone. Detailed analysis of the degradation mechanisms was performed using scanning and transmission electron microscopy. The results demonstrate a presence of chemical interactions between the alumina coating and non-metallic inclusions. The interaction resulted in the formation of mainly calcium aluminates and partly alumina-magnesia spinel. In-operando infrared thermography measurements indicate cutting temperatures of 850-1000 degrees C. Thermodynamic calculations give that CaO and MgO readily reacts with Al2O3, while the reaction with CaS requires presence of additional oxygen at these cutting conditions. Additional turning experiments investigate the influence of oxygen by controlling the cutting environment by adding oxygen (compressed air) or removing oxygen (supply argon). These additional tests show that the presence of additional oxygen has a limited impact on the possible Ca-Al2O3 interaction. This demonstrat a potential for further machinability improvements by controlling the chemical interaction between Ca and Mg based non-metallic inclusions and alumina coatings.
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| 10. |
- Bjerke, Axel, et al.
(author)
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Thermodynamic modeling framework for prediction of tool wear and tool protection phenomena in machining
- 2021
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In: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 484-485
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Journal article (peer-reviewed)abstract
- Chemical, oxidational and diffusional interactions between the tool, chip and cutting environment are known tool wear mechanisms in machining. However, the interaction between tool, coating, workpiece, coolant and atmospheric oxygen can, under favorable conditions, lead to formation of reaction products that retard tool wear. A method with the ability to predict theses interactions, would therefore enable a better control over tool life in machining. An attempt to create such a modelling framework is developed in this study. This method can predict the phase composition and the driving force for degradation and the formation of protective interaction products in the cutting zone. This modeling approach is applicable across cutting processes in which chemical, diffusional and oxidational wear are dominant or present. This framework has been applied to investigate the interactions occurring in the cutting zone during turning of a medium alloyed low-carbon steel (Hybrid Steel (R) 55). A range of degradation events are predicted, as well as the formation of a protective corundum (Al,Fe,Cr)(2)O-3 or spinel (Al, Fe,Cr)(3)O-4 film due to an interaction between the Al-alloyed steel and the environment. Validation of the modeling was performed by studying tool wear and reaction products formed when machining with ceramics, PcBN and coated carbide tooling. Inserts are studied by the use of scanning and transmission electron microscopy, after cutting tests were performed. Additional tests were performed in different environments (dry, argon and coolant). The results confirmed the model predictions of oxidation and diffusion wear as well as the formation of an (Al,Fe,Cr)(3)O-4 tool protection layer. Thus, the proposed thermodynamic framework seem promising to serve as a predictive instrument for the correct pairing of existing tool and workpiece combinations and cutting parameters, or for tailoring respective material compositions for intentional formation of a tool protection layer. As well as guidance on how to apply present and future kinetic models when concurrent interaction mechanisms are present. Which lead to a reduction and minimization of costly experimental machining tests.
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| 11. |
- Bjerke, Axel, et al.
(author)
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Understanding wear and interaction between CVD alpha-Al2O3 coated tools, steel, and non-metallic inclusions in machining
- 2022
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In: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 450, s. 128997-
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Journal article (peer-reviewed)abstract
- The aluminum oxide-coating on cemented carbide tools used for metal cutting have been regarded as inert during cutting of steels. Because diffusional dissolution is not possible. Chemical degradation of aluminum oxide coatings is often overlooked, especially in the presence of ambient oxygen and non-metallic inclusions. High-pressure diffusion couples, advanced microscopy, and thermodynamics are used to investigate and predict the chemical degradation of aluminum oxide-coated tools. During interactions with steel and different combinations of inclusions with and without ambient oxygen. The results show that alumina is resistant to chemical degra-dation by steel in the absence of oxygen. However, this is not the case when oxygen and non-metallic inclusions are present. These experiments and microscopy together with the thermodynamic calculations allow for the creation of a method and guidelines for chemical wear modeling and steel inclusion engineering when machining with aluminum oxide-coated tools.
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| 12. |
- Bushlya, Volodymyr, et al.
(author)
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Characterization of White Layer Generated when Turning Aged Inconel 718
- 2011
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In: Procedia Engineering. - : Elsevier BV. - 1877-7058. ; 19, s. 60-66
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Conference paper (peer-reviewed)abstract
- Abstract in UndeterminedWhite layer formation is considered as a part of minimum array of parameters characterizing surface integrity of the machined product. The paper is aimed on identification and characterization of white layer generated when finish turning aged Inconel 718 with Al2O3-SiCw ceramic tools under different cutting conditions, tool wear and coolant application. As expected intensity of white layer formation was proportional to cutting speed and tool wear. High resolution transmission electron microscopy (HRTEM) performed on white layer revealed formation of nanostructured material with grain size of 50-150 nm. Long-term ultrasonic-assisted etching of white layer allowed to uncover its morphology, where subsequent AFM measurements confirmed HRTEM findings. Observations by high resolution SEM provided evidence that gamma' Ni-3(Al,Ti) phase remained intact. (C) 2012 Published by Elsevier Ltd. Selection and peer-review under responsibility of Prof. E. Brinksmeier
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| 13. |
- Bushlya, Volodymyr, et al.
