Cutting Force Model Research Articles

Implementation of a cutting forces model through virtual simulation of machining process

Implementation of a cutting forces model through virtual simulation of machining process

Digital dynamic modeling and topology optimized design of shell face mills

This paper presents digital modeling of shell face mills in milling cylinder heads. The cutter's structural dynamics and its mode shapes are predicted using a Finite Element system. The geometries of the cutter body and inserts are imported from their Computer Aided Design (CAD) models. The insert edge is discretized into small segments to model its varying normal rake and inclination angles, which affect the cutting mechanics. The cutter is dynamically assembled with the target machine tool spindle using the receptance coupling method. A general dynamic cutting force model, which considers the varying edge geometry and inserts’ run-outs, is developed and used to predict cutting forces and chatter stability diagrams. The proposed model is experimentally verified to demonstrate the feasibility of the systematic application of physics-based digital design and analysis of tools for the mass machining of specific parts. The cutter body shape is optimized to increase the stiffness of the bending mode shape that caused chatter via topology optimization, which led to five-fold increase in the absolute stable depth of cut.

Cutting force modeling during turning Inconel 718 using unitary Al2O3 and hybrid MWCNT + Al2O3 nanofluids under minimum quantity lubrication

Cutting force modeling during turning Inconel 718 using unitary Al2O3 and hybrid MWCNT + Al2O3 nanofluids under minimum quantity lubrication

Cutting Force Model of SiCp/Al Composites in Ultrasonic Elliptical Vibration Assisted Cutting with Negative Rake Angle

Cutting Force Model of SiCp/Al Composites in Ultrasonic Elliptical Vibration Assisted Cutting with Negative Rake Angle

Efficient identification of cutter axis offset in five-axis ball-end interrupted milling using twin data method free from cutting force model

Although many methods for the identification of cutter axis offset have been proposed, almost all approaches are based on the computation models of cutting force. The mechanical behavior of the cutting tool cannot always be completely described by the existing force models. Once the cutting force is calculated inaccurately, the identification of cutter axis offset certainly is affected. In order to get rid of dependence on cutting force model, this paper presents a twin data driven model for the efficient identification of cutter axis offset in five-axis ball-end interrupted milling. The cutter coupled motion is divided into the two decouple standard movement units at first. The measured feature parameter of the axis offset is then extracted from cutting force signal by the geometric modeling technology. Subsequently, the theoretical and measured critical cutting positions are defined as a pair of twins. The axis offset parameters are identified by minimizing the distance of the twin data using the intelligent optimization algorithm. Lastly, the effectiveness of the proposed method is verified by the numerical examples and cutting experiments performed in five-axis ball-end milling.

Cutting Force Model of Ultrasonic Elliptical Vibration-Assisted Helical Milling of SiCp/Al Composites

Cutting Force Model of Ultrasonic Elliptical Vibration-Assisted Helical Milling of SiCp/Al Composites

Low-frequency chatter suppression for robotic milling using a novel MRF absorber

Robotic milling has a unique advantage for large and complex parts. However, it is extremely prone to low-frequency chatter due to the robot structure mode. In robotic milling, low-frequency chatter has a huge impact on machining quality and efficiency. In this paper, a novel MRF (Magnetorheological fluid) absorber is used to suppress low-frequency chatter during robotic milling based on the proposed low-frequency chatter suppression strategy. First, the GPR (Gaussian process regression) model is used to predict the impulse response function based on a few measured impulse response functions. Next, a cutting force model is developed considering the tool runout and the robot structure mode. The parameters and coefficients of the cutting force model are optimized by the measured cutting forces. Then, the low-frequency chatter frequency is predicted considering the modal coupling effect based on the predicted impulse response function and the simulated cutting force. Finally, an MRF absorber is designed based on the chatter frequency range. The controlled storage modulus of the MRF in the pre-yield region enables a wider frequency shift characteristic of the designed MRF absorber. The MRF absorber controls the input current based on the predicted low-frequency chatter frequency to achieve chatter suppression during robotic milling. Robotic milling experiments verified that the MRF absorber can effectively suppress low-frequency chatter. The experimental results show that the Energy Ratio Chatter Indicator of the industrial robot with MRF absorber is less than 0.1 under different milling conditions.

