A Sequential Greedy Search Algorithm With Bayesian Updating for Testing in High-Speed Milling Operations

2010 ◽  
Author(s):  
Mike Traverso ◽  
Raul Zapata ◽  
Jaydeep Karandikar ◽  
Tony L. Schmitz ◽  
Ali Abbas
Keyword(s):  
High Speed ◽  
Search Algorithm ◽  
Bayesian Updating ◽  
Test Point ◽  
Expected Value ◽  
Spindle Speed ◽  
Greedy Search ◽  
High Speed Milling ◽  
Stability Lobe ◽  
Axial Depth

This paper describes a probabilistic greedy search optimization algorithm for stability testing in high-speed milling. The test parameters (i.e., the experiment setup decisions) consist of the axial depth of cut and the spindle speed. These parameters are selected to maximize the expected value of profit using a greedy search approach (an approach that maximizes the expected value of each stage one step at a time). After a test is performed, Bayesian updating is applied to determine the posterior distribution of stability. The algorithm is then repeated to identify a new test point. The motivation for this work is that, while deterministic models for milling stability prediction are available, uncertainty in the inputs always exists. In this study, it is assumed that the tool point frequency response function, which is required for stability lobe diagram development, is unknown. Therefore, the probability of stability over the selected axial depth-spindle speed domain must be determined experimentally. The greedy search algorithm identifies the maximum expected value of profit within the selected domain, where profit is determined from the product of the profit function and the stability cumulative distribution function, referred to as the probability of stability. This optimal point is then tested to evaluate stability. Whether stable or unstable, the results are used to update the probability of stability. A stable test updates all axial depths smaller than test depth to be stable at the selected spindle speed, while an unstable test specifies that all axial depths above the test depth are unstable. After updating, a new test point is selected by the greedy search algorithm and the process is repeated. This select/test/update sequence is repeated until a preselected stopping criterion is reached. This paper presents both numerical results and experimental validation that the optimization/updating approach quickly converges to the well-known stability lobe behavior described in the literature. However, in this probabilistic technique the issue of uncertainty is also addressed and results can be obtained even if no information about the dynamic system is available.

scholarly journals Influence of the Cut Axial Depth on Surface Roughness at High-Speed Milling of Thin-Walled Workpieces

2021 ◽  
Vol 20 (2) ◽  
pp. 127-131
Author(s):  
A. I. Germashev ◽  
V. A. Logominov ◽  
S. I. Dyadya ◽  
Y. V. Kozlova ◽  
V. A. Krishtal
Keyword(s):  
High Speed ◽  
End Milling ◽  
Spindle Speed ◽  
Depth Of Cut ◽  
Work Piece ◽  
Natural Vibration Frequency ◽  
High Speed Milling ◽  
Wide Range ◽  
Thin Walled ◽  
Axial Depth

The paper presents the results of research on the dynamics of end milling of thin-walled work-pieces having complex geometric shapes. Since the milling process with shallow depths of cut is characterized by high intermittent cutting, the proportion of regenerative vibrations decreases, and the effect of forced vibrations on the dynamics of the process, on the contrary, increases. The influence of  axial depth of cut on the vibrations arising during processing, and roughness of the processed surface have been studied in paper.  The experiments have been carried out in a wide range of changes in the spindle speed at different axial cutting depths.  Vibrations of a thin-walled work-piece  have been recorded with an inductive sensor and recorded in digital form. Then an oscillogram has been used to estimate the amplitude and frequency of oscillations. The profilograms of the machined surface have been analysed. Roughness has been evaluated by the parameter Ra. The results have shown similar relationships for each of the investigated axial cutting depths. The worst cutting conditions  have been observed when the natural vibration frequency coincided with the tooth frequency or its harmonics. It is shown that the main cause of vibrations in high-speed milling  is forced rather than regenerative vibrations. Increasing the axial depth of cut at the same spindle speed increases the vibration amplitude. However, this does not significantly affect the roughness of the processed surface in cases when it comes to vibration-resistant processing.

Stability Prediction in High-Speed Milling Process Considering the Milling Force Coefficients Dependent on the Spindle Speed

2014 ◽  
Vol 13 (04) ◽  
pp. 247-255 ◽  
Author(s):  
Kunlong Wen ◽  
Houjun Qi ◽  
Gang Jin
Keyword(s):  
High Speed ◽  
Milling Process ◽  
Spindle Speed ◽  
Chatter Vibration ◽  
Milling Force ◽  
High Speed Milling ◽  
Force Coefficients ◽  
Stability Lobe ◽  
Vibration Model ◽  
The Stability