(author)
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Effect of ageing on machining performance of grey cast iron and its compensation by cutting speed management
- 2024
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In: CIRP Annals. - 0007-8506.
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Journal article (peer-reviewed)abstract
- Grey cast iron is known for its poor machinability directly after casting, but attains excellent machining performance after ageing. The present work explores the impact of cutting speed on the performance of pcBN machining for non-aged material. Findings suggest that tool wear can be minimized by identifying an optimal cutting speed that supports the formation of a stable Al2O3 and MnS build-up layer (BUL). Insufficient BUL protection accelerates pcBN wear by diffusion, while at very high speeds protective Al2O3 is replaced by weaker (Fe,Mn)2SiO4 and (Fe,Mn)O, and oxidation accelerates tool wear. The higher mechanical properties of aged GCI facilitate generation of high enough temperatures for stable deposition of Al2O3 BUL.
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| 14. |
- Bushlya, Volodymyr, et al.
(author)
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Effect of Cutting Conditions on Machinability of Superalloy Inconel 718 During High Speed Turning with Coated and Uncoated PCBN Tools
- 2012
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In: 45th CIRP Conference on Manufacturing Systems 2012. - : Elsevier BV. - 2212-8271. - 9781627485128 ; 3, s. 370-375
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Conference paper (peer-reviewed)abstract
- Inconel 718, an efficient superalloy for energy and aerospace applications, is currently machined with cemented carbide tools at low speed (vc≈60 m/min) due to its unfavorable mechanical and thermal properties. The article presents results of superalloy machinability study with uncoated and coated PCBN tools aiming on increased speed and efficiency. Aspects of tool life, tool wear and surface integrity were studied. It was found that protective function of the coating, increasing tool life up to 20%, is limited to low cutting speed range. EDX and AFM analyses suggested dominance of chemical and abrasive wear mechanisms. Residual stress analysis has shown advantageous compressive surface stresses.
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| 15. |
- Bushlya, Volodymyr, et al.
(author)
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Effects of Cutting Speed when Turning Age Hardened Inconel 718 with PCBN Tools of Binderless and Low-CBN Grades
- 2013
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In: Machining Science and Technology. - : Informa UK Limited. - 1091-0344 .- 1532-2483. ; 17:4, s. 497-523
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Journal article (peer-reviewed)abstract
- Application of polycrystalline cubic boron nitride (PCBN) tools as an alternative for ceramic and cemented carbide tools in machining superalloys has been frequently identified as a solution for enhancing process efficiency but only a limited number of studies has been done in this area. The current study explores the effect of the cutting speed, which was varied in a wide range (2-14m/s), on machinability of age hardened Inconel 718 with PCBN tools. Performance of binderless PCBN grade and grade with low-cBN content was evaluated in terms of tool life, tool wear, cutting forces and surface quality. Chip formation and process dynamics were analyzed as well. It was found that low-cBN grade provided 70-90% better surface finish and tool life than the binderless at moderate speeds (5-8m/s). Performance of both grades at low and high speed ranges was non-satisfactory due to notching and flaking respectively. At low cutting speed adhesive wear plays a major role while as the speed increases a chemical wear becomes dominant.
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| 16. |
- Bushlya, Volodymyr, et al.
(author)
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Influence of oxygen on the tool wear in machining
- 2018
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In: CIRP Annals - Manufacturing Technology. - : Elsevier BV. - 0007-8506. ; 67:1, s. 79-82
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Journal article (peer-reviewed)abstract
- High temperatures generated in machining are known to facilitate oxidation wear. A controlled atmosphere chamber was developed to investigate the effects of oxygen on tool wear and high speed machining tests were conducted on air and in argon. Cemented carbide, cermet and cubic boron nitride tooling was used on alloyed steel, hardened tool steel and superalloy Alloy 718. Machining in argon resulted in higher flank wear, higher cutting forces, and larger tool–chip contact length on the rake face. However, in hard machining, argon atmosphere reduced rake cratering. Transmission electron microscopy of tools worn on air showed formation of nanocrystalline Al2O3 film on the rake when machining aluminium containing Alloy 718, while no oxide films was detectable in the other cases.
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| 17. |
- Bushlya, Volodymyr, et al.
