The Experts below are selected from a list of 28380 Experts worldwide ranked by ideXlab platform
Junjie Zeng - One of the best experts on this subject based on the ideXlab platform.
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pvd craln and tialn coated si3n4 ceramic cutting tools 1 microstructure turning performance and wear mechanism
Ceramics International, 2017Co-Authors: Wei Liu, Quanqua Chu, Junjie ZengAbstract:Abstract In this work, CrAlN and TiAlN coatings were produced on silicon nitride cutting inserts via physical vapor deposition. The microstructure and hardness of the coatings, as well as the adhesive strength between the coating and the substrate were studied using a scanning electronic microscope, a micro hardness tester and a scratch tester, respectively. Continuous turning tests of the obtained CrAlN and TiAlN-coated silicon nitride cutting inserts were performed on gray cast iron to evaluate the cutting performances and the Machining Quality. The results show that the surface hardness of the Si 3 N 4 cutting inserts could be improved by 87% and 50%, respectively, when applying the CrAlN and TiAlN coatings, thereby enhancing the abrasion resistance of the cutting inserts. At different tested cutting speeds, abrasive wear under compressional deformation and adhesive wear were identified as the main failure mechanisms for the two cutting inserts during continuous turning of gray cast iron. The Machining Quality of the gray cast iron workpieces machined using the uncoated, the CrAlN- or the TiAlN-coated inserts increased with the increment of the cutting speed.
Wei Liu - One of the best experts on this subject based on the ideXlab platform.
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pvd craln and tialn coated si3n4 ceramic cutting tools 1 microstructure turning performance and wear mechanism
Ceramics International, 2017Co-Authors: Wei Liu, Quanqua Chu, Junjie ZengAbstract:Abstract In this work, CrAlN and TiAlN coatings were produced on silicon nitride cutting inserts via physical vapor deposition. The microstructure and hardness of the coatings, as well as the adhesive strength between the coating and the substrate were studied using a scanning electronic microscope, a micro hardness tester and a scratch tester, respectively. Continuous turning tests of the obtained CrAlN and TiAlN-coated silicon nitride cutting inserts were performed on gray cast iron to evaluate the cutting performances and the Machining Quality. The results show that the surface hardness of the Si 3 N 4 cutting inserts could be improved by 87% and 50%, respectively, when applying the CrAlN and TiAlN coatings, thereby enhancing the abrasion resistance of the cutting inserts. At different tested cutting speeds, abrasive wear under compressional deformation and adhesive wear were identified as the main failure mechanisms for the two cutting inserts during continuous turning of gray cast iron. The Machining Quality of the gray cast iron workpieces machined using the uncoated, the CrAlN- or the TiAlN-coated inserts increased with the increment of the cutting speed.
Xavier Cerutti - One of the best experts on this subject based on the ideXlab platform.
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Numerical modelling and mechanical analysis of the Machining of large aeronautical parts : Machining Quality improvement
2017Co-Authors: Xavier CeruttiAbstract:The manufacturing of aluminium alloy structural aerospace parts involves multiple forming (rolling, forging, etc.) and heat treatment steps. The mechanical and thermal loads that the workpieces undergo during these manufacturing steps result in unequal plastic deformation and in metallurgical changes which are both sources of residual stresses. Machining is usually the last manufacturing step during which the final geometry of the parts is obtained. Up to 90% of the initial volume of the workpiece can be removed during the Machining of aerospace structural parts which can furthermore have complex geometries. The residual stress redistribution is one of the main causes of the non-conformity of parts with the geometrical and dimensional tolerance specifications and therefore of the rejection of parts.Nowadays, initial residual stresses and their effect during the Machining are often not taken into account in the definition of the Machining process plan. This work aims to propose an evolution in the establishment of Machining process plans of aluminium structural parts. It has been organised along two principal lines of research: a numerical line and a mechanical analysis line.The numerical line is based on the development of a modelling approach and of a numerical tool adapted to the simulation of the Machining process. The modelling approach has been defined based on assumptions deduced from literature reviews on aluminium alloys, on the Machining process and on residual stresses. A massive material removal approach has then been developed. All the numerical developments have been implemented into the finite element software FORGE® and are suited to a parallel computing environment.The mechanical analysis line is based on the study of the residual stress redistribution and its effect on the workpiece deflections during the Machining as well as on the post-Machining distortion. A first study on the layer removal method used to determine the initial residual stress profiles in an AIRWARE® 2050-T84 2050-T84 alloy rolled plate has been realised. The simulation of these experiments has allowed a first validation of the numerical tool and to demonstrate the necessity to define Machining process plans in function of the residual stresses. Other studies on the influence of some Machining process parameters on the Machining Quality have then been performed. Simulation results have been validated by multiple comparisons with experimental tests, showing the capability of the numerical tool to predict the final machined part geometries.Using the results of the studies mentioned above, a numerical procedure and first recommendations for the definition of Machining process plans allowing to obtain the desired Machining Quality depending on the initial residual stresses have been established.