In order to further research the chatter vibration in high-speed milling, in this paper, a new regenerative chatter vibration model, considering the effect of milling force coefficients dependent on the spindle speed (MFCDSS) on the stability of high-speed milling process is proposed, and then milling stability lobe diagram is obtained, based on full-discretization method (FDM). The variable tendency of the stability of milling system is analyzed by comparisons in case of different radial immersion ratios in low-speed and high-speed milling regions, respectively. It is found that great stability predicting differences occur, especially in high-speed region when the MFCDSS is considered. This model can further supplement the theory of stability of high-speed milling process, it has certain engineering guidance significance in the selection of high-speed milling parameters.

scholarly journals Effect of High Speed Milling Process Parameters on the Milling Force and Surface Topography of AM50A Magnesium Alloy

2018 ◽  
Vol 36 (1) ◽  
pp. 124-131
Author(s):  
Hongji Zhang ◽  
Yuanyuan Ge ◽  
Hong Tang ◽  
Yaoyao Shi ◽  
Zengsheng Li
Keyword(s):  
Magnesium Alloy ◽  
Surface Quality ◽  
High Speed ◽  
Milling Process ◽  
Spindle Speed ◽  
Feed Speed ◽  
Milling Force ◽  
High Speed Milling ◽  
Milling Parameters

Within the scope of high speed milling process parameters, analyzed and discussed the effects of spindle speed, feed rate, milling depth and milling width on milling forces in the process of high speed milling of AM50A magnesium alloy. At the same time, the influence of milling parameters on the surface roughness of AM50A magnesium alloy has been revealed by means of the measurement of surface roughness and surface micro topography. High speed milling experiments of AM50A magnesium alloy were carried out by factorial design. Form the analysis of experimental results, The milling parameters, which have significant influence on milling force in high speed milling of AM50A magnesium alloy, are milling depth, milling width and feed speed, and the nonlinear characteristics of milling force and milling parameters. The milling force decreases with the increase of spindle in the given mill parameters. For the effects of milling parameters on surface quality of the performance, in the milling depth and feeding speed under certain conditions with the spindle speed increases the surface quality of AM50A magnesium alloy becomes better with the feed speed increases the surface quality becomes poor. When the spindle speed is greater than 12000r/min, the milling depth is less than 0.2mm, and the feed speed is less than 400mm/min, the milling surface quality can be obtained easily.

A Numerical Study of Uncertainty in Stability and Surface Location Error in High-Speed Milling

2005 ◽  
Author(s):  
Mohammad H. Kurdi ◽  
Tony L. Schmitz ◽  
Raphael T. Haftka ◽  
Brian P. Mann
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Removal Rate ◽  
Operating Conditions ◽  
Location Error ◽  
High Speed Milling ◽  
Surface Location Error ◽  
Input Parameters ◽  
Surface Location ◽  
Axial Depth

High-speed milling offers an efficient tool for developing cost effective manufacturing processes with acceptable dimensional accuracy. Realization of these benefits depends on an appropriate selection of preferred operating conditions. In a previous study, optimization was used to find these conditions for two objectives: material removal rate (MRR) and surface location error (SLE), with a Pareto front or tradeoff curve found for the two competing objectives. However, confidence in the optimization results depends on the uncertainty in the input parameters to the milling model (time finite element analysis was applied here for simultaneous prediction of stability and surface location error). In this paper the uncertainty of these input parameters such as cutting force coefficients, tool modal parameters, and cutting parameters is evaluated. The sensitivity of the maximum stable axial depth, blim, to each input parameter at each spindle speed is determined. This enables identification of parameters with high contribution to stability lobe uncertainty. Two methods are used to calculate uncertainty: 1) Monte Carlo simulation; and 2) numerical derivatives of the system eigenvalues. Once the uncertainty in axial depth is calculated, its effect is observed in the MRR and SLE uncertainties. This allows robust optimization that takes into consideration both performance and uncertainty.

scholarly journals SUPPRESSION OF PERIOD DOUBLING CHATTER IN HIGH-SPEED MILLING BY SPINDLE SPEED VARIATION

2011 ◽  
Vol 15 (2) ◽  
pp. 153-171 ◽  
Author(s):  
Sébastien Seguy ◽  
Tamás Insperger ◽  
Lionel Arnaud ◽  
Gilles Dessein ◽  
Grégoire Peigné
Keyword(s):  
High Speed ◽  
Period Doubling ◽  
Spindle Speed ◽  
High Speed Milling ◽  
Speed Variation ◽  
Spindle Speed Variation

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.

Avoiding Instability on the Milling of Parts with Thin Features

2006 ◽  
Vol 526 ◽  
pp. 37-42 ◽  
Author(s):  
Francisco Javier Campa ◽  
Luis Norberto López de Lacalle ◽  
S. Herranz ◽  
Aitzol Lamikiz ◽  
A. Rivero
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Spindle Speed ◽  
Depth Of Cut ◽  
Test Device ◽  
High Speed Milling ◽  
Thin Walls ◽  
Chatter Vibrations ◽  
The Stability ◽  
Selection Of

In this paper, a 3D dynamic model for the prediction of the stability lobes of high speed milling is presented, considering the combined flexibility of both tool and workpiece. The main aim is to avoid chatter vibrations on the finish milling of aeronautical parts, which include thin walls and thin floors. In this way the use of complex fixtures is eliminated. Hence, an accurate selection of both axial depth of cut and spindle speed can be accomplished. The model has been validated by means of a test device that simulates the behaviour of a thin floor.

