Chip Flow Angle Research Articles

D18 Simulation of Drilling Process for Control of Burr Formation(Analytical advancement of machining process)

The cutting force and the chip flow direction are simulated to reduce burr formation at the backside of the machined plate in an analytical model based on the minimum cutting energy. The curved lips drill is discussed to reduce the thrust and increase the chip flow angle with the orientation and the curvature. The counterclockwise orientation is effective to reduce the thrust and control the chip flow with the small curvature. A curved lip drill is designed with a large radial rake angle at the end of the lips based on the cutting simulation.

The prediction of cutting force for boring process

This article presents a methodology to predict the cutting force of boring process. The cutting force is represented by tangential F t, thrust F h and lateral F l components. Cutting force is correlated to chip area and cutting edge contact length with mechanistic cutting force coefficients. B-spline parametric curves are used to model the process geometry. The chip load boundary is first modeled using analytical parametric curve intersection approach. The chip area is then segmented into elements for which feed and approach angle can be considered constant. A method to predict the effective chip flow angle on the rake face of the tool is proposed and verified over a wide range of cutting conditions. Elemental tangential and thrust components of the cutting force are evaluated using an orthogonal cutting database. These values are summed up along the cutting edge to obtain the resultant tangential and thrust components. The third component, F l, is determined using the predicted value of the effective chip flow angle. To verify the proposed method, experimental tests have been conducted. Comparison between the predicted results and experimental observations confirms the validity of the proposed model within ±10% deviation.

Analysis of Cutting Forces and Mechanism of Chip Formation in Ball End Milling of Inclined Surface (2nd Report)

In order to predict cutting forces and chip formation in milling with a ball end mill for various tool paths, inclination of the workpiece surface and of the tool axis, a cutting model proposed in previous paper is extended to the milling process in which both cutting edges of the sphere and cylindrical portions engage with the workpiece. In the cutting model, elemental chip at any point on the cutting edge is described by simple shear plane oblique cutting model, and the condition of side-curl of the chip is considered. In this paper, cutting edge configurations, inclination and normal rake angles at the sphere and cylindrical portions are discussed. Geometric quantities such as contact region between the cutting edge and the workpiece surface, and undeformed chip thickness along the cutting edge in milling for the tool moving upward or downward on the inclined surface are analyzed, and variation of these geometric quantities with tool rotational angle are also discussed. Three components of the cutting force and chip formation such as chip flow angle, radius of side-curl of the chip and chip form are predicted by using developed cutting model and energy method. The preliminary examination shows that there is the large difference in cutting forces and the chip formation for the tool moving upward or downward on the inclined surface.

Modelling the cutting edge radius size effect for force prediction in micro milling

This paper presents a theoretical model for cutting force prediction in micro milling, taking into account the cutting edge radius size effect, the tool run out and the deviation of the chip flow angle from the inclination angle. A parameterization according to the uncut chip thickness to cutting edge radius ratio is used for the parameters involved in the force calculation. The model was verified by means of cutting force measurements in micro milling. The results show good agreement between predicted and measured forces. It is also demonstrated that the use of the Stabler's rule is a reasonable approximation and that micro end mill run out is effectively compensated by the deflections induced by the cutting forces.

Effect of Rotary Cutting Tool Posture on Machining Performance utilizing Multi-Tasking Lathe

In this report, a driven rotary tool's machining performance on SUS304 stainless steel was examined. The rotary tool was attached to a milling axis on a multi-tasking lathe which has B axis control. It is possible to adjust the tool's circumferential speed as the tool is controlled to rotate by a milling motor. As well, the contact angle between the work-piece and cutting point are controllable as the milling axis has four degrees of freedom of movement. The objective of this study is to clarify the influence of tool posture on the rotary cutting process. It was found that the tool temperature increase and also the chip flow angle increases, when the tool inclination angle increases.

