The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Radova Kovacevic - One of the best experts on this subject based on the ideXlab platform.
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hydro abrasive erosion of refractory ceramics
Journal of Materials Science, 2003Co-Authors: Andreas W Mombe, Radova KovacevicAbstract:The paper discusses the Material Removal Process in refractory ceramics eroded by hydro-abrasive jets. In particular, bauxite, sintered magnesia, and magnesia chromite are eroded. The influence of abrasive particle velocity, local exposure time, abrasive mass-flow rate, and abrasive type is investigated. Erosion depth, specific erosion rate, and geometry of the generated cavities are measured and analysed. For particle velocity as well as for local exposure time, threshold conditions are identified. At low erosion intensity, target Material properties and abrasive type do not affect the Material Removal Process notably. From optical and SEM-microscopy it is further found that the Material Removal mode changes with the progression of the erosion Process. In the upper region of the eroded kerf, the dominating Material Removal mode is the simultaneous cutting of matrix and inclusion grains (transgranular). In the lower range, the erosion Process is characterised by the Removal of the binding matrix followed by washing off the inclusion grains (intergranular). The balance between both modes depends on the energy delivered to the erosion site. These observations are explained by assuming a continuous loss in kinetic energy of the abrasive particles during HAE. Some features of non-linear fracture are noticed and suggestions are made how to use non-linear fracture parameters to evaluate erosion resistance.
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an acoustic emission study of cutting bauxite refractory ceramics by abrasive water jets
Journal of Materials Engineering and Performance, 1999Co-Authors: Andreas W Mombe, Rajagopalan Sabapathy T Moha, Radova KovacevicAbstract:This article discusses the Material Removal Process in bauxite refractory ceramics cut by abrasive water jets. Several parameters of the Process were changed during the experiments. The experiments were monitored online by the acoustic emission (AE) technique. It was found that AE signals are able to sense the Material Removal Process as well as the machining performances very reliably. Unsteady Material Removal mode consisting of matrix Removal and intergranular fracture was very well represented in the AE signals by an unsteady time dependent signal type characterized by burst emissions and a frequency domain signal associated with a twin-peak shape. The particular characteristics of the signal depend on the energy involved in the Process.
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machining refractory ceramics with abrasive water jets
Journal of Materials Science, 1996Co-Authors: Andreas W Mombe, I Eusch, Radova KovacevicAbstract:The Material Removal Process of refractory ceramics cut by abrasive water jets was investigated. In particular, bauxite, sintered magnesia, and magnesia chromite, were cut in a wide range of pump pressures up to 350 MPa. The Process parameters, such as pump pressure, traverse rate, abrasive flow rate, and abrasive type, were changed during the experiments in order to find an optimum parameter combination. For all experiments, the depth of cut, cut geometry, the surface structure of the generated cuts, and the Material Removal rates were measured and analysed. Based on these measurements the specific energies were estimated. Using scanning electron microscopy, it was found that the Material Removal mechanism changed with the depth of cut. In the upper region, the main Material Removal mechanism was the simultaneous cutting of matrix and inclusion grains (transgranular). In the lower range of the cut, the Removal Process was characterized by the Removal of the binding matrix followed by washing of the inclusion grains (intergranular).
Wenfeng Ding - One of the best experts on this subject based on the ideXlab platform.
