1,720,988 research outputs found
Influence of the worn tool affected by built-up edge (BUE) on micro end-milling process performance: A 3D finite element modeling investigation
Full text linkMicro milling process has been utilized for several decades due to the flexibility of the process in producing complex components. The small size of the process makes the comprehension of cutting phenomenon details more difficult. This study presents a 3D finite element modeling (3D FEM) approach for the micro end-milling process of Aluminum material (Al6082-T6). 3D FEM simulations are carried out in full slot micro end-milling and contour up milling. The model first implements the actual tool geometry and then the effect of typical built-up edge (BUE) on the milling tool. The influence of BUE on the process performance is investigated by comparing the predicted 3d chip flow shape, burr formation and cutting forces with experiments conducted on an ultra-high precision micro milling center. Simulations indicate that BUE has significant impact on the chip shape and chip load for different teeth engagements. Results prove that also burr height is negatively affected by the presence of BUE. The predicted micro milling cutting forces resulted affected by BUE with different teeth engagements. Analysis of experimental measured forces indicates comparable results in respect to simulated profiles confirming the usefulness of the develop 3D FE modelling approach
Improvement of surface flatness in high precision milling
Full text linkThe use of high precision micro components has increased in various industrial fields in recent years. Repeatable techniques are needed to face very tight tolerances and make micro fabrication processes industrially feasible against current micro machining limitation. Improving surface flatness in high precision milling is the main target of the present research. Critical issues such as machining strategy, spindle thermal transient management and tool wear compensation were considered for machining operations on a representative part
Finite Element Modeling and Process Performance of Micro End‐Milling of Aluminum 6082‐T6
No full textThis study investigates the micro end‐milling process by using a 3D finite element modeling (3D FEM) approach. The FE model is developed for contouring up-milling operation to predict chip flow, burr formation and cutting forces. Different cutting conditions were simulated in order to investigate the influence of process variables that might be difficult or even impossible to follow in the physical experiments, particularly at this scale. 3D simulations of chip flow and temperature distribution are compared in various cutting conditions. The results of the burr formation and cutting forces predictions are compared against the experiments. The correlations were observed in terms of burr dimension trends and force profile shapes and magnitude
3D finite element prediction of chip flow, burr formation, and cutting forces in micro end-milling of aluminum 6061-T6
Full text linkPredictive models for machining operations have been significantly improved through numerous methods in recent decades. This study proposed a 3D finite element modeling (3D FEM) approach for the micro end-milling of Al6061-T6. Finite element (FE) simulations were performed under different cutting conditions to obtain realistic numerical predictions of chip flow, burr formation, and cutting forces. FE modeling displayed notable advantages, such as capability to easily handle any type of tool geometry and any side effect on chip formation, including thermal aspect and material property changes. The proposed 3D FE model considers the effects of mill helix angle and cutting edge radius on the chip. The prediction capability of the FE model was validated by comparing numerical model and experimental test results. Burr dimension trends were correlated with force profile shapes. However, the FE predictions overestimated the real force magnitude. This overestimation indicates that the model requires further development
3D Finite Element Simulation of Micro End-Milling by Considering the Effect of Tool Run-Out
Full text linkUnderstanding the micro milling phenomena involved in the process is critical and difficult through physical experiments. This study presents a 3D finite element modeling (3D FEM) approach for the micro end-milling process on Al6082-T6. The proposed model employs a Lagrangian explicit finite element formulation to perform coupled thermo-mechanical transient analyses. FE simulations were performed at different cutting conditions to obtain realistic numerical predictions of chip formation, temperature distribution, and cutting forces by considering the effect of tool run-out in the model. The radial run-out is a significant issue in micro milling processes and influences the cutting Stability due to chip load and force variations. The Johnson–Cook (JC) material constitutive model was applied and its constants were determined by an inverse method based on the experimental cutting forces acquired during the micro end-milling tests. The FE model prediction capability was validated by comparing the numerical model results with experimental tests. The maximum tool temperature was predicted in a different angular position of the cutter which is difficult or impossible to obtain in experiments. The predicted results of the model, involving the run-out influence, showed a good correlation with experimental chip formation and the signal shape of cutting forces
Workpiece surface flatness improvement by tool length compensation in micromilling
Full text linkMicromilling quality improvement requires an accurate management of all the involved resources (machine tool, tool, fixture, workpiece). Specific attention has to be paid, comparing to macro operations, also to machining strategies and tool and workpiece measuring strategies. The extreme workpiece accuracy requires to reinterpret some procedures, already applied in the macro world, with the purpose to minimize errors. It is the case of the tool length compensation, which plays a strong role on the micromilling overall performance. In order to demonstrate the importance of factors affecting tool length, as machine spindle thermal transients and tool wear assessment, the present paper takes the workpiece flatness deviation as a case study and presents a manufacturing and measuring strategy able to meet a challenging flatness constraint
Finite Element Simulation and Validation of Chip Formation and Cutting Forces in Dry and Cryogenic Cutting of Ti–6Al–4V
No full textTi-6Al-4 V titanium alloy is a popular material in industrial applications (e.g. aerospace, oil & gas, medical) due to its superior mechanical properties, although its low thermal conductivity and high chemical reactivity with other materials make it a hard-to-cut material. A finite element model (FEM) was developed in the present investigation to simulate dry and cryogenic orthogonal cutting of Ti-6Al-4 V by using TiAlN coated carbide inserts. Numerical prediction of the effect of the superior cryogenic cooling on chip formation, cutting and thrust forces were investigated. The simulations were validated by the comparison with experimental results. The model calibration was performed with experimental data on dry cutting and then the model was used for predicting the cryogenic cooling case. The validated FEM models were used to compare the chip formation in dry cutting and cryogenic cutting in order to point out some differences in terms of chip segmentation frequency and chip thickness and gain additional knowledge
Performance of Micro End Milling Force Prediction on Aluminum 6061-T6 with 3D FE Simulation
No full textMicro-milling is a rather complicated process to simulate due to the complexities involved, such as the geometrical, mechanical, tribological, thermal and chemical aspects. They all lead to the generation of cutting forces and consequent material removal in micro scale which have some straight difference in respect to macro cutting. So far, not many 3D FEM have been presented along with their experimental validation results in micro milling. This study discusses the performance of 3D force prediction of a Finite Element model of micro end-mill cutting on Aluminum 6061-T6, implemented in AdvantEdge®. FE shows some important advantages, i.e. can easily deal with any kind of tool geometry and any side effects affecting chip formation such as thermal aspects and material properties changes. On the other hand, due to the small chip size of micro milling, extremely fine meshes and related automatic remeshing techniques are required thus increasing the computation efforts: the simulation of even a partial cutter engagement requires several hours/days of computation with the available power on to-date computing servers. In order to evaluate whether these efforts are worthy, compared to other modelling techniques, the performance of the FEM prediction were compared with the performance of a state-of-art mechanistic model, capable of including minimum chip thickness aspects as well effective rake angle effects and capable of providing force prediction with less computational time. The simulated cutting forces with the two models are then compared with experimental results and a supporting discussion is provided. Tolerable correlations between the forces profile shapes were observed. In terms of force magnitude, the predictions were overestimating the real values, also considering the results provided by the mechanistic model and to cope with that some further development area of the model are identified
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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