Chatter Stability of Micro-Milling by Considering the Centrifugal Force and Gyroscopic Effect of the Spindle

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Xiaohong Lu ◽  
Zhenyuan Jia ◽  
Shengqian Liu ◽  
Kun Yang ◽  
Yixuan Feng ◽  
...  
Keyword(s):  
Centrifugal Force ◽  
High Speed ◽  
Beam Theory ◽  
Milling Process ◽  
System Structure ◽  
Micro Milling ◽  
Gyroscopic Effect ◽  
Good Surface ◽  
Receptance Coupling ◽  
Milling Tool

Abstract In the micro-milling process, the minimization of tool chatter is critical for good surface finish quality. The analysis of chatter requires an understanding of the milling tool as well as the dynamics of milling system structure. Frequency response function (FRF) at the micro-milling tool point reflects dynamic behavior of the whole micro-milling machine–spindle–tool system. However, the tool point FRF of micro-milling cannot be obtained directly through the hammering test. To solve the problem, the authors get the FRF of the spindle system based on the rotating Timoshenko beam theory and the receptance coupling substructure analysis (RCSA), and the bearing characteristics are added into the spindle model through structural modification. Then, the centrifugal force and gyroscopic effect caused by the high-speed rotation of the micro-milling spindle are considered to better simulate the real scenario and increase the accuracy of modal parameters. The method has general usage and can be applied to all the micro-milling tools under which only the spindle dimension, bearing characteristics, and contact parameters need to be changed.

scholarly journals Optimization and Tuning of Passive Tuned Mass Damper Embedded in Milling Tool for Chatter Mitigation

2020 ◽  
Vol 5 (1) ◽  
pp. 2
Author(s):  
Wenshuo Ma ◽  
Jingjun Yu ◽  
Yiqing Yang ◽  
Yunfei Wang
Keyword(s):  
Tuned Mass Damper ◽  
Structural Features ◽  
Milling Process ◽  
Diameter Ratio ◽  
Depth Of Cut ◽  
Receptance Coupling ◽  
Milling Tool ◽  
Mass Damper ◽  
Large Length ◽  
Deep Depth

Milling tools with a large length–diameter ratio are widely applied in machining structural features with deep depth. However, their high dynamic flexibility gives rise to chatter vibrations, which results in poor surface finish, reduced productivity, and even tool damage. With a passive tuned mass damper (TMD) embedded inside the arbor, a large length–diameter ratio milling tool with chatter-resistance ability was developed. By modeling the milling tool as a continuous beam, the tool-tip frequency response function (FRF) of the milling tool with TMD was derived using receptance coupling substructure analysis (RCSA), and the gyroscopic effect of the rotating tool was incorporated. The TMD parameters were optimized numerically with the consideration of mounting position based on the maximum cutting stability criterion, followed by the simulation of the effectiveness of the optimized and detuned TMD. With the tool-tip FRF obtained, the chatter stability of the milling process was predicted. Tap tests showed that the TMD was able to increase the minimum real part of the FRF by 79.3%. The stability lobe diagram (SLD) was predicted, and the minimum critical depth of cut in milling operations was enhanced from 0.10 to 0.46 mm.

A Comparison of the Simulated Dynamics of Various Models Used to Predict Undeformed Chip Thickness in High-Speed Low-Radial-Immersion Milling Processes

2013 ◽  
Author(s):  
Josiah A. Bryan ◽  
Roger C. Fales
Keyword(s):  
High Speed ◽  
Chip Thickness ◽  
Milling Process ◽  
Precision Machining ◽  
Traditional Model ◽  
Cnc Milling ◽  
Undeformed Chip Thickness ◽  
Milling Tool ◽  
Tool Damage ◽  
Low Radial Immersion

Various models have been proposed to estimate the undeformed thickness of chips produced by a CNC milling tool, in order to calculate the forces acting on the tool. The choice of model significantly affects the simulated dynamics of the tool, thereby affecting the dynamic stability of the simulated process and whether or not chatter occurs in a given cutting scenario. Simulations of the dynamics of the milling process can be used to determine the conditions at which chatter occurs, which can lead to poor surface finish and tool damage. The dynamics of a traditional model and a more detailed numerical model are simulated here with particular emphasis on the differences in their chatter bifurcation points. High-speed, low-radial-immersion milling processes are simulated because of their application in industrial high-precision machining.

Substructure Coupling of Microend Mills to Aid in the Suppression of Chatter

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Brock A. Mascardelli ◽  
Simon S. Park ◽  
Theodor Freiheit
Keyword(s):  
Finite Element ◽  
Complex Geometry ◽  
Rotational Dynamics ◽  
Response Functions ◽  
Finite Element Analyses ◽  
Coupling Technique ◽  
Good Surface ◽  
Receptance Coupling ◽  
Milling Tool ◽  
Microend Milling

Microend milling offers the ability to machine microparts of complex geometry relatively quickly when compared with photolithographic techniques. The key to good surface quality is the minimization of tool chatter. This requires an understanding of the milling tool and the milling structure system dynamics. However, impact hammer testing cannot be applied directly to the prediction of tool tip dynamics because microend mills are fragile, with tip diameters as small as 10μm. This paper investigates the application of the receptance coupling technique to mathematically couple the spindle/micromachine and arbitrary microtools with different geometries. The frequency response functions (FRFs) of the spindle/micromachine tool are measured experimentally through impact hammer testing, utilizing laser displacement and capacitance sensors. The dynamics of an arbitrary tool substructure are determined through modal finite element analyses. Joint rotational dynamics are indirectly determined through experimentally measuring the FRFs of gauge tools. From the FRFs, chatter conditions are predicted and verified through micromilling experiments.

