Analytical Chatter Stability of Milling With Rotating Cutter Dynamics at Process Damping Speeds

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
M. Eynian ◽  
Y. Altintas
Keyword(s):  
Chip Thickness ◽  
Prediction Method ◽  
Vibration Velocity ◽  
Chatter Stability ◽  
Process Damping ◽  
End Mills ◽  
Nyquist Stability ◽  
Matrix Differential ◽  
The Stability ◽  
Delay Matrix

This paper presents a chatter stability prediction method for milling flexible workpiece with end mills having asymmetric structural dynamics. The dynamic chip thickness regenerated by the vibrations of the rotating cutter and the fixed workpiece is transformed into the principle modal directions of the rotating tool. The process damping is modeled as a linear function of vibration velocity. The dynamics of the milling system is modeled by a time delay matrix differential equation with time varying directional factors and speed dependent elements. The periodic directional factors are averaged over a spindle period, and the stability of the resulting time invariant but speed dependent characteristic equation of the system is investigated using the Nyquist stability criterion. The stability model is verified with time domain numerical simulations and milling experiments.

scholarly journals Mechanics and Dynamics of Serrated End Mills

Manufacturing ◽  
2002 ◽  
Author(s):  
S. Doruk Merdol ◽  
Yusuf Altintas
Keyword(s):  
Time Domain ◽  
Cutting Forces ◽  
Chip Thickness ◽  
Cutting Edge ◽  
Chatter Stability ◽  
Edge Point ◽  
Oblique Cutting ◽  
Edge Geometry ◽  
End Mills ◽  
Chatter Stability Lobes

Mechanics and dynamics of serrated milling cutters are presented in the article. The serrated flute design knots are fitted to a cubic spline, which is then projected on helical flutes. Cutting edge geometry at any point along the serrated flute is represented by its immersion angle and tangent vectors in radial, tangential and helix directions. The chip thickness removed by each cutting edge point is determined by using previously proposed exact kinematics of dynamic milling. The cutting forces are evaluated by orthogonal to oblique cutting mechanics transformation. The experimentally proven model is able to predict the cutting forces and chatter stability lobes in time domain.

Mechanics and Dynamics of Serrated Cylindrical and Tapered End Mills

2004 ◽  
Vol 126 (2) ◽  
pp. 317-326 ◽  
Author(s):  
S. D. Merdol ◽  
Y. Altintas
Keyword(s):  
Cutting Forces ◽  
Chip Thickness ◽  
Cutting Edge ◽  
Chatter Stability ◽  
Edge Point ◽  
Edge Geometry ◽  
Proposed Model ◽  
Chatter Vibrations ◽  
End Mills ◽  
Chatter Stability Lobes

Serrated end mills are effectively used in suppressing chatter vibrations in roughing operations. Mechanics and dynamics of serrated cylindrical and tapered helical end mills are presented in the article. The serrated flute design knots are fitted to a cubic spline, which is then projected on helical flutes. Cutting edge geometry at any point along the serrated flute is represented by its immersion angle and tangent vectors in radial, tangential and helical directions. The chip thickness removed by each cutting edge point is determined by using exact kinematics of dynamic milling. The cutting forces are evaluated by orthogonal to oblique cutting mechanics transformation. The experimentally proven model is able to predict the cutting forces and chatter stability lobes in time domain. It is shown that the proposed model can be used in evaluating the performance of serrated end mills during their stage.

Time Domain Simulation of Milling Chatter Stability

2016 ◽  
Vol 836-837 ◽  
pp. 94-98 ◽  
Author(s):  
Ying Chao Ma ◽  
Min Wan ◽  
Wei Hong Zhang
Keyword(s):  
Time Domain ◽  
Chip Thickness ◽  
Time Algorithm ◽  
Milling Process ◽  
Time Domain Simulation ◽  
Chatter Stability ◽  
Stability Lobe ◽  
Machining System ◽  
The Stability ◽  
Milling Chatter

In this paper, time domain simulation has been carried out to study the chatter stability of milling process. Dynamic chip thickness is calculated by analyzing the kinematics of the cutter, and thus dynamic governing equation revealing the dynamic behaviors between the cutter and workpiece is established. Solving framework is constructed by using the Simulink module and S-Function of Matlab software, and dynamic deflection is achieved with the four-order Runge-Kutta algorithm. With the simulated cutting forces, a criterion for the construction of the stability lobe is suggested. At the same time, algorithm for the prediction of the surface topography involving the dynamic response of the machining system is developed.