Prediction of cutting forces in ball-end milling by means of geometric analysis

A new geometric model of ball-end milling is proposed. The relationships among undeformed chip thickness, rake angle, cutting velocity, shear plane area and chip flow angle in ball-end milling are clearly described. The shear plane area of the shear deformation zone and the effective frictional area on tool face are calculated. The three-dimensional cutting forces in the tool axis system are then obtained by minimum energy method. The transformation matrices, including the effects of the axial depth of cut, helix angle, tool rotational angle, and indentation action of the tool tip, are presented. The three-dimensional cutting forces can be predicted via matrix transformation. A force model for a two-flute cutter is developed and a four-flute model is also obtained by superposing the two-flute model. Based on the basic geometric modeling, the cutting forces along horizontal and vertical directions are predicted. Several unveiled phenomena, such as the influence on cutting forces of the different engaged regions between cutting edge and undeformed chip thickness, and indentation action on tool tip that influences the Z-direction force, have been illustrated. Experiments are conducted to verify the developed model. It shows that the predicted cutting forces agree with the experimental data both in trends and values.

On Study of Cutting Forces Generated by Minor Cutting Edges

An experimental procedure was developed to separated the uncertain cutting forces generated by the minor cutting edges for interpreted the force components generated by the main and minor cutting edge. Cutting forces generated by minor cutting edges were investigated by experiments in precision hard part machining hardened GCr15 bearing steel with BZN8200 PCBN tool. With the improved chip loads, constitutive model and chip flow angle model, the predicted cutting forces show great agreement with the experimental results and verified the reliability of an improved cutting force model.

Prediction of chip flow angle in orthogonal turning of mild steel by neural network approach

Improvement of chip control is a necessity for automated machining. Chip control is closely related to chip flow and it plays also a predominant role in the effective control of chip formation and chip breaking for the easy and safe disposal of chips, as well as for protecting the surface-integrity of the workpiece. Although several ways to predict the chip flow angle (CFA) have been subjected in some researches, a good approximation has not been achieved yet. In this study, using different indexable inserts and cutting conditions for turning of mild steel, the chip flow angles were measured and some of the collected data from this experimental study were used for training with a two hidden layered backpropagation neural network algorithm. A group was formed from randomly selected data for testing. The chip flow angle values found from multiple regression, neural network (NN) and studies of previous researchers under the same turning conditions of the present study were compared. It has been seen that the best prediction was obtained by neural network approach.

Analysis and prediction of cutting forces in end milling by means of a geometrical model

The geometrical analysis of a new three-dimensional force model of end milling is presented. The analysis includes description of the relative relationships among undeformed chip thickness, rake angle, cutting velocity, shear plane area and chip flow angle during peripheral and face milling processes. The shear plane area of the shear deformation zone and the effective frictional area on the tool face are calculated and the shear energy per unit time and frictional energy per unit time are formulated. The three-dimensional cutting forces in the tool axis system are then obtained. In the developed model, the depth of cut, helix angle, tool rotational angle, and indentation action of the tool tip are taken into account by individual transformation matrices. The three-dimensional cutting forces in a Cartesian system can be predicted via matrix transformation. Experiments conducted to verify the developed model showed that the predicted cutting forces agreed well with the experimental data both in trends and values.

Prediction of chip flow direction during machining with self-propelled rotary tools

This paper presents a model for chip flow prediction during tube-end machining process using self-propelled rotary tools. The analysis performed is based on the transformation of the relative kinematic relationships in rotary cutting to that of the conventional cutting with large nose radius. Both relative and absolute chip flow angles are investigated. Tests were performed to measure the absolute chip flow angle, insert self propelled motion, and the deformed chip thickness during machining with self-propelled rotary tool under different cutting conditions. The predicted values of the absolute chip flow angle were in good agreement with that measured experimentally.

On the prediction of chip flow angle in non-free oblique machining

A new method for predicting the chip flow angle of inserts with different cutting conditions was studied in non-free oblique machining process. The effects of the major cutting edge, minor cutting edge, corner radius and cutting parameters (depth of cut and feed rate) on the chip flow direction were studied by calculating the components of the thrust cutting force for the major and minor cutting edges based on the hypothesis that the chip flow direction is also the thrust force direction. This method was verified by comparing the calculated and experimental results with the single-point and nose-radiused cutting edge for different cutting conditions. The prediction results under different cutting parameters show good agreement with experimental data.

