Cutting Force Prediction Model Research Articles

The finite element analysis–based simulation and artificial neural network–based prediction for milling processes of aluminum alloy 7050

The cutting forces will generally suffer massive complex factors, such as material deformation, tool eccentricity and system vibration, which will inevitably induce many great difficulties in accurately modeling the cutting force predictions that are very significant to investigate cutting processes. Therefore, the genetic algorithm optimized back-propagation and particle swarm optimization neural networks will be adopted to effectively construct cutting force prediction models. In these two back-propagation prediction models, the main milling parameters will be defined into their input vectors, and the transient milling forces along three different directions will be selected as their output vectors, then the implicit relationships between input and output vectors can be directly generated through practically training and learning these two built back-propagation models with a set of experimental milling force data. Meanwhile, the finite element analysis method will be also used to predict milling forces through programming two easy-to-operate plug-ins that can efficiently construct finite element analysis models, conveniently define processing parameters, and automatically perform mesh generation. Subsequently, the milling forces predicted by the established genetic algorithm optimized back-propagation and particle swarm optimization back-propagation models will be analytically compared with finite element analysis simulations and experiments; also the stress distribution and chip formations of finite element analysis and experiments will be comparatively investigated. Finally, the obtained results clearly indicate that these two back-propagation models built by artificial neural networks can well agree with finite element analysis simulations and experiments, but the particle swarm optimization back-propagation model is superior to the genetic algorithm optimized back-propagation model, which clearly demonstrate the particle swarm optimization back-propagation model has higher efficiencies and accuracies in predicting the average and transient cutting forces for different milling processes on aluminum alloy 7050.

A Cutting Force Prediction Model, Experimental Studies, and Optimization of Cutting Parameters for Rotary Ultrasonic Face Milling of C/SiC Composites

Ceramic matrix composites of type C/SiC have great potential because of their excellent properties such as high specific strength, high specific rigidity, high-temperature endurance, and superior wear resistance. However, the machining of C/SiC is still challenging to achieve desired efficiency and quality due to their heterogeneous, anisotropic, and varying thermal properties. Rotary ultrasonic machining (RUM) is considered as a highly feasible technology for advanced materials. Cutting force prediction in RUM can help to optimize input variables and reduce processing defects in composite materials. In this research, a mathematical axial cutting force model has been developed based on the indentation fracture theory of material removal mechanism considering penetration trajectory and energy conservation theorem for rotary ultrasonic face milling (RUFM) of C/SiC composites and validated through designed sets of experiments. Experimental results were found to be in good agreement with theoretically simulated results having less than 15% error. Therefore, this theoretical model can be effectively applied to predict the axial cutting forces during RUFM of C/SiC. The surface roughness of the workpiece materials was investigated after machining. The relationships of axial cutting force and surface roughness with cutting parameters, including spindle speed, feed rate, and cutting depth, were also investigated. In order to identify the influence of cutting parameters on the RUFM process, correlation analysis was applied. In addition, response surface methodology was employed to optimize the cutting parameters.

A modified analytical cutting force prediction model under the tool crater wear effect in end milling Ti6Al4V with solid carbide tool

This paper presents a study of the relationship between cutting force and tool crater wear of solid carbide tool during milling Ti6Al4V. The cutting force model in milling considering tool crater wear is discussed, which shows that for given the cutting conditions, tool geometries, and workpiece material, cutting force under the tool crater wear effect could be predicted easily and conveniently. The tool wear condition in milling Ti6Al4V is obtained by finite element simulation method. In addition, the experimental work of end milling Ti6Al4V with solid carbide tool is developed. Comparisons among experiment results, mathematical model results, and finite element simulation model results, including cutting force and tool wear, are discussed. The results show that the proposed mathematical model could predict cutting force under the tool crater wear effect with higher accuracy.

Discrete Element Modeling of the Effects of Cutting Parameters and Rock Properties on Rock Fragmentation

Rock properties (e.g., brittleness, fracture toughness, hardness, compressive strength and tensile strength), cutting parameters (e.g., cutting depth, attack angle, wedge angle, cutting velocity) and confining stress are closely related to rock fragmentation behaviors in the design and application of excavation and mining machinery. To investigate the influence mechanism of those factors on rock fragmentation, a series of linear cutting numerical tests were conducted using the discrete element method. Numerical models with different rock mechanical parameters were calibrated by changing the cohesion strength-to-tensile strength ratio of the linear parallel bond model in PFC2D. The effects of cutting parameters on rock fragmentation were studied using orthogonal test and range analysis. The numerical results indicated that the strength ratio had a dominant effect on the specific energy and that the cutting depth and attack angle had a dominant effect on the mean cutting force. The cutting velocity significantly influenced the specific energy, and a higher cutting velocity should be adopted in actual rock cutting. In addition, a cutting force prediction model was proposed that considered factors such as the compressive strength, wedge angle, attack angle and cutting depth. Moreover, the introduction of more rock mechanical parameters into the evaluation indicators can reflect a greater number of fragmentation characteristics.

