A New Model and Analysis of Orthogonal Machining With an Edge-Radiused Tool

1999 ◽  
Vol 122 (3) ◽  
pp. 384-390 ◽  
Author(s):  
Jairam Manjunathaiah ◽  
William J. Endres
Keyword(s):  
Shear Stress ◽  
Deformation Zone ◽  
Lower Boundary ◽  
Chip Thickness ◽  
Rake Angle ◽  
Shear Angle ◽  
Force Model ◽  
Uncut Chip Thickness ◽  
Edge Radius ◽  
Machining Force

A new machining process model that explicitly includes the effects of the edge hone is presented. A force balance is conducted on the lower boundary of the deformation zone leading to a machining force model. The machining force components are an explicit function of the edge radius and shear angle. An increase in edge radius leads to not only increased ploughing forces but also an increase in the chip formation forces due to an average rake angle effect. Previous attempts at assessing the ploughing components as the force intercept at zero uncut chip thickness, which attribute to the ploughing mechanism all the changes in forces that occur with changes in edge radius, are seen to be erroneous in view of this model. Calculation of shear stress on the lower boundary of the deformation zone using the new machining force model indicates that the apparent size effect when cutting with edge radiused tools is due to deformation below the tool (ploughing) and a larger chip formation component due to a lower shear angle. Increases in specific energy and shear stress are also due to shear strain and strain rate increases. A consistent material behavior model that does not vary with process input conditions like uncut chip thickness, rake angle and edge radius can be developed based on the new model. [S1087-1357(00)01302-2]

Experimental investigation of a slip-line field model for a worn cutting tool

2013 ◽  
Vol 228 (8) ◽  
pp. 1398-1404 ◽  
Author(s):  
Alper Uysal ◽  
Erhan Altan
Keyword(s):  
Wear Rate ◽  
Slip Line ◽  
Field Model ◽  
Cutting Tool ◽  
Flank Wear ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Rake Angle ◽  
Uncut Chip Thickness ◽  
Line Field

In this study, the slip-line field model developed for orthogonal machining with a worn cutting tool was experimentally investigated. Minimum and maximum values of five slip-line angles ( θ1, θ2, δ2, η and ψ) were calculated. The friction forces that were caused by flank wear land, chip up-curl radii and chip thicknesses were calculated by solving the model. It was specified that the friction force increased with increase in flank wear rate and uncut chip thickness and it decreased a little with increase in cutting speed and rake angle. The chip up-curl radius increased with increase in flank wear rate and it decreased with increase in uncut chip thickness. The chip thickness increased with increase in flank wear rate and uncut chip thickness. Besides, the chip thickness increased with increase in rake angle and it decreased with increase in cutting speed.

Micro Flat End Milling Simulation Model With Instantaneous Plowing Area Prediction

2016 ◽  
Vol 4 (2) ◽  
Author(s):  
Abdolreza Bayesteh ◽  
Junghyuk Ko ◽  
Martin Byung-Guk Jun
Keyword(s):  
Feed Rate ◽  
Tool Path ◽  
End Milling ◽  
Chip Thickness ◽  
Depth Of Cut ◽  
Uncut Chip Thickness ◽  
Chip Area ◽  
Edge Radius ◽  
Wide Range ◽  
Radial Depth

There is an increasing demand for product miniaturization and parts with features as low as few microns. Micromilling is one of the promising methods to fabricate miniature parts in a wide range of sectors including biomedical, electronic, and aerospace. Due to the large edge radius relative to uncut chip thickness, plowing is a dominant cutting mechanism in micromilling for low feed rates and has adverse effects on the surface quality, and thus, for a given tool path, it is important to be able to predict the amount of plowing. This paper presents a new method to calculate plowing volume for a given tool path in micromilling. For an incremental feed rate movement of a micro end mill along a given tool path, the uncut chip thickness at a given feed rate is determined, and based on the minimum chip thickness value compared to the uncut chip thickness, the areas of plowing and shearing are calculated. The workpiece is represented by a dual-Dexel model, and the simulation properties are initialized with real cutting parameters. During real-time simulation, the plowed volume is calculated using the algorithm developed. The simulated chip area results are qualitatively compared with measured resultant forces for verification of the model and using the model, effects of cutting conditions such as feed rate, edge radius, and radial depth of cut on the amount of shearing and plowing are investigated.

