Papers by Keyword: Tool Edge Radius

Abstract: In the meso-scale machining, feed rate, grain size and tool edge radius are in the same order of magnitude, and cutting process is often carried out in the grain interior and grain boundary. In this paper the meso-cutting process of hot-rolled AISI1045 steel is studied and its metallographic microstructure is analyzed for the establishment of multiphase models which incorporate the effect of ferrite and pearlite grains. In order to discover the applicability of multiphase models to the simulation of meso-cutting, three contrast simulation models including multiphase model with rounded-edge cutting insert (model I), multiphase model with sharp edge cutting insert (model II) and equivalent homogeneous material model with rounded-edge cutting insert (model III) are built up for the meso-orthogonal cutting processes of hot-rolled AISI1045. By comparison with the experiments in terms of chip morphology, cutting force and specific cutting force, the most suitable model is identified. Then the stress distiribution is analyzed. And it is found that multiphase model with tool edge radius can give a more accurate prediction of the global variables and reveal more about these important local variables distribution.

Abstract: An analysis of cutting force performance in the micro milling on steel has been carried out based on an experimental work using micro flat end mills on a precision CNC machine tool. It has been found that cutting forces occurred at low feed per tooth are relatively high by assessing the averaged peak forces from the experiments. When feed per tooth is relatively close to tool edge radius, the forces were not growing in linearity with the increasing feedrate. This finding indicates the significance of ploughing phenomenon as an effect of tool edge radius in micro milling.

Abstract: A finite element model of HSM (High Speed Machining) process of Ti6Al4V was developed with Abaqus 6.10. The flow stress of Ti6Al4V is taken as a function of strain, strain rate and temperature. Considering the fact that the tool edge radius is relatively large in HSM of Ti6Al4V and significantly influences the mechanical behaviour, thus a new Arbitrary Lagrangian-Eulerian (ALE) boundary technology was incorporated into the finite element model to simulate the flowing material around the tool edge.The adoption of ALE boundary technology could avoid using the traditional chip separation criterias and element deletion method in the model, which at the same time results in the less excessive element distortion and computational time in comparison with traditional finite element models of cutting process. The simulation results of Cutting force and temperature close to the experimental values in an acceptable range could be obtained and a stagnant zone in front of the tool edge was successfully observed in this new developed model with large tool edge radius.

Abstract: Today, there is a need to understand the micro mechanism of material removal to achieve a better roughness in ultra precision machining (UPM). The conventional finite element method becomes impossible to use because the target region and grids are very tiny. In addition, FEM cannot consider the micro property of the material such as atomic defect and dislocation. As an alternative, molecular dynamics (MD) simulation is significantly implemented in the field of nano-machining and nano-tribological problems to investigate deformation mechanism like work hardening, stick-slip phenomenon, frictional resistance and surface roughness [1]. One of the machining parameters than can affect nano-cutting deformation and the machined surface quality is tool nose radius [2]. In this paper molecular dynamics simulations of the nano-metric cutting on single-crystal copper were performed with the embedded atom method (EAM). To investigate the effect of tool nose radius, a comparison was done between a sharp tool with no edge radius and tools with a variety of edge radii. Tool forces, coefficient of friction, specific energy and nature of material removal with distribution of dislocations were simulated. Results show that in the nano-machining process, the tool nose radius cannot be ignored compared with the depth of cut and the edge of tool can change micro mechanism of chip formation. It appears that a large edge radius (relative to the depth of cut) of the tool used in nano-metric cutting, provides a high hydrostatic pressure. Thus, the trust force and frictional force of the tool is raised. In addition, increasing the tool edge radius and the density of generated dislocation in work-piece is scaled up that is comparable with TEM photographs [6].

Abstract: The micro-end-milling process of aluminum alloy Al2024-T6 has been investigated by numerical simulations and experimental approach. The effects of different tool edge radii on the micro-cutter wear were investigated. A three-dimensional finite element model is adopted to determine the effects of tool edge radii on the effective stress and micro-cutter wear during the micro-end-milling process. It is observed that the the tool nose wears out much more quickly due to the high maximal effective stress occurring in this zone. The experimental verification of the simulation model is carried out on a micro-end-milling process of aluminum alloy 2024-T6. The experimental results of the micro-cutter morphologies are in a good agreement with the simulation results. The experimental results show that the model is suitable for studying the mechanism of micro-cutter wear.

Abstract: In micro endmilling, because of small uncut chip thickness comparable to the tool edge radius and low rigidity of tool, the cutting process must frequently transit between rubbing/ploughing and cutting, and it may deteriorate the machining stability, surface finish and tool wear. In this report, such unique cutting phenomena are investigated by modeling a mechanism, computer simulations and experiments. As a result, a possibility of the unique cutting phenomena proposed has been certified.

Abstract: In machining, the size effect is typically characterized by a non-linear increase in the specific cutting energy (or specific cutting force) as the uncut chip thickness is decreased. A finite element model of orthogonal micro-cutting was established to study the influence of tool edge radius on size effect when cutting 7050-T7451 aluminum alloy. Diamond cutting tool was used in the simulation. Specific cutting force and specific cutting energy are obtained through the simulation. The nonlinear scaling phenomenon is evident. The likely explanations for the size effect in small uncut chip thickness were discussed in this paper.

Abstract: The finite element modeling and experimental validation of three-dimensional precision cutting of 3J33 maraging are presented. The commercial software MARC applied for the finite element modeling is studied the effect of tool nose radii considering tool edge radius on the principal cutting forces and the temperature fields. The model employs an updated Lagrangian formulation. The friction between the tool and the chip is assumed to follow a modified Coulomb friction law and the adaptive remeshing technique is using for the formation of chip. The tool edge radius significantly affects the cutting forces and the maximum temperature of the chip. The simulation results for tool with nose radius considering tool edge radius are compared with experimentally measured data and found to be in good agreement.