Article

Process simulation using finite element method — prediction of cutting forces, tool stresses and temperatures in high-speed flat end milling

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Abstract

End milling of die/mold steels is a highly demanding operation because of the temperatures and stresses generated on the cutting tool due to high workpiece hardness. Modeling and simulation of cutting processes have the potential for improving cutting tool designs and selecting optimum conditions, especially in advanced applications such as high-speed milling. The main objective of this study was to develop a methodology for simulating the cutting process in flat end milling operation and predicting chip flow, cutting forces, tool stresses and temperatures using finite element analysis (FEA). As an application, machining of P-20 mold steel at 30 HRC hardness using uncoated carbide tooling was investigated. Using the commercially available software DEFORM-2D™, previously developed flow stress data of the workpiece material and friction at the chip–tool contact at high deformation rates and temperatures were used. A modular representation of undeformed chip geometry was used by utilizing plane strain and axisymmetric workpiece deformation models in order to predict chip formation at the primary and secondary cutting edges of the flat end milling insert. Dry machining experiments for slot milling were conducted using single insert flat end mills with a straight cutting edge (i.e. null helix angle). Comparisons of predicted cutting forces with the measured forces showed reasonable agreement and indicate that the tool stresses and temperatures are also predicted with acceptable accuracy. The highest tool temperatures were predicted at the primary cutting edge of the flat end mill insert regardless of cutting conditions. These temperatures increase wear development at the primary cutting edge. However, the highest tool stresses were predicted at the secondary (around corner radius) cutting edge.

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... The main objective is to eliminate the need for experimental machining tests to characterize the specific cutting coefficients needed in mechanistic milling models. Özel and Zeren [12] simplified the straight tooth milling process by equivalent cutting layer simplification, simulated the milling force by orthogonal cutting model, and verified the correctness of the finite element model through cutting force experiment. Gao et al. [13] introduced a 3D Eulerian finite element simulation model of the end milling process based on ABAQUS/Explicit. ...
... Substituting θ ST = 0° to θ EX = 180° into Eqs. (10) and (11) It is obviously observed that the average milling forces in X and Y directions are linear equations of feed per tooth from Eqs. (12) and (13). This is precisely why the remaining experimental milling parameters are held constant, except for the feed per tooth, when utilizing the average force method to calibrate the milling force coefficients. ...
... The initial value of the cycle is substituted into average milling force Eqs. (12) and (13) for calculation, and the iteration operation is carried out according to the set rules. Running the optimization procedure numerous times reveals that the limit value of the mean error ratio between the average milling forces calculated results by the optimization method and the measured results is 3.5%. ...
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Accurate calibration of the milling force coefficients is essential for predicting the milling forces and characterizing the milling state. Cutter run-out is an unavoidable phenomenon in end milling process, which affects the working state of the cutter and the machining accuracy of the work-piece. This paper proposes an optimized method based on the average force method to calibrate milling force coefficients and cutter run-out parameters in the end milling process. The entire calibration procedure is divided into three steps. First, the milling force coefficients are initially calibrated through the utilization of the average force method. Then, further optimization is carried out based on the coefficients calibrated by the average force method; average milling force equations are used, and a calibration procedure is presented by defining an objective function which is utilized to limit the average force error ratios between the calculated results and the measured results. Finally, the milling force coefficients obtained in the second step are used to calibrate the cutter run-out parameters; the instantaneous milling force equations are used, and a calibration procedure is also presented by defining a new objective function with the minimum sum of squared errors between the instantaneous prediction results and the instantaneous measurement results. In comparison to the experimentally measured average milling forces and instantaneous milling force curves, the proposed method exhibits significantly smaller mean force error ratios than those of the average force method, while demonstrating improved agreement with the simulated milling force curves.
