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.

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.

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.

Discrete Time-Delay Optimal Control Method for Experimental Active Chatter Suppression and Its Closed-Loop Stability Analysis

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Xingwu Zhang ◽  
Ziyu Yin ◽  
Jiawei Gao ◽  
Jinxin Liu ◽  
Robert X. Gao ◽  
...  
Keyword(s):  
Optimal Control ◽  
Closed Loop ◽  
Control Method ◽  
Trial And Error ◽  
Stability Lobe Diagram ◽  
Weighting Matrix ◽  
Chatter Suppression ◽  
Stability Lobe ◽  
Optimal Control Method ◽  
Discrete Time Delay

Chatter is a self-excited and unstable vibration phenomenon during machining operations, which affects the workpiece surface quality and the production efficiency. Active chatter control has been intensively studied to mitigate chatter and expand the boundary of machining stability. This paper presents a discrete time-delay optimal control method for chatter suppression. A dynamical model incorporating the time-periodic and time-delayed characteristic of active chatter suppression during the milling process is first formulated. Next, the milling system is represented as a discrete linear time-invariant (LTI) system with state-space description through averaging and discretization. An optimal control strategy is then formulated to stabilize unstable cutting states, where the balanced realization method is applied to determine the weighting matrix without trial and error. Finally, a closed-loop stability lobe diagram (CLSLD) is proposed to evaluate the performance of the designed controller based on the proposed method. The CLSLD can provide the stability lobe diagram with control and evaluate the performance and robustness of the controller cross the tested spindle speeds. Through many numerical simulations and experimental studies, it demonstrates that the proposed control method can make the unstable cutting parameters stable with control on, reduce the control force to 21% of traditional weighting matrix selection method by trial and error in simulation, and reduce the amplitude of chatter frequency up to 78.6% in experiment. Hence, the designed controller reduces the performance requirements of actuators during active chatter suppression.

Modelling and simulation of surface topography machined by peripheral milling considering tool radial runout and axial drift

2019 ◽  
Vol 233 (12) ◽  
pp. 2227-2240 ◽  
Author(s):  
Hui-Qun Chen ◽  
Qing-Hui Wang
Keyword(s):  
Surface Roughness ◽  
Surface Topography ◽  
Surface Finish ◽  
Dominant Frequency ◽  
Peripheral Milling ◽  
Stability Lobe Diagram ◽  
Vector Operation ◽  
Good Surface ◽  
Stability Lobe ◽  
Feed Mark

Based on the Z-map model of a workpiece and the dynamic cutting forces model of peripheral milling in which the regenerative effect of tool radial runout and axial drift are considered, a model for the prediction of surface topography in peripheral milling operations is presented. According to the stability lobe diagram obtained by the zero-order analytical method, the relationship between spindle speed and surface topography, the tool radial runout, and the axial drift following the chatter are studied. The results show that a stable cutting status but a poor surface finish is obtained at the spindle speeds at which the dominant frequency of the milling system is integral multiples of the selected machining frequency, and a stable cutting status with a good surface finish can be obtained near and on the left side of the resonant spindle speeds determined by the predicted stability lobe diagram. The motion equations of any tooth end mill for peripheral milling are established, and these equations are based on the transformation matrix and the vector operation principle of motion-homogeneous coordinates. In addition, the simulation algorithm and the system of surface topography generated in peripheral milling are given based on the Z-map model. Cutting tests are carried out, and good agreement between the measured surface topographies and the topographies predicted by the model in this study is found in terms of their shape, magnitude, feed mark, profile height of cross-section, and surface roughness. The simulation results show that the milling surface roughness increases with the increase in feed per tooth, which further shows that this simulation system has high credibility. Thus, the simulation and experimental results can provide some practical instructions for the actual peripheral milling in determining the optimal machining conditions.

PREDICTION AND INVESTIGATION OF SURFACE ROUGHNESS WHILE TURNING SG IRON WITH CUBIC BORON NITRIDE (CBN) AND TUNGSTEN CARBIDE INSERTS

2017 ◽  
Vol 41 (1) ◽  
pp. 129-141 ◽  
Author(s):  
K.M. Kumar ◽  
P. Hariharan
Keyword(s):  
Surface Roughness ◽  
Boron Nitride ◽  
Tungsten Carbide ◽  
Cubic Boron Nitride ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Spheroidal Graphite ◽  
Surface Model ◽  
Sg Iron ◽  
The Impact

This work compares the effect of cubic boron nitride (CBN) and multilayer (TiCN+Al2O3+TiN) coated tungsten carbide (WC) tools during the turning of spheroidal graphite (SG) nodular iron. Nodular irons have more ductility which is required in mechanical components that demand high fatigue resistance like crankshafts, cam shafts, bearing caps and clutch housings. The impact of various process parameters like the depth of cut, cutting speed and feed on the surface roughness (Ra) of SG iron is studied and optimized using the response surface model. The chip morphology is also discussed for evaluation of the quality of the turned surface. The experimental outcomes reveal that the WC tool offers a high surface finish at the optimal combination of the cutting speed at 102 meter/minute, feed at 0.051 millimeter/revolution and depth of cut at 0.5 millimeter and that, for the CBN insert, at 245 meter/minute of cutting speed, 0.051 millimeter/revolution of feed and 0.75 millimeter of depth of cut.