A cutting force prediction model for rotary ultrasonic side grinding of CFRP composites considering coexistence of brittleness and ductility

Cutting force has a great effect on the machining surface/subsurface damage. The prediction model of cutting force is necessary to optimize input variables. During rotary ultrasonic side grinding (RUSG), the indentation depth of a single abrasive grain increases (up milling) from 0 to maximum or decreases (down milling) from maximum to 0 with the motion of abrasive grains. Therefore, the ductile removal mode and brittle fracture removal mode coexist. In this research, a mechanistic cutting force model in RUSG of carbon fiber–reinforced polymer (CFRP) composites, considering both brittleness and ductility, has been developed for the first time. The ductile-brittle ratio K has been put forward and obtained through experiments. The cutting force perpendicular to feed direction has been calculated by integration method from the point of force analysis. The results showed that K increases with the rise of spindle speed or the decrease of feed rate and cutting width. The cutting force behaves oppositely with respect to K. Finally, orthogonal experiments have been conducted to verify the cutting force model and the results show good consistency between theoretical cutting force and measured cutting force. The developed model is capable to predict the cutting force in RUSG of CFRP composites and provides a support for optimizing the process.

Development of a Cutting Force Prediction Model for Silica/Phenolic Composite in Mill-grinding

A cutting force model was developed from silica/phenolic composites for mill-grinding process. The experimental was carried out on silica/phenolic material and found that the cutting force decreased significantly with the increase of cutting speed, whereas the same was found increased with the increase of feed rate and cutting depth. By comparison of the experimental and simulation data of the cutting force, it was found that the errors are below than 30 % in most of the sets of parameters. The variation found is due to the heterogeneity and other complex properties of silica/phenolic composites. The results were almost the same as previous experiments. So, the cutting force model developed in this paper is robust and it can be applied to predict the cutting force and optimization of the process.

Effect of tool path on cutting force in end milling

Tool path generation is an important task in end milling. In the existing literature, the tool path pattern/style is determined based on geometric analysis. However, there is little analysis from the viewpoint of machining dynamics/cutting force, which is more related to the final manufacturing performance. Although there are many types of tool paths (e.g., zigzag, spiral, and ISO-scallop tool path), they can be decomposed into a number of circular tool paths with various path radii and cutting angles. Firstly, by investigating chip formation mechanism, the effect of tool path radius on uncut chip thickness is obtained. Analysis shows that tool path radius has a significant influence on uncut chip thickness, thus affecting the cutting force, especially when the tool path radius is small. Then, the effect of cutting angle on cutting force distribution is analyzed. It is found that the feed direction could vary the distribution of cutting force in X and Y direction in 3-axis end milling. Based on such analysis, the cutting force prediction model considering tool path effect is established. To validate the proposed model, various experiments have been carried out based on well-designed tool paths. The comparative results show that (1) tool path has great effect on cutting force through the tool path radius, rotation direction, and start/end point, and (2) the proposed model is capable of providing accurate cutting force prediction considering tool path effect. From a physical viewpoint, the proposed method provides huge potential in automated/intelligent tool path optimization towards better surface quality via minimizing cutting force, which significantly contributes to the state of the art in tool path generation.

A systemic investigation of tool edge geometries and cutting parameters on cutting forces in turning of Inconel 718

In metal cutting process, size effects and edge effects have a significant influence on cutting forces and therefore on the machining performance. This paper facilitates those behaviors with different cutting tool geometry, i.e., round edge and chamfered edge, using analytical cutting force prediction models when turning Inconel 718 with round cutting inserts. Analytical methods used for different edge preparation are developed with the consideration of size effects and edge effects. Then, an attempt is made to analyze the cutting investigations of the influence of size effects and edge features. The cutting forces and edge forces are estimated with the modified Johnson–Cook constitute model considering the size effects and edge effects. Rounded edge coefficients and chamfered edge coefficients estimated with different analytical methods are used in calculating edge forces for rounded edged tools and chamfered edged tools, respectively. Simulations with finite element model (FEM) and cutting experiments are used to verify the proposed model. Finally, the detailed influences of size effects, edge geometries, and feed rate on the cutting forces are studied based on the proposed model and FEM simulations.