Experimental Study on Ball End Mill in Glass Machining at High Speed

2011 ◽  
Vol 314-316 ◽  
pp. 1167-1170
Author(s):  
Zhi Wei ◽  
Ji Hong Jia ◽  
Mei Lin Gu ◽  
Chao Zuo ◽  
Xing Zhen Jin
Keyword(s):  
High Speed ◽  
Experimental System ◽  
Milling Process ◽  
End Mill ◽  
Ball End Mill ◽  
Milling Force ◽  
Milling Tool ◽  
Explicit Analysis ◽  
Stress And Deformation ◽  
The Relationship

This paper describes the experimental system of milling force, the tool geometrical feature and the certain experimental condition in the section of experimental case, which also makes an explanation about the designing of experimental case and the analysis of the experimental data. It also represents the relationship between coefficients associated with the milling process and the milling force applied on the tool in detail. A finite element method is used to make an explicit analysis on the stress and deformation of the milling tool under the application of certain milling force. Finally, a summary is made to conclude the study and its results.

Design of Precision Micro-Milling Machine for Meso-Scaled Parts

2010 ◽  
Vol 29-32 ◽  
pp. 1068-1073
Author(s):  
Zi Yang Cao ◽  
Hua Li
Keyword(s):  
Machine Tool ◽  
High Speed ◽  
Milling Process ◽  
Micro Milling ◽  
Milling Machine ◽  
Cnc System ◽  
Industrial Control ◽  
C Programming ◽  
Control Computer ◽  
Industrial Control Computer

To create miniaturized components, a 3-axis micro-milling machine tool composed of linear motor stages, high-speed air-bearing spindle and motion control card DMC-1842 is developed in this paper. The CNC system of the parallel double CPU based on industrial control computer and Windows operating system is constructed. The application software of CNC system is exploited by modularized mind in C# programming language, reasonable human-computer interface is designed. Finally, in order to validate the performance of the micro-milling machine, the miniaturized parts are machined o by developed CNC system. Through these tests analysis, the hardware and software architecture of the CNC system is verified to meet the requirements of the micro-milling machine tool. Micro-milling process with developed micro-milling machine tool is proved to be feasible and applicable, and can fully satisfy the producing requires of miniaturized components.

An Improved Tool Path Model Including Gyroscopic Effect for Instantaneous Cutting Force Prediction in High-Speed Milling

2011 ◽  
Vol 418-420 ◽  
pp. 840-843
Author(s):  
Qing Hua Song ◽  
Xing Ai
Keyword(s):  
Cutting Force ◽  
High Speed ◽  
Tool Path ◽  
Milling Process ◽  
Path Model ◽  
Force Model ◽  
Cutting Force Model ◽  
Gyroscopic Effect ◽  
Cutting Force Prediction ◽  
High Speed Milling

The efficiency of the high-speed milling process is often limited by the occurrence of chatter. In order to predict the occurrence of chatter, accurate models are necessary. With the speed increasing, gyroscopic effect plays an important pole on the system behavior, including dynamic characteristic and rotating behavior. Considering the influence of gyroscopic effect on rotating behavior, an updated model for the milling process is presented which features as model of the equivalent profile of tool. In combination with this model, a nonlinear instantaneous cutting force model is proposed. The use of this updated equivalent profile of tool results in significant differences in the static uncut thickness compared to the traditional model.

Substructure Coupling of Micro-End Mills

2006 ◽  
Author(s):  
Brock A. Mascardelli ◽  
Simon S. Park ◽  
Theodor Freiheit
Keyword(s):  
Complex Geometry ◽  
End Milling ◽  
Micro Milling ◽  
Good Surface ◽  
Receptance Coupling ◽  
Micro Parts ◽  
Micro End Milling ◽  
End Mills ◽  
Micro Machine ◽  
Micro Tools

Micro-end milling is an important micro-manufacturing technique which offers the ability to machine micro parts of complex geometry relatively quickly when compared with photolithographic techniques. Key to good surface quality in the micro milling operation is the minimization of tool chatter. This requires an understanding of the system dynamics; the system including both the milling tool and the milling structure. However, owing to the miniature nature of micro end mills whose diameters are as small as 50 micrometers, impact hammer testing cannot be applied directly to predict the dynamics at the tool tip. This paper investigates substructure coupling of the spindle/micro machine and arbitrary micro tools with different geometries. This is done through use of the receptance coupling technique. The frequency response functions (FRFs) of the spindle/micro machine are experimentally measured through impact hammer testing utilizing a laser displacement gauge. The dynamics of an arbitrary tool substructure are determined through modal finite element (FE) analyses. Joint rotational dynamics are indirectly determined through experimentally measuring FRFs of gauge tools. The method also enables designers to come up with the optimum design of tool geometries prior to actual fabrication to prevent chatter vibrations.

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.

Experimental Study of Sound Signal for Tool Condition Monitoring in Micro Milling Processes

2008 ◽  
Author(s):  
Chia-Liang Yen ◽  
Ming-Chyuan Lu ◽  
Ching-Yuan Lin ◽  
Tin-Hong Chen
Keyword(s):  
Tool Wear ◽  
Frequency Domain ◽  
High Speed ◽  
Wear Test ◽  
Milling Process ◽  
Micro Milling ◽  
Tool Condition ◽  
Audible Sound ◽  
End Mills ◽  
Speed Up

The audible sound signals obtained in micro-milling processes are analyzed in the time and frequency domain for the tool wear and breakage monitoring. Micro end-mills of φ 700 μm are implemented in the tool wear test, along with a high speed spindle with speed up to 60000 rpm. The audible sound signals and vibration signals for different tool conditions were collected simultaneously in the cutting. After transferring data from time domain to the frequency domain, as well as the Wavelet coefficients, the capability of audible sound signals in detecting the tool condition for the micro milling process was evaluated.

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