(author)
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Modeling and experimentation on multistage work-hardening mechanism in machining with nose-radiused tools and its influence on machined subsurface quality and tool wear
- 2014
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In: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 73:1-4, s. 545-555
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Journal article (peer-reviewed)abstract
- The paper reports on the modeling and respective experimental validation for the formation of the machined subsurface layer in turning with nose-radiused and round tools. An experimental work on the mechanisms of work-hardening of the machined surface and related wear of the cutting tools was conducted for high-speed turning of aged Inconel 718 with whisker-reinforced alumina tools. The model shows that multiple deformations of the machined surface occur when machining with small feeds and tools with large nose radius, thus changing the mechanics of surface formation. Experimental results confirm the localized increase in subsurface hardness in the vicinity of the tool tip. The variation in the degree of work-hardening and the extent of the area affected by it fully agree with the predictions of the model. The model also shows that a significant part of the cutting tool may cut through the extra work-hardened material. Tool wear tests show that the local increase in workpiece hardness results in a localized increase in the wear rate of the cutting tools.
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| 18. |
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| 19. |
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| 20. |
- Bushlya, Volodymyr, et al.
(author)
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On the Analytical Representation of Chip Area and Tool Geometry when Oblique Turning with Round Tools. Part 1: Chip Area Parameters under Variation of Side and Back Rake Angle
- 2015
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In: 15th CIRP Conference on Modelling of Machining Operations (15TH CMMO). - : Elsevier BV. - 2212-8271. ; 31, s. 417-422
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Conference paper (peer-reviewed)abstract
- Chip area parameters, such as undeformed chip thickness, equivalent chip thickness, contact edge length, etc., along with tool angles are among defining for the mechanical and thermal conditions of the cutting process. This paper considers the case of external turning with a round insert under variation, in wide range, of back and side rake angles and their influence on the main chip area and surface roughness parameters. Influence of other process variables, such as feed, depth-of-cut and nose radius, is also studied. The developed analytical models and algorithms allow, not only to study the fundamental relationships, but to apply them in the design of new tools for conventional and rotary turning.
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| 21. |
- Bushlya, Volodymyr, et al.
(author)
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On the Analytical Representation of Chip Area and Tool Geometry when Oblique Turning with Round Tools. Part 2: Variation of Tool Geometry along the Edge Line
- 2015
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In: 15th CIRP Conference on Modelling of Machining Operations (15TH CMMO). - : Elsevier BV. - 2212-8271. ; 31, s. 423-428
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Conference paper (peer-reviewed)abstract
- This paper presents the models, analytical equations and results of analysis for determination of major cutting edge, orthogonal and normal clearance and rake angles, and cutting edge inclination angle. The analysis is carried for variable side and back rake angles used by the tool manufacturers and a corresponding variation of the geometry along the edge line for the case of round tools. The influence of tool nose radius, chamfer/chipbreaker angle and depth-of-cut was considered as well. Significant variation in orthogonal geometry from that stated in catalogues was found in most cases. The developed analytical solutions and algorithms allow the establishment of fundamental geometrical relationships and giving a correct prediction when developing new tools for conventional and rotary turning. (C) 2015 The Authors. Published by Elsevier B.V.
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| 22. |
- Bushlya, Volodymyr, et al.
(author)
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Performance and wear mechanisms of novel superhard diamond and boron nitride based tools in machining Al-SiCp metal matrix composite
- 2017
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In: Wear. - : Elsevier BV. - 0043-1648. ; 376-377, s. 152-164
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Journal article (peer-reviewed)abstract
- Metal matrix composites are the desired materials in aerospace and automotive industries since they possess high specific strength. However addition of reinforcement to the matrix material brings the adverse effects of high wear rate of tool materials used in their machining. The current study addresses the issues of wear and performance of superhard tools when high speed machining cast Al-Si alloy reinforced with particulate SiC (20% vol.). A wide range of developed superhard materials was compared to the commercial PCD tools. Nano grain sized wBN-cBN, binderless cBN; B6O-cBN, nano-diamond with WC binder; diamond/MAX-phase; and diamond/SiC tool materials were employed. Use of nano-diamond/WC and diamond/MAX-phase composites resulted in their rapid deterioration due to primarily adhesive pluck-out of diamond and binder phase. Diamond/SiC material exhibited slightly lower performance than the PCD, with the primary wear being the abrasive on the SiC binder phase. Machining with cBN-based tooling at lower speed lead to formation of stable build-up layer, frequently accompanied by severe seizure of tool and workpiece material. However at speed of 400 m/min the absence of such build-up layer caused rapid tool wear. Presence of chemical and diffusional wear mechanisms for diamond tooling has been confirmed through scanning and transmission electron microscopy. Archard-type model of abrasive tool wear was developed for modelling of tool deterioration for all studied tool materials.