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Material Removal mechanism of PTMCs in high-speed grinding when considering consecutive action of two abrasive grains
The International Journal of Advanced Manufacturing Technology, 2018Co-Authors: Huan Zhou, Wenfeng Ding, Chaojie LiuAbstract:An effective finite element (FE) simulation model characterizing the Material Removal behavior of TiCp/Ti-6Al-4V titanium matrix composites in high-speed grinding Process was developed when considering consecutive action of two abrasive grains. The resultant stress and grinding force have been analyzed to study the crack propagation behavior. The effect of the undeformed chip thickness on the ground surface defects was discussed. It was found that in the Material Removal Process of PTMCs, the brittle Removal of TiCp and the plastic Removal of Ti-6Al-4V matrix would happen simultaneously until the reinforcing particle completely failed in the grinding Process. The maximum Mises stress and single-grain grinding forces fluctuate weakly and smoothly once the crack is produced in the reinforcing TiCp. As for the reinforcing TiCp without crack inside, the crushing depth increases with the increase of the undeformed chip thickness in grinding. However, as for the TiCp with residual crack inside, due to the stress concentration in the tip of the crack, the TiCp is always cracked in chunks when the undeformed chip thickness changes from 0.3 to 0.9 μm in grinding. Finally, the FE simulation results are validated true through the high-speed grinding experiment of PTMCs.
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influence of grain wear on Material Removal behavior during grinding nickel based superalloy with a single diamond grain
International Journal of Machine Tools & Manufacture, 2017Co-Authors: Chenwei Dai, Wenfeng DingAbstract:Abstract In order to explore the effect of grain wear on Material Removal behavior during grinding nickel-based superalloy Inconel 718, the grinding experiment with a single diamond grain was carried out. The variations of grain wear, grinding force and force ratio, and pile-up ratio were investigated under the conditions of undeformed chip thickness (UCT) ranging from 0.2 to 1 µm. The results show that a critical UCT value, such as 0.3 µm, could be determined according to the pile-up ratio and could also be used to quantify the Material Removal Process. The wear behavior of a diamond grain shows four types, such as crescent depression on the rake face, abrasion on the flank face, grain micro-fracture, and grain macro-fracture. Furthermore, these classifications are determined by the dwell time of rubbing, ploughing and cutting at different UCT values applied. The grinding force ratio increases with increasing of the negative rake angle of a diamond grain. In the rubbing and ploughing stages, the Material Removal efficiency is proportional to the wear width on the rake face. However, in the cutting stage, the Material Removal efficiency is diminished in the absence Process of crescent depression.
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the influence of speed on Material Removal mechanism in high speed grinding with single grit
International Journal of Machine Tools & Manufacture, 2015Co-Authors: Lin Tian, Yucan Fu, Jiuhua Xu, Haiyan Li, Wenfeng DingAbstract:Abstract In this paper, the effect of speed on Material Removal was investigated by single grit grinding of the GH4169 super alloy which is difficult to machine, with a new test method. During the tests the whole Material Removal Process, was observed and then the critical thickness of chip formation was quantitatively analyzed. In order to provide insight into the speed effect, the grinding forces, chip formation and pile-up ratio were investigated. It was found that the stages of Material Removal Process changed with the grinding speed, and the graphical relationships between grinding speed and the critical thickness of chip formation, grinding forces and the pile-up ratio were found to have a common characteristic, namely a common turnover point which was about 100 m/s. This trend in the results is attributed to alternating predominance between the strain hardening and thermal softening effects. The results of this study demonstrated that the grinding speed has a significant impact on Material Removal mechanism, and also provide a basis for sound understanding of the high speed grinding Process of difficult to cut Materials.
Andreas W Mombe - One of the best experts on this subject based on the ideXlab platform.
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hydro abrasive erosion of refractory ceramics
Journal of Materials Science, 2003Co-Authors: Andreas W Mombe, Radova KovacevicAbstract:The paper discusses the Material Removal Process in refractory ceramics eroded by hydro-abrasive jets. In particular, bauxite, sintered magnesia, and magnesia chromite are eroded. The influence of abrasive particle velocity, local exposure time, abrasive mass-flow rate, and abrasive type is investigated. Erosion depth, specific erosion rate, and geometry of the generated cavities are measured and analysed. For particle velocity as well as for local exposure time, threshold conditions are identified. At low erosion intensity, target Material properties and abrasive type do not affect the Material Removal Process notably. From optical and SEM-microscopy it is further found that the Material Removal mode changes with the progression of the erosion Process. In the upper region of the eroded kerf, the dominating Material Removal mode is the simultaneous cutting of matrix and inclusion grains (transgranular). In the lower range, the erosion Process is characterised by the Removal of the binding matrix followed by washing off the inclusion grains (intergranular). The balance between both modes depends on the energy delivered to the erosion site. These observations are explained by assuming a continuous loss in kinetic energy of the abrasive particles during HAE. Some features of non-linear fracture are noticed and suggestions are made how to use non-linear fracture parameters to evaluate erosion resistance.
