An Analytical Model of Cutting Dynamics. Part 2: Verification

1985 ◽  
Vol 107 (2) ◽  
pp. 112-118 ◽  
Author(s):  
D. W. Wu ◽  
C. R. Liu
Keyword(s):  
High Speed ◽  
Stability Boundary ◽  
Cutting Speed ◽  
Preceding Paper ◽  
Stability Limit ◽  
Force Model ◽  
Dynamic Force ◽  
Wide Range ◽  
Successful Prediction ◽  
Speed Stability

The dynamic force model developed in the preceding paper [1] is further examined. The analysis shows a successful prediction of the forms of stability boundary over a wide range of cutting speed. It reveals that the cutting force acting on tool rake face controls the high-speed stability, while the ploughing force acting on tool nose region dominates the low-speed stability. A series of cutting tests were carried out to examine the validity of the model. The result shows a fairly good agreement between the theoretical prediction of stability limit and the experimental determination of critical width of cut when the cutting conditions are properly chosen to avoid the presence of built-up-edge on tool tip.

Modeling of Dynamic Instability Via Segmented Cutting Coefficients and Chatter Onset Detection in High-Speed Micromilling of Ti6Al4V

2016 ◽  
Vol 139 (5) ◽  
Author(s):  
Kundan K. Singh ◽  
V. Kartik ◽  
Ramesh Singh
Keyword(s):  
Cutting Force ◽  
Cutting Forces ◽  
High Speed ◽  
Stability Boundary ◽  
Force Model ◽  
Dynamic Force ◽  
Force Prediction ◽  
High Speeds ◽  
Cutting Coefficients ◽  
Chip Load

Miniature components with complex shape can be created by micromilling with excellent form and finish. However, for difficult-to-machine materials, such as Ti-alloys, failure of low-flexural stiffness microtools is a big limitation. High spindle speeds (20,000–100,000 rpm) can be used to reduce the undeformed chip thickness and the cutting forces to reduce the catastrophic failure of the tool. This reduced uncut chip thicknesses, in some cases lower than the cutting edge radius, can result in intermittent chip formation which can lead to dynamic variation in cutting forces. In addition, the run-out and the misalignment effects are amplified at higher rotational speeds which can induce dynamic force variation. These dynamic force variations coupled with low-flexural rigidity of micro end mill can render the process unstable. Consequently, accurate prediction of forces and stability is essential in high-speed micromilling. Most of the previous studies reported in the literature use constant cutting coefficients in the mechanistic cutting force model which does not yield accurate results. Recent work has shown significant improvement in the prediction of cutting forces with velocity–chip load dependent coefficients but a single-function velocity–chip model fails to predict the forces accurately at very high speeds (>80,000 rpm). This inaccurate force prediction affects the predicted stability boundary at those speeds. Hence, this paper presents a segmented approach, wherein a function is fit for a given range of speeds to determine the chip load dependent cutting coefficients. The segmented velocity–chip load dependent cutting coefficient improves the cutting force prediction at high speeds, which yields much accurate stability boundary. This paper employs two degrees-of-freedom (2DOF) model with forcing functions based on segmented velocity–chip load dependent cutting coefficients. Stability lobe diagram based on 2DOF model has been created for different speed ranges using Nyquist stability criterion. Chatter onset has been identified experimentally via accelerometer data and the power spectral density (PSD) analysis of the machined surface topography. Critical spatial chatter frequencies and magnitudes of PSD corresponding to onset of instability have also been determined for different conditions.

scholarly journals Prediction of Tool Lifetime and Surface Roughness for Nickel-Based Waspaloy

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Shao-Hsien Chen ◽  
Chung-An Yu
Keyword(s):  
Surface Roughness ◽  
Tool Wear ◽  
High Speed ◽  
Cutting Speed ◽  
High Strength ◽  
Cutting Parameters ◽  
Experimental Results ◽  
Predictive Values ◽  
Actual Surface ◽  
Wide Range

