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Szymon Wojciechowski - One of the best experts on this subject based on the ideXlab platform.
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Prediction of cutting forces during micro End Milling considering chip thickness accumulation
International Journal of Machine Tools & Manufacture, 2019Co-Authors: Szymon Wojciechowski, Marcin Matuszak, Bartosz Powałka, Marek Madajewski, Radoslaw W. MarudaAbstract:Abstract This study focuses on the prediction of cutting forces during micro End Milling using a novel approach that takes into account the chip thickness accumulation phenomenon. The proposed original force model considers the micro End Milling kinematics, geometric errors of the machine tool–toolholder–mill system, elastic and plastic deformations of workpiece correlated with the minimum uncut chip thickness, and flexibility of the slEnder micro End mill. It also includes a novel analytical approach for the instantaneous area of cut. The chip thickness accumulation phenomenon can be manifested as chip thickness variations in the current tool rotation, resulting from material burnishing and elastic recovery in all previous tool rotations. The predicted forces consider the minimum uncut chip thickness value, which has been estimated directly from the microMilling process of AISI 1045 steel based on an original analytic–experimental approach that applies the identification of a stagnant point in the Milling process. The results obtained show that the instantaneous and average microMilling forces determined using the proposed model have considerably better conformity with the experimental forces than those predicted using the commonly used rigid micro End Milling model. Moreover, the non-linearity of the cutting forces as a function of feed per tooth is strongly affected by multiple cutting mechanism transitions observed during microMilling with uncut chip thicknesses close to the minimum uncut chip thickness value.
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application of signal to noise ratio and grey relational analysis to minimize forces and vibrations during precise ball End Milling
Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology, 2018Co-Authors: Szymon Wojciechowski, Radoslaw W. Maruda, Grzegorz Krolczyk, Piotr NieslonyAbstract:Abstract In this paper, a method for the minimization of cutting forces and vibrations during precise ball End Milling of hardened 55NiCrMoV6 steel is developed. The aim of this work concentrates on the optimal selection of surface inclination angle α and tool’s overhang l, which enables the minimization of cutting forces and vibrations in order to improve the machined surface quality. The experiment includes the measurement of cutting forces and acceleration of vibrations during the Milling tests with variable input parameters. The next step focuses on the optimization of the ball End Milling process with the consideration of the acquired signals. This procedure is carried out by the minimization of process responses with the application of signal to noise S/N ratio and grey relational analysis (GRA). Subsequently, the obtained optimal values of process input parameters are validated during the ball End Milling tests involving the measurements of machined surface topographies. Research reveals that surface inclination angle and tool’s overhang have significant influence on generated forces and vibration values. Moreover, the selection of the optimal values of α and l enables significant improvement of machined surface quality.
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Mechanical and technological aspects of micro ball End Milling with various tool inclinations
International Journal of Mechanical Sciences, 2017Co-Authors: Szymon Wojciechowski, Krzysztof MrozekAbstract:Abstract This paper is focused on the evaluation of mechanical and technological aspects of the micro ball End Milling of hardened TOOLOX 44 steel. The experiment includes the measurement of acceleration of vibrations during the micro Milling tests with variable feed per tooth and tool's axis inclination angle values. The next step involves the analysis of dynamics, based on the determination of measured signals’ statistical measures and Fast Fourier Transform (FFT). This stage includes also the prediction of micro ball End Milling forces on the basis of mechanistic model considering run out, variable edge forces, and kinematics of low radial immersion Milling with tool axis inclination. Subsequently, the optimization of the micro ball End Milling process is conducted. This procedure is carried out by the minimization of process responses with the application of a method based on the minimization of total desirability function. In the last stage, the obtained optimal values of tool's axis inclination angle and feed per tooth are validated during the micro Milling tests involving the measurements of machined surface roughness. Research reveals that micro ball End Milling with the optimally selected tool's axis slope along the toolpath and feed per tooth affects the minimization of Milling vibrations and improvement in surface finish.
