scholarly journals EFFICIENT DETERMINATION OF STABILITY LOBE DIAGRAMS DEPLOYING AN AUTOMATED, DATA-BASED ONLINE NC PROGRAM ADAPTION

2021 ◽  
Vol 2021 (4) ◽  
pp. 4830-4835
Author(s):  
CHRISTIAN BRECHER ◽  
◽  
RALPH KLIMASCHKA ◽  
ALEXANDER STEINERT ◽  
STEPHAN NEUS ◽  
...  
Keyword(s):  
Cutting Parameters ◽  
Cutting Depth ◽  
Fast Detection ◽  
Stability Lobe ◽  
Nc Program ◽  
The Stability ◽  
Machining Operations ◽  
Stability Limits ◽  
Analytical Approaches ◽  
Stability Lobe Diagrams

Process instabilities due to regenerative chatter pose significant limitations on the achievable material removal rates and thus on the profitability of machining operations. Stability lobe diagrams serve to exploit the maximum yet stable cutting depth and can be determined either analytically or experimentally. While analytical approaches suffer from inaccuracies because of the assumptions made for the specific models, experimental stability lobe diagrams require extensive cutting tests. Therefore, this paper introduces a new automated experimental method for determining stability lobe diagrams in milling with reduced effort regarding time. A closed-loop system is designed, containing a sensor-based online chatter detection along with a strategy to set parameters for subsequent cuts based on the stability boundaries known at each iteration. Both cuts with continuously increasing cutting depth and varied spindle speed are deployed to ensure fast detection of stability limits. The method is tested for a slot milling use case and the results are compared to a conventionally obtained stability lobe diagram yielding a significantly reduction in required time (-90 %) and resources (-67 %) whilst maintaining good accuracy. The reduced effort qualifies the proposed method as a tool to rapidly deliver maximum productive yet stable cutting parameters for optimization of existing or enhanced planning of new manufacturing processes.

Stability Modeling and Analysis of Orthogonal Turn-Milling with Variable Cutting Depth and Cutting Thickness

2014 ◽  
Vol 852 ◽  
pp. 419-426
Author(s):  
Yong Wang ◽  
Rong Yan ◽  
Fang Yu Peng ◽  
Feng Qiu
Keyword(s):  
Milling Process ◽  
Cutting Depth ◽  
Modeling And Analysis ◽  
Stability Lobe ◽  
Stability Model ◽  
The Stability ◽  
Turn Milling ◽  
Stability Lobe Diagrams ◽  
Better Than ◽  
Stability Modeling

In orthogonal turn-milling process, both of the workpiece and the cutter rotate at the same time, which causes cutting depth and cutting thickness to change instantaneously. In this paper, a new 2D stability model of orthogonal turn-milling is established, in which the effect of variable cutting depth and cutting thickness is considered. The stability lobe diagrams are obtained by using Full-discretization Method. By analyzing the stability of orthogonal turn-milling, it is found that it is better than that of ordinary milling in same machining conditions. It means that in orthogonal turn-milling process deep cutting depth can be chosen and high machining efficiency can be obtained compared to that in ordinary milling process.

scholarly journals Studies on Surface Roughness in Stable and Unstable End-Milling

2020 ◽  
Author(s):  
Mahdi Eynian ◽  
Sunday Ogheneochuko Usino ◽  
Ana Esther Bonilla Hernández
Keyword(s):  
Surface Roughness ◽  
End Milling ◽  
Spindle Speed ◽  
Depth Of Cut ◽  
Sudden Increase ◽  
Stability Lobe ◽  
Stable Conditions ◽  
End Mills ◽  
The Stability ◽  
Stability Lobe Diagrams

Surface roughness is an important aspect of a machined piece and greatly influences its performance. This paper presents the surface roughness of end-milled aluminium plates in stable and unstable machining conditions at various spindle speed and depth of cuts machined with cylindrical end-mills. The surface roughness is measured using high-resolution surface replicas with a white light interferometry (WLI) microscope. The measurements of the end-milled floors show that the surface roughness as long as the cutting is performed in stable conditions is insensitive to the depth of cut or spindle speed. In contrast, within chattering conditions, which appear according to stability lobes, surface roughness values increase almost 100%. While at the valleys of the stability lobe diagram, there is a gradual increase in roughness, at the peaks of the stability lobe, the transition from the stable to unstable condition occurs with a sudden increase of the roughness values. In the study of down-milled walls, while the roughness increases with the depth of cut within both the stable and the chattering regions, the transition from the stable to chattering condition can lead to a much larger increase in the surface roughness. These results could be used for strategic selection of operation considering the needs of robustness and possible variation of dynamic parameters that can affect the position of the cutting conditions within the stability lobe diagrams.

