Modeling Dynamic Stability and Cutting Forces in Micro Milling of Ti6Al4V Using Intermittent Oblique Cutting Finite Element Method Simulation-Based Force Coefficients

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Priyabrata Sahoo ◽  
Karali Patra ◽  
Vishnu K. Singh ◽  
Rinku K. Mittal ◽  
Ramesh K. Singh
Keyword(s):  
Finite Element Method ◽  
Cutting Force ◽  
Dynamic Stability ◽  
Micro Milling ◽  
Force Model ◽  
Cutting Simulation ◽  
Oblique Cutting ◽  
Force Coefficients ◽  
Stability Model ◽  
The Stability

Abstract Tool breakage is a significant issue in micro milling owing to the less stiffness of the micro tool. To cope up with such limitation, precise predictions of dynamic stability, and cutting force have the utmost importance to monitor and optimize the process. In this article, dynamic stability and cutting force are predicted precisely for micro milling of Ti6Al4V by obtaining force coefficients from a novel 3D intermittent oblique cutting finite element method (FEM) simulation considering the influence of tool run out. First, the stability model is modified by incorporating the appropriate values of limiting angles obtained analytically accounting the trajectories of the flutes due to tool run out. This stability model is utilized to select chatter-free parametric combinations for micro milling tests. Next, an improved cutting force model is developed by incorporating the force coefficients obtained from oblique cutting simulation in the mechanistic model and differentiating the whole machining region into three distinct region considering size effect. The force model also considers the effect of increased edge radius of the worn tool, run out, elastic recovery, ploughing, minimum undeformed chip thickness (MUCT), and limiting angles, cumulatively. The proposed dynamic stability and cutting force models based on the oblique cutting simulation show their adequacy by predicting the stability limit and cutting force more precisely, respectively, as compared to those obtained by orthogonal cutting simulation. Besides, the proposed force model for the worn tool is found to be viable as it is closer to the experimental forces, whereas force model without the incorporation of tool wear underestimated the experimental forces.

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.

Analysis of Cutting Force in Elastomer End-Milling

2017 ◽  
Vol 11 (6) ◽  
pp. 958-963
Author(s):  
Koji Teramoto ◽  
◽  
Takahiro Kunishima ◽  
Hiroki Matsumoto
Keyword(s):  
Parameter Identification ◽  
Cutting Force ◽  
Cutting Forces ◽  
End Milling ◽  
Process Models ◽  
Force Model ◽  
Cutting Force Model ◽  
Cutting Force Prediction ◽  
Force Prediction ◽  
The Stability

Elastomer end-milling is attracting attention for its role in the small-lot production of elastomeric parts. In order to apply end-milling to the production of elastomeric parts, it is important that the workpiece be held stably to avoid deformation. To evaluate the stability of workholding, it is necessary to predict cutting forces in elastomer end-milling. Cutting force prediction for metal workpiece end-milling has been investigated for many years, and many process models for end-milling have been proposed. However, the applicability of these models to elastomer end-milling has not been discussed. In this paper, the characteristics of the cutting force in elastomer end-milling are evaluated experimentally. A standard cutting force model and its parameter identification method are introduced. By using this cutting force model, measured cutting forces are compared against the calculated results. The comparison makes it clear that the standard cutting force model for metal end-milling can be applied to down milling for a rough evaluation.

Improved dynamic cutting force modelling in micro milling of metal matrix composites part II: Experimental validation and prediction

2019 ◽  
Vol 234 (8) ◽  
pp. 1500-1515
Author(s):  
Zhichao Niu ◽  
Kai Cheng
Keyword(s):  
Cutting Force ◽  
Metal Matrix Composites ◽  
Cutting Forces ◽  
Metal Matrix ◽  
Micro Milling ◽  
Force Model ◽  
Matrix Composites ◽  
Cutting Force Model ◽  
Side Milling ◽  
Dynamic Cutting Force

The effects of cutting dynamics and the particles' size and density cannot be ignored in micro milling of metal matrix composites. This article presents the improved dynamic cutting force modelling for micro milling of metal matrix composites based on the previous analytical model. This comprehensive improved cutting force model, taking the influence of the tool run-out, actual chip thickness and resultant tool tip trajectory into account, is evaluated and validated through well-designed machining trials. A series of side milling experiments using straight flutes polycrystalline diamond end mills are carried out on the metal matrix composite workpiece under various cutting conditions. Subsequently, the measured cutting forces are compensated by a Kalman filter to achieve the accurate cutting forces. These are further compared with the predicted cutting forces to validate the proposed dynamic cutting force model. The experimental results indicate that the predicted and measured cutting forces in micro milling of metal matrix composites are in good agreement.