Prediction of cutting forces, damage locations and machined surface integrity in machining of circular-cell honeycomb composites: Simulations, parametric effects and experimental validations

The machining of honeycomb cores presents challenges due to exerted unbalanced cutting forces from discontinuous hexagonal structures, where severe tool wear and cracking on the machined surface occurs. In this study, the established cutting force models consider alterations of the wall thickness and immersion angles when mono-oblique and duplex-oblique cutting tools are engaged. The maximum cutting forces and the produced damages compared to the tool positions are analytically simulated and validated. The increased cutting temperatures and the shear stress gradients with respect to cutting speeds and feed rates were analysed after fitting them with the experimental results. Moreover, the vibration-induced cutting-edge-rounding and fracturing on the machined surface were identified. In the validation experiments, a wide range of cutting speeds (100–300 m/min) and feed rates (0.2–1.0 mm/rev) were operated for practical utilities. It was proven that the highest cutting forces (∼26.59 N) took place at the entry node of the hexagonal cell; whilst the cutting forces’ fluctuations (±20.35 N) under high frequency (∼2.5 kHz) and high intensity (∼ 8290 dB) could result in cutting-edge rounding from tool wear. The damage locations on the machined surfaces, as well as the corresponding fracturing mechanisms of fibres incubating the in-plane and out-of-plane cracks were verified and discussed.

Forecasting the cutting force in end milling

The object of this study is the process of end milling, taking into account the discontinuity of the process, simultaneous cutting with several flutes arranged in a spiral, tool runout, and feedback in the elastic machining system, in particular, for the depth of cutting. The subject of the study is the cutting force and identification of its empirical model. During identification, the cutting force coefficient is automatically determined when matching the theoretical and experimental oscillograms of the cutting force component. The reported results related to forecasting the cutting force at end milling are based on a mechanistic approach and involve the process modeling method for forecasting. The simulation uses an algorithm for representing the interaction of the cutter flutes workpiece engagement, based on the scan of the cutter according to the rotation angle coordinate. The algorithm makes it possible to identify empirical coefficients and exponents of the cutting force model based on experimental oscillograms of cutting force components. The built model is implemented in an application program and owing to the representation of the machining system in the form of a closed structural diagram, it allows predicting the elastic displacement, which will determine the actual cutting depth. The developed program under an interactive mode using digital files of experimental cutting force components makes it possible to perform model identification and predict cutting force components with an error of 4.6 %. The adequacy of the algorithms was confirmed by measuring the profile of the machined surface in the places where the cutting mode changed with the feed stopped. The developed simulation algorithm makes it possible to take into account the simultaneous cutting by several flutes arranged in a spiral, the runout of the tool, and the feedback in the elastic machining system, in particular, the depth of cutting

Modeling and reliability analysis of the micro-milling process considering stochastic tool wear with surrogate models

Micro-milling technology is widely employed in manufacturing micro-precision parts due to its flexible processing and high accuracy. Compared to the macro-milling process, micro-milling has a smaller machining size, which leads to tool wear, tool runout, and other factors being more sensitive to the impact of machining quality. This work proposes a reliability evaluation framework for machining systems based on the micro-milling mechanical model and its surrogate method. Establish a cutting force model under shear and plow conditions with periodic variations in instantaneous uncut thickness. Subsequently, the probability distribution of the cutting parameters is obtained based on Bayesian updates. An improved buffer failure probability method is proposed to quickly get the micro-milling system failure probability. Developing new ensemble and adaptive sampling methods and introducing stochastic configuration network (SCN), an adaptive stochastic configuration network ensemble (ASCNE) model is established to alleviate the time-consuming problem of repeated calculations of mechanical models in reliability analysis. Experimental results indicate that the mechanical model can achieve good predictive performance, and the constructed ASCNE model can achieve high-precision surrogate effects. Additionally, the reliability analysis results of the system can guide tool replacement during the machining process, ensuring safe and efficient execution of the micro-milling.

