Cutting Force Prediction Model Research Articles

Determination of the cutting forces regression functions for milling machining of the X105CrMo17 material

The aim of the research presented in this paper is to determine a cutting force prediction model for milling machining of the X105CrMo17 stainless steel. The analysed material is a martensitic stainless steel which, due to the high Carbon content (∼1%) and Chromium (∼17%), has high hardness and good corrosion resistance characteristics. This material is used for the steel structures parts which are subject of wear in corrosive environments, for making valve seats, bearings, various types of cutters, high hardness bushings, casting shells and nozzles, measuring instruments, etc. The paper is structured into three main parts in accordance to the considered research program; they are preceded by an introduction and followed by relevant conclusions. In the first part, for a more detailed knowledge of the material characteristics, a quality and quantity micro-analysis X-ray and a spectral analysis were performed. The second part presents the physical experiment in terms of input, necessary means, process and registration of the experimental data. In the third part, the experimental data is analysed and the cutting force model is developed in terms of the cutting regime parameters such as cutting speed, feed rate, axial depth and radial depth.

Implementation of analytical boundary simulation method for cutting force prediction model in five-axis milling

ABSTRACTA simulation system was developed that deals with cut geometry and machining forces when a toroidal cutter is used during semifinishing in five-axis milling. The cut geometry was calculated using an analytical method called analytical boundary simulation (ABS). ABS was implemented to calculate the cut geometry when the machining used an inclination angle and a screw angle. The effect of tool orientation on the cut geometry was analyzed. The accuracy of the proposed method was verified by comparing the cut lengths calculated using ABS with cuts obtained experimentally. The result indicated that the method was accurate. ABS was subsequently applied to support a cutting force prediction model. A validation test showed that there was a good agreement with the cutting force generated experimentally.

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

Carbon fiber reinforced polymers (CFRP) have got paramount importance in aircraft, aerospace, and other fields due to their attractive properties of high specific strength/stiffness, high corrosion resistance, and low thermal expansion. These materials have also the properties of inhomogeneity, heterogeneity, anisotropy, and low heat dissipation which generate the issues of excessive cutting forces and machining damages (delamination, fiber pull out, matrix burning, etc.). The cutting forces are required to be modeled for their control/ minimization. In this research, a generalized cutting force model has been developed for rotary ultrasonic face milling of CFRP composites. The experimental machining was carried out on CFRP-T700 material. The cutting forces found decreased significantly with the increase of spindle speed while the same found increased with the increase of feed rate and cutting depth. The variation less than 10% has been found between experimental and simulated values (from the model) of cutting forces. However, the higher variation has also observed in the few groups of experiments due to the properties of inhomogeneity, heterogeneity, anisotropy, and low heat dissipation of such materials. The expression for the contact area of the abrasive core tools has been improved and an overlapping cutting allowance has been incorporated the first time. The developed cutting force model has been validated and found robust. So, the generalized cutting force model developed in this paper can be applied to control/minimize the cutting forces for rotary ultrasonic face milling of CFRP composite materials and optimization of the process.

Force Modelling in Orthogonal Cutting Considering Flank Wear Effect

In the present work, an attempt has been made to provide a predictive cutting force model during orthogonal cutting by combining two different force models, that is, a force model for a perfectly sharp tool plus considering the effect of edge radius and a force model for a worn tool. The first force model is for a perfectly sharp tool that is based on Oxley’s predictive machining theory for orthogonal cutting as the Oxley’s model is for perfectly sharp tool, the effect of cutting edge radius (hone radius) is added and improve model is presented. The second force model is based on worn tool (flank wear) that was proposed by Waldorf. Further, the developed combined force model is also used to predict flank wear width using inverse approach. The performance of the developed combined total force model is compared with the previously published results for AISI 1045 and AISI 4142 materials and found reasonably good agreement.

