| 1. |
- Bushlya, Volodymyr, et al.
(författare)
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Influence of oxygen on the tool wear in machining
- 2018
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Ingår i: CIRP Annals - Manufacturing Technology. - : Elsevier BV. - 0007-8506. ; 67:1, s. 79-82
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Chen, Zhe, 1987-, et al.
(författare)
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Effect of Machining Parameters on Cutting Force and Surface Integrity when High-Speed Turning AD730™ with PCBN Tools
- 2019
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Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer London. - 0268-3768 .- 1433-3015. ; 100:9-12, s. 2601-2615
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Tidskriftsartikel (refereegranskat)abstract
- The novel wrought nickel-based superalloy, AD 730™, is a good candidate material for turbine disc applications at high temperatures beyond 650 °C. The present study focuses on the machining performance of this newly developed alloy under high-speed turning conditions with advanced PCBN tools. Meanwhile, the machined surface integrity as influenced by cutting speed and feed rate was also investigated. The surface integrity was thoroughly characterized in terms of surface roughness and morphology, machining-induced plastic deformation, white layer formation, and residual stresses. It has been found that the cutting speed and feed rate had a strong effect on the cutting forces and resultant surface integrity. The cutting forces required when machining the alloy were gradually reduced with increasing cutting speed, while at 250 m/min and above, the flank tool wear became stronger which led to increased thrust force and feed force. A higher feed rate, on the other hand, always resulted in higher cutting forces. Increasing the cutting speed and feed rate in general deteriorated the surface integrity. High cutting speeds within the range of 200–250 m/min and a low feed rate of 0.1 mm/rev are preferable in order to implement more cost-effective machining without largely reducing the surface quality achieved. The formation of tensile residual stresses on the machined AD 730™, however, could be of a concern where good fatigue resistance is critical.
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| 3. |
- Hoseiny, Seyyed Mohammad Hamed, 1980, et al.
(författare)
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The Influence of Heat Treatment on the Microstructure and Machinability of a Prehardened Mold Steel
- 2015
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Ingår i: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science. - : Springer Science and Business Media LLC. - 1073-5623. ; 46A:5, s. 2157-2171
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Tidskriftsartikel (refereegranskat)abstract
- The machinability performance of a modified AISI P20 steel, heat treated to have the same hardness but three different microstructures, lower bainite, tempered martensite, and primary spheroidized carbides in a tempered martensite matrix, was studied. The microstructures were characterized using light optical and scanning electron microscopy and X-ray diffraction, and mechanical properties were compared by means of tensile and Charpy V-notch impact tests. The influence of microstructure and the resultant mechanical properties on machinability was studied in the context of single tooth end milling operation. The results showed that the material containing primary spheroidized carbides exhibited a superior machinability at the expense of a marginal loss of tensile strength and impact toughness, with comparable yield strength to that of the material containing tempered martensite. By contrast, the material with bainitic mi- crostructure showed the lowest yield strength and the poorest machinability performance while having the highest uniform elongation.
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| 4. |
- Hrechuk, Andrew, et al.
(författare)
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Experimental investigations into tool wear of drilling CFRP
- 2018
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Ingår i: Procedia Manufacturing. - : Elsevier BV. - 2351-9789. ; 25, s. 294-301
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Hrechuk, Andrew, et al.
(författare)
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Quantitative analysis of chip segmentation in machining using an automated image processing method
- 2019
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Ingår i: 17th CIRP Conference on Modelling of Machining Operations (17th CIRP CMMO). - : Elsevier BV. - 2212-8271. ; 82, s. 314-319
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Konferensbidrag (refereegranskat)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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| 6. |
- Johansson, Daniel, et al.
(författare)
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Assessment of Metal Cutting Tools using Cost Performance Ratio and Tool Life Analyses
- 2019
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Ingår i: Procedia Manufacturing. - : Elsevier BV. - 2351-9789. ; 38, s. 816-823
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Tidskriftsartikel (refereegranskat)abstract
- Critical raw materials (CRM) are extensively used in tools for metal cutting, such as in cemented carbide tools (cobalt and tungsten), because they provide desired characteristics of high fracture toughness and wear resistance. Both academia and industry are examining CRM-free material alternatives, such as tools based on polycrystalline diamond (PCD) or ceramic materials. These materials are generally more cost intensive as compared to cemented carbide but could also provide higher efficiency in terms of material removal rate. Material removal rate and tool costs have a substantial influence on the final part cost. When deciding on tool material, the manufacturing industry is either looking for the most cost effective alternative or the alternative providing the highest productivity output. The purpose of this paper is to provide industry with decision support for selection of tool and cutting data that provide the financial most sound production set-up. This work aims to present a novel methodology combining the Colding tool life model and a previously presented model for cost performance ratio. A previous publication provided a method to assess technological solutions and investments based on final part cost. The developed methodology in this article combines cutting performance and production performance to allow a comprehensive cost assessment for a production process. The assessment includes cutting data, tool life and costs of tooling, quality rejections, process availability, equipment investment, personnel and facility. A case study based on experimental data is presented to verify the proposed methodology.
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| 7. |
- Kryzhanivskyy, V., et al.
