Mechanism of Cutting Force and Surface Generation in Dynamic Milling

1991 ◽  
Vol 113 (2) ◽  
pp. 160-168 ◽  
Author(s):  
D. Montgomery ◽  
Y. Altintas
Keyword(s):  
Cutting Force ◽  
Surface Finish ◽  
Cutting Forces ◽  
Chip Thickness ◽  
Dominant Frequency ◽  
Milling Process ◽  
Cutting Edge ◽  
Surface Generation ◽  
Uncut Chip Thickness ◽  
Improved Model

An improved model of the milling process is presented. The model proposes a method of determining cutting forces in five distinct regions where the cutting edge travels during dynamic milling. Trochoidal motion of the milling cutter is used in determining uncut chip thickness. The kinematics of the cutter and workpiece vibrations are modelled, which identifies the orientation and velocity direction of the cutting edge during dynamic cutting. The model allows the prediction of forces and surface finish under rigid or dynamic cutting conditions. The proposed mechanism of chip thickness, force and surface generation is proven with simulation and experimental results. It is found that when the tooth passing frequency is selected to be an integer ratio of a dominant frequency of tool-workpiece structure in milling imprint of vibrations on the surface finish is avoided.

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.

Dynamic cutting force prediction for micro end milling considering tool vibrations and run-out

2018 ◽  
Vol 233 (7) ◽  
pp. 2248-2261 ◽  
Author(s):  
Xuewei Zhang ◽  
Tianbiao Yu ◽  
Wanshan Wang
Keyword(s):  
Cutting Force ◽  
Cutting Forces ◽  
End Milling ◽  
Chip Thickness ◽  
Milling Process ◽  
Force Model ◽  
Dynamic Cutting Force ◽  
Micro End Milling ◽  
Tool Vibrations ◽  
End Milling Process

An accurate prediction of cutting forces in the micro end milling, which is affected by many factors, is the basis for increasing the machining productivity and selecting optimal cutting parameters. This paper develops a dynamic cutting force model in the micro end milling taking into account tool vibrations and run-out. The influence of tool run-out is integrated with the trochoidal trajectory of tooth and the size effect of cutting edge radius into the static undeformed chip thickness. Meanwhile, the real-time tool vibrations are obtained from differential motion equations with the measured modal parameters, in which the process damping effect is superposed as feedback on the undeformed chip thickness. The proposed dynamic cutting force model has been experimentally validated in the micro end milling process of the Al6061 workpiece. The tool run-out parameters and cutting forces coefficients can be identified on the basis of the measured cutting forces. Compared with the traditional model without tool vibrations and run-out, the predicted and measured cutting forces in the micro end milling process show closer agreement when considering tool vibrations and run-out.

Analysis of Cutting Forces in Helical Milling Process

2011 ◽  
Vol 215 ◽  
pp. 9-13 ◽  
Author(s):  
H.Y. Wang ◽  
Xu Da Qin ◽  
Qi Wang
Keyword(s):  
Titanium Alloy ◽  
Cutting Force ◽  
Rotational Speed ◽  
Cutting Forces ◽  
Chip Thickness ◽  
Milling Process ◽  
Helical Milling ◽  
Depth Of Cut ◽  
Cutting Experiment ◽  
Tool Cutting

Helical milling is used to generate holes, in which a tool attached to the rotating spindle traverses a helical trajectory, and the diameter of holes will be larger than that of the tool. Based on the principle of helical milling, this paper establishes analytical model of cutting forces. As the cutter travels on the helical path, intersection between the tool and the workpiece changes continuously, in which chip thickness and direction of the cutting forces will vary simultaneously. The cutting forces are not only direct proportional to the axial depth of cut, but also related to the rotational speed and orbital speed of the tool. Cutting experiment is conducted for the titanium alloy. The result shows that the simulated cutting force can be used to predict the change of cutting force under different conditions.