scholarly journals Prediction of Nonlinear Micro-Milling Force with a Novel Minimum Uncut Chip Thickness Model

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1495
Author(s):  
Tongshun Liu ◽  
Kedong Zhang ◽  
Gang Wang ◽  
Chengdong Wang
Keyword(s):  
Cutting Force ◽  
Chip Thickness ◽  
Micro Milling ◽  
Force Model ◽  
Force Coefficient ◽  
Uncut Chip Thickness ◽  
Milling Force ◽  
Minimum Uncut Chip Thickness ◽  
Cutting Force Coefficient ◽  
Milling Force Model

The minimum uncut chip thickness (MUCT), dividing the cutting zone into the shear region and the ploughing region, has a strong nonlinear effect on the cutting force of micro-milling. Determining the MUCT value is fundamental in order to predict the micro-milling force. In this study, based on the assumption that the normal shear force and the normal ploughing force are equivalent at the MUCT point, a novel analytical MUCT model considering the comprehensive effect of shear stress, friction angle, ploughing coefficient and cutting-edge radius is constructed to determine the MUCT. Nonlinear piecewise cutting force coefficient functions with the novel MUCT as the break point are constructed to represent the distribution of the shear/ploughing force under the effect of the minimum uncut chip thickness. By integrating the cutting force coefficient function, the nonlinear micro-milling force is predicted. Theoretical analysis shows that the nonlinear cutting force coefficient function embedded with the novel MUCT is absolutely integrable, making the micro-milling force model more stable and accurate than the conventional models. Moreover, by considering different factors in the MUCT model, the proposed micro-milling force model is more flexible than the traditional models. Micro-milling experiments under different cutting conditions have verified the efficiency and improvement of the proposed micro-milling force model.

Voxel Based Cutting Force Simulation of Ball End Milling Considering Cutting Edge Around Center Web

2018 ◽  
Author(s):  
Isamu Nishida ◽  
Takaya Nakamura ◽  
Ryuta Sato ◽  
Keiichi Shirase
Keyword(s):  
Cutting Force ◽  
End Milling ◽  
Chip Thickness ◽  
Previous Method ◽  
Cutting Edge ◽  
Force Model ◽  
End Mill ◽  
Uncut Chip Thickness ◽  
Ball End Mill ◽  
Tool Rotation

A new method, which accurately predicts cutting force in ball end milling considering cutting edge around center web, has been proposed. The new method accurately calculates the uncut chip thickness, which is required to estimate the cutting force by the instantaneous rigid force model. In the instantaneous rigid force model, the uncut chip thickness is generally calculated on the cutting edge in each minute disk element piled up along the tool axis. However, the orientation of tool cutting edge of ball end mill is different from that of square end mill. Therefore, for the ball end mill, the uncut chip thickness cannot be calculated accurately in the minute disk element, especially around the center web. Then, this study proposes a method to calculate the uncut chip thickness along the vector connecting the center of the ball and the cutting edge. The proposed method can reduce the estimation error of the uncut chip thickness especially around the center web compared with the previous method. Our study also realizes to calculate the uncut chip thickness discretely by using voxel model and detecting the removal voxels in each minute tool rotation angle, in which the relative relationship between a cutting edge and a workpiece, which changes dynamically during tool rotation. A cutting experiment with the ball end mill was conducted in order to validate the proposed method. The results showed that the error between the measured and predicted cutting forces can be reduced by the proposed method compared with the previous method.

scholarly journals Influence of the Rake Angle on Nanocutting of Fe Single Crystals: A Molecular-Dynamics Study

