Papers by Keyword: Minimum Chip Thickness

Abstract: Chip formation is a dynamic process that is often nonlinear in nature. A chip may not form when the depth of cut is less than a minimum chip thickness. It is aimed to investigate influence of depth of cut on contact phenomenon in micromachining. This paper presents a series of simulation works by finite element method on depth of cut effect on micromachining. A model is developed with consideration of the Johnson-Cook material and Arbitrary Lagrangian–Eulerian (ALE) method. In this work investigate the effect of depth of cut on the contact phenomenon during micromachining AISI D2. The results of the analysis are showed in aspects of interrelationship between material separation and frictional shear contact, distribution of stick-slide regions and contact stress on the work piece and cutting tool. It is found that the sticking and sliding was occurred on three zones as primary, secondary and tertiary shear zone. The contact phenomena can be showed around the tool edge radius where material flows around it and piles in front of the cutting tool through material separation. The investigation of contact phenomena inclusive under three criteria such as a/r < 1, a/r > 1 and a/r = 1 on positive rake angle.

Abstract: Chip formation is a dynamic process that is often non linear in nature. A chip may not form when the depth of cut is less than a minimum chip thickness. This paper presents an investigation of cutting edge radius effect on micromachining AISI D2 tool steel via simulation. The chip growth, chip formation and material deformation mechanism was investigated using commercial finite element analysis software. A model is developed with consideration of the arbitrary LagrangianEulerian (ALE) method. The chip growth, chip formation and material deformation was investigate under three criteria such as a/r<1, a/r>1 and a/r=1. The model showed that the chip is formed at a/r >1 while material extrusion performed under a/r<1.

Abstract: The foundations of micro-milling are similar to macro-milling but the phenomena it involves are not a simple scaling-down of macro-cutting. The importance of the minimum chip thickness is one of the significant differences between the two processes. The lagrangian FEM model presented in this paper aims to study the depth of cut influence on chip formation of Ti6Al4V in orthogonal cutting. It is firstly used to compare the modelled saw-toothed macro-chip morphology and cutting forces to experimental cutting results from literature. Then a minimum chip thickness prediction is performed by decreasing the depth of cut. Finally this study is the opportunity to highlight the specific features of micro-cutting reported in literature, such as the effective negative rake angle of the tool or the size effect. The model presented brings therefore a numerical contribution to the comprehension of these phenomena.

Abstract: In this paper, the effect of minimum chip thickness on cutting temperature in micro-end- milling of aluminum alloy Al2024-T6 using a tungsten-carbide cutter are investigated and analyzed. The three-dimensional coupled thermal-mechanical finite element model is adopted to determine the effects of varying depth of cut on cutting temperature considering size effects. The simulation results show that the cutting temperature in micro-end-milling is lower than those occurring in conventional milling processes. When the depth of cut is approximately 40% of the cutting edge radius, there is no chip formation. The maximum temperature occurs at the contact region between micro cutting edge and workpiece, which shows an obvious size effect. The experimental verification of the simulation model is carried out on a micro-end-milling process of aluminum alloy 2024-T6 with a high precision infrared camera. The influence of various cutting depths on cutting temperature has been verified in experiments. The experimental measurements results are in a good agreement with the simulation results.

Abstract: In order to determine the minimum thickness of cutting under different cutting condition of aluminum alloy materials 2A12 of micro-milling, research the size effect caused by the cutting edge radius and few microns per tooth in micro-milling process. Using thermal coupling model of Johnson-Cook as a material model of the workpiece, using Johnson-Cook shear failure of the law as part of the failure criteria, using coupled plane strain thermal units and hybrid adaptive grid technology to mesh, the friction between the tool and workpiece take the amendment Coulomb's law that combine with the sliding friction areas and areas of the adhesive friction, to the micro-milling by nonlinear and elastic-plastic finite element simulation. Through finite element analysis, the ratio of minimum radius of thickness to the cutting edge tool radius under different conditions of cutting speed and cutter blade was got, the size effect, stress field and cutting force under different cutting depth was got, and comparing and analysis the results, getting the various factors impact on the size effect of micro-milling, it provide a basis for the actual processing.

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 micro-cutting, the uncut chip thickness is comparable or even less than the tool edge radius and as a result a chip will not be generated if the uncut chip thickness is less than a critical value, viz., the minimum chip thickness. Knowledge of the minimum chip thickness plays a key role of the selection of appropriate machining conditions and optimization the micro-cutting processes. An analytical model is developed to predict the minimum chip based on the strain gradient plasticity theory in this paper, and the model accounts for the effect of material property in micro-scale such as the shear modulus, intrinsic length scale, fracture toughness and the Burgers vector. Predicted results are validated by experimental data obtained from the orthogonal micro-cutting experiments.

Abstract: In this paper, a micro milling model is brought forward. The influences of different metal phases and the minimum chip thickness are considered in the model. The cutting forces and the surface generation in the micro milling process are predicted. Through the experiment validation, the results correlate to the model very well.