Axial cutting force prediction model of titanium matrix composites TiBw/TC4 in ultrasonic vibration–assisted drilling

Ultrasonic vibration–assisted drilling (UVAD) can significantly improve the quality of the hole while reducing the axial force of drilling, which has important application prospects. In order to reveal the variation law of drilling force under the joint action of ultrasonic vibration and cutting heat, and to guide the optimization of high-efficiency UVAD process, titanium matrix composites TiBw/TC4 (TiB whisker volume fraction of 8.5%) is taken as the research object. Firstly, based on the theory of fracture indentation and the theory of ordinary drilling (OD), the comprehensive softening coefficient of the material under the action of ultrasonic impact and cutting temperature is introduced, and the model of axial drilling force considering the softening effect is established. Secondly, the experiment of UVAD was carried out, and the interaction mechanism about drilling force and vibration impact and drilling temperature was analyzed. Finally, the experimental data was used to establish the softening coefficient response surface, which described visually the variation law of the softening coefficient. The feasibility of the drilling force model was verified, and the trend between the drilling parameters and the drilling force was analyzed. The results show that the error between experimental axial drilling force value and prediction value of UVAD is less than 10%, and the maximum axial drilling force is about 23.1% lower than OD.

An improved cutting force prediction model in the milling process with a multi-blade face milling cutter based on FEM and NURBS

Multi-blade face milling cutters are widely used in the finish machining of mechanical parts. The cutting force in the milling process is a crucial factor that promotes the chatter of the machine spindles, which can be used to predict the machined surface roughness. In this paper, a novel cutting force prediction model based on non-uniform rational basis splines (NURBS) and finite element method (FEM) is proposed. Single blade cutting forces under different parameters are simulated by FEM, and a cutting force model of the single blade is established by the NURBS interpolation method. Then, combined with the tool tip motion model, the cutting force of the multi-blade face milling cutter can be predicted. To verify the correctness of the cutting force predicted by the proposed method, the common coefficient-based cutting force mathematical prediction method is utilized as benchmark for comparison with the predicted results. The accuracy is verified by comparison with experimental data. According to the collected experimental data, the proposed model is proved to be an accurate and efficient method to predict the cutting force of the multi-blade face milling cutter in the milling process.

A 3-D instantaneous cutting force prediction model of indexable disc milling cutter for manufacturing blisk-tunnels considering run-out

This paper proposed a three-dimensional (3-D) instantaneous cutting force (ICF) forecasting model for an indexable disc milling cutter considering cutter run-out. For milling blisk-tunnels, the indexable disc milling cutter must rotates about Y-axis at a certain angle; therefore, the cutting force in Z-direction is related to tangential, radial, and axial components, which have a large influence on processing precision and stability. Herein, a systematic method is presented to effectively determine the 3-D instantaneous cutting force coefficients (ICFCS) through only several calibration experiments. It was found that the distribution laws of the ICFCS match exponent functions of instantaneous uncut chip thickness (IUCT). Experiments were carried out to validate the 3-D cutting force model, it turns out that the presented model can successfully and precisely predict the 3-D ICF of an indexable disc milling cutter under a variety of processing parameters.

Investigation on disc cutter behaviors in cutting rocks of different strengths and reverse estimation of rock strengths from experimental cutting forces

This paper investigates the disc cutter behaviors in full-scale linear cutting tests. The experimental results obtained from different rocks varying from relatively soft rock (σc=27.6 MPa) to extremely hard rock (σc=355.54 MPa) are compared to the results of the semi-theoretical prediction model (Rostami & Ozdemir, 1993; Rostami, Ozdemir, & Nilsen, 1996). Compared to the semi-theoretical results, higher experimental normal and rolling forces and lower experimental cutting coefficients and normalized resultant forces are obtained when cutting low strength rocks. Opposite results are found when cutting extremely hard rocks. An empirical disc cutter cutting force prediction model is suggested in which the input parameters are cutter diameter, cutter spacing, cutter penetration depth and rock uniaxial compressive strength. Furthermore, based on the semi-theoretical model and the new empirical model, reverse estimation of rock strengths from disc cutter cutting forces are undertaken. The results show that rock uniaxial compressive strength can be reliably evaluated from disc cutter cutting forces, but the estimation results for rock Brazilian tensile strength are not so good. This study is pertinent to the better understanding of the disc cutter behaviors in cutting rocks of different strengths and can improve the geological information acquisition and operation control during TBM tunneling.