In recent years, most of nickel-based materials have been used in aircraft engines. Nickel-based materials applied in the aerospace industry are used in a wide range of applications because of their strength and rigidity at high temperature. However, the high temperatures and high strength caused by the nickel-based materials during cutting also reduce the tool lifetime. This research aims to investigate the tool wear and the surface roughness of Waspaloy during cutting with various cutting speeds, feed per tooth, cutting depth, and other cutting parameters. Then, it derives the formula for the tool lifetime based on the experimental results and explores the impacts of these cutting parameters on the cutting of Waspaloy. Since the impacts of cutting speed on the cutting of Waspaloy are most significant in accordance with the experimental results, the high-speed cutting is not recommended. In addition, the actual surface roughness of Waspaloy is worse than the theoretical surface roughness in case of more tool wear. Finally, a set of mathematical models can be established based on these results, in order to predict the surface roughness of Waspaloy cut with a worn tool. The errors between the predictive values and the actual values are 5.122%∼8.646%. If the surface roughness is within the tolerance, the model can be used to predict the residual tool lifetime before the tool is damaged completely. The errors between the predictive values and the actual values are 8.014%∼20.479%.

Cutting Forces and Surface Roughness in High-Speed End Milling of Ti6Al4V

2013 ◽  
Vol 589-590 ◽  
pp. 76-81
Author(s):  
Fu Zeng Wang ◽  
Jun Zhao ◽  
An Hai Li ◽  
Jia Bang Zhao
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Cutting Forces ◽  
High Speed ◽  
End Milling ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Wide Range ◽  
Radial Depth ◽  
Coated Carbide

In this paper, high speed milling experiments on Ti6Al4V were conducted with coated carbide inserts under a wide range of cutting conditions. The effects of cutting speed, feed rate and radial depth of cut on the cutting forces, chip morphologies as well as surface roughness were investigated. The results indicated that the cutting speed 200m/min could be considered as a critical value at which both relatively low cutting forces and good surface quality can be obtained at the same time. When the cutting speed exceeds 200m/min, the cutting forces increase rapidly and the surface quality degrades. There exist obvious correlations between cutting forces and surface roughness.

Deficiencies in Turbulence Modelling for the Prediction of the Stability Boundary in Highly Loaded Compressors

2019 ◽  
Author(s):  
Jose Moreno ◽  
John Dodds ◽  
Mehdi Vahdati ◽  
Sina Stapelfeldt
Keyword(s):  
High Speed ◽  
Stability Boundary ◽  
Turbulence Models ◽  
Stability Limit ◽  
Major Effect ◽  
Navier Stokes ◽  
Tip Leakage Flow ◽  
Stall Margin ◽  
Multi Stage ◽  
The Stability

Abstract Reynolds-averaged Navier-Stokes (RANS) equations are employed for aerodynamic and aeroelastic modelling in axial compressors. Their solutions are highly dependent on the turbulence models for closure. The main objective of this work is to assess the widely used Spalart-Allmaras model’s suitability for compressor flows. For this purpose, an extensive investigation of the sources of uncertainties in a high-speed multi-stage compressor rig was carried out. The grid resolution near the casing end wall, which affects the tip leakage flow and casing boundary layer, was found to have a major effect on the stability limit prediction. Refinements in this region led to a stall margin loss prediction. It was found that this loss was exclusively due to the destruction term in the SA model.

Segmented Cutting Coefficient Based Chatter Modeling for High-Speed Micromilling of Ti6Al4V

2016 ◽  
Author(s):  
Kundan K. Singh ◽  
V. Kartik ◽  
Ramesh Singh
Keyword(s):  
Cutting Force ◽  
Cutting Forces ◽  
High Speed ◽  
Stability Boundary ◽  
Force Model ◽  
Force Prediction ◽  
High Speeds ◽  
Cutting Coefficients ◽  
Stability Lobe ◽  
Chip Load