... The most common one is the Johnson-Cook constitutive equation, which has been very often used in numerical models of the cutting process [52]. The application of the machined material model in the form of this equation has been mainly used in three-dimensional finite element models of material machining with end tools, in particular, models of drilling [53,54], milling [55,56], and other cutting processes. Moreover, the parameters of the constitutive equation were mostly taken from previously conducted studies, for example, those found in [57,58]. ...
... Experimental data (see, for example, [64]) were used as target values of the cutting process characteristics. To determine the parameters of contact interaction between the tool and the machined material [65], previously conducted studies on the estimation of friction parameters [54,56], as well as heat flows in the cutting zones [66] have been used in the vast majority of cases. For the numerical modeling of cutting processes with hard-to-machine materials, such as, for example, titanium and nickel alloys, it is necessary to know the fracture parameters of the machined material [67]. ...
... The same characteristics are needed for modeling the drilling processes of various non-metallic heterogeneous materials, such as composite materials [68]. They have been determined using the energy criteria of material damage [68][69][70] or by means of results comparing the shape and size of the generated chips [56,62,63]. ...
Article
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Analyzing the cutting process characteristics opens up significant opportunities to improve various material machining processes. Numerical modeling is a well-established, powerful technique for determining various characteristics of cutting processes. The developed spatial finite element model of short hole drilling is used to determine the kinetic characteristics of the machining process, in particular, the components of cutting force and cutting power. To determine the component model parameters for the numerical model of drilling, the constitutive equation parameters, and the parameters of the contact interaction between the drill and the machined material on the example of AISI 1045 steel machining, the orthogonal cutting process was used. These parameters are determined using the inverse method. The DOE (Design of Experiment) sensitivity analysis was applied as a procedure for determining the component models parameters, which is realized by multiple simulations using the developed spatial FEM model of orthogonal cutting and the subsequent determination of generalized values of the required parameters by finding the intersection of the individual value sets of these parameters. The target values for the DOE analysis were experimentally determined kinetic characteristics of the orthogonal cutting process. The constitutive equation and contact interaction parameters were used to simulate the short hole drilling process. The comparison of experimentally determined and simulated values of the kinetic characteristics of the drilling process for a significant range of cutting speed and drill feed changes has established their satisfactory coincidence. The simulated value deviation from the corresponding measured characteristics in the whole range of cutting speed and drill feed variation did not exceed 23%.
... The main objective is the elimination of the experimental machining test to characterize the specific cutting coefficients needed in the mechanistic milling models. Ozal et al. [12] simplified the straight tooth milling process by equivalent cutting layer simplification, simulated the milling force by orthogonal cutting model, and verified the correctness of the finite element model through cutting force experiment. Gao et al. [13] introduced a 3D Eulerian finite element simulation model of end mill milling process based on ABAQUS/Explicit. ...
... The milling force coefficients preliminarily calibrated by the average force method are enlarged and substituted the initial values into the average milling force Eqs. (12), (13) in reverse, then processed by a optimization program. After the optimized milling force coefficients are obtained, these coefficients are substituted into the instantaneous milling force Eqs. ...
... The iteration step size is 10. The initial values of the cycle are substituted into average milling force Eqs.(12) and ...
Preprint
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Accurate calibration milling force coefficients is essential for predicting milling forces and characterizing the milling state. Cutter run-out is an unavoidable phenomenon in end milling process, which affects the working state of the cutter and the machining accuracy of the work-piece. In this paper, an optimized method based on average force method is proposed to calibrate milling force coefficients and cutter run-out parameters in the end milling process. The whole calibration procedure is divided into three steps. Firstly, the average force method is used to preliminarily calibrate the milling force coefficients. Then, further optimization is carried out based on the coefficients calibrated by the average force method, average milling force equations are used and a calibration procedure is presented by defining an objective function which is utilized to limit the average forces error ratios between the calculated results and the measured results. Finally, the milling force coefficients obtained in the second step are used to calibrate the cutter run-out parameters, the instantaneous milling force equations are used and a calibration procedure is also presented by defining a new objective function with the minimum sum of squared errors between the instantaneous prediction results and the instantaneous measurement results. Compared with the average milling forces and the instantaneous milling force curves measured by experiments, the mean force error ratios of the presented method are much smaller than the average force method and the milling force curves simulated by the proposed method are more consistent.