Generalized Modeling of Milling Mechanics and Dynamics: Part I — Helical End Mills

1999 ◽  
Author(s):  
Serafettin Engin ◽  
Yusuf Altintas
Keyword(s):  
Cutting Forces ◽  
Chip Thickness ◽  
Milling Process ◽  
Cutting Edge ◽  
End Mill ◽  
Edge Point ◽  
Stability Lobes ◽  
End Mills ◽  
Helical Flute ◽  
Cutting Point

Abstract Variety of helical end mill geometry is used in industry. Helical cylindrical, helical ball, taper helical ball, bull nosed and special purpose end mills are widely used in aerospace, automotive and die machining industry. While the geometry of each cutter may be different, the mechanics and dynamics of the milling process at each cutting edge point are common. This paper presents a generalized mathematical model of most helical end mills used in industry. The end mill geometry is modeled by helical flutes wrapped around a parametric envelope. The coordinates of a cutting edge point along the parametric helical flute are mathematically expressed. The chip thickness at each cutting point is evaluated by using the true kinematics of milling including the structural vibrations of both cutter and workpiece. By integrating the process along each cutting edge, which is in contact with the workpiece, the cutting forces, vibrations, dimensional surface finish and chatter stability lobes for an arbitrary end mill can be predicted. The predicted and measured cutting forces, surface roughness and stability lobes for ball, helical tapered ball, and bull nosed end mills are provided to illustrate the viability of the proposed generalized end mill analysis.

FE analysis of the effects of process representations on the prediction of residual stresses and chip morphology in the down-milling of Ti6Al4V

2021 ◽  
pp. 1-40
Author(s):  
Nejah Tounsi ◽  
Tahany El-Wardany
Keyword(s):  
Residual Stresses ◽  
Flank Wear ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Chip Morphology ◽  
Milling Process ◽  
Cutting Edge ◽  
Uncut Chip Thickness ◽  
Cutting Edge Radius ◽  
Edge Radius

Abstract In part II of these two-part papers, the effects of four FEM representations of the milling process on the prediction of chip morphology and residual stresses (RS) are investigated. Part II focuses on the milling of conventional uncut chip thickness h with finite cutting edge radius and flank wear, while part I of these two-part papers has reported on the results in the case of milling small uncut chip thickness in the micrometre range with finite cutting edge radius. Two geometric models of the flank-wear land composed of flat and curved wear land are proposed and assessed. The four process representations are: i) orthogonal cutting with flat wear land and with the mean uncut chip thickness h ¯; ii) orthogonal cutting with flat wear land and with variable h, which characterises the down-milling process and which is imposed on a flat surface of the final workpiece; iii) modelling the true kinematics of the down milling process with flat wear land and iv) modelling the true kinematics of the down milling process with curved wear land. They are designated as Cte-h, Var-h, True-h and True-h*. The effectiveness of these representations is assessed when milling Ti6Al4V with a flank-wear land of VB = 200µm.

On Tool Instability During Machining

1991 ◽  
Author(s):  
C. Sahay ◽  
R. N. Dubey
Keyword(s):  
Cutting Force ◽  
Shear Deformation ◽  
Static Analysis ◽  
Cutting Forces ◽  
Chip Thickness ◽  
Uncut Chip Thickness ◽  
Frictional Interaction ◽  
Machining System ◽  
The Relationship

Abstract The present paper describes the role of the tool in vibrations of a machining system. The cutting force has been assumed to be constant. The shear deformation of the tool is considered. The quasi-static analysis of the situation yields a maximum allowable uncut chip thickness, which shows how the frictional interaction at the tool face and the ratio of the components of cutting forces alter this value. The relationship also expresses the effect of tool dimensions and work material on the vibration of the tool.

A Mechanistic Cutting Force Model for 3D Ball-end Milling

2000 ◽  
Vol 123 (1) ◽  
pp. 23-29 ◽  
Author(s):  
Hsi-Yung Feng ◽  
Ning Su
Keyword(s):  
Cutting Force ◽  
Cutting Forces ◽  
End Milling ◽  
Chip Thickness ◽  
Milling Process ◽  
Force Model ◽  
Cutting Force Model ◽  
Ball End Milling ◽  
End Milling Process ◽  
Force Relationship

This paper presents an improved mechanistic cutting force model for the ball-end milling process. The objective is to accurately model the cutting forces for nonhorizontal and cross-feed cutter movements in 3D finishing ball-end milling. Main features of the model include: (1) a robust cut geometry identification method to establish the complicated engaged area on the cutter; (2) a generalized algorithm to determine the undeformed chip thickness for each engaged cutting edge element; and (3) a comprehensive empirical chip-force relationship to characterize nonhorizontal cutting mechanics. Experimental results have shown that the present model gives excellent predictions of cutting forces in 3D ball-end milling.

