| 1. |
- Bushlya, Volodymyr, et al.
(författare)
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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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Ingår i: Wear. - : Elsevier BV. - 0043-1648. ; 376-377, s. 152-164
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Kirkhorn, Lanny, et al.
(författare)
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Nano graphite flakes as lubricant additive
- 2014
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Ingår i: Proceedings of the 6th Swedish Production Symposium.
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Konferensbidrag (refereegranskat)abstract
- The fundamental method of reducing friction and wear in metal to metal contact manufacturing processes like forging, extrusion, sheet metal forming etc. is based upon surface separation. The separation is usually obtained by adding different types of lubricants to the process. In this work, graphite nano platelets (GNp) powder has been used as a lubrication additive to explore and evaluate the influence on the frictional outcome. The xperiments have been performed utilizing laboratory test equipment based on strip drawing. Three different lubricant systems are tested ‘oil’, ‘oil-GNp’ and GNp only. The result clearly shows that the specific type of nano-graphite used has a favorable effect of reducing the frictional forces both in mixture with a base oil and as a standalone coating.
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| 3. |
- Agmell, Mathias, et al.
(författare)
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Investigation of mechanical and thermal loads in pcBN tooling during machining of Inconel 718
- 2020
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Ingår i: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 107, s. 1451-1462
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Agmell, Mathias, et al.
(författare)
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The influence of tool micro-geometry on stress distribution in turning operations of AISI 4140 by FE analysis
- 2017
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Ingår i: International Journal of Mechanical Sciences. - : Springer Science and Business Media LLC. - 1879-2162. ; 89:9-12, s. 3109-3122
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Tidskriftsartikel (refereegranskat)abstract
- Abstract This paper aims to gain a better understanding of the impact different micro-geometries has on stress distribution in cutting tools. Both principal and effective stress distribution are studied since these quantities have a major impact on the occurrence of damages in the cutting tool such as crack formation, flaking, chipping, breakage and plastic deformation. The development of a stagnation zone has also been investigated and the effect tool micro-geometries have on this zone. A finite element model has been developed which enables the examination of these aspects, in detail. The model was able to predict these metal cutting phenomena with high accuracy. Cutting forces is within the standard deviation of experimental results, stress distributions and the stagnation zone is also simulated correctly indicated by experimental results. This study has shown that the micro-geometries of the cutting tool have a great potential in order to reduce the maximal tensile/principal stress. This research work also shows that the size of the stagnation zone can be controlled by micro-geometries on the cutting tool, which can have an effect on the wear on the cutting edge.
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| 5. |
- Akujärvi, Ville, et al.
(författare)
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Evolution of magnetic properties during tempering
- 2021
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Ingår i: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015.
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Tidskriftsartikel (refereegranskat)abstract
- Quality control in heat treatment of steel is often conducted after the treatment. Failure to confine within the specified range of mechanical properties may lead to wasted energy and production resources. Performing quality control in-line in the heat treatment process allows for early detection and possibility to react to changes in the process. The prospects of utilizing the change in the electromagnetic (EM) properties of steel, as means for quality control, are investigated in this paper. The focus is on the tempering process of hardened SS2244 (42CrMoS4) steel. The tempering takes the hardness of the steel from approximately 600 HV down to around 400 HV. The EM signature of the steel is recorded during the tempering process. This is later compared with results from more traditional means of material characterization, such as laser scanning microscopy, X-ray diffractometry and Vickers microhardness measurement. This initial study shows clear indications of precise detection of the hardness through EM properties during the tempering process of selected material.
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| 6. |
- Bello bermejo, Juan manuel, et al.
(författare)
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A Methodology Using Monte-Carlo Simulation on Nanoindentation Deconvolution for Metal Classification
- 2024
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Ingår i: Proceedings of the 11th Swedish Production Symposium (SPS2024). - 2352-7528 .- 2352-751X. - 9781643685106 - 9781643685113 ; 52, s. 613-627
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Bokkapitel (refereegranskat)abstract
- This paper investigates a methodology for the precise statistical deconvolution of hardness properties within various metallic matrix multiphase materials. The central focus is on accurately characterizing mechanical behaviour in the context of complex materials. To meet these objectives, we implemented an approach involving nanoindentation analyses of the selected materials. This technique allowed for the creation of material profiles based on micromechanical properties. Statistical cumulative density function (CDF) deconvolution was employed to disentangle the complex distributions of multiphase material hardness using cross-validation. Throughout the course of this study, several multicomponent CDF combinations were tested, including Weibull, Exponential, and Gaussian distributions. This approach challenges the conventional practice of assuming multiple Gaussian distributions of hardness, revealing the limitations of this approach. In addition, Monte-Carlo simulations were harnessed to generate probability density functions (PDFs) that capture the intricate footprint variations in hardness profiles. By implementing our methodology, we strive to offer a comprehensive and refined approach to materials analysis. This potential for differentiation has the significant implication of investigating the impact of impurities and trace elements on the mechanical properties and thus, machinability of metal materials. The ultimate aim is to enhance their recyclability, thereby advancing the principles of the circular economy and contributing to the sustainable development goals. Our study thus underscores the profound impact of material analysis on environmental sustainability and the efficient use of resources, while offering a fresh perspective on the role of statistics in materials science.
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| 7. |
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| 8. |
- Bushlya, Volodymyr, et al.
(författare)
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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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Ingår i: Machining Science and Technology. - : Informa UK Limited. - 1091-0344 .- 1532-2483. ; 17:4, s. 497-523
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Tidskriftsartikel (refereegranskat)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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| 9. |
- Bushlya, Volodymyr, et al.
(författare)
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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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Ingår i: 15th CIRP Conference on Modelling of Machining Operations (15TH CMMO). - : Elsevier BV. - 2212-8271. ; 31, s. 417-422
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Konferensbidrag (refereegranskat)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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| 10. |
- Bushlya, Volodymyr, et al.
(författare)
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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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Ingår i: 15th CIRP Conference on Modelling of Machining Operations (15TH CMMO). - : Elsevier BV. - 2212-8271. ; 31, s. 423-428
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Konferensbidrag (refereegranskat)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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