... (i) The material removal occurs on the circumference of the milling cutter with multiple cutting edges, which move perpendicular to the axis of the workpiece; (ii) The machining starts as milling cutters enter the workpiece, and the multiple cutting edges of the milling cutter penetrate the workpiece and shave off the chips; (iii) The chips are formed due to shear deformation, as the material is pushed off from the workpiece into tiny clumps which combine to a greater or lesser extent. Figure 2a states the mechanism of the metal cutting in the milling process, and Fig. 2b explains the milling cutter movement on the workpiece while slot milling operation [9]. ...
... In this process, the steels are machined in their hardened state (usually 45HRC and more) under dry conditions for reducing overhead costs and protecting the environment. Under the right conditions, the combination of light cuts at high feed rates and spindle speeds makes it possible to efficiently remove steel in the hardened state during the process [9,10]. Hard milling increases the forces, temperature, and tool wear, which directly affects the cost in the industrial aspects [12,14]. ...
... Figure 8 shows the dynamic explicit FEM model flowchart. Altan [9] developed a system for using finite element analysis to simulate the machining process in flat end milling operations on plastic mold tool steel and predicted chip flow, cutting forces, tool tensions, and temperatures. The maximum cutting forces, i.e., F y = 500 N, were recorded at rotation angle ϕ = 120°. ...
Article
Over a century, metal cutting has been observed as a vital process in the domain of manufacturing. Among the numerous available metal-cutting processes, milling has been considered as one of the most employable processes to machine a variety of engineering materials productively. In the milling process, material removal occurs when the workpiece is fed against a rotating tool with multiple cutting edges. In order to maximize the profitability of metal cutting operations, it is essential that the various input and output variable relationships are analyzed and optimized. The experimental method of studying milling processes is costly and time demanding, particularly when a large variety of elements such as cutting tool shape, materials, cutting conditions, and so on, are included. Due to these issues, other alternatives emerged in the form of mathematical simulations that employ numerical methods. The finite element approaches have well-proven to be the most practical and commonly utilized numerical methods. The finite element model (FEM) can be used to determine the various physical interactions occurring during the machining process along with the prediction of various milling characteristics, such as cutting forces, cutting temperature, stresses, etc., with the help of milling inputs. In the present article, various research studies in the broad milling process domain practiced with numerous finite element approaches have been critically reviewed and reported. It further highlights the several experimental and finite element approaches-based research studies that attempted to analyze and optimize the overall performance of the different milling processes. In recent years, various investigators have explored numerous ways to enhance milling performance by probing the different factors that influence the quality attributes. Some of the studies have also been found to be focused on the economic impacts of milling and various process inputs that affect milling performance. Furthermore, various milling factors’ impact on the performance characteristics are presented and critically discussed. The issues related to the recent improvements in tool-work interaction modeling, experimental techniques for acquiring various milling performance measures, and the aspects of turn and micro-milling with finite element-based modeling have been further highlighted. Among the various available classifications in the milling process as employed in industries, face milling is more strongly established compared to other versions such as end milling, helical milling, gear milling, etc. The final section of this research article explores the various research aspects and outlines future research directions.
... The chip deformation is essentially plane strain [36], since the chip width is very large compared to the undeformed chip thickness. This approximation is used in several methods where the cutting forces are predicted, examples are the finite element method [37,38], the slip-line field theory [39,40], and the mechanistic approach [41]. ...
... A majority of the presented research is limited to two-dimensional analysis, see e.g. [37,38,43], and still requires great computational effort. The more geometrical complex chip geometry and the great variety of chip forms in gear milling would make it practically impossible to calculate the instantaneous cutting forces using the finite element method. ...