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| 23. |
- Bushlya, Volodymyr, et al.
(author)
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Performance and wear mechanisms of whisker-reinforced alumina, coated and uncoated PCBN tools when high-speed turning aged Inconel 718
- 2013
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In: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 66:9-12, s. 2013-2021
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Journal article (peer-reviewed)abstract
- Abstract in UndeterminedInconel 718, an efficient superalloy for energy and aerospace applications, is currently machined with cemented carbide tools at low speed (vc≈60 m/min) due to its unfavorable mechanical and thermal properties. The article presents results of a study of superalloy machinability with whisker reinforced alumina, uncoated and coated PCBN tools. Turning of age hardened Inconel 718 (45 HRC) was done under high speed machining conditions (vc=250…350 m/min). Aspects of tool life, tool wear and generated surface quality were studied. Application of uncoated PCBN tools resulted in surface quality and force level superior to other tool materials. Considerable side-flow of workpiece material was found to affect surface quality, especially for coated PCBN and ceramic tools. It was found that protective function of the coating, which increases the tool life up to 20%, is limited only to low cutting speed range. EDX and AFM analyses suggested dominance of chemical and abrasive wear mechanisms. EDX mapping of worn tools pointed absence of diffusional wear for PCBN tools and intensive degradation of whisker reinforcement in ceramic tools due to diffusion of Ni, Fe and Cr.
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| 24. |
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| 25. |
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| 26. |
- Bushlya, Volodymyr, et al.
(author)
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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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In: Journal of Superhard Materials. - 1934-9408. ; 36:1, s. 49-60
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Journal article (peer-reviewed)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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| 27. |
- Bushlya, Volodymyr, et al.
(author)
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Tool wear mechanisms of PcBN in machining Inconel 718: Analysis across multiple length scale
- 2021
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In: CIRP Annals - Manufacturing Technology. - : Elsevier BV. - 1726-0604 .- 0007-8506. ; 70:1, s. 73-78
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Journal article (peer-reviewed)abstract
- Recently, PcBN tooling have been successfully introduced in machining Ni-based superalloys, yet our knowledge of involved wear mechanisms remains limited. In this study, an in-depth investigation of PcBN tool degradation and related wear mechanisms when machining Inconel 718 was performed. Diffusional dissolution of cBN is an active wear mechanism. At high cutting speed oxidation of cBN becomes equally important. Apart from degradation, tool protection phenomena were also discovered. Oxidation of Inconel 718 resulted in formation of γ-Al2O3 and (Al,Cr,Ti)3O4 spinel that were deposited on the tool rake. Also on the rake, formation of (Ti,Nb,Cr)N takes place due to cBN-workpiece interaction. This creates a sandwich tool protection layer forming continuously as tool wear progresses. Such in operando protection enabled counterbalancing tool wear mechanisms and achieved high performance of PcBN in machining.
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| 28. |
- Bushlya, Volodymyr, et al.
(author)
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Wear mechanisms of silicon carbide-whisker-reinforced alumina (Al2O3-SiCw) cutting tools when high-speed machining aged Alloy 718
- 2013
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In: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 68:5-8, s. 1083-1093
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Journal article (peer-reviewed)abstract
- The paper is aimed at the identification and characterization of wear mechanisms of SiC whisker-reinforced alumina when turning aged Alloy 718 under different cutting conditions and when machining dry and with coolant. Secondary and backscatter electron microscopy accompanied by focus ion beam milling and EDX techniques were used for analysis of worn-out tools. Notch wear on the major cutting edge was found to consist of two notches: depth-of-cut notch and secondary notch located outside the chip area. The last was found to be governed by adhesion and attrition associated with adverse chip flow conditions. Formation of a minor notch was related to attrition by the defects found on the machined surface. Diffusion of Ni, Fe, and Cr into SiC whiskers was found to degrade them and facilitate adhesion. Chemical wear mechanisms were found to be responsible for degradation and decomposition of whiskers and formation of tribolayer on tool surfaces, which in turn was related to the reduced adhesion of Alloy 718 on the tool. Cracking on the tool rake and localized plastic deformation were found to further accelerate tool deterioration.
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| 29. |
- Bushlya, Volodymyr, et al.