Stability of Micro-Milling Tool Considering Tool Breakage

Micro-milling, widely employed across various fields, faces significant challenges due to the small diameter and limited stiffness of its tools, making the process highly susceptible to cutting chatter and premature tool breakage. Ensuring stable and safe cutting processes necessitates the prediction of chatter by considering the tool breakage. Crucially, the modal parameters of the spindle–holder–tool system are important prerequisites for such stability prediction. In this paper, the FRFs of the micro-milling tool are calculated by direct frequency response functions (FRFs) of the micro-milling cutter and cross-FRFs between a point on the shank and one on the tool tip. Additionally, by utilizing a cutting force model specific to micro-milling, the bending stress experienced by the tool is computed, and the tool breakage curve is subsequently determined based on the material’s permissible maximum allowable stress. The FRFs of the micro-milling tool, alongside the tool breakage curve, are then integrated to generate the final stability lobe diagrams (SLDs). The effectiveness and reliability of the proposed methodology are confirmed through a comprehensive series of numerical and experimental validations.

Влияние динамических характеристик процесса резания на шероховатость поверхности детали при токарной обработке

Introduction. The formation of the surface of a part when processing it on a metal-cutting machine is based on properly selected cutting modes. Complex methods of ensuring the specified quality of the part surface also take into account the tool geometry, its condition, and include corrections for tool deviation from the trajectory set by the CNC system under the influence of kinematic disturbances and spindle wavering. Subject. The paper analyzes the relationship between cutting modes and dynamic characteristics of the turning process, and its mapping into surface roughness. The aim of the work is to evaluate the influence of technological cutting modes taking into account the vibration activity of the tool on the roughness of the machined surface by means of simulation modeling. Method and methodology. Mathematical simulation of the dynamics of the cutting process is given, on the basis of which a digital simulation model is built. A methodology of using the simulation model for determining optimal cutting modes and predicting surface roughness taking into account tool vibrations is proposed. By means of experiments and analysis of the frequency characteristics of tool vibrations, the created model is validated, parameters of the cutting forces model subsystem and dynamic tool subsystem are specified, and geometrical topologies of the part surface are constructed. The calculated cutting forces are compared with experimental forces, and similar patterns and levels of characteristics are observed. An assessment of the optimality of the selected cutting modes is proposed based on the analysis of the tool vibration spectrum relative to the workpiece and the results of the numerical model simulation. Results and Discussion. A comparison of the results of digital modeling of the geometrical surface of the workpiece and the real surface obtained during the field experiment is given. It is shown that the roughness of the real surface obtained by machining with constant cutting modes varies relative to the surface roughness of the simulation model within the limits of not more than 0.066 µm.

Milling Stability Modeling by Sample Partitioning with Chatter Frequency-Based Test Point Selection

This paper describes a sample partitioning approach to retain or reject samples from an initial distribution of stability maps using milling test results. The stability maps are calculated using distributions of uncertain modal parameters that represent the tool tip frequency response functions and cutting force model coefficients. Test points for sample partitioning are selected using either (1) the combination of spindle speed and mean axial depth from the available samples that provides the high material removal rate, or (2) a spindle speed based on the chatter frequency and mean axial depth at that spindle speed. The latter is selected when an unstable (chatter) result is obtained from a test. Because the stability model input parameters are also partitioned using the test results, their uncertainty is reduced using a limited number of tests and the milling stability model accuracy is increased. A case study is provided to evaluate the algorithm.

Stability analysis of multi-insert rotating boring bar with stiffness variation

Manufacturing faces challenges in boring processes, critical for hole enlargement and finishing, due to low stiffness leading to static deflection and regenerative chatter. Stiffness variation has emerged as a promising solution for effectively suppressing chatter, while multi-insert rotating boring bars offer a viable approach to addressing static deflection in long and slender boring bars, enabling better tolerance with a large operational length-to-diameter ratio. However, integrating technological innovations to suppress chatter and prevent static deflection complicates the problem from a modeling and stability analysis perspective, making it challenging to find a comprehensive solution in the existing literature. This study explores the stability of multi-insert rotating boring bars with stiffness variation, providing insights into selecting optimal stiffness variation parameters. It introduces a novel extension of the multi-dimensional cutting force model to rotating boring tools with multiple inserts, employing the zero-order harmonic solution to analyze the stability of boring processes with time-varying dynamics. Experimental validation demonstrates the effectiveness of the proposed methodology, achieving 5 out of 6 matches in stability lobe diagrams for multi-insert rotating boring bars without stiffness variation. The model’s comprehensiveness is further demonstrated by comparing the results with those of existing studies in the literature for single-insert stationary boring bars. In the case without stiffness variation, the model successfully reproduces 4 out of 5 operating points, and with stiffness variation, it accurately predicts all 5 operating points. Sensitivity analyses guide the selection of optimal stiffness variation parameters for effective chatter suppression, favoring moderate frequencies and up to a 30% amplitude ratio.