... Cylindrical gears on parallel axes will have line contact if perfectly aligned, and point contact if they are not. If point contact is present by non-aligned 37 axes, the contact will be at tooth ends where the gear teeth are most vulnerable. To avoid hard bearing at tooth ends, lead crown modification is added to center the load. ...
Thesis
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The modern requirements on power transmissions focus on energy efficiency, low noise and dynamic vibrations, and power density. In order to meet these requirements, the gear wheels must be manufactured to very high precision. Additionally, it should be economical to manufacture these gears within the tight requested tolerances. Gears manufactured within automotive, truck, and construction equipment are usually cut using milling tools. The profile accuracy and the surface roughness achieved after manufacturing, which determines the gear quality, are connected to the process parameters and possible manufacturing related errors. Prediction models to accurately determine gear quality, where tool and process related errors are taken into account, are needed in order to improve the manufacturing process. Tool life has also a strong economic impact in machining operations. Tool life prediction is an important part in optimization of the machining processes, where tool life is strongly connected the cutting forces and the geometry of the cut chips. In this work mathematical models are established in parametric form, based on analytical differential description. These models are developed in order to increase knowledge and understanding of the complex machining processes involved in gear manufacturing. Focus is on the cut gear tooth surface quality, and on milling related topics, such as cut chip geometry, tool cutting forces, and tool wear prediction. The mathematical models are used in a number of experimental studies presented in this thesis. The experimental studies were performed in industrial conditions, where tool and process related errors that are common in industrial applications have been considered. The correlation is very good, which shows the industrial applicability of the presented models.
... As a result, an accurate prediction of cutting forces prior to actual machining is critical for gaining a good understanding of the process and producing high-quality machined parts. Previously, various researchers have studied the force prediction model in HSM based on analytical [3], numerical [4], and mechanistic [5,6] models. The use of analytical models began in the early 1940s, when researchers such as Merchant, Shaffer, and Lee represented cutting mechanics mathematically. ...
... To study the sensitivity of the input parameters (V , f , A t , and A r ) in high speed ball end milling process, partial differentiations with respect to V , f , A t , and A r are applied to the determined mathematical Eqs. (1)(2)(3)(4) have been performed to obtain the sensitivity equations for Fx, Fy, and Fz and Ra. The sensitivity equations of F X are obtained by obtaining partial differentiations of Eq. (1) with respect to V , f , At and A r and is given in Eq. (6). ...
Article
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Ball end milling cutter is a special type of end milling cutter which is frequently used for producing complex geometries and intricate shapes on variety of materials. Selection of the cutting parameters are very critical in order to achieve good surface finish, dimensional accuracy and lower cutting forces. Sensitivity analysis is the technique which is used to identify the critical cutting parameters and rank them according to their importance. In the present research a mathematical model for cutting forces and surface roughness in high speed ball end milling developed using rotary central composite design. The experiments were conducted using for parameters such as cutting speed (V), feed (f), axial (At) and radial (Ar) depth of cut. Analysis of variance (ANOVA) revealed a strong correlation exists between the predicted and experimental results as evidenced by the obtained the value of R²-adj (98.36%). At was the most influencing parameters accounting 47.12% followed by f and V. The developed models were used for sensitivity analysis based on the absolute method. The developed mathematical was checked for adequacy using the ANOVA. From the sensitivity analysis it was observed that radial (Fy) and axial (Fz) forces are highly sensitive to At whereas tangential cutting force (Fx) is most sensitive to the Ar. All the force components decreased with increasing V. Surface roughness is partially sensitive to cutting speed. For axial depth of cut 1.4 mm, Ra not influenced with the change in radial depth of cut and cutting speed.