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optimisation of machining parameters during ball End Milling of hardened steel with various surface inclinations
Measurement, 2017Co-Authors: Szymon Wojciechowski, Radoslaw W. Maruda, Simon Barrans, Piotr Nieslony, Grzegorz KrolczykAbstract:This paper proposes a method for the reduction of forces and the improvement of efficiency during finish ball End Milling of hardened 55NiCrMoV6 steel. The primary objective of this work concentrates on the optimal selection of Milling parameters (cutting speed – vc, surface inclination angle α), which enables the simultaneous minimisation of cutting force values and increased process efficiency. The research includes the measurement of cutting forces (Fx, Fy, Fz) during Milling tests with variable input parameters and calculation of process efficiency accounting for cutting parameters and surface inclination. The paper then focuses on the multi-criteria optimisation of the ball End Milling process in terms of cutting forces and efficiency. This procedure is carried out with the application of the response surface method, based on the minimisation of a total utility function. The work shows that surface inclination angle has a significant influence on the cutting force values. Minimal cutting forces and relative high efficiency can be achieved with cutting speed vc = 375 m/min and surface inclination angle α = 15°.
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the estimation of cutting forces and specific force coefficients during finishing ball End Milling of inclined surfaces
International Journal of Machine Tools & Manufacture, 2015Co-Authors: Szymon WojciechowskiAbstract:Abstract The majority of cutting force models applied for the ball End Milling process includes only the influence of cutting parameters (e.g. feedrate, depth of cut, cutting speed) and estimates forces on the basis of coefficients calibrated during slot Milling. Furthermore, the radial run out phenomenon is predominantly not considered in these models. However this approach can induce excessive force estimation errors, especially during finishing ball End Milling of sculptured surfaces. In addition, most of cutting force models is formulated for the ball End Milling process with axial depths of cut exceeding 0.5 mm and thus, they are not oriented directly to the finishing processes. Therefore, this paper proposes an accurate cutting force model applied for the finishing ball End Milling, which includes also the influence of surface inclination and cutter's run out. As part of this work the new method of specific force coefficients calibration has been also developed. This approach is based on the calibration during ball End Milling with various surface inclinations and the application of instantaneous force signals as an input data. Furthermore, the analysis of specific force coefficients in function of feed per tooth, cutting speed and surface inclination angle was also presented. In order to determine geometrical elements of cut precisely, the radial run out was considered in equations applied for the calculation of sectional area of cut and active length of cutting edge. Research revealed that cutter's run out and surface inclination angle have significant influence on the cutting forces, both in the quantitative and qualitative aspect. The formulated model enables cutting force estimation in the wide range of cutting parameters, assuring relative error's values below 16%. Furthermore, the consideration of cutter's radial run out phenomenon in the developed model enables the reduction of model's relative error by the 7% in relation to the model excluding radial run out.
Yusuf Altintas - One of the best experts on this subject based on the ideXlab platform.
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Chatter free tool orientations in 5-axis ball-End Milling
International Journal of Machine Tools & Manufacture, 2016Co-Authors: Yusuf AltintasAbstract:Abstract Dies, molds and parts with complex free form surfaces are usually machined with ball End mills on 5-axis CNC machining centers. This paper presents automatic adjustment of tool axis orientations to avoid chatter along the tool path. The process mechanics and dynamics of ball End Milling are modeled in cutter-workpiece engagement coordinate system. The structural dynamics of tool and workpiece are transformed to cutter-workpiece engagement coordinates by considering the tool path and the kinematics of the machine tool. The stability of the 5-axis ball End Milling is modeled at each tool path location, and the chatter free tool axis orientations are searched iteratively using Nyquist criterion while avoiding gouging limits. The tool path, i.e. cutter location (CL) file, is updated to generate chatter free, 5-axis ball End Milling of the parts. The proposed algorithm has been experimentally proven in 5-axis ball End Milling tests.