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 516 ◽  
Author(s):  
Iyad Alabd Alhafez ◽  
Herbert M. Urbassek
Keyword(s):  
Molecular Dynamics ◽  
Chip Thickness ◽  
Mass Conservation ◽  
Friction Angle ◽  
Rake Angle ◽  
Shear Angle ◽  
Dynamics Simulation ◽  
Burgers Vector ◽  
Edge Dislocations ◽  
Cutting Direction

Using molecular dynamics simulation, we study the cutting of an Fe single crystal using tools with various rake angles α . We focus on the (110)[001] cut system, since here, the crystal plasticity is governed by a simple mechanism for not too strongly negative rake angles. In this case, the evolution of the chip is driven by the generation of edge dislocations with the Burgers vector b = 1 2 [ 111 ] , such that a fixed shear angle of ϕ = 54.7 ∘ is established. It is independent of the rake angle of the tool. The chip form is rectangular, and the chip thickness agrees with the theoretical result calculated for this shear angle from the law of mass conservation. We find that the force angle χ between the direction of the force and the cutting direction is independent of the rake angle; however, it does not obey the predictions of macroscopic cutting theories, nor the correlations observed in experiments of (polycrystalline) cutting of mild steel. Only for (strongly) negative rake angles, the mechanism of plasticity changes, leading to a complex chip shape or even suppressing the formation of a chip. In these cases, the force angle strongly increases while the friction angle tends to zero.

Investigation on Mechanism of Ultra-Smoothed Surface with a Micro Slot on the Flank Face in Micro Cutting

2014 ◽  
Vol 651-653 ◽  
pp. 764-767
Author(s):  
Tao Zhang ◽  
Hou Jun Qi ◽  
Gen Li
Keyword(s):  
Surface Roughness ◽  
Chip Thickness ◽  
Cutting Edge ◽  
Back Side ◽  
Uncut Chip Thickness ◽  
Micro Cutting ◽  
Cutting Edge Radius ◽  
Edge Radius ◽  
Flank Face ◽  
Side Flow

Micro cutting is a promising manufacturing method to obtain good surface integrity. Surface roughness shows size effect when the uncut chip thickness is smaller than the cutting edge radius. A special micro slot on the flank face of cutting tools was manufactured with discharge. Two groups of micro orthogonal cutting were conducted. The surface roughness of machined surface was measured and compared to each other. The results show that surface roughness decreases first and then increases with the ratio of uncut chip thickness to cutting edge radius. The surface machined with micro slot is better than that of without micro slot due to the micro slot restrain the back side flow of work piece based on the finite element model.

Size Effects in Cutting With a Diamond-Coated Tool

2011 ◽  
Author(s):  
Feng Qin ◽  
Xibing Gong ◽  
Kevin Chou
Keyword(s):  
Residual Stresses ◽  
Size Effect ◽  
Normal Stress ◽  
High Speed ◽  
Chip Thickness ◽  
Tool Geometry ◽  
Uncut Chip Thickness ◽  
Edge Radius ◽  
Coated Tool ◽  
Tool Stresses

In machining using a diamond-coated tool, the tool geometry and process parameters have compound effects on the thermal and mechanical states in the tools. For example, decreasing the edge radius tends to increase deposition-induced residual stresses at the tool edge interface. Moreover, changing the uncut chip thickness to a small-value range, comparable or smaller than the edge radius, will involve the so-called size effect. In this study, a developed 2D cutting simulation that incorporates deposition residual stresses was applied to evaluate the size effect, at different cutting speeds, on the tool stresses, tool temperatures, specific cutting energy as well as the interface stresses around a cutting edge. The size effect on the radial normal stress is more noticeable at a low speed. In particular, a large uncut chip thickness has a substantially lower stress. On the other hand, the size effect on the circumferential normal stress is more noticeable at a high speed. At a small uncut chip thickness, the stress is largely compressive.

