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Shreyes N Melkote - One of the best experts on this subject based on the ideXlab platform.
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effect of finite Edge Radius on ductile fracture ahead of the cutting tool Edge in micro cutting of al2024 t3
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: Sathyan Subbiah, Shreyes N MelkoteAbstract:Abstract Evidence of ductile fracture leading to material separation has been reported recently in ductile metal cutting [S. Subbiah, S.N. Melkote, ASME J. Manuf. Sci. Eng. 28(3) (2006)]. This paper investigates the effect of finite Edge Radius on such ductile fracture. The basic question of whether such ductile fracture occurs in the presence of a finite Edge Radius is explored by performing a series of experiments with inserts of different Edge radii at various uncut chip thickness values ranging from 15 to 105 μm. Chip–roots are obtained in these experiments using a quick-stop device and examined in a scanning electron microscope. Clear evidence of material separation is seen at the interface zone between the chip and machined surface even when the Edge Radius is large compared to the uncut chip thickness. Failure is seen to occur at the upper, middle, and/or the lower Edges of the interface zone. Based on these observations, a hypothesis is presented for the events leading to the occurrence of this failure when cutting with an Edge Radius tool. Finite element simulations are performed to study the nature of stress state ahead of the tool Edge with and without Edge Radius. Hydrostatic stress is seen to be tensile in front of the tool and hence favors the occurrence of ductile fracture leading to material separation. The stress components are, however lower than those seen with a sharp tool.
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finite element analysis of the influence of tool Edge Radius on size effect in orthogonal micro cutting process
International Journal of Mechanical Sciences, 2007Co-Authors: Kai Liu, Shreyes N MelkoteAbstract:Abstract The size effect in metal cutting is evident in the nonlinear scaling phenomenon observed in the specific cutting energy with decrease in uncut chip thickness. It has been argued by many researchers that this scaling phenomenon is caused mainly by the cutting tool Edge Radius, which purportedly affects the micro-cutting process by altering the effective rake angle, enhancing the plowing effect or introducing an indenting force component. However, the phenomenological reasons why the tool Edge Radius causes size effect and the relationship between the tool Edge Radius and the characteristic length scale associated with the size effect in micro-cutting has not been sufficiently clarified. In this paper, a strain gradient plasticity-based finite element model of orthogonal micro-cutting of Al5083-H116 alloy developed recently is used to examine fundamentally the influence of tool Edge Radius on size effect. The applicability of two length scales—tool Edge Radius and the material length scale l in strain gradient plasticity—are also examined via analysis of data available in the literature.
Konrad Wegener - One of the best experts on this subject based on the ideXlab platform.
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Influence of cutting Edge Radius on surface integrity and burr formation in milling titanium
International Journal of Advanced Manufacturing Technology, 2013Co-Authors: Dominik Jaeger, Carl-frederik Wyen, Konrad WegenerAbstract:The influence of the cutting Edge micro geometry on cutting process and on tool performance is subject to several research projects. Recently, published papers mainly focus on the cutting Edge rounding and its influence on tool life and cutting forces. For applications even more important, however, is the influence of the cutting Edge Radius on the integrity of the machined part. Especially for titanium, which is used in environments requiring high mechanical integrity, the information about the dependency of surface integrity on cutting Edge geometry is important. This paper therefore studies the influence of the cutting Edge Radius on surface integrity in terms of residual stress, micro hardness, surface roughness and optical characterisation of the surface and near surface area in up and down milling of the titanium alloy Ti-6Al-4V. Moreover, the influence of the cutting Edge Radius on burr formation is analysed. The experiments show that residual stresses increase with the cutting Edge Radius especially in up milling, whereas the influence in down milling is less pronounced. The influence of the cutting Edge Radius on surface roughness is non-uniform. The formation of burr increases with increasing cutting Edge Radius, and is thus in agreement with the residual stress tests.