(author)
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Wear mechanisms of uncoated and coated cemented carbide tools in machining lead-free silicon brass
- 2017
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In: Wear. - : Elsevier BV. - 0043-1648. ; 376-377, s. 143-151
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Journal article (peer-reviewed)abstract
- Free-machining brass containing 2–3% of lead is a preferred industrial material as it shows excellent machinability where low cutting forces, short chips and reduced tool wear are attained. However this addition of lead, a highly toxic and hazardous material, leads to health and environmental issues. Alternative lead-free brasses are known for poor chip control and accelerated tool wear. The current study focuses on wear mechanisms of uncoated and coated cemented carbide tools when high-speed machining lead-free CuZn21Si3P silicon brass. The study shows that severe crater formation on the rake is the dominant tool failure mode. Microscopy observations indicate the diffusion wear mechanism to be driven by diffusion of cobalt binder into the chips and minor cross-diffusion of copper and zinc. Loss of the binder in cemented carbide is accompanied by adhesive pluck-out of WC grains. As a way to hinder the loss of Co, the diffusion preventing capacity of a-C:H diamond like carbon and (Ti,V,Zr,Nb,Hf,Ta)N nitride coating were tested. SEM, EDX and TEM data show that formation of amorphous SiO2 and stoichiometric β-SiAlON stable layers was observed on the nitride coating, thus preventing diffusional tool wear. O-rich and N-rich glassy amorphous layers in Si-Al-O-N system with ZnS inclusions were found on the DLC coating. Partial delamination of the DLC coating and removal of the glassy phases resulted in localized crater formation associated with diffusional wear.
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| 30. |
- Chen, Ling, et al.
(author)
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Influences of micro mechanical property and microstructure on performance of machining high chromium white cast iron with cBN tools
- 2015
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In: 15th CIRP Conference on Modelling of Machining Operations (15TH CMMO). - : Elsevier BV. - 2212-8271. ; 31, s. 172-178
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Conference paper (peer-reviewed)abstract
- The variation of the micro mechanical properties, such as hardness and modulus, of the material is important potential factor influencing the machinability of the material. The presented paper is to study the influence of variation in micro hardness and microstructure of the materials on machining performance in terms of tool wear and tool life, cutting forces and surface quality. The work material is high chromium white cast iron and material of cutting tool is cBN. The variation of micro hardness were measured and analyzed by grid nano indentation approach. Volume fraction phases of the material were identified through Weibull mixture distribution from result of grid nano indentation. High chromium white cast irons were prepared with two groups of composition, lower carbon silicon and higher carbon silicon, in the state of as-cast and hardened condition. Results from the machining test indicate that the variation of micro hardness of the work materials show significant impacts on cutting tool wear, tool life, cutting forces and surface quality in the machining of these materials. The effect of micro mechanical properties needs to be taken into account in the modelling and predicting tool life and surface quality. In addition, the mechanism of interaction between the cBN tool and the high chromium white cast iron under the range of machining parameters was also addressed. Lastly, surface roughness measurements complemented the results and a qualitative relationship between the surface roughness generated during the machining and the materials is also laid out. (C) 2015 The Authors. Published by Elsevier B. V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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| 31. |
- Chen, Ling, et al.
(author)
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Performance assessment of pCBN and bCBN tools in machining of high-chromium white cast iron
- 2015
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In: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 79:1-4, s. 635-644
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Journal article (peer-reviewed)abstract
- This paper presents an experimental evaluation of the performance of cubic boron nitride (CBN) tools in the machining of high-chromium white cast iron. Two types of CBN tool materials were evaluated in the tests, including polycrystalline cubic boron nitride (pCBN) and binder-less crystalline cubic boron nitride (bCBN). Performance in terms of the levels of cutting forces, tool wear, surface roughness and process stability was evaluated during and after cutting tests. The work materials used in the cutting tests included two groups with chemical compositions of two levels of carbon silicon (lower C-Si and higher C-Si) in as-cast and hardened states, respectively. Test results indicate that the cutting tool materials clearly exhibited different behaviour in the machining of high-chromium white cast iron. The pCBN tools demonstrated lower tool wear rates than the bCBN tools but had higher roughness levels on the workpiece surfaces. The cutting tools also behaved differently according to the different levels of C-Si content and heat treatment of the work materials. In addition, the study reveals the mechanism of the interactions between CBN tools and high-chromium white cast iron under a range of machining parameters.
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| 32. |
- Chen, Zhe, et al.
(author)
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ECCI and EBSD study of subsurface damages in high speed turning of inconel 718 under different tools and machining parameters
- 2013
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In: 13th International Conference on Fracture 2013, ICF 2013. - 9781629933696 ; 6, s. 4697-4704
-
Conference paper (peer-reviewed)abstract
- Inconel 718 is a Ni-based superalloy that can perform excellently at elevated temperatures. However, surface and subsurface damages in the form of microstructural and property changes and tensile residual stresses are common in a machined Inconel 718 component because of its poor machinability. Such damages have a significant influence on performance and the life time of the part. To characterise microstructural damages and understand how they are correlated to machining conditions are not only important for the evaluation of surface integrity but also for the optimization of machining operations to minimise effects from the machining process. This paper uses the ECCI (electron channelling contrast imaging) and EBSD (electron back scatter diffraction) methods to study the effect of cutting tools and cutting speeds on subsurface plastic deformation of machined Inconel 718. When turning at 200 m/min, a comparable level of plastic deformation was found under the surface machined with uncoated cubic boron nitride (CBN), titanium nitride coated CBN and whisker reinforced alumina (WRA). With an increase in cutting speed, the plastic deformation depth increased, and uncoated CBN tools showed superior performance in term of subsurface microstructure alterations compared to the other tool materials.