Coupling effect of machine tool dynamic characteristics and cutting conditions on the cutting process vibration and high-speed micro-planing surface mid-frequency waviness

In addition to the dynamic characteristics of the machine tool, cutting conditions significantly influences the vibration of the cutting system and mid-frequency waviness of the workpiece surface in ultra-precision machining (UPM). In this work, the effects of cutting conditions on machining vibration and surface waviness were investigated by high-speed micro-planning experiments. The origin of vibration and waviness were elucidated by frequency-domain processing of the vibration signal and surface waviness analysis. The dynamic characteristics of machine tool are determined using modal test and analysis. The results revealed that the cutting force has different contributions to the workpiece vibration and tool vibration. In the time domain, distinct differences can be found in stability and attenuation of various waviness components. The divergent effects of cutting force components in different vibration forms are confirmed through a novel cutting force model of micro-planing. The investigation can further reveal the formation mechanisms of cutting system vibration and surface waviness during the micro-cutting process, which can provide practical guidance for suppressing mid-frequency waviness on machined surfaces.

Improving Machined Accuracy Under a Constant Feed Speed Vector at the End-Milling Point by Estimating Machining Force in Tool Approach

A five-axis machining center (5MC) is capable of synchronous control, which makes it a feasible tool for quickly and accurately machining complicated three-dimensional surfaces, such as propellers and hypoid gears. Recently, the necessity of improving both the machined shape accuracy and the machined surface roughness of free-form surfaces is growing. Therefore, in our previous study, we aimed to maintain the feed speed vector at the end-milling point by controlling two linear axes and a rotary axis of the 5MC to improve the quality of the machined surface. Additionally, we developed a method for maintaining the feed speed vector at the end-milling point by controlling the three axes of the 5MC to reduce the shape error of the machined workpieces (referred to as the shape error herein), considering the approach path of the tool determined via calculation. However, a high machining force at the start of the workpiece cutting was observed and the factor contributing to this phenomenon was not determined, although this phenomenon leads to a shape error to a certain degree according to the machining condition. In this study, the main objective is to suggest a method to reduce the machining force at the start of the workpiece cutting and shape error. Hence, we develop a theoretical method to estimate the machining force by using an instantaneous cutting force model, which considers the synchronized motion of two linear axes and a rotary axis of the 5MC. Subsequently, we determine the most suitable approach path of the tool considering the prediction of the machining force. The results of this study indicate that the machining force can be estimated by applying an instantaneous cutting force using the feed per tooth and machining angle, and that both a high machining force at the start of the workpiece cutting and shape error reduction can be realized by using the proposed approach path of the tool.

Force and wear prediction model of disc cutter under compression shear failure mode based on dense core–cavity expansion theory (U-713)

Calculating disc cutter wear and predicting wear life are long-standing issues affecting the efficiency and cost of tunnel boring machines (TBMs). During the TBM excavation process, the wear of the disc cutter is a comprehensive outcome of the interaction between the tool and rock. Studying the mechanisms of tool rock breaking and wear can assist in developing a more precise model for predicting cutter wear. Therefore, based on the rock-breaking and wear mechanisms of a cutter, this study developed a model for predicting the cutter wear rate and life. The model is based on the theory of dense core–cavity expansion combined with the motion state of a cutter. First, the TBM excavation process and rock-breaking mechanism of a cutter were analyzed in detail. A cutting force model under the compression shear failure mode based on the dense core–cavity expansion theory was established. Based on the force model, a prediction model for the wear rate and life of the disc cutter was established, considering the working characteristics and wear mechanism. Furthermore, the impact of penetration on the prediction model was investigated. In addition, to demonstrate the practicality of the method, this study conducted a comprehensive examination using engineering examples. The results showed that the average difference in the cutter average wear rate using the developed model was less than 3% compared with the actual engineering result. In addition, the average difference in the wear life rate was less than 5%. Finally, the developed prediction method was compared with other models. The wear rate fitting accuracy was improved by 4.91–10.85% and the wear life fitting accuracy was improved by 5.11–12.19% by the developed method. This improvement confirms the reasonableness and reliability of the method. This method can estimate the wear rate and lifespan of a cutter more accurately and reliably than other methods, providing a practical tool to TBM engineers to make informed decisions and optimize tool replacement programs.