Miniature components with complex shape can be created by micromilling with high surface accuracy. However, for difficult-to-machine materials, such as Ti-alloys, failure of low flexural stiffness micro-tools is a big limitation. High spindle speeds (20,000 to 100,000 rpm) can be used to reduce the undeformed chip thickness and the cutting forces and hence the catastrophic failure of the tool can be avoided. This reduced uncut chip thicknesses, in some cases lower than the cutting edge radius, can result in intermittent chip formation which can lead to dynamic variation in cutting forces. These dynamic force variations coupled with low flexural rigidity of micro end mill can render the process unstable. Consequently, accurate prediction of forces and stability is essential in high-speed micromilling. Most of the previous studies reported in the literature use constant cutting coefficients in the mechanistic cutting force model which does not yield accurate results. Recent work has shown significant improvement in the prediction of cutting forces with velocity-chip load dependent coefficients but a single function velocity-chip model fails to predict the forces accurately at very high speeds (>80,000 rpm). This inaccurate force prediction affects the predicted stability boundary at those speeds. Hence, this paper presents a segmented approach wherein a function is fit for a given range of speed to determine the chip load dependent cutting coefficients. The segmented velocity-chip load cutting coefficient improves the cutting force prediction at high speeds. R2 value is found to be improved significantly (>90% for tangential cutting coefficient) which yields the better forces prediction and hence more accurate stability boundary. This paper employs two degrees of freedom (2-DOF) model with forcing functions based on segmented velocity-chip load dependent cutting coefficients. Stability lobe diagram based on 2-DOF model has been created for different speed ranges using Nyquist stability criteria. Chatter frequency ranges between 1.003 to 1.15 times the experimentally determined first modal frequency. Chatter onset has been identified via a laser displacement sensor to experimentally validate the predicted stability lobe.

Deficiencies in the Spalart–Allmaras Turbulence Model for the Prediction of the Stability Boundary in Highly Loaded Compressors

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Jose Moreno ◽  
John Dodds ◽  
Sina Stapelfeldt ◽  
Mehdi Vahdati
Keyword(s):  
High Speed ◽  
Stability Boundary ◽  
Turbulence Models ◽  
Stability Limit ◽  
Major Effect ◽  
Navier Stokes ◽  
Tip Leakage Flow ◽  
Stall Margin ◽  
Multi Stage ◽  
The Stability

Abstract Reynolds-averaged Navier–Stokes (RANS) equations are employed for aerodynamic and aeroelastic modeling in axial compressors. Their solutions are highly dependent on the turbulence models for closure. The main objective of this work is to assess the widely used Spalart–Allmaras model suitability for high-speed compressor flows. For this purpose, an extensive investigation of the sources of uncertainties in a high-speed multi-stage compressor rig was carried out. The grid resolution near the casing end wall, which affects the tip leakage flow and casing boundary layer, was found to have a major effect on the stability limit prediction. Refinements in this region led to a stall margin loss prediction. It was found that this loss was exclusively due to the destruction term in the SA model.

Initial tool wear behavior in high-speed turning of Inconel 718

2020 ◽  
Vol 44 (3) ◽  
pp. 395-404
Author(s):  
Morvarid Memarianpour ◽  
Seyed Ali Niknam ◽  
Sylvain Turenne ◽  
Marek Balazinski
Keyword(s):  
Steady State ◽  
Tool Wear ◽  
Inconel 718 ◽  
High Speed ◽  
Wear Behavior ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Industrial Applications ◽  
Wide Range ◽  
Tool Wear Mechanism

Three distinctive regions of tool wear, known as initial wear, steady-state wear, and accelerated wear, are well understood. However, the effects of cutting parameters on the initial tool wear mechanism, morphology, and size have received less attention as compared to the other two regions. Knowing that adequate control of initial tool wear may lead to extended tool life, in particular in hard-to-cut metals such as superalloys, this topic has become a source of attention. Amongst superalloys, Inconel 718 is considered as one of the most difficult to cut materials, which has a wide range of industrial applications. This study intends to evaluate the effects of cutting parameters on initial tool wear, as well as tool wear progression, when turning Inconel 718. Therefore, microstructural evaluation of the initial tool wear mode under various cutting conditions, as well as tool wear measurements, were conducted. It was observed that certain elements of the workpieces were migrated to the insert flank face. This is evidence of adhesion at the initial moments of the cutting process. In contrast to many other easy-to-cut materials, the steady-state wear period when turning Inconel 718 is significantly short under a higher level of cutting speed and feed rate.