Chatter Stability in Micro Milling Processes Considering Ploughing and Process Damping Effects

2009 ◽  
Author(s):  
Ramin Rahnama ◽  
Mozhdeh Sajjadi ◽  
Simon S. Park
Keyword(s):  
Time Domain ◽  
Chip Thickness ◽  
Experimental Tests ◽  
Micro Milling ◽  
Chatter Stability ◽  
Workpiece Material ◽  
Process Damping ◽  
Milling Operations ◽  
Milling Operation ◽  
Cutting Mechanisms

Micro milling operations utilize miniature tools to remove workpiece material, in order to create the desired 3D miniature components. One of the challenges in a micro milling operation is the unstable phenomenon called regenerative chatter. The occurrence of chatter in the micro domain, as in macro machining, is detrimental to part finishes and significantly reduces the longevity of tools. There are two different cutting mechanisms in micro milling operations, which are determined by the critical chip thickness. When the chip thickness is less than the critical chip thickness, no chip forms and ploughing occurs; whereas, when the chip thickness is greater than the critical chip thickness, a chip forms and shearing cutting happens. During each rotation of the tool, the cutting mechanisms switch from ploughing to shearing and vice versa. This paper introduces a time domain chatter model to investigate the effects of the ploughing and shearing mechanisms on stability. The model also considers the effects of process damping in micro milling, especially at low spindle speeds. Several experimental tests have been performed to validate the model.

Stability Prediction of Surrounding Rocks and Optimum Design of Roof-Bolt Parameters in Deep Roadway

2013 ◽  
Vol 353-356 ◽  
pp. 436-439
Author(s):  
De Sen Kong ◽  
Yong Po Chen
Keyword(s):  
Prediction Method ◽  
Simulation Method ◽  
Complex Stress ◽  
Roof Bolt ◽  
Deformation And Failure ◽  
Long Run ◽  
Research Findings ◽  
Stress Environment ◽  
Classification Prediction ◽  
The Stability

In order to forecast the stability of deep roadway and optimize the parameters of bolts, the complex stress environment and the multivariate surrounding rocks characteristics of deep roadway were analyzed. Then the classification prediction method and the numerical simulation method were simultaneously used to analysis the stability of surrounding rocks. Furthermore, the supporting parameters of bolts were also designed optimally. It was shown that the characteristics of stress distribution, deformation and failure zone of surrounding rocks are not ideal. So it is necessary to optimize the supporting parameters of deep roadway. All these research findings will provide the theory basis for bolts of deep roadway and will ensure the optimization of bolts and the stability of deep roadway in the long run.

Research on chatter stability in milling and parameter optimization based on process damping

2017 ◽  
Vol 24 (12) ◽  
pp. 2642-2655 ◽  
Author(s):  
Lida Zhu ◽  
Baoguang Liu ◽  
Hongyu Chen
Keyword(s):  
Surface Roughness ◽  
Frequency Method ◽  
Processing Efficiency ◽  
Machined Surface ◽  
Process Damping ◽  
Analysis Methodology ◽  
Optimization Of Process Parameters ◽  
Orthogonal Experiments ◽  
Cutting Chatter ◽  
The Stability

Cutting stability is the prerequisite to ensure efficient and high-precision machining, resulting in poor surface quality and damaged tool, which is the basis for the optimization of process parameters and improvement of processing efficiency. Aiming at process damping caused by interference between a tool flank face and a machined surface of part, the dynamic model and critical condition of stability is proposed in the paper. The frequency method is applied to solve the stability of the cutting chatter, and the correctness of the model is validated by experiments. Moreover, through orthogonal experiments, regression analysis methodology are adopted to establish a prediction model of surface roughness and finally combined with the study findings on milling stability based on process damping and surface roughness, achieved optimization of the milling parameters by genetic optimization algorithm. This conclusion provides a theoretical foundation and reference for the milling mechanism research.