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| 33. |
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| 34. |
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| 35. |
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| 36. |
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| 37. |
- Gutnichenko, Oleksandr, et al.
(author)
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Influence of cutting speed and tool wear on vibrations and process stability when turning Inconel 718 with PCBN tools
- 2014
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In: International Journal of Manufacturing Research. - 1750-0591. ; 9:2, s. 173-193
-
Journal article (peer-reviewed)abstract
- Results of the study of cutting speed and tool wear influence on the vibrations and their nature during machining superalloy Inconel 718 with low cBN content (cBN-L) and binderless pcBN (bcBN) tools are presented. Cutting speed was varied from 2 to 14 m/sec while other cutting conditions were constant. The process evolution was studied with the wavelet transform of tool acceleration spectra. Behaviour of the dynamic system was found to vary with the cutting speed and the specifics of tool wear. It is shown that machining with bcBN tools was accompanied by appearance of significant vibration when cutting speed exceeded 5 m/sec, but the machining with cBN-L was characterised by the suppression of vibrations over the entire speed range. This was related to the difference of tool microgeometry development during the course of wear. The wear of bcBN tools, in contrast to cBN-L, was characterised by merger of crater and flank wear and formation of negative clearance angle. Such difference results in an increase of cutting forces 2-4 times as compared to cBN-L tools. Estimation of dynamic stability by 0-1 test confirmed the process instability when turning with bcBN tools at cutting speeds higher than 8 m/sec which concurs with chatter appearance.
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| 38. |
- Gutnichenko, Oleksandr, et al.
(author)
-
Influence of GnP additive to vegetable oil on machining performance when MQL-assisted turning Alloy 718
- 2018
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In: Procedia Manufacturing. - : Elsevier BV. - 2351-9789. ; 25, s. 330-337
-
Journal article (peer-reviewed)abstract
- The current study demonstrates through experiment the effect of solid lubricant assisted minimum quantity lubrication (MQL) on the machining performance when turning Alloy 718 with cemented carbide tools. A powder of nanosized (~30 nm) graphite nanoplatelets (GnP) was dispersed (0.2% vol.) in a vegetable oil-based lubricant “ECOLUBRIC E200L” and used in MQL-assisted machining. The effect of cutting conditions on the machining performance parameters such as forces, tool wear, surface finish, and vibrations generated was studied. Results demonstrate a significant improvement of the machining performance when MQL-assisted turning of Alloy 718 with GnP-modified oil in terms of tool life, surface finish and process stability.
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| 39. |
- Gutnichenko, Oleksandr, et al.
(author)
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Influence of graphite nanoadditives to vegetable-based oil on machining performance when MQCL assisted hard turning
- 2018
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In: 8th CIRP Conference on High Performance Cutting. - : Elsevier BV. - 2212-8271. ; 77, s. 437-440
-
Conference paper (peer-reviewed)abstract
- The current study demonstrates through experiment, the effect of solid lubricant assisted minimum quantity cooling lubrication (MQCL) when turning tempered (~60 HRC) alloyed steel Uddeholm Caldie with cemented carbide tools on the process performance. In MQCL application, nanosized graphite nanoplatelets (GnP) solid lubricant powder was dispersed (0.2% vol.) in rapeseed oil based lubricant “ECOLUBRIC”. The effect of cutting parameters at dry machining and with MQCL lubrication on the machined surface finish, tool forces, tool wear and vibrations generated were studied.
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| 40. |
- Gutnichenko, Oleksandr, et al.
(author)
-
Machinability and process stability when turning Alloy 718 with standard and produced by selective laser sintering toolholders
- 2014
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In: [Host publication title missing].
-
Conference paper (peer-reviewed)abstract
- The paper presents the results of a comparative analysis of machinability and dynamic stability when turning a nickel-based superalloy with WRA tools in a conventional and prototype toolholders. The use of the prototype toolholder with a spatial structure is shown to significantly suppress vibrations during the machining and stabilize the process within the cutting speed range between 200 and 400 m/min. The above mentioned benefits are demonstrated to be owing to damping properties of the proposed toolholder.
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| 41. |
- Gutnichenko, Oleksandr, et al.
(author)
-
Self-generated vibrations and process stability when turning high chromium white cast iron with PCBN tools
- 2014
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In: Proceedings of the 6th Swedish Production Symposium.
