scholarly journals Identification of process damping for chatter prediction in milling

2018 ◽  
Vol 175 ◽  
pp. 02002
Author(s):  
Charles M. Zheng ◽  
Chou-Fu Liang ◽  
Hai-Yi Cai ◽  
Shui-Shen Zhang
Keyword(s):  
Damping Ratio ◽  
Depth Of Cut ◽  
Structural Damping ◽  
Stability Lobe Diagram ◽  
Easy Method ◽  
Process Damping ◽  
Stability Lobe ◽  
Mathematical Expressions ◽  
The Stability ◽  
The Impact

Traditionally, forecasting stability lobe diagram in milling is limited by complex damping identification procedures, so only structural damping from the impact experiment is used for predicting stability lobe diagram in most milling cases. In this study, by using the mathematical expressions among damping ratio, “critical limiting depth of cut” and “worst spindle speed”, it is shown that the predicted “critical limiting depth of cut” based on the structural damping divided by the measured “critical limiting depth of cut” can be approximately equal to the structural damping divided by the total damping. Based on this relationship, it is easy to estimate the total damping or process damping from the experiment within the selected spindle speeds. In practice, this paper presents an easy method for predicting stability lobe diagram using the total damping. At the same time, experiments have confirmed that using the prediction model of total damping can more accurately predict the stability lobe diagram.

scholarly journals Research of Chatter Suppression in Turning Operation with Process Damping using Stability Lobe Diagram

2019 ◽  
Vol 8 (12S2) ◽  
pp. 539-543
Keyword(s):  
Surface Roughness ◽  
Cutting Speed ◽  
Modal Testing ◽  
Stability Lobe Diagram ◽  
Diagram Method ◽  
Process Damping ◽  
Chatter Suppression ◽  
Stability Lobe ◽  
The Stability ◽  
The Impact

This paper presents a chatter detection technique based on the stability of the measured Ra and Rz values of process damping and surface roughness in low cutting speed activities. In practice, process damping during machining procedures is hard to predict and identify due to the model and technique of limitation. The impact of cutting conditions on process damping in turning with P20 steel pre-hardened metal in terms of cutting velocity, feed rate and cutting depth was explored by the Stability Lobe Diagram method. A CNC turning machine was used in dry turning procedures with carbide insert. The highest and minimum value of natural frequencies and damping ratios were evaluated by modal testing and the stability lobe diagram analysis was applied. It is concluded that in the same region of the Stability Lobe Diagram, the chatter and measured surface roughness values were correlated and shown to have strong consensus.

The Effect of Cutting Process Parameters on the Stability in Milling

2014 ◽  
Vol 887-888 ◽  
pp. 1200-1204 ◽  
Author(s):  
Te Ching Hsiao ◽  
Shyh Chour Huang
Keyword(s):  
Damping Ratio ◽  
Milling Process ◽  
Material Behavior ◽  
Cutting Process ◽  
Force Model ◽  
Stability Lobe Diagram ◽  
Workpiece Material ◽  
Stability Lobe ◽  
The Stability ◽  
Tool Diameter

In the milling process, the dynamic system in the cutting process is composed of the tool, workpiece, and machine tools themselves. Therefore the mill geometric parameter, workpiece material behavior, and the modal parameters of the cutting system all will influence the stability in milling. Using FLN method and convolution force model to predict the chatter stability of milling process, and discussing the effect of milling parameter on the stability in this article. According to the result: with the increase of the tool diameter, stiffness, damping ratio or the reducing of tangential cutting force coefficient and radial width of cut, the stability lobe diagram tends to move upward. With the increase of natural frequency, the stability lobe diagram tends to move to right side. With the increase of the number of tooth, the stability lobe diagram tends to move downward.