Modeling and optimization of high-grade compacted graphite iron milling force and surface roughness via response surface methodology

In this study, RuT400(σb ≥ 500 MPa) was milled with different cutting speeds, feeding rates and cutting depths to construct cutting force and surface roughness prediction models via response surface method (RSM). The milling parameters were optimised via response surface, contour map and iterative algorithm. The results show that that feeding rate and cutting depth are factors that significantly affect the cutting force. Similarly, cutting speed and feeding rate were found to be significant in regards to surface roughness. The multivariate linear equations yield more accurate surface roughness and cutting force predictions than fitting the linearised multivariate non-linear equations. The cutting force prediction model is F = 60.823 − 0.020V + 149.489f + 41.932a; the surface roughness prediction model is Ra = 1.633 − 0.00161V + 1.803f + 0.0289a. The use of high-strength tools and a high-endurance manufacturing system for cutting force can greatly enhance the machining efficiency in a processing system with favourable rigidity.

A modified analytical cutting force prediction model under the tool flank wear effect in micro-milling nickel-based superalloy

This study attempts to develop a micro-milling force model under cutting conditions considering tool flank wear effect during micro-milling of nickel-based superalloy with coated carbide micro-milling tools based on our three-dimensional dynamic cutting force prediction model established earlier. The tool wear condition in micro-milling nickel-based superalloy was obtained by finite element method. A 3D thermal-mechanical coupled simulation model for micro-milling nickel-based superalloy was developed to obtain the tool wear conditions and the distribution of stress. For the given tool geometries and machining conditions, the cutting forces considering tool flank wear effect could be determined conveniently. In addition, experiments of micro-milling nickel-based superalloy were conducted to estimate the validity of the modified model. The results showed that the proposed modified force analytical model could predict micro-milling cutting forces more accurately.

Solid subtraction model for the surface topography prediction in flank milling of thin-walled integral blade rotors (IBRs)

Current CAM and milling verification software packages are not ready to predict form and surface errors derived from non-ideal conditions such as runout tool error or tool–workpiece flexibility. As a consequence, high-end parts like integral blade rotors (IBR) suffer from this lack of estimation to achieve a sound manufacturing process preparation. This work describes the implementation of a cutting force prediction model that introduces the radial engagement reduction caused by (i) tool runout and (ii) workpiece flexibility. The model is used as the seed for a calculation module based on solid modeling to obtain the surface roughness and topography applying the cutting force–wall restitution equilibrium, making use of the power of CAM solid modelers for the final topography definition. This idea takes advantage of the good accuracy of current solid modelers in comparison with the z-map topographical approach for obtaining the cutter–workpiece engagement (CWE) at each tool path step. Several flank milling tests were carried out to validate the simulations. The results demonstrated a significant level of accuracy to predict shape errors. The model may be integrated in a CAM procedure, and it is a useful utility for reducing deformation on the manufacturing of blisks and impellers.

Effects of geometric parameters of wavy-edge bull-nose helical end-mill on cutting force prediction in end-milling of Inconel 718 under MQL cooling strategy

This paper presents the results of the development of a mechanistic cutting force prediction model for wavy-edge, bull-nose, helical endmill (WEBNHE), which was validated and used to investigate the effects of the geometric parameters of the WEBNHE on the predicted cutting force components and the resultant cutting force. The mechanistic cutting force prediction model was validated by conducting end-milling experiments on Inconel 718 and incorporating the effect of the Minimum Quantity Lubrication (MQL) cooling strategy through experimentally identified six cutting force and edge force coefficients. The geometric parameters investigated in this research were: the wavelength, wave magnitude, axial shift of the linear part, and the helix angle of the wavy cutting edges. These parameters were varied one at a time, and the cutting force components for each variation were predicted using the mechanistic cutting force prediction model. The results show that the predicted and measured cutting force components were in good agreement in magnitude and shape. The cutting force components generated from the end-milling under the MQL cooling strategy were lower than under the emulsion cooling strategy. The magnitudes and shapes of the predicted cutting force components and the resultant cutting force of the WEBNHE were unique (asymmetric) in magnitude and shape compared to those of standard, bull-nose, helical endmill (SBNHE) due to the uniqueness of the wavy-cutting edge geometry.The results also show that the predicted cutting force component in the feed direction Fy is the largest and the most affected by the geometric parameters, followed by Fx. However, Fz is insignificantly affected. It was also observed that the maximum magnitudes and ranges of the cutting force component in the feed direction Fy and the resultant cutting force FR increased with an increase in the wave magnitude and decrease with increase of the wavelength, axial shift, and the helix angle. The wavy cutting edge spends more time in the cutting zone than the standard, helical, cutting edge; this extra time affects the frequency content of the cutting force signals generated by the endmill and improves the end-milling dynamics. Additionally, the distribution of the cutting forces on the wavy cutting edges was not equal due to the asymmetric cutting edge geometry.