-
Conference paper (peer-reviewed)abstract
- The dynamic instability and related problems when turning high chromium cast iron (HCCI) with two polycrystalline cubic boron nitride (PCBN) tools in wide range of cutting speeds and feed rates were studied in the article. The tool wear mechanisms and specifics for both tools as a main criterion of appearance of process instability were investigated. In spite of the chatter-like surface of machined workpieces it was shown the dynamic stability of process by two method ‘0-1 test’ and determination of maximum Lyapunov exponent. Taking into account the strong periodicity of process with several clear harmonics it was concluded that such process is related to self-resonant phenomena.
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| 42. |
- Gutnichenko, Oleksandr, et al.
(author)
-
Tool wear and machining dynamics when turning high chromium white cast iron with pcBN tools
- 2017
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In: Wear. - : Elsevier BV. - 0043-1648. ; 390-391, s. 253-269
-
Journal article (peer-reviewed)abstract
- High chromium white cast irons (HCCI) with high hardness and abrasiveness owing to a particular combination of hard primary and eutectic carbides were used as workpiece materials for longitudinal turning with binderless cBN (bcBN) and high cBN (hcBN) tools. The materials with low and high Si content were used in as-cast and quenched states. Binderless cBN is prone to cratering and flank wear, while hcBN is more prone to significant cutting edge rounding. Atypical behavior was found when machining high-Si material where the increase in cutting forces was accompanied by suppression of vibrations. The observed formation of a tool protection layer (TPL) on the tool–chip interface was found to be responsible for the improved dynamic stability. Electron microscopy and EDX analysis revealed that the TPL consists of nanocrystalline Al2O3 with SiO2 inclusions, both present in the workpiece materials. The stability of TPL was found to depend on both workpiece and tool materials. The absence or removal of the layer resulted in the development of self-excited vibrations with a frequency of 380 Hz, which affected the machined surface.
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| 43. |
- Hrechuk, Andrew, et al.
(author)
-
Application of Colding tool life equation on the drilling fiber reinforcement polymers
- 2018
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In: Procedia Manufacturing. - : Elsevier BV. - 2351-9789. ; 25, s. 302-308
-
Journal article (peer-reviewed)abstract
- Fiber reinforcement polymer (FRP) is a hard-to-treat material used in different areas of up-to-date machine building. It has excellent mechanical properties making the material unique in different engineering solutions such as aircraft, aerospace and boatbuilding. The optimization of holemaking operations in FRP is the main aim of the current investigation. This paper presents an approach of defining the most effective cutting data and costs of drilling Saab’s carbon fiber reinforcement plastic (CFRP) using cemented carbide and PCD drills. The experiment results included force and torque monitoring, tool wear defining and holes quality analyzing.
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| 44. |
- Hrechuk, Andrii, et al.
(author)
-
Automated detection of tool wear in machining and characterization of its shape
- 2023
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In: Wear. - : Elsevier BV. - 0043-1648. ; 523
-
Journal article (peer-reviewed)abstract
- Flank wear VBmax remains one of the most essential and used metrics for measuring tool wear. VBmax is used to characterize tool wear rate, machinability of materials, the quality of machined surface. While VBmax measures the size of wear scar, the shape of the tool wear remains less used but not the least applicable for such characterization. However, quantification of the wear shape requires a more detailed information about the wear contour. This study develops an Image Processing solution for automated tool wear detection and applies Delaunay triangulation and implenarity parameter for characterizing the shape of the wear scar. Validation of the approach has been performed for machining stainless steel 316L without and with abrasive Al2O3 and SiO2 inclusions. It is shown that VBmax and area parameters of the wear scar are insensitive to wear shape, while implenarity can accurately quantify irregularity, curvature, asymmetry of the scar. The results also show a strong relationship between the tool wear shape, the hardness and size of inclusions in the steel.
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| 45. |
- Hrechuk, Andrew, et al.
(author)
-
Experimental investigations into tool wear of drilling CFRP
- 2018
-
In: Procedia Manufacturing. - : Elsevier BV. - 2351-9789. ; 25, s. 294-301
-
Journal article (peer-reviewed)abstract
- Carbon Fiber Reinforced Polymer (CFRP) has highly abrasive microstructure due to carbon fiber reinforcement and requires the use of tool materials with good resistance to abrasive wear. The paper presents a study of tool wear in drilling operation. Drill bits with uncoated and diamond coated cemented carbide and polycrystalline diamond were tested in drilling PAN-based CFRP samples. Registered thrust force, torque, flank wear, cutting edge radius (CER), drilled holes quality are correlated with the tool material type. Experimental results showed existence of CER critical values and flank wear that are affecting acceptable hole quality and CFRP chip structure.
