Machine Tool Dynamics

A special issue of Journal of Manufacturing and Materials Processing (ISSN 2504-4494).

Deadline for manuscript submissions: closed (30 November 2020) | Viewed by 35915

Special Issue Editors

Manufacturing Engineering, Sabanci University, Orhanli, Tuzla, Istanbul 34956, Turkey
Interests: machining processes and machine tools; machine dynamics; cutting tools; precision manufacturing; process monitoring
Dynamics &Control, IK4-Ideko, 20870 Elgoibar, Basque Country, Spain
Interests: machine tool dynamics; chatter; modelling

Special Issue Information

Dear Colleagues,

The dynamics of machine tools play an important role in productivity in machining processes, and the resulting part quality. The stability of the process against chatter strongly depends on the dynamic characteristics of the machine including the peripherals such as the tooling assembly. Various methods are used to measure, model and simulate the dynamics of machine tools. The results of these are essential in evaluating dynamic rigidity and machining process stability as well as weak parts and components of a machine tool. The research related to the theoretical, numerical and experimental modelling of machine tool dynamic properties will be covered in this Special Issue.
Some authors state that machine dynamics are the main source of errors in predicting stability. The variations of the dynamic parameters in high speed spindles due to thermomechanical effects have attracted strong attention in this field. For this reason, current dynamic characterization procedures have been questioned, and new experimental procedures have been proposed. Nowadays, impact hammer testing is the most common method for dynamic parameter identification. Different authors have proposed the use of alternative excitation methods closer to operational conditions by means of special devices. Some authors have also tried to identify the dynamic parameters under cutting conditions using inverse methods, OMA or controlled cutting force variations. They identified deviations compared to traditionally obtained FRFs.
The analysis of damping is especially interesting. The main source of damping is at the interfaces and joints of the system. Several attempts to increase damping have been reported including passive dampers, the creation of highly damped interfaces, and the introduction of special materials, coatings and foams has been proposed. This Special Issue will cover different attempts to increase the damping of machine tools.

  • Modelling of machine tool dynamics.
  • FEA of machine tools
  • Experimental identification of machine tool structural dynamics
  • Modal analysis of manufacturing systems
  • Operational modal analysis for machining
  • Application of receptance coupling in machine tools
  • Inverse methods based on cutting or chatter tests
  • Spindle dynamics
  • Non-conventional methods to measure dynamic parameters.
  • New concepts of vibration absorbers and dampers
  • Dynamic characterization of machine tool joints
  • Active damping and dampers
  • Dynamic validation of machine tools
  • Theoretical/experimental correlation and model updating of machine tools

Prof. Dr. Erhan Budak
Dr. Jokin Munoa
Guest Editors

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Published Papers (10 papers)