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Influence of cutting Edge Radius on cutting forces in machining titanium
CIRP Annals - Manufacturing Technology, 2010Co-Authors: Carl-frederik Wyen, Konrad WegenerAbstract:The performance of machining titanium can be enhanced by using cutting tools with rounded cutting Edges. In order to better understand the influence of rounded cutting Edges and to improve the modelling of the machining process, their impact on active force components including ploughing forces and tool face friction is analysed. This paper presents experimental results of orthogonal turning tests conducted on Ti-6Al-4V with different cutting Edge radii and changing cutting speeds and feeds. As an accurate characterisation method for the determination of the cutting Edge Radius is prerequisite for this analysis, a new algorithm is described which reduces uncertainties of existing methods. © 2010 CIRP.
Carl-frederik Wyen - One of the best experts on this subject based on the ideXlab platform.
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Influence of cutting Edge Radius on surface integrity and burr formation in milling titanium
International Journal of Advanced Manufacturing Technology, 2013Co-Authors: Dominik Jaeger, Carl-frederik Wyen, Konrad WegenerAbstract:The influence of the cutting Edge micro geometry on cutting process and on tool performance is subject to several research projects. Recently, published papers mainly focus on the cutting Edge rounding and its influence on tool life and cutting forces. For applications even more important, however, is the influence of the cutting Edge Radius on the integrity of the machined part. Especially for titanium, which is used in environments requiring high mechanical integrity, the information about the dependency of surface integrity on cutting Edge geometry is important. This paper therefore studies the influence of the cutting Edge Radius on surface integrity in terms of residual stress, micro hardness, surface roughness and optical characterisation of the surface and near surface area in up and down milling of the titanium alloy Ti-6Al-4V. Moreover, the influence of the cutting Edge Radius on burr formation is analysed. The experiments show that residual stresses increase with the cutting Edge Radius especially in up milling, whereas the influence in down milling is less pronounced. The influence of the cutting Edge Radius on surface roughness is non-uniform. The formation of burr increases with increasing cutting Edge Radius, and is thus in agreement with the residual stress tests.
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Influence of cutting Edge Radius on cutting forces in machining titanium
CIRP Annals - Manufacturing Technology, 2010Co-Authors: Carl-frederik Wyen, Konrad WegenerAbstract:The performance of machining titanium can be enhanced by using cutting tools with rounded cutting Edges. In order to better understand the influence of rounded cutting Edges and to improve the modelling of the machining process, their impact on active force components including ploughing forces and tool face friction is analysed. This paper presents experimental results of orthogonal turning tests conducted on Ti-6Al-4V with different cutting Edge radii and changing cutting speeds and feeds. As an accurate characterisation method for the determination of the cutting Edge Radius is prerequisite for this analysis, a new algorithm is described which reduces uncertainties of existing methods. © 2010 CIRP.
Fengzhou Fang - One of the best experts on this subject based on the ideXlab platform.
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Effect of tool Edge Radius on material removal mechanism in atomic and close-to-atomic scale cutting
Applied Surface Science, 2020Co-Authors: Wenkun Xie, Fengzhou FangAbstract:Abstract For mechanical cutting, when cutting depth is decreased to atomic and close-to-atomic scale(ACS), the material removal mechanism would be dominated by dislocation motion, different from conventional cutting and nanocutting. It is is greatly influenced by cutting Edge Radius effect in the aspects of chip formation, cutting forces, and stress distribution, etc. There appear three deformation zones in ACS cutting, including dislocation slip zone, chip formation zone and elastic deformation zone. As cutting-Edge Radius increases, both of dislocation slip zone and chip formation zone are suppressed while the elastic deformation zone tends to continually grow. When cutting Edge Radius is increased to be larger than a threshold, the elastic deformation zone is further transformed into one elastic and plastic deformation zone, while a very small chip formation zone, and dislocation zone is remained ahead of rounded cutting Edge. Consequently, though the minimum cutting depth is decreased to single atomic layer, the material removal behaviour is also dominated by extrusion action of cutting tool, following the mechanism of nanocutting. The research findings would provide theoretical guidelines to the cutting tool design for atomic and close-to-atomic scale cutting.