Simultaneous Optimization of Removal Rate and Part Accuracy in High-Speed Milling

2004 ◽  
Author(s):  
Mohammad H. Kurdi ◽  
Tony L. Schmitz ◽  
Raphael T. Haftka ◽  
Brian P. Mann
Keyword(s):  
Optimization Algorithm ◽  
High Speed ◽  
Removal Rate ◽  
Spindle Speed ◽  
Successful Implementation ◽  
Location Error ◽  
High Speed Milling ◽  
Surface Location Error ◽  
Surface Location ◽  
Selection Of

High-speed milling provides an efficient method for accurate discrete part fabrication. However, successful implementation requires the selection of appropriate operating parameters. Balancing the multiple process requirements, including high material removal rate, maximum part accuracy, sufficient tool life, chatter avoidance, and adequate surface finish, to arrive at an optimum solution is difficult without the aid of an optimization framework. In this paper an initial effort is made to apply analytical tools to the selection of optimum cutting parameters (spindle speed and depth of cut are considered at this stage). Two objectives are addressed simultaneously, maximum removal rate and minimum surface location error. The Time Finite Element Analysis method is used in the optimization algorithm. Sensitivity of the surface location error to small changes in spindle speed near tooth passing frequencies that are integer fractions of the system’s natural frequency corresponding to the most flexible mode is calculated. Results of the optimization algorithm are verified by experiment.

3D Numerical Investigation of Effect of Milling Process Parameters on High Speed Milling of Ti-Al6-V4

2012 ◽  
Author(s):  
J. Ma ◽  
Shuting Lei ◽  
Huaqi Lu
Keyword(s):  
Titanium Alloy ◽  
Titanium Alloys ◽  
Numerical Investigation ◽  
Process Parameters ◽  
High Speed ◽  
Chemical Reactivity ◽  
Milling Process ◽  
Depth Of Cut ◽  
High Speed Milling ◽  
Axial Depth

Titanium alloys are widely used in aerospace industry owing to excellent mechanical properties. While because of high chemical reactivity and low thermal conductivity, titanium alloys are classified as hard-to-cut materials. In this paper, Finite Element Method (FEM) is employed to conduct numerical investigation in the effects of milling process parameters (milling speeds, feed per tooth, and axial depth of cut) on three-dimensional (3D) high speed milling of Titanium alloy (Ti-6Al-4V). The tool material used is Carbide and Johnson-Cook plastic model is employed to model the workpiece due to its capability of modeling large strains, high strain rates, and temperature dependent visco-plasticity. Different milling speeds, feed per tooth, and axial depth of cut are used to explore the effects of the milling process parameters on the cutting temperature, cutting forces, and power required for machining. This model provides fundamental understanding of cutting mechanics of the 3D high speed milling of Titanium alloy (Ti-6Al-4V).

Experimental Study on High-Speed Milling of Aluminum Alloy 2A70

2011 ◽  
Vol 314-316 ◽  
pp. 1788-1791 ◽  
Author(s):  
Feng Yun Yu ◽  
Ming Jun Feng ◽  
Ming Jun Dai ◽  
Hong Jiang Sun
Keyword(s):  
Aluminum Alloy ◽  
Cutting Force ◽  
High Speed ◽  
Periodic Variation ◽  
Spindle Speed ◽  
Milling Force ◽  
Experimental Conditions ◽  
High Speed Milling ◽  
High Speed Cutting ◽  
Test Study

High-speed cutting technology is widely used in aviation, mold, automotive industries and other fields for its high machining efficiency, smaller cutting force, less cutting heat and high machining precision. However, the production site in China, high-speed machine tools do not really play its role in some enterprises, without real sense of the high-speed machining. Aluminum alloy 2A70 as the research object, using single-factor test, study the effect law of high-speed milling parameters on milling force here. The results show that: the cutting force is varying for high-speed milling, showing a periodic variation, with the transient characteristic, the milling force is large amplitude fluctuations in X and Y direction, the amount of change is respectively 55.544N and 56.306N. Milling force influenced by the spindle speed, with the increase of spindle speed, X contribute to the greatest change in the direction of milling, Y direction second, Z direction is almost unchanged. Under the experimental conditions, the stability high-speed cutting area of 2A70 is the spindle speed in the area of 21000rpm~27000rpm. The results of high-speed milling of aluminum alloy have certain significance.

Sign in / Sign up

Export Citation Format

Share Document