An Experimental Study of High Speed Orthogonal Cutting

1998 ◽  
Vol 120 (1) ◽  
pp. 169-172 ◽  
Author(s):  
G. Sutter ◽  
A. Molinari ◽  
L. Faure ◽  
J. R. Klepaczko ◽  
D. Dudzinski
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
High Speed Machining ◽  
Workpiece Material ◽  
Wide Range ◽  
Longitudinal Cutting ◽  
Material Interaction ◽  
Cutting Speeds

A new high speed machining experiment is designed to obtain orthogonal cutting in a wide range of cutting speeds from 7 m/s to 100 m/s. Quasi-stationary cutting conditions are obtained. The measurement of the longitudinal cutting force reveals the existence of an optimal cutting speed for which the energy consumption is minimum. The genuine tool-workpiece material interaction can be analyzed with that experimental device.

Material Characterization for Metal-Cutting Force Modeling

1989 ◽  
Vol 111 (2) ◽  
pp. 210-219 ◽  
Author(s):  
D. A. Stephensen
Keyword(s):  
Shear Stress ◽  
Strain Rate ◽  
Cutting Force ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Shear Plane ◽  
Stress And Strain ◽  
Force Model ◽  
Wide Range

Widely applicable machining simulation programs require reliable cutting force estimates, which currently can be obtained only from process-dependent machinability databases. The greatest obstacle to developing a more basic, efficient approach is a lack of understanding of material yield and frictional behavior under the unique deformation and frictional conditions of cutting. This paper describes a systematic method of specifying yield stress and friction properties needed as inputs to process-independent cutting force models. Statistically designed end turning tests are used to generate cutting force and chip thickness data for a mild steel and an aluminum alloy over a wide range of cutting conditions. Empirical models are fit for the cutting force and model-independent material parameters such as the tool-chip friction coefficient and shear stress on the shear plane. Common material yield behavior assumptions are examined in light of correlations between these parameters. Results show no physically meaningful correlation between geometric shear stress and strain measures, a weak correlation between geometric stress and strain rate measures, and a strong correlation between material properties and input variables such as cutting speed and rake angle. An upper bound model is used to fit four- and five-parameter polynomial strain-rate sensitive constitutive equations to the data. Drilling torques calculated using this model and an empirical turning force model agree reasonably well with measured values for the same material combination, indicating that end turning test results can be used to estimate mean loads in a more complicated process.

On Saw-Tooth Chip Formation in High Speed Cutting GH4169

2007 ◽  
Vol 10-12 ◽  
pp. 359-363 ◽  
Author(s):  
Dong Jin Zhang ◽  
Gang Liu ◽  
X. Sun ◽  
Ming Chen
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Cutting Speed ◽  
Chip Morphology ◽  
High Yield ◽  
Forming Process ◽  
Element Analysis ◽  
High Speed Cutting ◽  
Nickel Based Superalloy ◽  
Wide Range

The nickel-based superalloy GH4169 is a typical difficult-to-cut material, but it has been used in a good many kinds of aeronautical key structures because of its high yield stress and anti-fatigue performance at the temperature below 650°C. In this paper, finite element method (FEM) was introduced to study the saw-tooth chip forming process in detail when machining nickel-based superalloy GH4169. By the way of Lagrangian visco-elastic plastic approach, adiabatic shear band (ASB) was simulated in high speed machining condition by general commercial finite element code, and the mechanism of the adiabatic shearing phenomenon at primary shear zone was analyzed with the help of finite element analysis (FEA). The comprehensive comparisons of saw-tooth chip morphology under a wide range of cutting speed were also presented.

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