An instantaneous cutting force model for disc mill cutter based on the machining blisk-tunnel of aero-engine

This paper presents an instantaneous cutting force prediction model for a disc mill cutter with indexable inserts. Cutting characteristics, including the normal friction angles, normal shear angles, and shear stress, are decisive factors in determining the instantaneous cutting force coefficients. The cutting characteristics can be determined by several specialized milling experiments, instead of the numerous orthogonal turning experiments that are traditionally used. In this study, the normal friction angles, normal shear angles, and shear stress are determined by a coordinate transformation of the cutting forces and the geometrical parameters of oblique cutting. Then, experiments were used to verify the cutting forces model. The results clearly indicate that shear stress can be described by a constant, nevertheless distributive law of normal shear angle and friction angle fit exponential functions of instantaneous uncut chip thickness. In conclusion, the presented model was found to successfully and accurately forecast the cutting forces of the disc mill cutter with indexable inserts under various machining conditions.

Predictive cutting force model for ductile-regime machining of brittle materials

Ductile-regime machining is a promising technique for processing brittle materials. Although it has been widely investigated, there are few studies on the cutting force in the ductile-regime machining of brittle materials. This paper proposes a predictive cutting force model for ductile-regime machining of brittle materials, with an integration of the elastic recovery of the workpiece on the tool flank face and three parts of material removal on the tool rake face, i.e., the plowing effect, the plastic deformation, and the brittle fracture. Using the predictive cutting force model, it was found that the cutting force caused by the brittle fracture takes a dominant place in the total cutting force in the cutting process. Groove cutting experiments were carried out on the MgF2 (100) crystal to validate the predictive cutting force model. The measured cutting forces showed good agreement with the predicted cutting forces. In addition, it was found that the fluctuation of the measured cutting force increases with the increase of the cutting force caused by the brittle fracture.

Analytical Calculation of Cutting Forces in Ball-End Milling with Inclination Angle

The traditional analytical cutting force prediction method for ball-end milling ignores the effect of the inclination angle on cutting forces. In this paper, a new experimental method for cutting force prediction methods considering the inclination angle in the ball-end milling process is proposed. First, the actual immersion ranges of cutter in the ball-end milling process with and without an inclination angle are analyzed by a geometrical method and the cutting force prediction model with an inclination angle is developed by a numerical integration method. Second, considering that entry and exit angles of cutting zones for different cutter layers vary due to the inclination angle, a milling force coefficients identification approach for different cutter layers is established by experimental calibration. Comparing the traditional analytical cutting force prediction method that ignores the inclination angle, the numerical simulation results show that the prediction force values calculated by the proposed method have a better consistency with the measured values.

Analytical Modeling and Experimental Validation of Cutting Forces Considering Edge Effects and Size Effects With Round Chamfered Ceramic Tools

The cutting force is one of the key factors for planning and optimizing the machining operation in material removal processes. An analytical cutting force prediction model that takes into consideration both edge effects and size effects based on the oblique cutting theory is developed and analyzed in this study. A detailed analysis of the cutting geometry is presented based on the coordinate system transformation and uncut chip thickness (UCT), which is evaluated on the rake plane instead of the reference plane. Then, the developed Johnson–Cook constitutive model of the workpiece that takes into consideration the size effects is then applied to the prediction of edge forces coefficients and cutting forces coefficients. The edge forces are predicted using the edge coefficients prediction model with the regularity found in the orthogonal simulations, which reflect the influences of chamfered length and chamfered angle. The developed model is validated using the turning operations of super alloys with round chamfered inserts. Finally, the effects of the cutter edge, cutting parameters, and UCT on the cutting forces are investigated using the developed model. The reasonableness and effectiveness of the proposed model is demonstrated through the comparison of the measured and predicted cutting forces for various chamfer characteristics.