... Though this finding does not agree with what work from Uhlmann et al[159], different cutting parameters such as cutting speed may result into the differences. The temperature of the chip can also be estimated using a thermal expansion coefficient (TEC) of 1.4 × 10 −5 1/K[164], to be approximately 620-710 • C, which is close to the predicted temperature for chips at the secondary cutting edge[164]. ...
... Though this finding does not agree with what work from Uhlmann et al[159], different cutting parameters such as cutting speed may result into the differences. The temperature of the chip can also be estimated using a thermal expansion coefficient (TEC) of 1.4 × 10 −5 1/K[164], to be approximately 620-710 • C, which is close to the predicted temperature for chips at the secondary cutting edge[164]. ...
... Localized heating and plastic deformation during die steel machining induce significant changes in surface properties [71,72]. Surface hardening enhances wear resistance and extends material life [73]. ...
Article
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Die steels are heavily used in the die/mold manufacturing industry. Their excellent mechanical and chemical properties make them very attractive for this industry. They are well-known materials as "difficult-to-machine" and shaping them requires necessary precautions. This study investigates the machining of these materials through a literature survey. The selection of cutting tool geometry and machining parameters is examined and reported results are discussed in detail. Moreover, the effect of cutting fluid applications in machining die steels is investigated. The influential parameters on machining performance are mentioned. The surface quality of machined materials is analyzed. Overall machining efficiency is demonstrated according to reported studies.
... Table 4 presents the observed cutting forces for a constant feed rate. The thrust force ranges from 313.8128 N to 617.8189 N for drill diameters of 6 mm, [27][28][29]. ...
Article
This study examines the intricate dynamics of friction and emphasizes how crucial it is to global energy use. Inspired by a 1493 discovery of Leonardo da Vinci, the study establishes the independence of friction force from contact area and highlights the significance of the friction coefficient as a load-related metric. The mechanical and chemical characteristics of aluminum alloys are discussed in this article along with an assessment of how well high-speed steel (HSS) drill bits work in drilling operations. Samples of aluminum are thoroughly analyzed for characteristics like yield stress, ultimate tensile strength, and elongation. The results show that aluminum makes up the majority of the sample, with trace elements like silicon and magnesium. At the same time, characteristics including Young’s modulus, thermal conductivity, and specific heat capacity are investigated for HSS drill bits, which are renowned for their durability and thermal resistance. To quantify thrust force and torque, experimental methods use a drill dynamometer built into a vertical drilling machine. Drill bits with different diameters (6 mm, 8 mm, and 12 mm) are evaluated at controlled feed rates and speeds. Accurate cutting force recording is ensured by real-time sensor data. The application of Finite Element Analysis (FEA) provides insights into how to optimize drilling processes for increased productivity and tool longevity by examining the stress distribution and deformation in drill bits under various operating situations.
... For example, a study by Zhang et al. [1] used finite element analysis to simulate the cutting forces and vibrations in the machining process and found that the cutting forces had a significant impact on the surface finish and tool life of the manufactured parts. Another study by Li et al. [2] developed a cutting force model based on the finite element method and used it to predict the cutting forces and chatter in the machining process. The study found that the cutting force model was effective in predicting the cutting forces and chatter, and it could be used to optimize the machining process and improve the quality and efficiency of the manufactured parts. ...
Article
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This paper presents the development of a methodology for monitoring the part machining process on CNC machine tools using a virtual machine model in the MATLAB/Simulink environment. The focus is on monitoring the components of cutting forces that occur during the milling process. A vertical milling machine was used for model validation. By integrating the existing cutting force model and the virtual machine model in MATLAB/Simulink, the visualization of real-time cutting force values, which depend on the change of the current engagement map along the programmed toolpath, is enabled. The development of the presented simulation environment forms the basis for the implementation of new functions in G-code, contributing to the stability and optimization of the machining process.
... The friction coefficient of friction is 0.2 27 . The calculation and solution are performed using the generalized Lagrangian method [28][29][30] . To reduce the computational effort and increase the mesh density, the mesh was divided, with consideration given to only 1/10 of the entire wheel. ...