Cutting forces in micro-end-milling processes

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.

Analytical modeling and experimental validation of residual stress in micro-end-milling

Micro-milling is widely used in aerospace and precision optical part manufacturing. Residual stress is an important index of surface integrity, which signally affects the performance of the micro-parts. This paper presents an analytical model to predict micro-milling residual stresses considering tool edge radius, material strengthening effects, and initial stress. A micro-milling cutting force prediction model is proposed, in which tool edge radius and material strengthening effects are taken into account. The imaginary heat source is utilized to estimate the temperature distribution in the workpiece. This model considers the prediction results of cutting force and temperature as thermomechanical loads experienced by the workpiece. Also, the effect of initial stress is taken into account during the estimation of residual stresses. After loading, unloading, and stresses release, the results of residual stresses in micro-milling are finally obtained. Both the micro-milling cutting force and residual stresses prediction results are validated by NAK80 steel on a three-axis ultra-precision machine. The predicted results capture the experiment results well in terms of distribution and value. Finally, the model is analyzed and discussed. The influences of tool edge radius, rake angle, feed per tooth, and spindle speed on residual stresses are preliminarily explored.

Identification of constitutive model parameters for nickel aluminum bronze in machining

The material of nickel aluminum bronze (NAB) presents superior properties such as high strength, excellent wear resistance and stress corrosion resistance and is extensively used for marine propellers. In order to establish the constitutive relation of NAB under high strain rate condition, a new methodology was proposed to accurately identify the constitutive parameters of Johnson–Cook model in machining, combining SHPB tests, predictive cutting force model and orthogonal cutting experiment. Firstly, SHPB tests were carried out to obtain the true stress–strain curves at various temperatures and strain rates. Then, an objective function of the predictive and experimental flow stresses was set up, which put the identified parameters of SHPB tests as the initial value, and utilized the PSO algorithm to identify the constitutive parameters of NAB in machining. Finally, the identified parameters were verified to be sufficiently accurate by comparing the values of cutting forces calculated from the predictive model and FEM simulation.

A new cutting force prediction method in ball-end milling based on material properties for difficult-to-machine materials

As the machining process is remarkably influenced by the cutting force, its prediction is of great significance. For most of the commonly used cutting force prediction models, they are no longer applicable once the workpiece material is altered. Consequently, a new ball-end milling force prediction method with the consideration of the workpiece material properties is presented in this study for difficult-to-machine materials in high-speed milling. Based on differential and oblique cutting mechanisms, the metal cutting process in this method is taken as the linear superposition of a series of differential oblique cutting processes. With laboring the force-loading status of rake face, the yield strength, the heat conductivity, and the plasticity of the material which are the most important factors to influence cutting force are involved as the input elements. Furthermore, the interaction between material properties and machining conditions is also introduced to broadened the scope of applications of this method. In accordance with specific needs, an inverse method using the average cutting force of a single disk after cutting edge discretization is proposed to obtain the specific coefficients, and the cutter engagement is determined by Z-map method. Finally, the comparison between the simulated result and the experimental result confirms the effectiveness of the presented method for different difficult-to-machine materials in high-speed milling based on slot milling and curved surface milling.