Investigation of effect of uncut chip thickness to edge radius ratio on nanoscale cutting behavior of single crystal copper: MD simulation approach

2020 ◽  
pp. 251659842093763
Author(s):  
A. Sharma ◽  
P. Ranjan ◽  
R. Balasubramaniam
Keyword(s):  
Molecular Dynamics ◽  
Single Crystal ◽  
Material Removal ◽  
Chip Thickness ◽  
Cutting Process ◽  
Uncut Chip Thickness ◽  
Edge Radius ◽  
Nanoscale Cutting ◽  
Cutting Behavior ◽  
Subsurface Defects

Extremely small cutting depths in nanoscale cutting makes it very difficult to measure the thermodynamic properties and understand the underlying mechanism and behavior of workpiece material. Highly precise single-crystal Cu is popularly employed in optical and electronics industries. This study, therefore, implements the molecular dynamics technique to analyze the cutting behavior and surface and subsurface phenomenon in the nanoscale cutting of copper workpieces with a diamond tool. Molecular dynamics simulation is carried out for different ratios of uncut chip thickness ( a) to cutting edge radius ( r) to investigate material removal mechanism, cutting forces, surface and subsurface defects, material removal rate (MRR), and stresses involved during the nanoscale cutting process. Calculation of forces and amount of plowing indicate that a/ r = 0.5 is the critical ratio for which the average values of both increase to maximum. Material deformation mechanism changes from shear slip to shear zone deformation and then to plowing and elastic rubbing as the cutting depth/uncut chip thickness is reduced. The deformation during nano-cutting in terms of dislocation density changes with respect to cutting time. During the cutting process, it is observed that various subsurface defects like point defects, dislocations and dislocation loops, stacking faults, and stair-rod dislocation take place.

An Analytical Model for the Prediction of Minimum Chip Thickness in Micromachining

2005 ◽  
Vol 128 (2) ◽  
pp. 474-481 ◽  
Author(s):  
X. Liu ◽  
R. E. DeVor ◽  
S. G. Kapoor
Keyword(s):  
Analytical Model ◽  
Chip Thickness ◽  
Machining Process ◽  
Thickness Effect ◽  
Uncut Chip Thickness ◽  
Minimum Chip Thickness ◽  
Tool Edge Radius ◽  
Edge Radius ◽  
Tool Edge ◽  
Cutting Velocity

In micromachining, 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. The minimum chip thickness effect significantly affects machining process performance in terms of cutting forces, tool wear, surface integrity, process stability, etc. In this paper, an analytical model has been developed to predict the minimum chip thickness values, which are critical for the process model development and process planning and optimization. The model accounts for the effects of thermal softening and strain hardening on the minimum chip thickness. The influence of cutting velocity and tool edge radius on the minimum chip thickness has been taken into account. The model has been experimentally validated with 1040 steel and Al6082-T6 over a range of cutting velocities and tool edge radii. The developed model has then been applied to investigate the effects of cutting velocity and edge radius on the normalized minimum chip thickness for various carbon steels with different carbon contents and Al6082-T6.

On the Effects of a Built-Up Edge on Acoustic Emission in Metal Cutting

1990 ◽  
Vol 112 (2) ◽  
pp. 184-189 ◽  
Author(s):  
D. V. Hutton ◽  
Qinghuan Yu
Keyword(s):  
Acoustic Emission ◽  
Experimental Evidence ◽  
Deformation Zone ◽  
Metal Cutting ◽  
Cutting Tools ◽  
Cutting Speed ◽  
Rake Angle ◽  
Shear Angle ◽  
Cutting Conditions ◽  
Effective Rake Angle

Experimental evidence is presented which indicates that the presence of a built-up edge can significantly affect the generation of acoustic emission in metal cutting. Results for machining SAE 1018 and 4140 steels show that the built-up edge can mask the generally accepted AE-cutting speed relation when cutting tools having small rake angles are used. Under cutting conditions conducive to development of a built-up edge, it is shown that increased acoustic emission is generated as a result of increased effective rake angle and corresponding increase of shear angle in the primary deformation zone. Three distinct types of built-up edge have been observed and classified as immature, periodic, or developed, according to effect on acoustic emission.

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