Article
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The rail profile milling process allows considerable thickness to be removed in a single pass. However, the residual waviness formation law after milling and its subsequent effect on rail performance remains uncertain. In this paper, the wavelength and wave height of the residual waviness are identified as the key characteristics. The relationship between milling speed and residual waviness is determined, and a numerical model of the residual waviness formed on the surface after milling is established based on the commonly used three milling speeds of 300, 600, and 1000 m/h, and its accuracy is verified using the parameters of the residual waviness detected by the milling experiments. A three-dimensional finite element analysis model of wheel-rail contact was employed to analyze the contact stresses and low fatigue cycles at a wheel load of 11.5 tons with no residual waviness on the rail profile surface and with three types of residual waviness, respectively. The results show that the residual waviness changes the wheel-rail contact position and the morphology of the contact area, reduces the maximum contact stress and increases the strain fatigue cycles. The application of elevated milling speeds reduces the wheel-rail contact stresses after milling, thereby increasing the low fatigue cycles.
... For different cutting speeds, the resultant cutting force decreases along with the increased cutting speed at 100-200 m/min, which may be attributed to the changes in the shear strength and hardness of the workpiece due to thermal softening. 25 And when the cutting speed is over 200 m/min, the increased cutting temperature declines the strength of cutting tools due to the metal softening effect, 26 and the mechanical shock increases remarkably with the increased cutting speed, which causes an increase in cutting force. Furthermore, owing to the low thermal conductivity of the Al 2 O 3 coating, much of the cutting heat generated during the cutting process is absorbed by the workpiece; thus, the Al 2 O 3coated carbide tool has a better red hardness, 27 and the thermal softening effect at high temperature reduces the hardness and strength of the workpiece. ...
Article
SA508-3 steel is popularly used to produce core unit of nuclear power reactors due to its outstanding ability of anti-neutron irradiation and good fracture toughness. Additive forging is a new technology for manufacturing SA508-3 steel forgings. However, the production efficiency and interface bonding quality of heavy forgings are respectively limited by the processing efficiency and surface quality of substrates in the additive forging process. High-speed milling technology is an effective method for improving machining efficiency and quality. Unfortunately, only a few studies on the milling of SA508-3 steel have been reported. In this study, we studied high-speed milling of SA508-3 steel and compared the cutting performances of uncoated, titanium aluminum nitride (TiAlN)-coated, and Al 2 O 3 -coated carbide tools. The tool life and cutting force were evaluated using various milling parameters under dry milling conditions. The wear modes and mechanisms were also investigated. The results show that adhesive wear occurs more frequently in the uncoated carbide tool, whereas coating flaking is predominant in the Al 2 O 3 - and TiAlN-coated carbide tools. Furthermore, the Al 2 O 3 -coated carbide tool showed better cutting performance than the TiAlN-coated and uncoated carbide tools considering the tool life and surface quality. The tool life of the Al 2 O 3 -coated carbide tool reached 200 min and the removed workpiece material was 182 × 10 ³ mm ³ under the blunt tool criteria. The study of tool life and wear behavior based on the practical cutting experiments contribute to the improvement of the milling quality and provides a theoretical basis for tool material selection and process optimization in milling SA508-3 steel.
... Widely known materials such as mild steel AISI1045 [11], aluminium (Al7075) [12], titanium alloy (Ti6Al-4V) [13] and AISI P20 mould steel alloy [14] was done in FEM machining simulation and have a quite good concurrency with experimental results. In this study, laser sintered material will be applied as main material properties and AISI1055 will be the comparison. ...