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cutting based single atomic layer removal mechanism of monocrystalline copper Edge Radius effect
Nanoscale Research Letters, 2019Co-Authors: Wenkun Xie, Fengzhou Fang, Fengzhou FangAbstract:The ultimate objective of mechanical cutting is to down minimum chip thickness to single atomic layer. In this study, the cutting-based single atomic layer removal mechanism on monocrystalline copper is investigated by a series of molecular dynamics analysis. The research findings report that when cutting depth decreases to atomic scale, minimum chip thickness could be down to single atomic layer by mechanical cutting using rounded Edge tool. The material removal behaviour during cutting-based single atomic layer removal exhibits four characteristics, including chip formation by shearing-stress driven dislocation motion, elastic deformation on the processed surface, atomic sizing effect, and cutting-Edge Radius effect. Based on this understanding, a new cutting model is proposed to study the material removal behaviour in cutting-based single atomic layer removal process, significantly different from those for nanocutting and conventional cutting. The outcomes provide theoretical support for the research and development of the atomic and close-to-atomic scale manufacturing technology.
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An experimental study of Edge Radius effect on cutting single crystal silicon
The International Journal of Advanced Manufacturing Technology, 2003Co-Authors: Fengzhou Fang, Guoxiong ZhangAbstract:According to the hypothesis of ductile machining, brittle materials undergo a transition from brittle to ductile mode once a critical undeformed chip thickness is reached. Below this threshold, the energy required to propagate cracks is believed to be larger than the energy required for plastic deformation, so that plastic deformation is the predominant mechanism of material removal in machining these materials in this mode. An experimental study is conducted using diamond cutting for machining single crystal silicon. Analysis of the machined surfaces under a scanning electron microscope (SEM) and an atomic force microscope (AFM) identifies the brittle region and the ductile region. The study shows that the effect of the cutting Edge Radius possesses a critical importance in the cutting operation. Experimental results of taper cutting show a substantial difference in surface topography with diamond cutting tools of 0° rake angle and an extreme negative rake angle. Cutting with a diamond cutting tool of 0° rake angle could be in a ductile mode if the undeformed chip thickness is less than a critical value, while a ductile mode cutting using the latter tool could not be found in various undeformed chip thicknesses.
M. Rahman - One of the best experts on this subject based on the ideXlab platform.
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Investigation of the critical cutting Edge Radius based on material hardness
The International Journal of Advanced Manufacturing Technology, 2016Co-Authors: M. Rahman, M. Azizur Rahman, A. Senthil Kumar, Muhammad Raihan AmrunAbstract:This paper is aimed to investigate the influence of material hardness on the behaviour of cutting Edge Radius in tool-based micromachining process. The main governing process parameter considered for this study is relative tool sharpness (RTS) which is quantified as the ratio of undeformed chip thickness (a) to tool Edge Radius (r). The variation of RTS influences the chip formation behaviour with transition from concentrated shearing to ‘extrusion-like’ mechanism for achieving ‘grinding-like’ surface finishing by the extensive tool Edge Radius effect. As different materials have different characteristics and properties, the critical threshold RTS value (RTS critical ) may vary with material hardness by significantly affecting the surface topography during ‘extrusion-like’ mechanism. In this study, material hardness is found to be an important mechanical property in orthogonal micro turning experiments conducted with a CBN tool for metal alloys. Best finishing (R a ) values of workpiece surfaces were used to determine the material hardness effect on RTS critical . Firstly, Aluminium and Magnesium alloys were used to construct a graphical trend for the relationship of material hardness and relative tool sharpness. Secondly, a random material was selected to predict the RTS value from the graphical trend based on material hardness. Thirdly, micro turning experiments were conducted to validate the predicted result. Finally, the graphical trend was updated to get the relationship of material hardness and critical relative tool sharpness (RTS critical ) with the three experimental materials which are most widely used in micromachining industries.
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the effects of tool Edge Radius on drill deflection and hole misalignment in deep hole gundrilling of inconel 718
Cirp Annals-manufacturing Technology, 2014Co-Authors: K S Woon, M. Rahman, Akshay Chaudhari, Senthil A KumarAbstract:Abstract Straightness control in gundrilling of deep, thin-walled holes on Inconel-718 is challenging due to insufficiently explored phenomena governed by the tool Edge Radius effects. Such effects are activated by conservative drilling conditions for Inconel-718, which transforms the chip formation mode to a thrust-dominated mechanism. Critical changes in force generation are thus resulted, which affect the characteristics of drill deflection and thin wall deformation. In consequence, the drill's self-piloting capability deteriorates – leading to uncontrollable deflection and hole misalignment. A mechanistic model uniting the underlying force, drill deflection, wall deformation and process kinematics is proposed and substantiated, as well.