Simulationsbasierte Fräsprozessauslegung*/Simulation-based design of milling-processes - Sensitivity analysis of stability lobe diagrams for automotive large-scale production

2017 ◽  
Vol 107 (11-12) ◽  
pp. 841-846
Author(s):  
J. Rempel ◽  
P. Jacobi ◽  
J. Friedrich ◽  
A. Prof. Verl ◽  
P. Prof. Wiederkehr ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Large Scale ◽  
Scale Production ◽  
Stability Lobe ◽  
Receptance Coupling ◽  
Large Scale Production ◽  
Simulation Based Design ◽  
Analysis Of Stability ◽  
Stability Limits ◽  
Stability Lobe Diagrams

In diesem Fachartikel werden die Einflüsse von Unsicherheiten in den Modellparameterwerten auf die Stabilitätsgrenze einer Stabilitätskarte aufgezeigt. Dazu wird an einem Beispielsystem eine Sensitivitätsanalyse für ein Verfahren zur Erzeugung von Stabilitätskarten durchgeführt. Zur Bestimmung des dynamischen Verhaltens der Werkzeugmaschine kommt eine Methode der Frequenzgang-Kopplung zum Einsatz.   To estimate the effect of uncertainties on the prediction of stability limits, a sensitivity analysis was conducted for a procedure to determine stability lobe diagrams for an example system. Thereby, a method of receptance coupling to identify the dynamic behavior of the tool center point was applied.

Research on Mechanism and Model of Cutting Chatter Based on the Cutting Parameters

2012 ◽  
Vol 479-481 ◽  
pp. 217-220
Author(s):  
Jin Hua Li ◽  
Yong Xian Liu ◽  
Hua Long Xie ◽  
Wei Wang ◽  
Bao Zhong Feng
Keyword(s):  
Cutting Force ◽  
Dynamic Theory ◽  
Cutting Parameters ◽  
Modal Parameters ◽  
Stability Zone ◽  
Cutting Depth ◽  
Cutting Force Coefficients ◽  
Depth Limit ◽  
Cutting Chatter ◽  
The Stability

According to the kinematics and dynamic theory, the regenerative cutting chatter is derived on the math and simplified within the probable range. The correlation is gained between the cutting depth limit and the spindle speed about the regenerative chatter. In Matlab, the mathematical modal is simulated based on the modal parameters, cutting parameters and cutting-force coefficients. The stability lobes are drawn in the diagram, the stability zone lies under the curve and avoid the occurrence of cutting chatter.

Dynamic modeling and stability prediction in milling process of thin-walled workpiece with multiple structural modes

2020 ◽  
pp. 095440542093371
Author(s):  
Zhao Zhang ◽  
Ming Luo ◽  
Baohai Wu ◽  
Dinghua Zhang
Keyword(s):  
Dynamic Model ◽  
Dynamic Modeling ◽  
Milling Process ◽  
Test Results ◽  
Stability Lobe ◽  
Milling Tool ◽  
Thin Walled ◽  
The Stability ◽  
Structural Mode ◽  
Stability Lobe Diagrams

Regenerative chatter can easily occur in the milling process of thin-walled workpiece due to the inherently low stiffness. This article aims to predict the stability of thin-walled workpiece in the milling process with a complete dynamic model. First, multiple structural modes of thin-walled workpiece are taken into consideration, and a complete dynamic model of thin-walled workpiece milling system is developed. Then, a numerical integration method is used to achieve the stability lobe diagrams of the milling system and identify the chatter frequency. Besides, the major structural mode, which is responsible for the occurrence of thin-walled workpiece chatter in the milling process, is predicted. A series of milling tests concerning a general cantilever plate are conducted, and the test results agree well with the predicted results, which shows the effectiveness of the proposed method. Finally, the effects of milling tool and structural modes on milling stability are discussed separately, which could provide theoretical basis for the dynamic modeling of thin-walled workpiece in milling process.