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| 46. |
- Hrechuk, Andrew, et al.
(author)
-
Hole-quality evaluation in drilling fiber-reinforced composites
- 2018
-
In: Composite Structures. - : Elsevier BV. - 0263-8223. ; 204, s. 378-387
-
Journal article (peer-reviewed)abstract
- This paper presents a novel approach for a complex evaluation of the quality of drilled holes in fiber-reinforced composite materials. The proposed methodology is based on non-destructive quantification of visible defects based on the numerical analysis of drilled hole images. Automatic contour definition and profile formation for the uncut fibers and delamination were implemented via modularized algorithms. Four criteria for the evaluation of the defect height and width distribution were developed and combined into an overall quality parameter, Q. The methodology was validated experimentally by drilling carbon-fiber-reinforced polymer (CFRP) samples with a cemented carbide drill bit. The results showed a linear relation between the hole quality Q, the drilled hole number, and tool wear.
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| 47. |
- Hrechuk, Andrii, et al.
(author)
-
Novel metric “Implenarity” for characterization of shape and defectiveness : The case of CFRP hole quality
- 2021
-
In: Composite Structures. - : Elsevier BV. - 0263-8223. ; 265
-
Journal article (peer-reviewed)abstract
- Image Processing is rapidly expanding as a technique for object and defect analysis because of the high ease of its coupling to automation and IT solutions. Yet, issues with transferability of the measurement approaches and metrics currently used in mechanical systems often remain unsolved. Study reports on the developed approach for shape and defectiveness characterization by combining Delaunay triangulation of object's contour with uniformity analysis of triangles in the generated mesh using developed metric “Implenarity”. When analyzing hole drilling in CFRP, experimental validation found that for highest quality of CFRP holes, implenarity shifts from its maximum of I = 0.22 for a circle to I ≈ 0.16 for microdefects below 100 µm—normally not quantifiable with conventional techniques. In presence of larger hole defects, implenarity demonstrated similar capabilities to standard metrics, but avoided their inherent flaws. Implenarity continued distinguishing degree of defectiveness for the same area of uncut fibers (Fa-cov) and the same delamination diameter (Fd,Fda).
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| 48. |
- Hrechuk, Andrew, et al.
(author)
-
Quantitative analysis of chip segmentation in machining using an automated image processing method
- 2019
-
In: 17th CIRP Conference on Modelling of Machining Operations (17th CIRP CMMO). - : Elsevier BV. - 2212-8271. ; 82, s. 314-319
-
Conference paper (peer-reviewed)abstract
- Analysis of chip formation is one of the most established and informative methods for description of the cutting process. A number of established techniques ranging from optical to electron microscopy have been developed for analysis of continuous chips. Yet, machining of difficult-to-cut materials is accompanied by segmented chip formation. This paper presents an original algorithm based on image processing of segmented chips that quantifies chip compression ratio, dimensions of segments, segmentation frequency, etc. The algorithm was validated when analyzing chip cross-sections for the cases of orthogonal turning of stainless steel 316L and Inconel 718.
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| 49. |
- Hörndahl, Mikael, et al.
(author)
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EFFECTS OF COOLING RATE AND SILICON CONTENT ON AL/SICp MMC
- 2014
-
Conference paper (peer-reviewed)abstract
- This paper reports the results of the study ofthe microstructural and mechanical properties ofmetal matrix composites (MMC) based on Al-Si matrix alloyandsilicon carbideparticulates. The scope of the studyis to investigate the effects of cooling rate and silicon content on the microstructure and the mechanical propertiesof MMC.Samples were cast in mouldsof different temperature in order to identifythe effects of the cooling rate while silicon content was varied from 7 to 12.5 %in the matrix material.The conclusion is that the cooling rate has little effect on the properties unless it is taken to the extreme and the effects of the silicon content is no more pronounced than for non-reinforced aluminium.
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| 50. |
- Johansson, Daniel, et al.
(author)
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Assessment of Commonly used Tool Life Models in Metal Cutting
- 2017
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In: Procedia Manufacturing. - : Elsevier BV. - 2351-9789. ; 11, s. 602-609
-
Journal article (peer-reviewed)abstract
- In this work, eleven different combinations of work piece materials and tool grades have been evaluated in wear test when turning with cemented carbide insert. The most commonly used tool life models such as the Taylor model, the Extended Taylor model, the Coromant Turning model version 1 and the Colding model have been tested on the data and their accuracy is presented. The well-known Taylor model proves to have a limited ability to reproduce the data. The most accurate model is the Colding model, with an average model error of approximately 4.0% and Woxén equivalent chip thickness proves to work well for all presented tool life models. This work also discusses the models ability to reproduce cutting data for finishing operations and possible limitations when extrapolating the models for smaller chip thicknesses.
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