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Research

12 pages, 4630 KiB  
Article
Optimization and Tuning of Passive Tuned Mass Damper Embedded in Milling Tool for Chatter Mitigation
by Wenshuo Ma, Jingjun Yu, Yiqing Yang and Yunfei Wang
J. Manuf. Mater. Process. 2021, 5(1), 2; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp5010002 - 25 Dec 2020
Cited by 9 | Viewed by 2907
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Machine Tool Dynamics)
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17 pages, 2661 KiB  
Article
Validation of a Coupled Simulation for Machine Tool Dynamics Using a Linear Drive Actuator
by Michael Wiesauer, Christoph Habersohn and Friedrich Bleicher
J. Manuf. Mater. Process. 2021, 5(1), 1; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp5010001 - 23 Dec 2020
Cited by 4 | Viewed by 2911
Abstract
In order to ensure high productivity capabilities of machine tools at a low cost but at increased geometric accuracy, modeling of their static and dynamic behavior is a crucial task in structure optimization. The drive control and the frictional forces acting in feed [...] Read more.
In order to ensure high productivity capabilities of machine tools at a low cost but at increased geometric accuracy, modeling of their static and dynamic behavior is a crucial task in structure optimization. The drive control and the frictional forces acting in feed axes significantly determine the machine’s response in the frequency domain. The aim of this study was the accurate modeling and the experimental investigation of dynamic damping effects using a machine tool test rig with three-axis kinematics. For this purpose, an order-reduced finite element model of the mechanical structure was coupled with models of the drive control and of the non-linear friction behavior. In order to validate the individual models, a new actuator system based on a tubular linear drive was used for frequency response measurements during uniaxial carriage movements. A comparison of the dynamic measurements with the simulation results revealed a good match of amplitudes in the frequency domain by considering dynamic damping. Accordingly, the overall dynamic behavior of machine tool structures can be predicted and thus optimized by a coupled simulation at higher level of detail and by considering the damping effects of friction. Dynamic testing with the newly designed actuator is a prerequisite for model validation and control drive parameterization. Full article
(This article belongs to the Special Issue Machine Tool Dynamics)
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19 pages, 49563 KiB  
Article
Passive Chatter Suppression of Thin-Walled Parts by Means of High-Damping Lattice Structures Obtained from Selective Laser Melting
by Federico Scalzo, Giovanni Totis, Emanuele Vaglio and Marco Sortino
J. Manuf. Mater. Process. 2020, 4(4), 117; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp4040117 - 10 Dec 2020
Cited by 12 | Viewed by 3005
Abstract
Chatter vibrations arising during machining operations are detrimental for cutting process performance, since they may cause poor surface quality of the machined part and severe damages to machine tool elements. Passive approaches for chatter suppression are based on the integration of special mechanical [...] Read more.
Chatter vibrations arising during machining operations are detrimental for cutting process performance, since they may cause poor surface quality of the machined part and severe damages to machine tool elements. Passive approaches for chatter suppression are based on the integration of special mechanical components with high-damping properties within the machining system. They represent a good solution to this problem thanks to their intrinsic simplicity. Recently, the application of metallic lattice structures inside 3D printed parts obtained from the Selective Laser Melting technology have proven superior damping properties with respect to the same full density material. Here, this idea is further explored by considering the novel configuration where the unmelted powder grains are retained inside the lattice structure by an external shell, acting as a multiplicity of microscopic mechanical dampers. This concept is applied for passive chatter suppression of thin-walled parts that are of particular relevance for industry. Preliminary experimental investigation was first carried out on simple beam-like specimens, and then on thin-walled benchmarks that were identified through modal analysis and tested under real cutting conditions. The main conclusion is that the novel proposed configuration (lattice plus unmelted powder) has higher damping properties with respect to the full density and lattice alternatives. Accordingly, it may be successfully applied for passive chatter suppression in real machining operations. Full article
(This article belongs to the Special Issue Machine Tool Dynamics)
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18 pages, 10326 KiB  
Article
The Influence of Servo Drive Control on the NC Vertical Milling Machine Dynamic Compliance
by Jan Grau, Pavel Souček and Matěj Sulitka
J. Manuf. Mater. Process. 2020, 4(4), 111; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp4040111 - 26 Nov 2020
Cited by 1 | Viewed by 2288
Abstract
A model Numerical Control (NC) machine tool dynamic compliance is analyzed, including the influence of its mechanical structure and position control feed drive algorithms. The dynamic model of the machine tool is divided into two main parts, which are closest to the machining [...] Read more.