Upper Bound Analysis of Turning Using Sharp Corner Tools

A generalized upper bound model of turning operations using flat-faced sharp corner tools with both the side and end cutting edges engaged in cutting is described. The projection of the uncut chip area on the rake face plane is divided into a few regions separated by lines parallel to the chip flow direction at transition points. The area of each of these regions is transformed to the area of the corresponding regions of the shear surface using the ratio of the shear speed to the chip speed. Summing up the area of these regions, the total shear surface area is obtained. The tool-chip contact length at vertices is obtained from the length along the shear surface using the similarity between orthogonal and oblique cutting in the “equivalent” plane (the plane formed by the cutting velocity and chip velocity). Knowing the tool-chip contact length, the friction area is calculated. The chip flow angle and chip speed are obtained by minimizing the cutting power with respect to both these variables. Comparison of the chip flow angle predicted by the current model with the chip flow angle measured by direct high speed photography of the chip motion over the tool rake face shows good correlation between the two for various tool geometries and cutting conditions. The shape of the shear surface and the chip cross section predicted by the model are also presented.

Thermomechanical modelling of oblique cutting and experimental validation

An analytical approach is used to model oblique cutting process. The material characteristics such as strain rate sensitivity, strain hardening and thermal softening are considered. The chip formation is supposed to occur mainly by shearing within a thin band called primary shear zone. The analysis is limited to stationary flow and the material flow within the primary shear zone is modelled by using a one-dimensional approach. Thermomechanical coupling and inertia effects are accounted for. The chip flow angle is determined by the assumption that the friction force on the tool face is collinear to the chip flow direction. At the chip–tool interface, the friction condition can be affected by the important heating induced by the large values of pressure and sliding velocity. In spite of the complexity of phenomena governing the friction law in machining, a reasonable assumption is to consider that the mean friction coefficient is primarily function of the average temperature at the tool–chip interface. Comparisons between model predictions and experimental results are performed for different values of cutting speed, undeformed chip thickness, normal cutting angle and inclination angle. A critical study is presented in order to show the influences of the input parameters of the model including the normal shear angle, the thickness of the primary shear zone and the pressure distribution at the tool–chip interface. The model permits to predict the cutting forces, the chip flow direction, the contact length between the chip and the tool and the temperature distribution at the tool–chip interface which has an important effect on tool wear.

Thermomechanical modelling of oblique cutting and experimental validation

An analytical approach is used to model oblique cutting process. The material characteristics such as strain rate sensitivity, strain hardening and thermal softening are considered. The chip formation is supposed to occur mainly by shearing within a thin band called primary shear zone. The analysis is limited to stationary flow and the material flow within the primary shear zone is modelled by using a one-dimensional approach. Thermomechanical coupling and inertia effects are accounted for. The chip flow angle is determined by the assumption that the friction force on the tool face is collinear to the chip flow direction. At the chip–tool interface, the friction condition can be affected by the important heating induced by the large values of pressure and sliding velocity. In spite of the complexity of phenomena governing the friction law in machining, a reasonable assumption is to consider that the mean friction coefficient is primarily function of the average temperature at the tool–chip interface. Comparisons between model predictions and experimental results are performed for different values of cutting speed, undeformed chip thickness, normal cutting angle and inclination angle. A critical study is presented in order to show the influences of the input parameters of the model including the normal shear angle, the thickness of the primary shear zone and the pressure distribution at the tool–chip interface. The model permits to predict the cutting forces, the chip flow direction, the contact length between the chip and the tool and the temperature distribution at the tool–chip interface which has an important effect on tool wear.

Upper Bound Analysis of Turning Using Sharp Corner Tools

Abstract A generalized upper bound model of turning operations using flat-faced sharp corner tools with both the side and end cutting edges engaged in cutting is described. The projection of the uncut chip area on the rake face plane is divided into a few regions separated by lines parallel to the chip flow direction at transition points. The area of each of these regions is transformed to the area of the corresponding regions of the shear surface using the ratio of the shear speed to the chip speed. Summing up the area of these regions, the total shear surface area is obtained. The tool-chip contact length at vertices is obtained from the length along the shear surface using the similarity between orthogonal and oblique cutting in the “equivalent” plane (the plane formed by the cutting velocity and chip velocity). Knowing the tool-chip contact length, the friction area is calculated. The chip flow angle and chip speed are obtained by minimizing the cutting power with respect to both these variables. Comparison of the chip flow angle predicted by the current model with the chip flow angle measured by direct high speed photography of the chip motion over the tool rake face shows good correlation between the two for various tool geometries and cutting conditions. The shape of the shear surface and the chip cross section predicted by the model are also presented.

