The present work aims at improving tool wear simulation in orthogonal turning operations by considering local wear properties at the scale of the coating. A multi-step procedure developed in previous studies is first ...
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The present work aims at improving tool wear simulation in orthogonal turning operations by considering local wear properties at the scale of the coating. A multi-step procedure developed in previous studies is first employed to predict cutting tool wear by combining a pure thermal model to an Arbitrary-Lagrangian-Eulerian (ALE) thermomechanical sub-model in order to predict the thermomechanical loadings applied onto the tool. The tool geometry is updated by moving the tool nodes, taking into account the local contact pressure, sliding velocity and temperature. The key improvement of this paper is to implement a specific wear model for each of the coating layer and substrate depending on the current position of each node at the contact interface. A comparative study is performed between the homogenous wear equation and the improved multi-layer model. This work highlights that an adaptive wearrate calculation based on nodal position has to be considered to achieve an actual predictive model.
Fused Filament Fabrication (FFF) is an additive manufacturing process based on material Extrusion (MEX) of polymeric filament. This manufacturing technology is commonly used for personalized production applications an...
Fused Filament Fabrication (FFF) is an additive manufacturing process based on material Extrusion (MEX) of polymeric filament. This manufacturing technology is commonly used for personalized production applications and prototyping, allowing to obtain customized parts with complex geometries at a low cost. However, this production technique has its limitations regarding dimensional accuracy and surface roughness of the final parts. To overcome these limitations, finish milling is considered to be a promising technique as it is widely used for metallic parts. Yet, the specific thermal properties of polymers such as low thermal conductivity and low melting temperature are adding a challenge in the determination of optimal cutting conditions. In this context, the use of cutting fluid could be the key to keep the material from melting during milling. Therefore, this paper proposes to compare the impact of using a compressed air flow to dry conditions on the cutting forces and the surface quality obtained on 3d-printed polylactide (PLA) parts. The qualification test of the tool-material couple standard (NF E 66-520-6) will be used as a guideline to determine the relevance of cutting fluid use for cutting conditions varying around an operating point. Moreover, simulated cutting forces using a mechanistic model will be compared to experimental data to evaluate the applicability of the model.
Understanding the link between titanium-aluminium nitride’s (Ti1-xAlxN) physicochemical properties and structural dynamics during operation is essential to designing and fabricating advanced ceramic coatings. Herein ...
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This paperdeals with the determination of the constitutive model coefficients used in machining simulations. An optimization-based procedure is developed and applied to constitutive model coefficients determination o...
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This paperdeals with the determination of the constitutive model coefficients used in machining simulations. An optimization-based procedure is developed and applied to constitutive model coefficients determination of Ti6Al4V titanium alloy. The procedure is implemented in LS-dyna/LS-Opt software, coupled with abaqus/Explicit to calculate the force-displacement curve at each iteration, which is required for the optimization-based procedure. The robustness of the procedure to determine the constitutive model coefficients is evaluated by comparing the predicted and measured plastic strain distributions in the samples.
The paper addresses the inverse heat transfer problem, in which the dependence of the flux on time is determined on the basis of the measured temperatures in remote points of the tool body. The nonlinear heat equation...
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The paper addresses the inverse heat transfer problem, in which the dependence of the flux on time is determined on the basis of the measured temperatures in remote points of the tool body. The nonlinear heat equation is considered since the properties of the tool material are temperature-dependent. The machining time interval is divided into subintervals within which the change in the tool material properties is ignored. Therefore, it possible to consider a sequence of linear programming problems, each of which minimizes the maximum deviation of the measured temperatures from the calculated ones.
Ti6Al4V titanium alloy is widely used in aero-engines due to its superior performance. However, as a difficult-to-cut alloy, it induces short cutting tool life and poor surface integrity. To improve these process outc...
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Ti6Al4V titanium alloy is widely used in aero-engines due to its superior performance. However, as a difficult-to-cut alloy, it induces short cutting tool life and poor surface integrity. To improve these process outcomes, numerical simulations are of importance. The predictive ability of such simulation depends on the accuracy of the constitutive model which describes the work material behavior under loading conditions specific to metal cutting. Therefore, the focus of this paper is the formulation of a constitutive model to be used in the orthogonal cutting simulation of Ti6Al4V. The distinguished feature of this model is its simplicity, accounting for the strain-rate and state of stress effects in the work materialdeformation and fracture. The model coefficients were identified using mechanical tests and numerical simulations with specially-designed test specimens to cover a wide range of strain-rates and state of stress. Orthogonal cutting simulations were performed and the obtainedresults were compared with those measured.
Primary manufacturing of steels by powder metallurgy (PM) is of increasing interest for a wide range of industrial applications. Especially in automotive parts andtools, PM materials are utilized, as they show advant...
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Primary manufacturing of steels by powder metallurgy (PM) is of increasing interest for a wide range of industrial applications. Especially in automotive parts andtools, PM materials are utilized, as they show advantageous behaviorregarding chemical, mechanical and functional properties as well as resource efficiency. Consequently, machining of these materials is an emerging topic for both, industry and science. This paper addresses the machinability of PM steels. Two PM high speed steels (HSS) were characterized and machined varying the machining parameters and edge preparation (PcBN inserts) in longitudinal and orthogonal hard turning. Furthermore, the influence of manganese sulfides (MnS) in the PM material was analyzed by comparing experiments applying alloys with defined content of MnS. Besides tool life and achievable surface roughness, the surface integrity was assessed. The results reveal that the amount and shape of carbides as well as the porosity of the PM steels play an important role in the wear mechanism when machining this kind of materials. As expected, addition of MnS leads to a decrease of cutting forces and allows for significantly higher tool life. The influence of machining parameters and the tool edge geometry is discussed. Based on the results, suitable cutting conditions for machining of PM steels can be derived.
Machining behaviour of Ti-5553, Ti-6Al-4 V mill-annealed (MA) and Ti-6Al-4 V solution treated and aged (STA) alloys was studied in different interrupted cutting operations using PVd coated cemented carbi...
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Machining behaviour of Ti-5553, Ti-6Al-4 V mill-annealed (MA) and Ti-6Al-4 V solution treated and aged (STA) alloys was studied in different interrupted cutting operations using PVd coated cemented carbide tools. Single tooth face milling was employed to study the wear behaviour and tool life of the coatedtools that were further inspected using scanning electron microscopy. The results indicated that a poor machinability was observed for Ti-5553 when compared to Ti-6Al-4 V (STA) and Ti6Al-4 V (MA). This was found to correlate reasonably well with an increase of work material adhesion severity on the cutting tool that resulted in an increased chipping and led to catastrophic tool failure. Series of orthogonal interrupted cutting tests were performed subsequently to investigate the role of work material and cutting data on the chip formation, mechanical loads and frictional conditions at the tool-chip contact. A detailed analysis of the chip segmentation characteristics of the different Ti alloys is provided and the results are employed in different analytical models to assess the shear strain, strain rate and segmentation frequency. Finally, a comparison of Ti-5553 and Ti-6-4 (MA) in interrupted turning is presented where the differences in terms of cutting temperature are discussed.
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