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study of the upper bound of tool Edge Radius in nanoscale ductile mode cutting of silicon wafer
The International Journal of Advanced Manufacturing Technology, 2010Co-Authors: Minbo Cai, M. Rahman, Steven Y. LiangAbstract:In cutting of brittle materials, experimentally it was observed that there is an upper bound of tool cutting Edge Radius, beyond which, although the undeformed chip thickness is smaller than the tool cutting Edge Radius, the ductile mode cutting cannot be achieved. However, why there is an upper bound of tool cutting Edge Radius in nanoscale ductile mode cutting of brittle materials has not been fully understood. In this study, based on the tensile stress distribution and the characteristics of the distribution obtained from molecular dynamics simulation of nanoscale ductile cutting of silicon, an approximation for the tensile stress distribution was obtained. Using this tensile stress distribution with the principles of geometrical similarity and fracture mechanics, the critical conditions for the crack initiation have been determined. The result showed that there is a critical tool cutting Edge Radius, beyond which crack initiation can occur in the nanoscale cutting of silicon, and the chip formation mode is transferred from ductile to brittle. That is, this critical tool cutting Edge Radius is the upper bound of the tool cutting Edge Radius for ductile mode cutting of silicon.
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the effect of the cutting Edge Radius on a machined surface in the nanoscale ductile mode cutting of silicon wafer
Proceedings of the Institution of Mechanical Engineers Part B: Journal of Engineering Manufacture, 2007Co-Authors: S Arefin, M B Cai, Kui Liu, M. Rahman, A TayAbstract:AbstractIn this study, the effect of the cutting Edge Radius on a machined surface and subsurface in the nanoscale ductile mode cutting of silicon wafer is investigated through cutting tests using tools with Edge radii ranging from 23 nm to 807 nm. The machined surface is examined using SEM, AFM, and Formtracer, with an etching technique used for SEM observation. The results show that if the cutting Edge Radius does not exceed a certain upper bound value, and the undeformed chip thickness is less than the cutting Edge Radius, it is possible to achieve both a surface and a subsurface free of cracks. Based on the molecular dynamics simulation of the nanoscale ductile mode cutting process of monocrystalline silicon wafer, it is found that the critical upper bound for the cutting Edge Radius in the ductile mode chip formation relates to the stress condition in the cutting region. The shear stress decreases as the tool Edge Radius is increased. As the cutting Edge Radius increases beyond the limit, the insuffi...
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A study of the effect of tool cutting Edge Radius on ductile cutting of silicon wafers
The International Journal of Advanced Manufacturing Technology, 2006Co-Authors: X P Li, M. RahmanAbstract:Ductile mode cutting of silicon wafers can be achieved under certain cutting conditions and tool geometry. An experimental investigation of the critical undeformed chip thickness in relation to the tool cutting Edge Radius for the brittle-ductile transition of chip formation in cutting of silicon wafers is presented in this paper. Experimental tests for cutting of silicon wafers using diamond tools of different cutting Edge radii for a range of undeformed chip thickness are conducted on an ultra-precision lathe. Both ductile and brittle mode of chip formation processes are observed in the cutting tests. The results indicate that ductile cutting of silicon can be achieved at certain values of the undeformed chip thickness, which depends on the tool cutting Edge Radius. It is found that in cutting of silicon wafers with a certain tool cutting Edge Radius there is a critical value of undeformed chip thickness beyond which the chip formation changes from ductile mode to brittle mode. The ductile-brittle transition of chip formation varies with the tool cutting Edge Radius. Within the range of cutting conditions in the present study, it has also been found that the larger the cutting Edge Radius, the larger the critical undeformed chip thickness for the ductile-brittle transition in the chip formation.