Identification of Process Damping Coefficient Based on Material Constitutive Property

2014 ◽  
Author(s):  
Xiaoliang Jin
Keyword(s):  
Energy Dissipation ◽  
Flank Wear ◽  
Orthogonal Cutting ◽  
Element Model ◽  
Machining Process ◽  
Damping Coefficient ◽  
Chatter Stability ◽  
Workpiece Material ◽  
Process Damping ◽  
Constitutive Property

The contact between the tool flank wear land and wavy surface of workpiece causes energy dissipation which influences the tool vibration and chatter stability during a dynamic machining process. The process damping coefficient is affected by cutting conditions and constitutive property of workpiece material. This paper presents a finite element model of dynamic orthogonal cutting process with tool round edge and flank wear land. The process damping coefficient is identified based on the energy dissipation principle. The simulated results are experimentally validated.

Chatter Prediction Based on NC Physical Simulation in Machining Ti6Al4V Thin-Walled Components

2013 ◽  
Vol 395-396 ◽  
pp. 1008-1014
Author(s):  
Yu Li ◽  
Chao Sun
Keyword(s):  
Tool Path ◽  
Physical Simulation ◽  
Prediction Method ◽  
Cutting Parameters ◽  
Simulation Software ◽  
Cnc Machining ◽  
Machining Process ◽  
Chatter Stability ◽  
Chatter Prediction ◽  
Thin Walled

Chatter has been a problem in CNC machining process especially during machining thin-walled components with low stiffness. For accurately predicting chatter stability in machining Ti6Al4V thin-walled components, this paper establishes a chatter prediction method considering of cutting parameters and tool path. The fast chatter prediction method for thin-walled components is based on physical simulation software. Cutting parameters and tool path is achieved through the chatter stability lobes test and finite element simulation. Machining process is simulated by the physical simulation software using generated NC code. This proposed method transforms the NC physical simulation toward the practical methodology for the stability prediction over the multi-pocket structure milling.

Mechanics and Dynamics of Multifunctional Tools

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Min Wan ◽  
Zekai Murat Kilic ◽  
Yusuf Altintas
Keyword(s):  
Time Domain ◽  
Prediction Models ◽  
Chip Thickness ◽  
Combined Processes ◽  
Multiple Delays ◽  
Stability Prediction ◽  
Chatter Stability ◽  
Regenerative Effect ◽  
Hole Making ◽  
Chatter Stability Prediction

The mechanics and dynamics of the combined processes are presented for multifunctional tools, which can drill, bore, and chamfer holes in one operation. The oblique cutting forces on each cutting edge with varying geometry are modeled first, followed by their transformations to tangential, radial, and axial directions of the cutter. The regenerative effect of lateral and torsional/axial vibrations is considered in predicting the dynamic chip thickness with multiple delays due to distribution of cutting edges on the cutter body. The lateral and torsional/axial chatter stability of the complete hole making operation is predicted in semidiscrete time domain. The proposed static cutting force and chatter stability prediction models are experimentally proven for two different multifunctional tools in drilling Aluminum Al7050 and Steel AISI1045.

scholarly journals ON CONDITIONING FOR A GENERAL SYSTEM OF FOUR POINT BOUNDARY VALUE PROBLEMS

1996 ◽  
Vol 27 (3) ◽  
pp. 219-225
Author(s):  
M. S. N. MURTY
Keyword(s):  
Differential Equation ◽  
Fundamental Matrix ◽  
Close Relationships ◽  
General System ◽  
Point Boundary ◽  
Matrix Differential Equation ◽  
Growth Behaviour ◽  
First Order ◽  
Matrix Differential ◽  
The Stability

In this paper we investigate the close relationships between the stability constants and the growth behaviour of the fundamental matrix to the general FPBVP'S associated with the general first order matrix differential equation.

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