(författare)
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Computational and Experimental Inverse Problem Approach for Determination of Time Dependency of Heat Flux in Metal Cutting
- 2017
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Ingår i: 16th CIRP Conference on Modelling of Machining Operations (16th CIRP CMMO). - : Elsevier BV. - 2212-8271. - 9781510842762 ; 58, s. 122-127
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Konferensbidrag (refereegranskat)abstract
- This study develops the method for solution of inverse heat conduction problem applied to metal cutting. The proposed method operates with a selection procedure involving iterative solutions of heat forward problem. In such formulation, it allows avoiding difficulties associated with ill-posed inverse problems inherent to conventional formulations. Inverse heat problem was transformed into constrained optimization problem via objective function which metrizes the difference between FE and experimental data. Specially designed solid HSS cutting tool with embedded thermocouples was manufactured. The method was validated for the case of orthogonal machining of 6061 aluminum alloy. The numerical simulations were performed with the help of COMSOL Multiphysics and MATLAB scripts. Heat flux exhibits descending trend over the time of the cutting test and closely follows hyperbola function behavior with the average value of q = 4.6 MW/m2.
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| 8. |
- Persson, Henrik, et al.
(författare)
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Modelling tool life in high speed machining of AD730
- 2018
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Ingår i: Procedia Manufacturing. - : Elsevier BV. - 2351-9789. ; 25, s. 316-321, s. 316-321
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Tidskriftsartikel (refereegranskat)abstract
- AD730® is a new type of nickel-based superalloy, developed by Aubert & Duval, with high temperature properties exceeding conventional superalloys such as Alloy 718. This paper presents the tool life model for this superalloy for the purpose of process optimization and manufacturing cost estimation. The tool life modelling is based on comprehensive machining tests, using the Colding model. The cutting tool material used is CBN 170, a grade specially designed and optimized for machining of nickel-based superalloys.
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| 9. |
- Saketi, Sara, et al.
(författare)
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Wear of a high cBN content PCBN cutting tool during hard milling of powder metallurgy cold work tool steels
- 2015
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Ingår i: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 332, s. 752-761
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Tidskriftsartikel (refereegranskat)abstract
- The wear characteristics of a high cBN content PCBN cutting tool during hard milling of two different hardened cold work tool steels have been evaluated. Post-cutting examination of the worn cutting inserts were performed using high resolution field emission gun scanning electron microscopy, energy dispersive X-ray spectroscopy, Auger electron spectroscopy and optical surface profilometry. Also, the machined work material surfaces and collected chips were characterized in order to evaluate the prevailing wear mechanisms.The results show that both flank and crater wear is controlled by continuous wear due to tribochemical reactions, adhesive wear and mild abrasive wear. Besides, the cutting inserts show a tendency to micro chipping along the cutting edge especially at higher cutting speed. The latter mechanism was also found to be dependent on type of work material. High lateral resolution Auger electron spectroscopy of the crater region show that the worn surface is covered by a thin SixOy rich tribofilm with a thickness of 50-500 nm, the tribofilm being thicker on the binder phase regions. Also, the Co-rich regions of the binder phase seem to be more tribochemically affected by the prevailing contact conditions as compared with the Wrich regions of the binder phase and the cBN phase.
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| 10. |
- Sheikh, Saad, 1987-, et al.
(författare)
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Fracture toughness of cemented carbides : Testing method andmicrostructural effects
- 2015
-
Ingår i: International journal of refractory metals & hard materials. - : Elsevier. - 0263-4368 .- 2213-3917. ; 49, s. 153-160
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Tidskriftsartikel (refereegranskat)abstract
- Fracture toughness is one the most important parameters for design applications and performance assessment of WC–Co cemented carbides (hardmetals). Different from hardness, fracture toughness is commonly a property more difficult to evaluate, particularly in brittle materials. A large number of different testing methods have been introduced to evaluate toughness of hardmetals, but in general all of them have either theoretically debatable issues or important experimental difficulties. In this study, three different fracture toughness testing methodologies are investigated: three-point bending on Chevron notched specimen (“reference” baseline), Palmqvist indentation test, and Hertzian indentation method. The work is conducted in several cemented carbide grades with different microstructures, in terms of both WC grain size and Co binder content. It is found that Chevronnotched three-point bending test yields suitable fracture toughness values for a wide range of cemented carbide grades with varying hardness. Concerning indentation methods, the Hertzian one may be particularly recommended, as compared to Palmqvist method, as far as hardness (HV30) drops below 1300. On the other hand, if HV30 is higher than 1300 Palmqvist indentation procedure yields reliable fracture toughness measurements. Experimental findings are finally analyzed and discussed on the basis of two theoretical models proposed in the literature.
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| 11. |
- Zhou, Jinming, et al.
(författare)
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Comparative assessment of the surface integrity of AD730® and IN718 superalloys in high-speed turning with a CBN tool
- 2019
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Ingår i: Journal of Manufacturing and Materials Processing. - : MDPI AG. - 2504-4494. ; 3:3
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Tidskriftsartikel (refereegranskat)abstract
- Nickel-based superalloys are typical materials used in components of aeroengines and gas turbine machinery. The strength properties of these alloys at high temperatures are crucial not only to the performance (e.g., power generation efficiency, energy consumption, and greenhouse gas emissions) of aeroengines and industrial gas turbines, but also to machinability during component manufacturing. This study comparatively evaluated the surface integrity of two superalloys, AD730® and Inconel 718 (IN718), during high-speed finishing turning using cubic boron nitride (CBN) tools. IN718 is a conventional superalloy used for the hot section components of aeroengines and industrial gas turbines, while AD730® is a novel superalloy with enhanced high-temperature mechanical properties and good potential as a next-generation superalloy for these components. High-speed turning tests of two superalloys were conducted using a CBN cutting tool and jet stream cooling. The achieved surface integrity of the AD730® and IN718 superalloys was characterized and analyzed to assess the comparability of these alloys.
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