A Mechanistic Model of Cutting Forces in Micro-End-Milling With Cutting-Condition-Independent Cutting Force Coefficients

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Han Ul Lee ◽  
Dong-Woo Cho ◽  
Kornel F. Ehmann
Keyword(s):  
Cutting Force ◽  
Cutting Forces ◽  
End Milling ◽  
Cutting Conditions ◽  
Thickness Effect ◽  
Force Model ◽  
Cutting Force Coefficients ◽  
Force Coefficients ◽  
Micro End Milling ◽  
Cutting Mechanisms

Complex three-dimensional miniature components are needed in a wide range of industrial applications from aerospace to biomedicine. Such products can be effectively produced by micro-end-milling processes that are capable of accurately producing high aspect ratio features and parts. This paper presents a mechanistic cutting force model for the precise prediction of the cutting forces in micro-end-milling under various cutting conditions. In order to account for the actual physical phenomena at the edge of the tool, the components of the cutting force vector are determined based on the newly introduced concept of the partial effective rake angle. The proposed model also uses instantaneous cutting force coefficients that are independent of the end-milling cutting conditions. These cutting force coefficients, determined from measured cutting forces, reflect the influence of the majority of cutting mechanisms involved in micro-end-milling including the minimum chip-thickness effect. The comparison of the predicted and measured cutting forces has shown that the proposed method provides very accurate results.

Modeling and Simulation of Cutting Forces in Side Milling

2016 ◽  
Vol 693 ◽  
pp. 843-849
Author(s):  
An Hai Li ◽  
Jun Zhao ◽  
He Lin Pan ◽  
Zhao Chao Gong
Keyword(s):  
Cutting Force ◽  
Cutting Forces ◽  
Milling Process ◽  
Force Model ◽  
Machining Parameters ◽  
Machining Time ◽  
Side Milling ◽  
Force Coefficients ◽  
Solid Carbide ◽  
Edge Force

In order to acquire high machining quality and minimum machining time, cutting forces are usually modeled to understand the milling process, simulate or predict cutting forces, and optimize the machining parameters. In this paper, side milling tests were conducted on superalloy Inconel 718 with a solid carbide end mill, and the cutting forces vs. cutting time were measured. The average cutting forces were extracted from the measured instantaneous cutting forces under different feed rates of experiments, and the components of the shear forces and edge forces were determined by using the linear regression of the experimental data. The cutting force coefficients, including shear force coefficients and edge force coefficients, were identified. In addition, the algorithms of the mathematical model were implemented in Matlab. The predicted cutting forces were in good agreement with the experimentally measured forces, and the validation of the cutting force model was demonstrated.

scholarly journals Estimation of the Bistable Zone for Machining Operations for the Case of a Distributed Cutting-Force Model

2016 ◽  
Vol 11 (5) ◽  
Author(s):  
Tamás G. Molnár ◽  
Tamás Insperger ◽  
S. John Hogan ◽  
Gábor Stépán
Keyword(s):  
Cutting Force ◽  
Distributed Delay ◽  
Nonlinear Function ◽  
Force Model ◽  
Center Manifold Reduction ◽  
Stability Boundaries ◽  
Force System ◽  
Bistable Region ◽  
The Stability ◽  
Machining Operations

Regenerative machine tool chatter is investigated for a single-degree-of-freedom model of turning processes. The cutting force is modeled as the resultant of a force system distributed along the rake face of the tool, whose magnitude is a nonlinear function of the chip thickness. Thus, the process is described by a nonlinear delay-differential equation, where a short distributed delay is superimposed on the regenerative point delay. The corresponding stability lobe diagrams are computed and are shown numerically that a subcritical Hopf bifurcation occurs along the stability boundaries for realistic cutting-force distributions. Therefore, a bistable region exists near the stability boundaries, where large-amplitude vibrations (chatter) may arise for large perturbations. Analytical formulas are obtained to estimate the size of the bistable region based on center manifold reduction and normal form calculations for the governing distributed-delay equation. The locally and globally stable parameter regions are computed numerically as well using the continuation algorithm implemented in dde-biftool. The results can be considered as an extension of the bifurcation analysis of machining operations with point delay.

Generic Simulation Approach for Multi-Axis Machining, Part 2: Model Calibration and Feed Rate Scheduling

2002 ◽  
Vol 124 (3) ◽  
pp. 634-642 ◽  
Author(s):  
T. Bailey ◽  
M. A. Elbestawi ◽  
T. I. El-Wardany ◽  
P. Fitzpatrick
Keyword(s):  
Cutting Force ◽  
Feed Rate ◽  
Model Calibration ◽  
Metal Removal ◽  
Calibration Procedure ◽  
Model Verification ◽  
Force Model ◽  
Cutting Force Coefficients ◽  
Force Coefficients ◽  
Rate Scheduling

This is the second part of a two-part paper presenting a new methodology for analytically simulating multi-axis machining of complex sculptured surfaces. The first section of this paper offers a detailed explanation of the model calibration procedure. A new methodology is presented for accurately determining the cutting force coefficients for multi-axis machining. The force model presented in Part 1 of this paper is reformulated so that the cutting force coefficients account for the effects of feed rate, cutting speed, and a complex cutting edge design. Experimental results are presented for the calibration procedure. Model verification tests were conducted with these cutting force coefficients. These tests demonstrate that the predicted forces are within 5% of experimentally measured forces. Simulated results are also shown for predicting dynamic cutting forces and static/dynamic tool deflection. The second section of the paper discusses how the modeling methodology can be applied for feed rate scheduling in an industrial application. A case study for process optimization of machining an airfoil-like surface is used for demonstration. Based on the predicted instantaneous chip load and/or a specified force constraint, feed rate scheduling is utilized to increase metal removal rate. The feed rate scheduling implementation results in a 30% reduction in machining time for the airfoil-like surface.