Optimization of different parameters related to milling tools to maximize the allowable cutting depth for chatter-free machining

2020 ◽  
Vol 235 (1-2) ◽  
pp. 230-241
Author(s):  
Ali Mokhtari ◽  
Mohammad Mahdi Jalili ◽  
Abbas Mazidi
Keyword(s):  
Genetic Algorithm ◽  
Cutting Tool ◽  
Milling Process ◽  
Optimization Process ◽  
Micro Milling ◽  
Beam Model ◽  
Cutting Depth ◽  
Stability Lobe ◽  
Milling Tool ◽  
Stability Lobe Diagrams

Determination of optimal parameters of cutting tool is one of the most significant factors in any operation planning of metal elements, especially in micro-milling process. This article presents an optimization procedure, based on genetic algorithms, to optimize some parameters related to micro-milling tool including number of teeth, shank diameter, fluted section diameter, shank length, taper length, and length of fluted section. The aim of this optimization is maximizing the minimum value of cutting depth on the border of stability lobe diagrams, which is called allowable cutting depth, for chatter-free machining. Cutting tool is modeled as a three-dimensional spinning cantilever Timoshenko beam based on strain gradient elasticity theory. Structural nonlinearity, gyroscopic moment, rotary inertia, and velocity-dependent process damping are also considered in the cutting tool model. The values of natural frequency, damping ratio, and material length scale of the micro-milling tool are calculated using a system identification based on genetic algorithm to match the analytical response with recorded experimental vibration signal. Using beam model, the allowable cutting depth is increased in the optimization process for a specific range of spindle speed to avoid the chatter phenomenon. Analytical study of micro-milling process stability is carried out to determine the cost function of the genetic algorithm. A plot of the greatest fitness in each generation is sketched. In addition, stability lobe diagrams before and after optimization process are presented to show the efficiency of the optimized micro-milling tool. In the presented examples, the results of genetic algorithm may lead to design or find a micro-milling tool that its acceptable cutting depth increases up to 1.9313 times.

scholarly journals A Tool Tuning Approximation Method: Exploration of the System Dynamics and its Impact on Milling Stability when Amending Tool Stickout

2021 ◽  
Author(s):  
Nikolai Bertelsen ◽  
Robert A. Alphinas ◽  
Klaus Bonde Ørskov
Keyword(s):  
Best Practices ◽  
Experimental Studies ◽  
Advanced Manufacturing ◽  
Approximation Solution ◽  
Linear Change ◽  
Stability Lobe ◽  
Vibrational Characteristics ◽  
The Stability ◽  
Validation Tests ◽  
Stability Lobe Diagrams

The shortest possible tool stickout has been the traditional go-to approach with expectations of increased stability and productivity. However, experimental studies at Danish-Advanced-Manufacturing-Research-Center (DAMRC) have proven that for some tool stickout lengths, there exist local productivity optimums when utilizing the Stability Lobe Diagrams for chatter avoidance. This contradicts with traditional logic and the best practices taught to machinists. This paper explores the vibrational characteristics and behaviour of a milling system over the tool stickout length. The experimental investigation has been conducted by tap testing multiple endmills where the tool stickout length has been varied. For each length, the modal parameters have been recorded and mapped to visualize behavioural tendencies. The insights are conceptualized into a tool tuning approximation solution. It builds on an almost linear change in the natural frequencies when amending tool stickout, which results in changed positions of the Chatter-free Stability Lobes. Validation tests on the tool tuning approximation solution have shown varying success of the solution. This outlines the need for further research on the boundary conditions of the solution, to understand at which conditions the tool tuning approximation solution is applicable.

An Analytical Model to Predict Chatter in Multi-Dimensional Periodically Time-Varying Machining Processes

Manufacturing ◽  
2003 ◽  
Author(s):  
William T. Corpus ◽  
William J. Endres
Keyword(s):  
Three Dimensional ◽  
Dimensional Case ◽  
Machining Processes ◽  
Damped System ◽  
Stability Lobe ◽  
Analytical Result ◽  
The Stability ◽  
The One ◽  
Time Invariant ◽  
Stability Limits

An approach is presented to determine the stability limits for machining processes that exhibit periodic time variation and multi-dimensional structural dynamics. The approach leverages the solution for the single-dimensional case, which identified an added set of stability lobes in addition to those corresponding to the time-invariant case. The solution is developed for two-dimensional dynamics for both a damped system and an undamped system; it may be expanded to any order and extended to three-dimensional dynamics. The undamped solution provides a mathematical description of the stability lobe locations along the speed axis and asymptotes for the damped case. Numerical time-domain simulation is used to confirm the analytical solution. While the agreement is good even for a first-order analytical result, yet another extra stability lobe, not seen in the one-dimensional case, is now seen in the numerical simulation results. Some of its characteristics are noted; however, further study is needed to understand its source.

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