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.

scholarly journals Analysis and prediction of the impact of technological parameters on cutting force components in rough milling of AZ31 magnesium alloy

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
M. Kulisz ◽  
I. Zagórski ◽  
A. Weremczuk ◽  
R. Rusinek ◽  
J. Korpysa
Keyword(s):  
Neural Networks ◽  
Magnesium Alloy ◽  
Cutting Force ◽  
High Speed ◽  
Cutting Speed ◽  
Az31 Magnesium Alloy ◽  
High Speed Machining ◽  
Stability Lobe Diagram ◽  
Machining Conditions ◽  
Stability Lobe

AbstractThis paper presents the results of experimental study of the AZ31 magnesium alloy milling process. Dry milling was carried out under high-speed machining conditions. First, a stability lobe diagram was determined using CutPro software. Next, experimental studies were carried out to verify the stability lobe diagram. The tests were carried out for different feed per tooth and cutting speed values using two types of tools. During the experimental investigations, cutting forces in three directions were recorded. The obtained time series were subjected to general analysis and analysis using composite multiscale entropy. Modelling and prediction were performed using Statistica Neural Network software, in which two types of neural networks were applied: multi-layered perceptron and radial basis function. It was observed that milling with high cutting speed values allows for component values of cutting force to be lowered as a result of the transition into the high-speed machining conditions range. In most cases, the highest values for the analysed parameters were recorded for the component Fx, whereas the lowest were recorded for Fy. Additionally, the paper shows that a prediction (with the use of artificial neural networks) of the components of cutting force can be made, both for the amplitudes of components of cutting force Famp and for root mean square Frms.

scholarly journals Multi-objective optimization and analysis for laser beam cutting of stainless steel (SS304) using hybrid statistical tools GA-RSM

2021 ◽  
Vol 1201 (1) ◽  
pp. 012030
Author(s):  
A D Tura ◽  
H B Mamo ◽  
D G Desisa
Keyword(s):  
Genetic Algorithm ◽  
Surface Roughness ◽  
Stainless Steel ◽  
Laser Beam ◽  
Response Surface ◽  
Focal Point ◽  
Cutting Speed ◽  
Machining Parameters ◽  
Multi Objective ◽  
The Impact

Abstract A laser beam machine is a non-traditional manufacturing technique that uses thermal energy to cut nearly all types of materials. The quality of laser cutting is significantly affected by process parameters. The purpose of this study is to use a genetic algorithm (GA) in conjunction with response surface approaches to improve surface roughness in laser beam cutting CO2 with a continuous wave of SS 304 stainless steel. The effects of the machining parameters, such as cutting speed, nitrogen gas pressure, and focal point location, were investigated quantitatively and optimized. The tests were carried out using the Taguchi L9 orthogonal mesh approach. Analysis of variance, main effect plots, and 3D surface plots were used to evaluate the impact of cutting settings on surface roughness. A multi-objective genetic algorithm in MATLAB was used to achieve a minimum surface roughness of 0.93746 μm, with the input parameters being 2028.712 mm/m cutting speed, 11.389 bar nitrogen pressure, and a focal point position of - 2.499 mm. The optimum results of each method were compared, as the results the response surface approach is less promising than the genetic algorithm method.

Stability Prediction of Milling Process With Closed Machining System Dynamics With Flexible Thin-Walled Workpiece

2015 ◽  
Author(s):  
Chao Xu ◽  
Pingfa Feng ◽  
Dingwen Yu ◽  
Zhijun Wu ◽  
Jianfu Zhang
Keyword(s):  
Support System ◽  
Milling Process ◽  
Machining Process ◽  
Stability Lobe Diagram ◽  
Closed Model ◽  
Flexible Support ◽  
Stability Lobe ◽  
Machining System ◽  
Thin Walled ◽  
The Stability

Despite recent advances and improvements in modeling and prediction of the dynamics of the machining process, an efficient machining process is limited due to chatter and instability of machining system. In fact, the machining system contains various kinds of joints, which cause difficulties in dynamics modeling, simulation and prediction. Moreover, the flexible support system results in large deformation and violent vibration of the workpiece when machining, and the thin-walled workpiece easily gives rise to the chatter of the machining system. Therefore, the dynamics of the flexible support system was considered to calculate stability lobe diagram in the modeling of milling process. The whole machining system was regarded as a closed loop composed by the machine tool structures, support, workpiece and machining process. In this paper, the receptance coupling (RC) method was introduced to predict the dynamics of the closed machining system. A milling process was taken for example to predict the chatter limitations using the dynamics of closed model. The mathematical model of the machining system (machine tool structures, spindle, holder and tool), together with the details of joint contacts, was given based on the RC method. The RC model was used to obtain the dynamics of the system, while receptance of the tool point was coupled. Based on the coupling model of the machining system, the depth limitations under different speeds were estimated for the technology parameter optimization in milling process. The response was considered to be the sum of the cutting point and the support system. The flexibility of the support system was considered to be the feedback of the cutting stiffness. By this means, the traditional model was modified to calculate the stability lobe diagram based on the dynamics of the spindle and support system. Furthermore, the milling experiment was carried out to verify the prediction results, and the dominant natural frequencies of receptance at tool point were obtained by modal testing to define the stability lobe diagram. It was found that the chatter results matched well with the stability lobes. It was concluded that the support system with poor stiffness might cause violent chatter especially when the workpiece was thin-walled. The cutting depth limitations of the flexible support system were lower than that of the rigid one. Moreover, this closed model of the machining system is appropriate for the chatter prediction of the flexible support system or thin-walled workpiece, so it is helpful for a better parameter optimization.

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