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prediction of cutting forces in three and five axis ball End Milling with tool indentation effect
International Journal of Machine Tools & Manufacture, 2013Co-Authors: Oguzhan Tuysuz, Yusuf Altintas, Hsi-yung FengAbstract:Abstract Simulation of multi-axis ball-End Milling of dies, molds and aerospace parts with free-form surfaces is highly desirable in order to optimize the machining processes in virtual environment ahead of costly trials. This paper presents a mechanics model that predicts the cutting forces in feed ( x ), normal ( y ) and axial ( z ) directions by modeling the chip thickness distribution, and cutting and indentation mechanics. The shearing forces are based on commonly known cutting mechanics models. The indentation of the cutting edge into the work material is modeled analytically by considering elasto-plastic deformation of the work material pressed by a rigid cutting tool edge with a positive or negative rake angle. The distribution of chip thickness and geometry of indentation zone are evaluated by considering five-axis motion of the tool along the toolpath. The proposed model has been experimentally validated in plunge indentation, as well as in three and five-axis ball-End Milling of free-form surfaces. The prediction of axial ( z ) cutting forces is shown to be improved significantly when the proposed indentation model is integrated into the mechanics of ball-End Milling.
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Analytical Prediction of Stability Lobes in Ball End Milling
Journal of Manufacturing Science and Engineering-transactions of The Asme, 1999Co-Authors: Yusuf Altintas, Eiji Shamoto, Erhan BudakAbstract:The paper presents an analytical method to predict stability lobes in ball End Milling. Analytical expressions are based on the dynamics of ball End Milling with regeneration in the uncut chip thickness, time varying directional factors and the interaction with the machine tool structure. The cutting force coefficients are derived from orthogonal cutting data base using oblique transformation method. The influence ofcutting coefficients on the stability is investigated. A computationally efficient, an equivalent average cutting force coefficient method is developed for ball End Milling. The prediction of stability lobes for ball End Milling is reduced to the solution of a simple quadratic equation. The analytical results agree well with the experiments and the computationally expensive and complex numerical time domain simulations.
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Mechanics and Dynamics of Ball End Milling
Journal of Manufacturing Science and Engineering-transactions of The Asme, 1998Co-Authors: Yusuf AltintasAbstract:Mechanics and dynamics of cutting with helical ball End mills are presented. The helical ball End mill attached to the spindle is modelled by orthogonal structural modes in the feed and normal directions at the tool tip. For a given cutter geometry, the cutting coefficients are transformed from an orthogonal cutting data base using an oblique cutting model. The three dimensional swept surface by the cutter is digitized using the true trochoidal kinematics of ball End Milling process in time domain. The dynamically regenerated chip thickness, which consists of rigid body motion of the tooth and structural displacements, is evaluated at discrete time intervals by comparing the present and previous tooth marks left on the finish surface. The process is simulated in time domain by considering the instantaneous regenerative chip load. local cutting force coefficients, structural transfer functions and the geometry of ball End Milling process. The proposed model predicts cutting forces, surface finish and chatter stability lobes, and is verified experimentally under both static and dynamic cutting conditions.
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prediction of ball End Milling forces
Journal of Engineering for Industry, 1996Co-Authors: G Yucesan, Yusuf AltintasAbstract:Mechanics of Milling with ball Ended helical cutters are modeled. The model is based on the analytic representation of ball shaped helical flute geometry, and its rake and clearance surfaces. It is assumed that friction and pressure loads on the rake face are proportional to the uncut chip thickness area. The load on the flank contact face is concentrated on the in cut portion of the cutting edge. The pressure and friction coefficients are identified from a set of slot ball End Milling tests at different feeds and axial depth of cuts, and are used to predict the cutting forces for various cutting conditions. The experimentally verified model accurately predicts the cutting forces in three Cartesian directions.
I N Tansel - One of the best experts on this subject based on the ideXlab platform.
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modeling micro End Milling operations part i analytical cutting force model
International Journal of Machine Tools & Manufacture, 2000Co-Authors: W Y Bao, I N TanselAbstract:A new analytical cutting force model is proposed for micro-End-Milling operations. The model calculates the chip thickness by considering the trajectory of the tool tip while the tool rotates and moves ahead continuously. The proposed approach allows the calculation of the cutting forces to be done accurately in typical micro-End-Milling operations with very aggressively selected feed per tooth to tool radius ( ft/r) ratio. The difference of the simulated cutting forces between the proposed and conventional models can be experienced when ft/r is larger than 0.1. The estimated cutting force profile of the proposed model had good agreement with the experimental data. © 2000 Elsevier Science Ltd. All rights reserved.