A Contribution to Improve the Accuracy of Chatter Prediction in Machine Tools Using the Stability Lobe Diagram

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Raphael Galdino dos Santos ◽  
Reginaldo Teixeira Coelho
Keyword(s):  
End Milling ◽  
Depth Of Cut ◽  
Electronic Control ◽  
Stability Lobe Diagram ◽  
Simple Method ◽  
Free Zone ◽  
Stability Lobe ◽  
Chatter Prediction ◽  
The Stability ◽  
Selection Of

The chatter phenomenon can severely limit the power available for milling. The stability lobe diagram (SLD) is a very fast and simple method to predict the chatter free zone, allowing the selection of the most adequate spindle speed and depth of cut for higher productivity. However, the data used to calculate the SLD, coming from frequency response functions (FRFs), must be acquired adequately to improve the predictability. FRFs result differently depending on the activation of the spindle electronic control. The present work uses SLDs to investigate these differences and experimental end milling tests to assess the accuracy of SLDs curves. Results indicate that the inclusion of spindle electronic control provides better accuracy in predicting the chatter in milling.

scholarly journals Measurement-Based Modal Analysis and Stability Prediction on Turn-Milling of Hollow Turbine Blade

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Zhengcai Zhao ◽  
Junming Hou ◽  
Yucan Fu
Keyword(s):  
Modal Analysis ◽  
Damping Ratio ◽  
Stability Prediction ◽  
Stability Lobe Diagram ◽  
Structural Part ◽  
Stability Lobe ◽  
Hollow Blade ◽  
Machining System ◽  
The Impact ◽  
Turn Milling

Hollow blades with honeycomb structures are increasingly used in the turbine engines for reducing weight and saving costs. The hollow blade is a typical thin-walled structural part with low stiffness, the machining system of which is often unstable and likely to chatter. The most effective solution to avoid the machining chatter is to guide the hollow blade to be machined in a stable machining zone. This paper proposes a measurement-based approach for modal analysis and stability prediction of turn-milling hollow blade. The impact test was carried out to achieve the FRF curves on the hollow blade and the milling tool. An extremum method was employed to obtain an equivalent FRF curve, from which the modal parameters involving the natural frequency, damping ratio, and stiffness were computed. Afterwards, the semidiscretization method was used to draw a stability lobe diagram to predict the stability when turn-milling hollow blades. The experimental results confirm the feasibility of the predicted stability lobe diagram.

scholarly journals Chatter identification in milling of Inconel 625 based on recurrence plot technique and Hilbert vibration decomposition

2018 ◽  
Vol 148 ◽  
pp. 09003 ◽  
Author(s):  
Paweł Lajmert ◽  
Rafał Rusinek ◽  
Bogdan Kruszyński
Keyword(s):  
Stability Limit ◽  
Recurrence Plot ◽  
Milling Process ◽  
Machining Process ◽  
Inconel 625 ◽  
Depth Of Cut ◽  
Force Measurements ◽  
Stability Lobe ◽  
Theoretical Finding ◽  
The Stability

In the paper a cutting stability in the milling process of nickel based alloy Inconel 625 is analysed. This problem is often considered theoretically, but the theoretical finding do not always agree with experimental results. For this reason, the paper presents different methods for instability identification during real machining process. A stability lobe diagram is created based on data obtained in impact test of an end mill. Next, the cutting tests were conducted in which the axial cutting depth of cut was gradually increased in order to find a stability limit. Finally, based on the cutting force measurements the stability estimation problem is investigated using the recurrence plot technique and Hilbert vibration decomposition method.

Dynamics and Stability of Milling Process Considering the Gyroscopic Effects

2009 ◽  
Vol 76-78 ◽  
pp. 624-629 ◽  
Author(s):  
Shan Shan Sun ◽  
W.X. Tang ◽  
H.F. Huang ◽  
Xi Qing Xu
Keyword(s):  
High Speed ◽  
Milling Process ◽  
Depth Of Cut ◽  
Stability Lobe Diagram ◽  
High Speed Milling ◽  
Stability Lobe ◽  
Ultra High Speed ◽  
Resonance Response ◽  
Critical Depth Of Cut ◽  
Gyroscopic Effects