Development of a cutting force prediction model based on brittle fracture for C/SiC in rotary ultrasonic facing milling

Ceramic matrix composites of type C/SiC got par- amount importance due to their special properties like high specific strength, high specific rigidity, high-temperature strength, and high wear resistance. Their applications are in- creasing rapidly for space, military, and aerospace industries. However, due to inhomogeneous, anisotropic and varying thermal properties of these composites, there are issues to achieve desired quality, high efficiency, and cost-effective processing in machining. In this regard, the cutting force is the most critical parameter which is required to be minimized for such composites to achieve better quality and minimum defects,especially inmilling processes.In this research, brittle fracture approach was adopted and a cutting force model was developed from C/SiC composites for rotary ultrasonic face milling (RUFM) process. The experimental RUFM was car- ried out on C/SiC 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 experimen- tal and simulation data of the cutting force, it was found that the errors are below than 10 % in most of the sets of param- eters.Thevariationfoundisduetotheheterogeneityandother complex properties of C/SiC composites. The developed cut- ting force model then further validated through another set of experiments, and the results were almost the same as before experiments. So, the cutting force model developed in this paperisrobustanditcanbeappliedtopredict thecuttingforce and optimization of the process.

Development of a cutting force prediction model based on brittle fracture for carbon fiber reinforced polymers for rotary ultrasonic drilling

Abstract Carbon fiber reinforced polymers (CFRP) T700 have got increasing demand in the aerospace industry due to their high specific strength, specific stiffness, and other unique properties. Due to their inhomogeneous, anisotropic, and thermal properties, it is challenging to achieve desired accuracy and to avoid from delamination, chip-off, cracking, and burning especially in the drilling process. The cutting force is the critical parameter which is required to minimize in order to drill a hole with better accuracy and minimize defects. In this research, the brittle fracture approach was adopted and a cutting force model was developed for CFRP-T700 based on the rotary ultrasonic drilling (RUD) process. The experimental RUD was carried out on CFRP-T700 material and found that the feed rate and spindle speed are two main parameters that affect the cutting force in RUD. The cutting force data obtained from the model and experimental setup were then analyzed and found that there is small variation even below 10 % (max value of variation is 8.5 % and the average value is 0.49 %) between simulated and measured values. So, the developed cutting force model was validated and found robust. Also, it was found that with four times increase of feed rate, there is also an increase of material removal rate (MRR) four times with the decrease in the cutting force. Moreover, this model will be much helpful to keep cutting force within limits through the optimal set of parameters as feed rate and spindle speed without extensive experimentation of such costly materials.

A hybrid analytical- and discrete-based methodology for determining cutter-workpiece engagement in five-axis milling

This paper presents a new method to determine the cutter-workpiece engagement (CWE) for a toroidal cutter during free-form surface machining in five-axis milling. A hybrid method, which is a combination of a discrete model and an analytical approach, was developed. Although the workpiece surface was discretized by a number of normal vectors, there was no calculation to determine the intersection between the normal vector and the cutting tool. The normal vectors were used to define the workpiece surface mathematically; next, the engagement point was calculated using a combination of the workpiece surface equation, the parametric equation of the cutting tool, and the tool orientation data. Three model parts with different surface profiles were tested to verify the validity of the proposed method; the results indicated that the method was accurate. The method also eliminated the need for a large number of discrete vectors to define the workpiece surface. A comparison showed that the proposed method was computationally more efficient. The CWE model was subsequently applied to support the cutting force prediction model. A validation test demonstrated that in terms of trends and amplitudes, the predicted cutting forces exhibit good agreement with the cutting force generated experimentally.