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an acoustic emission study of cutting bauxite refractory ceramics by abrasive water jets
Journal of Materials Engineering and Performance, 1999Co-Authors: Andreas W Mombe, Rajagopalan Sabapathy T Moha, Radova KovacevicAbstract:This article discusses the Material Removal Process in bauxite refractory ceramics cut by abrasive water jets. Several parameters of the Process were changed during the experiments. The experiments were monitored online by the acoustic emission (AE) technique. It was found that AE signals are able to sense the Material Removal Process as well as the machining performances very reliably. Unsteady Material Removal mode consisting of matrix Removal and intergranular fracture was very well represented in the AE signals by an unsteady time dependent signal type characterized by burst emissions and a frequency domain signal associated with a twin-peak shape. The particular characteristics of the signal depend on the energy involved in the Process.
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machining refractory ceramics with abrasive water jets
Journal of Materials Science, 1996Co-Authors: Andreas W Mombe, I Eusch, Radova KovacevicAbstract:The Material Removal Process of refractory ceramics cut by abrasive water jets was investigated. In particular, bauxite, sintered magnesia, and magnesia chromite, were cut in a wide range of pump pressures up to 350 MPa. The Process parameters, such as pump pressure, traverse rate, abrasive flow rate, and abrasive type, were changed during the experiments in order to find an optimum parameter combination. For all experiments, the depth of cut, cut geometry, the surface structure of the generated cuts, and the Material Removal rates were measured and analysed. Based on these measurements the specific energies were estimated. Using scanning electron microscopy, it was found that the Material Removal mechanism changed with the depth of cut. In the upper region, the main Material Removal mechanism was the simultaneous cutting of matrix and inclusion grains (transgranular). In the lower range of the cut, the Removal Process was characterized by the Removal of the binding matrix followed by washing of the inclusion grains (intergranular).
Xiaodong Yang - One of the best experts on this subject based on the ideXlab platform.
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molecular dynamics simulation of Material Removal Process and mechanism of edm using a two temperature model
Applied Surface Science, 2020Co-Authors: Xiaoming Yue, Xiaodong YangAbstract:Abstract Molecular dynamics (MD) simulation has been used to investigate the Material Removal mechanism in electrical discharge machining (EDM). However, in the previous researches, the simulation model was too small, and the effect of free electrons on the heat conduction has not been considered. To solve the above two problems, in this study, a 2-D sub-micrometer scale simulation with a two-temperature model (TTM) was conducted to simulate the discharge Process of EDM, which can consider the effect of both the lattice vibration and free electrons on the heat conduction simultaneously. This 2-D sub-micrometer scale simulation model based on TTM has successfully obtained a sub-micrometer scale discharge crater which was close to the smallest discharge crater reported. Furthermore, the simulation result demonstrates that the pressure generated inside the molten pool serves as one of the Removal mechanisms of molten Material in the discharge Process of EDM. In addition, compared with the monocrystal copper, discharge on the polycrystalline copper can generate much more defect structures and larger denatured layer. Moreover, the smaller the grain size of polycrystalline copper, the more the defect structures and the larger the denatured layer will be.