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modeling micro End Milling operations part ii tool run out
International Journal of Machine Tools & Manufacture, 2000Co-Authors: W Y Bao, I N TanselAbstract:The effect of run-out is clearly noticed in micro-End-Milling operations, while the same run-out creates negligible change at the cutting force profile of conventional End-Milling operations. In this paper, the cutting force characteristics of micro-End-Milling operations with tool run-out are investigated. An analytical cutting force model is developed for micro-End-Milling operations with tool run-out. The proposed model has a compact set of expressions to be able to estimate the cutting force characteristics very quickly compared to the numerical approaches. The cutting forces of micro-End-Milling operations simulated by the proposed model had good agreement with the experimental data.
Kornel F. Ehmann - One of the best experts on this subject based on the ideXlab platform.
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Surface roughness modeling in micro End-Milling
The International Journal of Advanced Manufacturing Technology, 2018Co-Authors: Yanjie Yuan, Xiubing Jing, Kornel F. EhmannAbstract:Micro End-Milling is widely used in many industries to produce micro products with complex 3D shapes. The accurate modeling and prediction of surface roughness are important for evaluating the productivity of the machine tools and the surface quality of the machined parts. This paper presents an accurate surface roughness model based on the kinematics of cutting process and tool geometry by considering the effects of tool run-out and minimum chip thickness. The proposed surface roughness model is validated by micro End-Milling experiments with the miniaturized machine tool. The results show that the proposed surface roughness model can accurately predict both the trEnds and magnitude of the surface roughness in micro End-Milling.
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modeling of cutting forces in micro End Milling
Journal of Manufacturing Processes, 2018Co-Authors: Yanjie Yuan, Xiubing Jing, Kornel F. Ehmann, Jian Cao, Dawei ZhangAbstract:Abstract Accurate modeling and prediction of cutting forces are important for process planning and optimization in micro End-Milling process. In order to exactly predict the cutting forces, an innovative uncut chip thickness algorithm is proposed by considering the combination of the exact trochoidal trajectory of the tool tip and the cutting trajectory of all previously passing teeth, tool run-out, minimum chip thickness and the material’s elastic recovery. The proposed uncut chip thickness algorithm also considers the variation of the entry and exit angles caused by tool run-out. To determine the cutting force coefficients, a finite element model (FEM) of orthogonal micro-cutting that considers strain hardening, strain rate sensitivity, thermal softening behavior, and temperature-depEndent flow has been established. Based on the results from FEM analysis, the cutting force coefficients are identified and represented by a nonlinear equation of the uncut chip thickness, cutting edge radius and cutting velocity. The identified cutting force coefficients are integrated into a mechanistic cutting force model and used to simulate micro End-Milling forces. The simulation results show a very satisfactory agreement with the experimental results.
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cutting forces in micro End Milling processes
International Journal of Machine Tools & Manufacture, 2016Co-Authors: Kornel F. Ehmann, Xuewei Zhang, Wanshan WangAbstract:Abstract Micro-End-Milling is capable of machining complex structures in a wider variety of materials at the micro- and meso-scales as compared to other micro machining processes. However, the exact prediction of cutting forces in micro-End-Milling is still not fully developed. In order to predict the general three-dimensional cutting force components, the related cutting edge radius size-effect, tool run-out, tool deflection and the exact trochoidal trajectory of tool flute are considered and presented in the proposed analytical prediction model. The proposed cutting force model also includes an algorithm for the calculation of the variable entry and exit angles caused by tool run-out and tool deflection. In the cutting force prediction model, the actual instantaneous uncut chip thickness is evaluated by considering the theoretical instantaneous uncut chip thickness, the minimum uncut chip thickness and a certain critical chip thickness value governed by three types of material removal mechanisms, in the elastic and the elastic–plastic deformation region and the complete chip formation region, respectively. To verify the model, the parameters of tool run-out and tool deflection were obtained from experimental measurements. The proposed cutting force model is validated through micro slot End Milling tests with a two-flute carbide micro-End-mill on Al6061 workpieces. The experimental results agree with simulation results very well. The proposed theoretical model offers a basis for real-time machining process monitoring as well as cutting parameters optimization.