Comparison of two models for predicting tool wear and cutting force components during high speed trimming of CFRP

Because of the low thermal conductivity of Carbon Fibre Reinforced Polymers (CFRPs) during high speed-trimming, cutting forces and tool wear significantly increase the temperature at the contact zone, which is then completely transferred to the cutting tool and exceeds the permitted thermal stability limit of the cutting material. This then leads to a drastic reduction of the tool life, thermal damage, poor quality, and in some cases, rejection of machined parts. This paper presents the development of tool wear and cutting force prediction models in the trimming of CFRPs. A 3/8 in. diameter CVD diamond-coated carbide tool with six straight flutes was used to trim 24-ply carbon fibre laminates. The results obtained using a scanning electron microscope (SEM) showed increasing defect rates with increased tool wear. Two models were adjusted to predict tool wear and cutting force for different values of cutting speed, feed and cutting length. One of them is a multiplicative statistical model, and the other, an exponential model. Outcomes from the two models were analysed and compared. The ANOVA approach was also used to test the overall significance of the models by applying F-tests. The results obtained show that the exponential model is better capable of accurately predicting the cutting force and tool wear under the conditions studied. To enhance the prediction accuracy of the tool wear model, the cutting force was added as a variable in the tool wear model. Results show that the enhanced multiplicative model provided higher predictive capabilities than the exponential model.

An examination of the fundamental mechanics of cutting force coefficients

In metal cutting, the cutting force is the key factor affecting the machined surface, and is also important in determining reasonable cutting parameters. The research and construction of cutting force prediction models therefore has a great practical value. The accuracy of cutting force prediction largely depends on the cutting force coefficients of the material. In the average cutting force model, cutting force coefficients are considered to be constant. This study makes use of experiments to investigate the cutting force coefficients in the average cutting force model, with a view to accurately identifying cutting force coefficients and verifying that they are related only to the tool–workpiece material couple and the tool geometrical parameters, and are not affected by milling parameters. To this end, the paper first examines the theory behind identifying cutting force coefficients in the average cutting force model. Based on this theory, a series of slot-milling experiments are performed to measure the milling forces, fixing spindle speeds and radial/axial depths of cutting, and linearly varying the feed per tooth. The tangential milling force coefficient and the radial milling force coefficient are then calculated by linearly fitting the experimental data. The obtained results show that altering the milling parameters does not change the milling force coefficients for the selected tool/workpiece material combination.

Research on Force and Temperature in Milling Ti6Al4V Titanium Alloy Based on Tool Geometry

First, quadratic regression general rotary combination experimental design is adopted in this paper. The cutting force prediction model based on tool rake angle and helix angle is established using regression analysis. And the proper cutter for milling Ti6Al4V is selected, rake angle = 12.5 °, helix angle = 34.5 °.Secondly, milling temperature during different milling process is simulated by the use of finite element simulation software. And the variation rule of milling temperature along with the rake angle and helix angle is obtained which provided the basis for the selecting tool.

계단형상 체적의 엔드밀 가공시 절삭력 변화 특성에 관한 연구

Article history: This study analyzed thevariation in the cutting force when the cutting area of a terrace volume is machined, which is generally left after the rough cutting of a sculptured surface. The numerically simulated results for the cutting forces are compared with cutting force measurements by considering the theoretical prediction of the cutting area formation and specific cutting volume. The variation in the cutting force is measured using a dynamometer installed on a machining center for 19 different kinds of test pieces, which are selected according to the variation in the terrace volume factor, tool diameter factor, and cutting depth factor. As a result, it is verified that the cutting forces evaluated by the numerical analysis coincide with the measured cutting forces, and it is proposed as a practical cutting force prediction model.

Cutting force prediction for circular end milling process

A deduced cutting force prediction model for circular end milling process is presented in this paper. Traditional researches on cutting force model usually focus on linear milling process which does not meet other cutting conditions, especially for circular milling process. This paper presents an improved cutting force model for circular end milling process based on the typical linear milling force model. The curvature effects of tool path on chip thickness as well as entry and exit angles are analyzed, and the cutting force model of linear milling process is then corrected to fit circular end milling processes. Instantaneous cutting forces during circular end milling process are predicted according to the proposed model. The deduced cutting force model can be used for both linear and circular end milling processes. Finally, circular end milling experiments with constant and variable radial depth were carried out to verify the availability of the proposed method. Experiment results show that measured results and simulated results corresponds well with each other.