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Numerical modelling and mechanical analysis of the Machining of large aeronautical parts : Machining Quality improvement
2017Co-Authors: Xavier CeruttiAbstract:The manufacturing of aluminium alloy structural aerospace parts involves multiple forming (rolling, forging, etc.) and heat treatment steps. The mechanical and thermal loads that the workpieces undergo during these manufacturing steps result in unequal plastic deformation and in metallurgical changes which are both sources of residual stresses. Machining is usually the last manufacturing step during which the final geometry of the parts is obtained. Up to 90% of the initial volume of the workpiece can be removed during the Machining of aerospace structural parts which can furthermore have complex geometries. The residual stress redistribution is one of the main causes of the non-conformity of parts with the geometrical and dimensional tolerance specifications and therefore of the rejection of parts.Nowadays, initial residual stresses and their effect during the Machining are often not taken into account in the definition of the Machining process plan. This work aims to propose an evolution in the establishment of Machining process plans of aluminium structural parts. It has been organised along two principal lines of research: a numerical line and a mechanical analysis line.The numerical line is based on the development of a modelling approach and of a numerical tool adapted to the simulation of the Machining process. The modelling approach has been defined based on assumptions deduced from literature reviews on aluminium alloys, on the Machining process and on residual stresses. A massive material removal approach has then been developed. All the numerical developments have been implemented into the finite element software FORGE® and are suited to a parallel computing environment.The mechanical analysis line is based on the study of the residual stress redistribution and its effect on the workpiece deflections during the Machining as well as on the post-Machining distortion. A first study on the layer removal method used to determine the initial residual stress profiles in an AIRWARE® 2050-T84 2050-T84 alloy rolled plate has been realised. The simulation of these experiments has allowed a first validation of the numerical tool and to demonstrate the necessity to define Machining process plans in function of the residual stresses. Other studies on the influence of some Machining process parameters on the Machining Quality have then been performed. Simulation results have been validated by multiple comparisons with experimental tests, showing the capability of the numerical tool to predict the final machined part geometries.Using the results of the studies mentioned above, a numerical procedure and first recommendations for the definition of Machining process plans allowing to obtain the desired Machining Quality depending on the initial residual stresses have been established.
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Influence of the Machining sequence on the residual stress redistribution and Machining Quality: analysis and improvement using numerical simulations
International Journal of Advanced Manufacturing Technology, 2017Co-Authors: Xavier Cerutti, Katia MocellinAbstract:The manufacturing of aluminium alloy structural aerospace parts involves multiple steps, the principal ones being the forming (rolling, forging etc.), the heat treatments and the Machining. During this last step, the final geometry of the part is obtained. Before Machining, the workpiece has therefore undergone several manufacturing steps resulting in unequal plastic deformation and metallurgical changes which are both sources of residual stresses. On large and complex aluminium alloy aeronautical parts, up to 90 % of the initial workpiece volume can be removed by Machining. During Machining, the mechanical equilibrium of the part is in constant evolution due to the redistribution of the initial residual stresses.The residual stress redistribution is the main cause of workpiece deflections during Machining as well as of post-Machining distortion (after unclamping). Both can lead to the non-conformity of the part with the geometrical and dimensional tolerance specifications and therefore to a rejection of the part or to additional conforming steps. In order to improve the Machining accuracy and the robustness of the process, the effect of the residual stresses has to be considered for the definition of the Machining process plan. In this paper, a specific numerical tool [2] allowing to predict workpiece deflections during Machining and post-Machining distortion is used to study the influence of the Machining sequence on the Machining Quality in taking into consideration the initial residual stresses. A first Machining process plan defined as the reference case is simulated. Simulation results are then compared with experimental ones showing the feasibility to use the developed tool to predict the Machining Quality depending on the initial residual stresses, the fixture layout and the Machining sequence. Using the computational tool, a method to optimise the Machining Quality depending on the initial workpiece and on the Machining sequence is presented. A Machining process plan allowing to respect the tolerance specifications is then defined. This demonstrates the feasibility to adapt and to optimise the Machining process plan to ensure conformity of the part with the tolerance specifications.