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molecular dynamics simulation of Material Removal Process and crystal structure evolution in edm with discharge on different crystal planes
The International Journal of Advanced Manufacturing Technology, 2017Co-Authors: Xiaoming Yue, Xiaodong YangAbstract:The extensive application of electrical discharge machining (EDM) in the manufacturing industry and the advancement of EDM towards the micro-nano fields make the incompleteness and imperfection of fundamental theory in EDM a more acute problem and even become a huge bottleneck, hindering its further application and development. In this paper, single-pulse discharges on the {100}, {110}, and {111} planes were simulated to study the Material Removal Process, crystal structure evolution, and influence of crystal plane. The research results show that during the discharge Process, there generated high pressure inside the melting area, which makes the melting Material expand outward and the swell was formed (forming Process of swell). When the pressure inside the melting area overcame the bonding force among atoms, the swell broke open and the Material started to depart from the electrode surface (blasting Process of swell). In addition, it was found that after the end of discharge, there existed the stacking faults, dislocations, and vacancies or interstitial defects inside the electrode. The crystal defects mainly existing in the denatured layer had direct relation with the formation of cracks on the discharge surface. It was also found that the crystal plane had influence on the Material Removal Process. Specifically, the volume of the discharge crater and bulge, the depth of crater, and the occurring moment of the Material ablation on the {111} > {110} > {100} plane indicated that the machining on the {111} plane was the easiest while on the {100} plane was the hardest. However, the crystal plane had hardly any influence on the melting and solidifying Process of Material, and the occurring moment of Material ablation was not equal to the melting moment of Material, but later than the melting moment.
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Molecular dynamics simulation of the Material Removal Process and gap phenomenon of nano EDM in deionized water
RSC Advances, 2015Co-Authors: Xiaoming Yue, Xiaodong YangAbstract:Nano electrical discharge machining (nano EDM) is a very promising technique to fabricate nanoscale structures on superhard and difficult-to-cut Materials, however, the incompleteness and imperfection of the fundamental theory seriously hinders its further application and development. In this paper, a single pulse discharge with nano EDM in deionized water was simulated to study the Material ablation Process and the bubble dynamic behavior using molecular dynamics. The research results showed that it was not the case that the molten Material could not be removed during the discharge duration, instead it was the case that Material Removal would occur all the time during the whole of the discharge duration, and even after the end of the discharge molten Material could still be ablated for a period of time. In addition, it was found that in the early discharge stage, the bubble expansion was impeded by a dielectric liquid, causing an extremely high pressure inside the bubble. It was also found that the expanding bubble and flowing liquid had effects on the removing, carrying, cooling and blocking of the molten and removed Material. As a result, the proportion of the removed debris in deionized water was far more than that in gas, while the proportions of spattering Material, returning Material and bulge Material were lower than those in gas, and the range of the volume distribution for the removed debris in deionized water was larger, but the range of the velocity distribution of the removed debris was lower than that in gas. In addition, the bulge generated in gas was much larger and plumper compared to the fragmentary and small bulge generated in deionized water.
Tao Peng - One of the best experts on this subject based on the ideXlab platform.
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Decision rules for energy consumption minimization during Material Removal Process in turning
Journal of Cleaner Production, 2017Co-Authors: Qianqian Zhong, Renzhong Tang, Tao PengAbstract:Optimizing energy consumption has become a priority in advanced manufacturing industry due to increasing sustainability and environmental consciousness, resulting in various models to characterize the relationship between cutting parameters and energy consumption for Material Removal Processes. These existing models are subject to a principle, the higher the Material Removal rate, the lower the specific energy consumption, without considering the effects of cutting parameter combinations at a certain Material Removal rate. To address this problem in minimizing energy consumption, three tasks are conducted in this paper. First, specific energy consumption is identified as an optimization objective and expressed as a function of spindle rotation speed, cutting speed, feed rate and depth of cut. Second, based on the candidate options, decision rules are proposed for selecting optimal cutting parameters to achieve minimum energy consumption. Third, the decision rules are applied with experimental data of rough external turning. This work is expected to assist computer numerical control machine tool practitioners in selecting optimal cutting parameters for minimum energy consumption.