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a mechanistic model of cutting forces in micro End Milling with cutting condition indepEndent cutting force coefficients
Journal of Manufacturing Science and Engineering-transactions of The Asme, 2008Co-Authors: Han Ul Lee, Dongwoo Cho, Kornel F. EhmannAbstract:Complex three-dimensional miniature components are needed in a wide range of industrial applications from aerospace to biomedicine. Such products can be effectively produced by micro-End-Milling processes that are capable of accurately producing high aspect ratio features and parts. This paper presents a mechanistic cutting force model for the precise prediction of the cutting forces in micro-End-Milling under various cutting conditions. In order to account for the actual physical phenomena at the edge of the tool, the components of the cutting force vector are determined based on the newly introduced concept of the partial effective rake angle. The proposed model also uses instantaneous cutting force coefficients that are indepEndent of the End-Milling cutting conditions. These cutting force coefficients, determined from measured cutting forces, reflect the influence of the majority of cutting mechanisms involved in micro-End-Milling including the minimum chip-thickness effect. The comparison of the predicted and measured cutting forces has shown that the proposed method provides very accurate results.
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instantaneous shear plane based cutting force model for End Milling
Journal of Materials Processing Technology, 2005Co-Authors: Chu Hsiang Chiou, Min Sung Hong, Kornel F. EhmannAbstract:Abstract The purpose of this paper is to further extEnd the theoretical understanding of the dynamic End Milling process and to derive a computational model to predict the Milling force components. A comparative assessment of different cutting force models is performed to demonstrate that the instantaneous shear plane based formulation is physically sound and offers the best agreement with experimental results. The procedure for the calculation of the model parameters used in the cutting force model, based on experimental data, has been presented. The influences of the helix angle on the shear stress, friction angle, and shear angle have also been investigated. The helix angle effect on the cutting force model was experimentally determined and it was shown that the cutting force model is applicable for a wide range of cutter helix angles. The validity of the proposed computational model, based on a discrete representation of the End Milling process, has been experimentally verified through a series of cutting tests. The resultant cutting forces were computed as the sum of elemental cutting forces composed of a chip shearing and of a tool–workpiece contact force component.
W Y Bao - One of the best experts on this subject based on the ideXlab platform.
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modeling micro End Milling operations part i analytical cutting force model
International Journal of Machine Tools & Manufacture, 2000Co-Authors: W Y Bao, I N TanselAbstract:A new analytical cutting force model is proposed for micro-End-Milling operations. The model calculates the chip thickness by considering the trajectory of the tool tip while the tool rotates and moves ahead continuously. The proposed approach allows the calculation of the cutting forces to be done accurately in typical micro-End-Milling operations with very aggressively selected feed per tooth to tool radius ( ft/r) ratio. The difference of the simulated cutting forces between the proposed and conventional models can be experienced when ft/r is larger than 0.1. The estimated cutting force profile of the proposed model had good agreement with the experimental data. © 2000 Elsevier Science Ltd. All rights reserved.
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modeling micro End Milling operations part ii tool run out
International Journal of Machine Tools & Manufacture, 2000Co-Authors: W Y Bao, I N TanselAbstract:The effect of run-out is clearly noticed in micro-End-Milling operations, while the same run-out creates negligible change at the cutting force profile of conventional End-Milling operations. In this paper, the cutting force characteristics of micro-End-Milling operations with tool run-out are investigated. An analytical cutting force model is developed for micro-End-Milling operations with tool run-out. The proposed model has a compact set of expressions to be able to estimate the cutting force characteristics very quickly compared to the numerical approaches. The cutting forces of micro-End-Milling operations simulated by the proposed model had good agreement with the experimental data.