A dynamics model is established considering gyroscopic effects due to high speed rotating spindle-tool system in ultra-high speed milling (USM). The proposed method for predicting stability enables a new 3D stability lobe diagram to be developed in the presence of gyroscopic effects, to cover all the intermediate stages of spindle speed. The influences of the gyroscopic effects on dynamics and stability in USM are analyzed. It is shown that the gyroscopic effects lower the resonance response frequencies of the spindle-tool system and the stable critical depth of cut in ultra-high speed milling.

scholarly journals Torsional and longitudinal vibration of suspension bridge subject to aerodynamic forces

1998 ◽  
Vol 4 (5) ◽  
pp. 393-421 ◽  
Author(s):  
N. U. Ahmed ◽  
H. Harbi
Keyword(s):  
Longitudinal Vibration ◽  
Suspension Bridge ◽  
Stability Of Motion ◽  
Structural Damping ◽  
Aerodynamic Forces ◽  
Coupled Partial Differential Equations ◽  
The Road ◽  
The Stability ◽  
The Impact ◽  
Nonlinear Operation

In this paper we consider a dynamic model of suspension bridge governed by a pair of coupled partial differential equations which describe both torsional and longitudinal vibration of the road bed. The vertical and torsional motions are coupled through a nonlinear operation with the nonlinearity arising from loss of tension in the vertical cables supporting the decks. We study the impact of wind forces on the stability of motion of this system both in the absence and presence of viscous and structural damping. The results are illustrated by numerical simulation.

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.

scholarly journals Effects of Machine Tool Spindle Decay on the Stability Lobe Diagram: An Analytical-Experimental Study

2021 ◽  
Author(s):  
Omar Gaber ◽  
Seyed M. Hashemi
Keyword(s):  
Machine Tool ◽  
Natural Frequency ◽  
Dynamic Stiffness ◽  
Significant Shift ◽  
Stability Lobe Diagram ◽  
Element Analysis ◽  
Stability Lobe ◽  
Machine Tool Spindle ◽  
Linear Spring ◽  
The Stability

An analytical-experimental investigation of machine tool spindle decay and its effects of the system’s stability lobe diagram (SLD) is presented. A dynamic stiffness matrix (DSM)model for the vibration analysis of the OKADA VM500 machine spindle is developed and is validated against Finite Element Analysis (FEA).The model is then refined to incorporate flexibility of the system’s bearings, originally modeled as simply supported boundary conditions, where the bearings are modeled as linear spring elements.The system fundamental frequency obtained from the modal analysis carried on an experimental setup is then used to calibrate the DSM model by tuning the springs’ constants. The resulting natural frequency is also used to determine the 2D stability lobes diagram (SLD) for said spindle. Exploiting the presented approach and calibrated DSM model it is shown that a hypothetical 10% change in the natural frequency would result in a significant shift in the SLD of the spindle system, which should be taken into consideration to ensure chatter-free machining over the spindle’s life cycle.

Preliminary Study on the Effect of Mass-Induced Damping on Machining Delicate Workpiece Geometry

2013 ◽  
Vol 764 ◽  
pp. 83-89
Author(s):  
A. Kamaruddin ◽  
W.C. Pan ◽  
S.L. Ding ◽  
J. Mo
Keyword(s):  
Machining Process ◽  
Depth Of Cut ◽  
Machining Processes ◽  
Stability Lobe ◽  
Mechanical Factors ◽  
Preliminary Study ◽  
Thin Walled ◽  
Enhance Efficiency ◽  
The Stability ◽  
Minor Increment

Study of predicting chatter has been around for many years. These studies are crucial for our understanding of machining processes and to enhance efficiency in manufacturing. This paper presents a new mechanism affecting the stability of machining process called mass induced damping. This effect is simulated numerically with tested values of initial parameters taken for impact tests of a thin-walled workpiece. Results from the simulation shows minor increment in allowable depth of cut by numerically calculated using stability lobe theory. This effect will open a new understanding how certain mechanical factors would affect the value of damping of a system.

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