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Methodology for aluminium part Machining Quality improvement considering mechanical properties and process conditions
CIRP Journal of Manufacturing Science and Technology, 2016Co-Authors: Xavier Cerutti, Sami Hassini, Katia Mocellin, Benoit Blaysat, Emmanuel DucAbstract:The manufacturing of structural aluminium alloy parts requires several steps of both forming processes and heat treatments. Before Machining, which is usually the last step of the manufacturing, the workpiece has thus undergone multiple manufacturing steps involving unequal plastic deformations which are source of residual stresses. During Machining, where up to 90% of the initial workpiece volume can be removed, the mechanical equilibrium of the part evolves constantly with the redistribution of the initial residual stresses. For thick, large and complex parts in highly alloyed aluminium, this redistribution of the residual stresses can leads to an unexpected behaviour of the workpiece and is the main reason for both workpiece deflections (during Machining) and post-Machining distortions (after unclamping). These two phenomena can lead to the nonconformity of the part with the geometrical and dimensional tolerance specifications and therefore to the rejection of the part or to additional conforming steps. As a consequence, the mechanical behaviour of the workpiece has to be considered during the definition of the Machining process plan to improve the Machining accuracy and the robustness of the process and thus to ensure the conformity of the machined part with the dimensional and geometrical specifications, i.e. to ensure the desired Machining Quality. In this paper, the numerical tool developed in [1] is used to conduct an analysis on the influence of the initial workpiece residual stress state, of the fixture layout as well as of the Machining sequence on the Machining Quality. This analysis is performed on a part which has been specially designed and which can be considered as being representative of real aerospace parts. Several comparisons with experimental results are performed, one of them using digital image correlation (DIC) measurements. Results obtained show a good agreement, validating both the prediction of the behaviour of the workpiece during Machining and the prediction of the machined part geometry. Based on the results of this analysis, a classification of the parameters has been performed depending on their influence on the Machining Quality. A first methodology allowing to define Machining process plans adapted to the initial workpiece stress state has then been created based on the previous classification. This methodology is composed of a procedure and basic guidelines which are both presented in detail. An example of an application of this methodology is then introduced, demonstrating the benefits of the approach developed in this work.
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Prediction of Machining Quality due to the initial residual stress redistribution of aerospace structural parts made of low-density aluminium alloy rolled plates
International Journal of Material Forming, 2016Co-Authors: Xavier Cerutti, Sorin Arsene, Katia MocellinAbstract:During the Machining of thick, large and complex aluminium parts, the redistribution of initial residual stresses is the main reason for Machining errors such as dimensional variations and the post-Machining distortions. These errors can lead to the rejection of the parts or to additional conforming operations increasing production costs. It is therefore a requirement to predict potential geometrical and dimensional errors resulting from a given Machining process plan and in taking into consideration the redistribution of the residual stresses. A specific finite element tool which allows to predict the behaviour of the workpiece during Machining due to its changing geometry and to fixture-workpiece contacts has been developed. This numerical tool uses a material removal approach which enables to simulate the Machining of parts with complex geometries. In order to deal with industrial problems this numerical tool has been developed for parallel computing, allowing the study of parts with large dimensions. In this paper, the approach developed to predict the Machining Quality is presented. First, the layer removal method used to determine the initial residual stress profiles of an AIRWAREⓇ 2050-T84 alloy rolled plate is introduced. Experimental results obtained are analysed and the same layer removal method is simulated to validate the residual stress profiles and to test the accuracy of the developed numerical tool. The Machining of a part taken from this rolled plate is then performed (experimentally and numerically). The Machining Quality obtained is compared, showing a good agreement, thus validating the numerical tool and the developed approach. This study also demonstrates the importance of taking into account the mechanical behaviour of the workpiece due to the redistribution of the initial residual stresses during Machining when defining a Machining process plan.
Quanqua Chu - One of the best experts on this subject based on the ideXlab platform.