Experimental Identification of Cutting Force Coefficients for Finish-Milling Operations Considering the Sensor’s Transmissibility

2015 ◽  
Author(s):  
S. Rekers ◽  
O. Adams ◽  
D. Veselovac ◽  
F. Klocke
Keyword(s):  
Cutting Force ◽  
Turbine Blades ◽  
Force Model ◽  
Force Measurements ◽  
Process Stability ◽  
Cutting Force Coefficients ◽  
Force Coefficients ◽  
Aerodynamic Properties ◽  
Marquardt Algorithm ◽  
Highly Nonlinear

Due to lightweight construction numerous parts in turbomachinery industry with aerodynamic properties exhibit thin-walled features. Typical examples are compressor blades or turbine blades. Finish-milling depicts a stage of the manufacturing process of these parts with significant value creation. A major limitation of productivity is process stability in terms of self-excited or forced vibration. Different simulation approaches attempt determining a priori the process stability to avoid a bad surface quality, accelerated tool wear, tool breakage or scrapped parts. One distinctive part of these simulations is a cutting force model which incorporates material and tool dependent coefficients. The simulation accuracy directly depends on the exactness of these coefficients. Usually, these coefficients are identified experimentally from cutting force measurements with piezoelectric sensors, whose transmissibility is nonlinear. In this paper a multidimensional stationary inverse filter for compensating the influence of the nonlinear transmissibility of force sensors is presented. In a subsequent step, a Levenberg–Marquardt algorithm is used to identify cutting force coefficients from filtered force measurements. The functionality of the filter is validated by comparing highly nonlinear and almost linear piezoelectric force measurement sensors connected in series during finish-milling experiments. The accuracy of the identified cutting force coefficients is assessed by comparing cutting force simulations to measurements.

Stability Predictions for End Milling Operations With a Nonlinear Cutting Force Model

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Alex Elías-Zúñiga ◽  
Jovanny Pacheco-Bolívar ◽  
Francisco Araya ◽  
Alejandro Martínez-López ◽  
Oscar Martínez-Romero ◽  
...  
Keyword(s):  
Experimental Data ◽  
Cutting Force ◽  
End Milling ◽  
Stability Conditions ◽  
Force Model ◽  
Process Stability ◽  
Cutting Force Model ◽  
Stability Lobes ◽  
Milling Operations ◽  
The Stability

The aim of this paper is to obtain the stability lobes for milling operations with a nonlinear cutting force model. The work is focused on the generation of stability lobes based on a formulation with Chebyshev polynomials and the semidiscretization method, considering a nonlinear cutting force model. Comparisons were conducted between experimental data at 5% radial immersion with aluminum workpiece and predictions based on Chebyshev and semidiscretization. In all cases, the use of nonlinear cutting force model provides better prediction of process stability conditions.

Identification of Polynomial Cutting Coefficients for a Dual-Mechanism Ball-end Milling Force Model

2019 ◽  
Vol 13 (3) ◽  
pp. 232-240
Author(s):  
Zhixin Feng ◽  
Meng Liu ◽  
Guohe Li
Keyword(s):  
Cutting Force ◽  
End Milling ◽  
Least Square ◽  
Force Model ◽  
Cutting Force Coefficients ◽  
Milling Force ◽  
Ball End Milling ◽  
Force Coefficients ◽  
Cutting Coefficients ◽  
Milling Force Model

Background: Calibration of cutting coefficients is the key content in modeling a mechanistic cutting force model. Generally, in modeling cutting force for ball end milling, the tangent, radial and binormal cutting force coefficients are each considered as a polynomial, respectively. This fact is due to the dependency between the cutting force coefficients and the cutting edge inclination angle which is variable in ball-end mills. Objective: This paper presents an approach to determine the polynomial cutting force coefficients. Methods: In this approach, the cutting force coefficients are expressed as explicit linear equations about the average slotting forces. After analysis of the least square regression method which is utilized in the cutting coefficients evaluation, the principle of cutting parameters choice in calibration experiment and the relationship between the order of polynomial and the number of experiments are presented. Besides, a lot of patents on identification of polynomial cutting coefficients for milling force model were studied. Results: Finally, a series of semi-slotting verification cutting tests were arranged, the measured force agrees well with the predicted force, which demonstrates the effectiveness of this approach. Conclusion: Based on the calibration method proposed in this paper, the cutting coefficients can be determined through (m+2) slotting experiments for m-degree shearing coefficients polynomial theoretically.

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