Predictive cutting force model for a cryogenic machining process incorporating the phase transformation of Ti-6Al-4V

Titanium alloys have been attracting interest in aerospace industries because of their high strength-to-weight ratio. However, they are classified as difficult-to-machine materials due to poor tool life in machining processes. Cryogenic machining is a process that uses liquid nitrogen (LN2) as a coolant, and proposed as a method to enhance tool life in the present study. This paper presents a theoretical study to develop a predictive cutting force model for cryogenic machining of Ti-6Al-4V. A modified (in terms of cutting temperature) Johnson-Cook model that considers phase transformation, and a friction coefficient were used as input parameters for inclusion of the cryogenic cooling effect. The predictive cutting force model was validated based on an orthogonal cutting test. The predicted forces showed good agreement with the experimental data, with minimum and maximum error magnitudes of 1.9 and 17.7% for cutting force, and 0.3 and 32.8% for thrust force, respectively. Investigation of the effects of cryogenic cooling on the cutting force, micro-structure, surface integrity and burr height were conducted. The cutting force during cryogenic machining was increased compared to dry machining by a martensitic phase transformation of the work material. There was no effect of cooling condition on the surface roughness. The burr height under cryogenic conditions was decreased by 56.2 and 28.2% compared to the dry and wet conditions, respectively.

Development of cutting force prediction model for vibration-assisted slot milling of carbon fiber reinforced polymers

Carbon fiber reinforced polymers (CFRP) have got rapidly increased applications in aerospace/aircraft and other fields due to their attractive properties of high specific strength/stiffness, high corrosion resistance, and low thermal expansion. These materials have also some challenging properties like heterogeneity, anisotropy, and low heat dissipation. Due to these properties, the issues of excessive cutting forces and machining damages (delamination, fiber pull-out, surface/subsurface defects, etc.) are encountered in machining. The cutting forces are required to be minimized for qualified machining with reduced damages. In this research, a novel cutting force prediction model has been developed for vibration-assisted slot milling. The experimental machining has been carried out on CFRP-T700 composite material. The effective cutting time per vibration cycle and the force of friction have been expressed/calculated. The feasibility of vibration-assisted machining for CFRP composites has also been evaluated. The relationships of the axial and feed cutting forces with machining parameters were investigated. The results have shown the variations below 10% among experimental and corresponding simulation values (from the model) of cutting forces. However, the higher variations have been found in some experiments which are mainly due to heterogeneity, anisotropy, and some other properties of such materials. The developed cutting force model then validated through pilot experiments and found the same results. So, the developed cutting force model is robust and can be applied to predict cutting forces and optimization for vibration-assisted slot milling of CFRP composite materials at the industry level.

An analytical cutting force model for plunge milling of Ti6Al4V considering cutter runout

As one of the most efficient machining methods, plunge milling has gained more attention as a promising cutting process. This strategy is often used for roughing and semi-roughing processes for the more vibration free than other cutting operations. The motivation of this paper is that the cutting forces in plunge milling differ from that in side milling for the complex cutting condition and tool geometry. In this work, a systematic and analytical cutting force prediction model considering cutter runout for plunge milling is proposed. The detailed analysis of cutting geometry is important for modeling. The precise uncut width is calculated with consideration of the cutting step. In addition, the real-time uncut chip thickness of different inserts is calculated with consideration of the effect of cutter runout. The deduced cutting force model based on the predictive model can be used in various cutting conditions in the plunge milling process. Plunge milling tests with various cutting steps are carried out to verify the proposed model with the quantitative analysis of the results. The results indicate that the simulated results show quite good agreements with the measured cutting forces, which proves the correctness and accuracy of the proposed model.

Development of cutting force prediction model for carbon fiber reinforced polymers based on rotary ultrasonic slot milling

ABSTRACTCarbon fiber reinforced polymers (CFRP) have got widely increased applications in aviation, defense and other industries due to their properties of high specific strength/stiffness, high corrosion resistance and low-thermal expansion. The issues like excessive cutting forces and machining damages are encountered in machining due to heterogeneity, anisotropy and low heat dissipation of these materials. The cutting forces are required to be predicted/minimized through modeling. In this article, the novel axial and feed cutting force model has been developed and validated through rotary ultrasonic slot milling of CFRP composites. The variations less than 10% have been found between the measured and corresponding simulated values of the cutting forces. However, some higher variations have also been observed in the few cases mainly due to heterogeneity and anisotropy of such material. The cutting depth is a significant parameter for axial and feed forces, while the feed rate is significant for the axial force. Both the forces decreased with the increase of spindle speed, while they increased with the increase of feed rate and cutting depth. The developed models have been found to be robust and can be applied to optimize the cutting forces for such materials at the industry level.