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pvd craln and tialn coated si3n4 ceramic cutting tools 1 microstructure turning performance and wear mechanism
Ceramics International, 2017Co-Authors: Wei Liu, Quanqua Chu, Junjie ZengAbstract:Abstract In this work, CrAlN and TiAlN coatings were produced on silicon nitride cutting inserts via physical vapor deposition. The microstructure and hardness of the coatings, as well as the adhesive strength between the coating and the substrate were studied using a scanning electronic microscope, a micro hardness tester and a scratch tester, respectively. Continuous turning tests of the obtained CrAlN and TiAlN-coated silicon nitride cutting inserts were performed on gray cast iron to evaluate the cutting performances and the Machining Quality. The results show that the surface hardness of the Si 3 N 4 cutting inserts could be improved by 87% and 50%, respectively, when applying the CrAlN and TiAlN coatings, thereby enhancing the abrasion resistance of the cutting inserts. At different tested cutting speeds, abrasive wear under compressional deformation and adhesive wear were identified as the main failure mechanisms for the two cutting inserts during continuous turning of gray cast iron. The Machining Quality of the gray cast iron workpieces machined using the uncoated, the CrAlN- or the TiAlN-coated inserts increased with the increment of the cutting speed.
Emmanuel Duc - One of the best experts on this subject based on the ideXlab platform.
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Methodology for aluminium part Machining Quality improvement considering mechanical properties and process conditions
CIRP Journal of Manufacturing Science and Technology, 2016Co-Authors: Xavier Cerutti, Sami Hassini, Katia Mocellin, Benoit Blaysat, Emmanuel DucAbstract:The manufacturing of structural aluminium alloy parts requires several steps of both forming processes and heat treatments. Before Machining, which is usually the last step of the manufacturing, the workpiece has thus undergone multiple manufacturing steps involving unequal plastic deformations which are source of residual stresses. During Machining, where up to 90% of the initial workpiece volume can be removed, the mechanical equilibrium of the part evolves constantly with the redistribution of the initial residual stresses. For thick, large and complex parts in highly alloyed aluminium, this redistribution of the residual stresses can leads to an unexpected behaviour of the workpiece and is the main reason for both workpiece deflections (during Machining) and post-Machining distortions (after unclamping). These two phenomena can lead to the nonconformity of the part with the geometrical and dimensional tolerance specifications and therefore to the rejection of the part or to additional conforming steps. As a consequence, the mechanical behaviour of the workpiece has to be considered during the definition of the Machining process plan to improve the Machining accuracy and the robustness of the process and thus to ensure the conformity of the machined part with the dimensional and geometrical specifications, i.e. to ensure the desired Machining Quality. In this paper, the numerical tool developed in [1] is used to conduct an analysis on the influence of the initial workpiece residual stress state, of the fixture layout as well as of the Machining sequence on the Machining Quality. This analysis is performed on a part which has been specially designed and which can be considered as being representative of real aerospace parts. Several comparisons with experimental results are performed, one of them using digital image correlation (DIC) measurements. Results obtained show a good agreement, validating both the prediction of the behaviour of the workpiece during Machining and the prediction of the machined part geometry. Based on the results of this analysis, a classification of the parameters has been performed depending on their influence on the Machining Quality. A first methodology allowing to define Machining process plans adapted to the initial workpiece stress state has then been created based on the previous classification. This methodology is composed of a procedure and basic guidelines which are both presented in detail. An example of an application of this methodology is then introduced, demonstrating the benefits of the approach developed in this work.
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Process parameter definition with respect to the behaviour of complex kinematic machine tools
The International Journal of Advanced Manufacturing Technology, 2013Co-Authors: Sylvain Pateloup, Hélène Chanal, Emmanuel DucAbstract:The definition of Machining processes with respect to complex kinematic machine tool behaviour involves the control of machine accuracy and kinematic performances. The aim is to propose process settings and tool paths which guarantee the required Machining Quality while maximizing productivity. This article presents an experimental protocol which enables the determination of machine tool structure behaviours which have an influence on Machining Quality. In parallel, an experimental analysis of the different kinds of settings which can improve Machining Quality is carried out. Two kinds of settings appear: the first class of settings improves Machining Quality or Machining time, and the second class has an antagonistic influence on Machining Quality and Machining time. Thus, the definition of the second class of settings arises from an optimisation between first-order defects, second-order defects and Machining time. The developed method is illustrated on a parallel kinematic machine tool, the Tripteor X7. Note that this study is a first step towards controlling machine tool behaviour during Machining.