Cutting Force Prediction of Ball End Milling Based on Fully Voxel Representation of Cutting Edge and Instantaneous Workpiece Shape

2017 ◽  
Author(s):  
Isamu Nishida ◽  
Ryuma Okumura ◽  
Ryuta Sato ◽  
Keiichi Shirase
Keyword(s):  
Cutting Force ◽  
End Milling ◽  
Chip Thickness ◽  
Cutting Edge ◽  
Surface Shape ◽  
Uncut Chip Thickness ◽  
Ball End Milling ◽  
Voxel Model ◽  
Voxel Representation ◽  
Milling Forces

A new cutting force simulator has been developed to predict cutting force in ball end milling. This new simulator discretely calculates uncut chip thickness based on a fully voxel representation of the cutting edge and instantaneous workpiece shape. Previously, a workpiece voxel model was used to calculate uncut chip thickness under a complex change of workpiece shape. Using a workpiece voxel model, uncut chip thickness is detected by extracting the voxels removed per cutting edge tooth for the amount of material fed into the cutting edge. However, it is difficult to define the complicated shape of a cutting edge using the workpiece voxel model; the shape of the cutting edge must be defined by a mathematical expression. It is also difficult to model the voxels removed by the cutting edge when the tool posture is non-uniformly changed. We therefore propose a new method to detect uncut chip thickness, one in which both the cutting edge and the instantaneous workpiece shape are fully represented by a voxel model. Our proposed method precisely detects uncut chip thickness at minute tool rotational angles, making it possible to detect the uncut chip thickness between the complex surface shape of the workpiece and the particular shape of the cutting edge. To validate the effectiveness of our proposed method, experimental 5-axis milling tests using a ball end mill were conducted. Estimated milling forces for several tool postures were found to be in good agreement with the measured milling forces. Results from the experimental 5-axis milling validate the effectiveness of our proposed method.

Identification of Cutter Axis Tilt in End Milling

1997 ◽  
Vol 119 (2) ◽  
pp. 178-185 ◽  
Author(s):  
Li Zheng ◽  
S. Y. Liang
Keyword(s):  
Cutting Force ◽  
Cutting Forces ◽  
End Milling ◽  
Chip Thickness ◽  
Cutting Parameters ◽  
Milling Process ◽  
Mathematical Representation ◽  
Thickness Variation ◽  
Dynamic Force ◽  
Force Components

The scope of the paper is to discuss the identification of cutter axis tilt in end milling process via cutting force analysis. Cutter axis tilt redistributes the chip load among flutes thereby generating minor frequency components of cutting forces. These minor components can be utilized to infer the tilt geometry during the cutting action. This study involved the mathematical representation of chip thickness variation due to tilt, the modeling of local forces in relation to instantaneous chip thickness, the formulation of total cutting forces through convolution integration in the angle domain, the derivation of dynamic force components in the frequency domain, and the solution for tilt geometry from the dynamic cutting forces. Results show that the tilt magnitude and orientation can be estimated given the dynamic cutting force components along with the tool/work geometry, cutting parameters, and machining configuration. Numerical simulation results confirmed the validity of the angle domain convolution approach, and the end milling experimental data agreed with the analytical model.

A Micro Milling Model Considering Metal Phases and Minimum Chip Thickness

2008 ◽  
Vol 375-376 ◽  
pp. 505-509 ◽  
Author(s):  
Jin Sheng Wang ◽  
Jia Shun Shi ◽  
Ya Dong Gong ◽  
G. Abba ◽  
Guang Qi Cai
Keyword(s):  
Cutting Forces ◽  
Chip Thickness ◽  
Milling Process ◽  
Micro Milling ◽  
Surface Generation ◽  
Minimum Chip Thickness ◽  
Experiment Validation ◽  
Metal Phases

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.

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