A model Numerical Control (NC) machine tool dynamic compliance is analyzed, including the influence of its mechanical structure and position control feed drive algorithms. The dynamic model of the machine tool is divided into two main parts, which are closest to the machining process. First, the milling head assembly group is presented as a system of one mass oscillating in a 2D plane and 3D space. Second, the motion axes assembly group, XY cross table with linear feed drive, is presented. A square 2×2 dimension matrix of the total dynamic compliance is evaluated within the feed drive control system included. Partial elements of the mechanical structure dynamic compliance matrix of the general N×N dimension are contained in the total dynamic compliance matrix. Full article
(This article belongs to the Special Issue Machine Tool Dynamics)
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22 pages, 24228 KiB  
Article
Learning-Based Prediction of Pose-Dependent Dynamics
by Felix Finkeldey, Andreas Wirtz, Torben Merhofe and Petra Wiederkehr
J. Manuf. Mater. Process. 2020, 4(3), 85; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp4030085 - 31 Aug 2020
Cited by 7 | Viewed by 2909
Abstract
The constantly increasing demand for both, higher production output and more complex product geometries, which can only be achieved using five-axis milling processes, requires elaborated analysis approaches to optimize the regarded process. This is especially necessary when the used tool is susceptible to [...] Read more.
The constantly increasing demand for both, higher production output and more complex product geometries, which can only be achieved using five-axis milling processes, requires elaborated analysis approaches to optimize the regarded process. This is especially necessary when the used tool is susceptible to vibrations, which can deteriorate the quality of the machined workpiece surface. The prediction of tool vibrations based on the used NC path and process configuration can be achieved by, e.g., applying geometric physically-based process simulation systems prior to the machining process. However, recent research showed that the dynamic behavior of the system, consisting of the machine tool, the spindle, and the milling tool, can change significantly when using different inclination angles to realize certain machined workpiece shapes. Intermediate dynamic properties have to be interpolated based on measurements due to the impracticality of measuring the frequency response functions for each position and inclination angle that are used along the NC path. This paper presents a learning-based approach to predict the frequency response function for a given pose of the tool center point. Full article
(This article belongs to the Special Issue Machine Tool Dynamics)
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16 pages, 4595 KiB  
Article
In-Process Monitoring of Changing Dynamics of a Thin-Walled Component During Milling Operation by Ball Shooter Excitation
by Daniel Bachrathy, Adam K. Kiss, Attila Kossa, Szabolcs Berezvai, David Hajdu and Gabor Stepan
J. Manuf. Mater. Process. 2020, 4(3), 78; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp4030078 - 03 Aug 2020
Cited by 9 | Viewed by 2738
Abstract
During the milling of thin-walled workpieces, the natural frequencies might change radically due to the material removal. To avoid resonant spindle speeds and chatter vibration, a precise knowledge of the instantaneous modal parameters is necessary. Many different numerical methods exist to predict the [...] Read more.
During the milling of thin-walled workpieces, the natural frequencies might change radically due to the material removal. To avoid resonant spindle speeds and chatter vibration, a precise knowledge of the instantaneous modal parameters is necessary. Many different numerical methods exist to predict the changes; however, small unmodelled effects can lead to unreliable results. The natural frequencies could be measured by human experts based on modal analysis for an often interrupted process; however, this method is not acceptable during production. We propose an online measurement method with an automatic ball shooter device which can excite a wide frequency range of the flexible workpiece. The method is presented for the case of blade profile machining. The change of the natural frequencies is predicted based on analytical models and finite element simulations. The measurement response for the impulse excitation of the ball shooter device is compared to the results of impulse modal tests performed with a micro hammer. It is shown that the ball shooter is capable of determining even the slight variation of the natural frequencies during the machining process and of distinguishing the slight change caused by different clamping methods. An improved FE model is proposed to include the contact stiffness of the fixture. Full article
(This article belongs to the Special Issue Machine Tool Dynamics)
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13 pages, 2351 KiB  
Article
The Basics of Time-Domain-Based Milling Stability Prediction Using Frequency Response Function
by Zoltan Dombovari, Markel Sanz-Calle and Mikel Zatarain
J. Manuf. Mater. Process. 2020, 4(3), 72; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp4030072 - 16 Jul 2020
Cited by 4 | Viewed by 2664
Abstract
This study presents the fundamentals of the usage of frequency response functions (FRF) directly in time-domain-based methods. The methodology intends to combine the advantages of frequency- and time-domain-based techniques to determine the stability of stationary solutions of a given milling process. This is [...] Read more.
This study presents the fundamentals of the usage of frequency response functions (FRF) directly in time-domain-based methods. The methodology intends to combine the advantages of frequency- and time-domain-based techniques to determine the stability of stationary solutions of a given milling process. This is achieved by applying the so-called impulse dynamic subspace (IDS) method, with which the impulse response function (IRF) can be disassembled to separated singular IRFs that form the basis of the used transformation. Knowing the IDS state, the linear stability boundaries can be constructed and a measure of stability can be determined using the Floquet multipliers via the semidiscretization method (SDM). This step has a huge importance in parameter optimization where the multipliers can be used as objective functions, which is hardly achievable using frequency-domain-based methods. Here we present the basic idea of utilizing the IDS method and analyze its convergence properties. Full article