Cutting force reduction mechanism in ultrasonic cutting of aramid honeycomb

Aramid honeycomb has extensive applications in the aerospace and rail transportation industries. Ultrasonic cutting (UC) with the straight blade (SB) is an advanced technology used for the profile machining of honeycomb materials. Cutting force is an important factor affecting machining quality, and its accurate modelling is particularly important. However, SB is a flake tool, and chips of honeycomb are removed in block or strip forms during cutting, and its structure and material removal method are obviously different from conventional machining. Existing simplified cutting force models based on kinematic analyses and experiments are incapable of describing the cutting process. In this paper, a geometrical kinematics analysis of SB is conducted. Further, the modelling of tool-workpiece contact rate (TWCR) for UC with SB is established, which is utilized to analyze the tool-material contact state. Based on the principle of conservation of energy, the fracture force at the blade edge is analyzed. Based on the analysis of instantaneous friction force, the friction force model on blade surfaces is established. Multiple-cutting experiments are conducted to separate fracture force and friction force. The influence of machining parameters (ultrasonic amplitude, lead angle, cutting speed) on TWCR, cutting force, fracture force, and friction force have been theoretically and experimentally studied, and the reduction mechanism of the cutting force is revealed. Furthermore, the machining quality under different machining parameters is observed and the relationship with cutting force is analyzed. The paper not only provides theoretical guidance for the study of the UC mechanism but also helps to guide the UC process of aramid honeycomb.

Modelling cutting force for turning AISI 304 stainless steel with PVD-AlTiN coated, PVD-AlTiN coated-microblasted, and MTCVD-TiCN/Al2O3 coated tools

ABSTRACT Stainless steel is challenging to machine, and to avoid any negative consequences, it is essential to comprehend the cutting forces. With this view, this study has developed a cutting force model for turning AISI 304 stainless steel with the most preferred PVD-AlTiN coated (C-type), PVD-AlTiN coated-microblasted (CMB), and MTCVD-TiCN/Al2O3 coated carbide tools (MTCVD). Empirical models are developed to predict the chip thickness ratio, the normal shear angle, and sharp tool cutting forces. Studies showed the reduction in forces with the cutting speed for C-type, CMB, and MTCVD tools was 12–20%, 11–32%, and 6–29%, respectively. However, the corresponding increases with the feed and depth of cut were 60–134%, 125–146%, and 97–178%; 76–186%, 55–384%, and 14–274%, respectively. Additionally, a cutting force model considering the tool wear effect is developed for MTCVD tools, which exhibited lower tool wear compared to other tools. The study accurately predicted sharp tool and worn tool cutting forces, showing good quantitative agreement with experimental results with an average error of less than 10%. However, some discrepancies were observed beyond the flank wear length of 0.2 mm. It was due to the chipping of the coating layers and the pitting of the substrate from the nose area.

Analytical modeling of cutting force in vibration-assisted helical milling of Al 7075 alloy

Vibration-assisted helical milling is considered a promising hole-making process in the aerospace industry. The prediction of cutting force magnitude and behavior is very important to determine the cutting power, produce tight tolerance, eliminate tool wear, and improve the hole quality. Therefore, the main goal of this work is to establish a cutting force model and evaluate the cutting force coefficients, based on a mechanistic approach, during vibration-assisted helical milling of aerospace aluminum alloy (Al 7075). The process kinematics, the chip geometry including the chip width and chip thickness variations, and the tool-workpiece engagement are theoretically analyzed throughout the whole machining time. A set of experimental tests is implemented at different conditions of tangential feed and helical pitch. Additionally, model validation is performed to discuss the quality and accuracy of the presented model. Consequently, the behavior of the cutting force components against the application of ultrasonic vibration at different cutting conditions is demonstrated. The results show that the analytical and the experimental results are well agreed with a relatively small error percentage. The cutting force components generally increase as tangential feed and helical pitch increase. Moreover, the superimposed ultrasonic vibration causes a rapid tool-workpiece separation increasing the analytical and the experimental oscillation of the cutting force components, thus decreasing the average calculated cutting force.