An improved chip flow model considering cutting geometry variations based on the equivalent cutting edge method

An improved chip flow model of a nose-radiused cutting tool in oblique turning is developed considering cutting geometry variations based on the equivalent cutting edge method. The model-building procedure divided the arbitrary cutting area engaged with workpiece into a single edge and a nose-radiused cutting edge according to the depth of cut and tool nose radius. The individual effects on the chip flow angle are distinguished by the equivalent cutting edge method and the total chip flow angle obtained. The chip flow angle prediction results obtained under different cutting parameters show good agreement with experimental data.

Upper bound analysis of oblique cutting: improved method of calculating the friction area

This paper describes further development of the upper bound analysis of oblique cutting with nose radius tools described previously by Adibi-Sedeh et al. [ 1] by incorporation of an improved method for calculating the friction area at the chip-tool interface. Previously, the friction area was obtained from the shear surface area assuming that the ratio of these areas is the same as in orthogonal machining. Our results showed that this led to overestimation of the effect of friction on the chip flow angle, thereby resulting in smaller changes in the chip flow angle with inclination angle as compared to experimental data. In the new approach, the chip-tool contact length is obtained from the length of the shear surface assuming that the ratio of the lengths is the same as in orthogonal machining and the friction area is calculated using this length. The chip flow angle predicted using the new approach shows much better agreement with experimental data. In particular, the dependence of the chip flow angle on the inclination angle is accurately reproduced. Upper bound analysis of oblique cutting using this new model for the friction area provides an elegant explanation for the relative influence of the normal and equivalent rake angles on the cutting force.

A hybrid model for analysis of 3-D machining operations

This paper describes the development of a physically based model for the analysis of commonly encountered 3-D machining processes using arbitrarily oriented cutting tools. This model consists of two modules, a generalized upper bound analysis module capable of handling any given cutting edge geometry, and a 2-D machining analysis module capable of using a wide range of constitutive equations to handle most commonly machined materials. The upper bound module is used for prediction of the chip flow angle and is followed by application of the extended Oxley's analysis of machining (Adibi-Sedeh, Madhavan, and Bahr 2003a) in the equivalent plane to obtain two components of the cutting force in the plane. The out-of-plane component is calculated by applying the constraint that the resultant cutting force should not have any component along the rake face in a direction perpendicular to the chip flow direction. The performance of the hybrid model is validated through extensive comparison with experimental data for different operations and materials.

Prediction of Cutting Process with Curved-Edge End Mill (1st Report, Application of Ball End Milling Process in Energy Approach)

An approach is presented to predict the chip formation and the three components of cutting force in the machining with the curved-edge end mill, which has the tool geometries changing with the cutter height. Those geometrical parameters are defined as the functions of the cutter height. The chip formation in the milling process is modeled as a pilling up of orthogonal cuttings along the cutting edge. The orthogonal cuttings are made in the planes containing the cutting velocities and the chip flow velocities so that chip flows up to a certain direction as a rigid body. The chip flow direction can be given to minimize the cutting energy, which can be given as the sum of the shear energy on shear plane and the friction energy on rake face. The cutting force, then, can be predicted with the chip formation having the minimum cutting energy. The presented approach is applied to the prediction of cutting process in the machining with the insert-ball end mill. The predicted results are verified to be accurate enough in a variety of depth of cut. The change of the chip flow angle and that of the orthogonal cutting model during a rotation of the cutter can be shown in the presented approach.

Basic Approach to a Prediction System for Burr Formation in Face Milling

Geometric parameters and material properties are the two major categories of factors affecting burr formation in the milling process. Geometric parameters such as tool geometry, workpiece geometry, or process condition influence workpiece edge quality at the tool-chip interface. This study identifies a unified criterion to analyze burr formation for different tool engagements. The criterion exploits the exit order of cutting edges of the tool along the workpiece edge, which essentially includes the 3-D nature of the process. The criterion correlates the cutting mechanism and burr formation using the exit order sequence (EOS) as an approximation of chip flow angle. The impact of different possible exit order sequences on burr formation is analyzed. Previously observed phenomena are explained based on the EOS. Also, experiments are done with three different materials (with different ductilities) to analyze the impact of material properties on burr formation for a given EOS. Although burr sizes are different quantitatively with different material, the ranking of burr size for different EOS remained the same. An algorithm for the prediction of burr formation in face milling based on EOS is developed and tested and validated on two different profiles of an automotive part.