(This article belongs to the Special Issue Machine Tool Dynamics)
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26 pages, 4565 KiB  
Article
Design of Chatter-Resistant Damped Boring Bars Using a Receptance Coupling Approach
by Ajay Yadav, Devangkumar Talaviya, Ankit Bansal and Mohit Law
J. Manuf. Mater. Process. 2020, 4(2), 53; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp4020053 - 03 Jun 2020
Cited by 16 | Viewed by 5836
Abstract
Deep hole boring using slender bars that have tuned mass dampers integrated within them make the boring process chatter vibration resistant. Dampers are usually designed using classical analytical solutions that presume the (un)damped boring bar which can be approximated by a single degree [...] Read more.
Deep hole boring using slender bars that have tuned mass dampers integrated within them make the boring process chatter vibration resistant. Dampers are usually designed using classical analytical solutions that presume the (un)damped boring bar which can be approximated by a single degree of freedom system, and the damper is placed at the free end. Since the free end is also the cutting end, analytical models may result in infeasible design solutions. To place optimally tuned dampers within boring bars, but away from the free end, this paper presents a receptance coupling approach in which the substructural receptances of the boring bar modelled as a cantilevered Euler–Bernoulli beam are combined with the substructural receptances of a damper modelled as a rigid mass integrated anywhere within the bar. The assembled and damped system response thus obtained is used to predict the chatter-free machining stability limit. Maximization of this limit is treated as the objective function to find the optimal mass, stiffness and damping of the absorber. Proposed solutions are first verified against other classical solutions for assumed placement of the absorber at the free end. Verified models then guide prototyping of a boring bar integrated with a damper placed away from its free end. Experiments demonstrate a ~100-fold improvement in chatter vibration free machining capability. The generalized methods presented herein can be easily extended to design and develop other damped and chatter-resistant tooling systems. Full article
(This article belongs to the Special Issue Machine Tool Dynamics)
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18 pages, 6797 KiB  
Article
Effect of Rack and Pinion Feed Drive Control Parameters on Machine Tool Dynamics
by Oier Franco, Xavier Beudaert and Kaan Erkorkmaz
J. Manuf. Mater. Process. 2020, 4(2), 33; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp4020033 - 21 Apr 2020
Cited by 7 | Viewed by 3768
Abstract
In large heavy-duty machine tool applications, the parametrization of the controller that is used for the positioning of the machine can affect the machine tool dynamics. The aim of this paper is to build a Multiple-Input and Multiple-Output model that couples the servo [...] Read more.
In large heavy-duty machine tool applications, the parametrization of the controller that is used for the positioning of the machine can affect the machine tool dynamics. The aim of this paper is to build a Multiple-Input and Multiple-Output model that couples the servo controller and machine tool dynamics to predict the frequency response function (FRF) at the cutting point. The model is experimentally implemented and validated in an electronically preloaded rack and pinion machine tool. In addition, the influence of each control parameter on the machine tool’s compliance is analysed. Full article
(This article belongs to the Special Issue Machine Tool Dynamics)
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15 pages, 4045 KiB  
Article
Machining Chatter Prediction Using a Data Learning Model
by Harish Cherukuri, Elena Perez-Bernabeu, Miguel Selles and Tony Schmitz
J. Manuf. Mater. Process. 2019, 3(2), 45; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp3020045 - 08 Jun 2019
Cited by 43 | Viewed by 5532
Abstract
Machining processes, including turning, are a critical capability for discrete part production. One limitation to high material removal rates and reduced cost in these processes is chatter, or unstable spindle speed-chip width combinations that exhibit a self-excited vibration. In this paper, an artificial [...] Read more.
Machining processes, including turning, are a critical capability for discrete part production. One limitation to high material removal rates and reduced cost in these processes is chatter, or unstable spindle speed-chip width combinations that exhibit a self-excited vibration. In this paper, an artificial neural network (ANN)—a data learning model—is applied to model turning stability. The novel approach is to use a physics-based process model—the analytical stability limit—to generate a (synthetic) data set that trains the ANN. This enables the process physics to be combined with data learning in a hybrid approach. As anticipated, it is observed that the number and distribution of training points influences the ability of the ANN model to capture the smaller, more closely spaced lobes that occur at lower spindle speeds. Overall, the ANN is successful (>90% accuracy) at predicting the stability behavior after appropriate training. Full article
(This article belongs to the Special Issue Machine Tool Dynamics)
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