Article
In this paper, finite element analysis (FEA) on machinability of laser sintered material with mean of predicted cutting force and temperature distribution is explained. The process involved 2D orthogonal down-cut milling with the application of two dimension thermo mechanical plane strain model. The updated Lagrangian formulation was used where cutting simulation does not involve element separation but remesh automatically when element distorted critically. AISI1055 mild steel properties were used as the comparison. Various types of friction models were adopted in obtaining precise results. Predicted cutting force and cutting edge temperature are validated against corresponding experimental values by previous researchers. From the simulations, the shear friction model of 0.8 is the best friction model where 10% errors were obtained for comparison mild steel AISI1055 FEA results with the experimental approach for increasing radial depth. Lower cutting force predicted for laser sintered materials compared to AISI1055 due to lower Young modulus. Cutting edge temperature predicted for laser sintered material is higher due to its low thermal conductivity compared to AISI1055.
... 2,3 In cutting applications such as high speed milling, the temperature can be easily improved to exceed 800°C. 4 To address this problem, an effective design strategy to enhance the oxidation resistance and mechanical properties is introducing a third element Al or Si into the TM nitrides to form ternary or quaternary systems like TiAlN, TiSiN, TiAlCrN, TiAlCN, etc. [5][6][7][8][9][10] These aluminum or silicon nitrides have a distinct improvement of oxidation resistance. Furthermore, the introduction of the third element also induces the formation of a nanocomposite structure containing a non-miscible nanocrystalline or amorphous structures and results in high hardness. ...
Article
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Si-containing transition-metal nitrides Ti0.5Si0.5N, Zr0.5Si0.5N and Hf0.5Si0.5N with conventional rock salt B1 structure exhibit superior hardness, strength and oxidation resistance. However, the potential phases of the ternary systems at various pressures remain unexplored. In this work, we firstly studied the potential structures of Ti0.5Si0.5N, Zr0.5Si0.5N and Hf0.5Si0.5N in pressures of 0-100 GPa. A hexagonal phase with P63/mmc symmetry was uncovered and verified to be quenchable in the ambient conditions. The structural, mechanical and electronic properties were systematically studied and compared with the well-known ordered B1 structure. We surprisingly found that Ti0.5Si0.5N within this hexagonal phase displayed much improved ideal indentation shear strength from about 10 GPa for a B1 structure to 30 GPa. The estimated hardness based on the empirical formula is up to 38 GPa, greatly exceeding that of the B1 structure. By the detailed electronic analysis, the underlying atomic mechanism for the outstanding mechanical properties was also studied.
... Strenkowski y Carroll en 1985 [53] son los primeros en integrar a la formación de viruta, la separación de esta de la pieza de trabajo. La formación de viruta fue lograda por varios autores que usaron criterios predefinidos de separación de la viruta [54], mecanismos de fractura [55], técnicas MEF de re-enmallado [56] y eliminación de elementos [6], [57], aplicada en modelos complejos para operaciones de torneado [57], [58], taladrado [59] y fresado [60], [61]. ...
Thesis
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Este trabajo presenta la aproximación por el método libre de malla de Smoothed Particle Hydrodynamics (SPH) para el modelamiento de la formación de la viruta en el proceso de maquinado ortogonal de metales. Se aborda el problema considerando el maquinado como un proceso con altas deformaciones y para modelarlo se emplean las ecuaciones de conservación discretizadas por SPH para masa, momento y energía, bajo los principios de la mecánica de solidos para un modelo elástico-plástico perfecto. Se utilizó el modelo de Johnson y Cook para la determinación del régimen plástico. En el desarrollo del trabajo se muestran los principios básicos de la formación de la viruta, la implementación del método SPH, se explica el modelo de maquinado utilizado y su comparación con datos experimentales y con otros modelos. El modelo de maquinado desarrollado con SPH muestra un comportamiento realista de la morfología de la viruta en los momentos iniciales de formación de la misma y en la temperatura en la zona principal de cizallamiento. / Abstract. This paper presents the approximation by the mesh-free method Smoothed Particle Hydrodynamics (SPH) for modeling the orthogonal metal machining process for the chip formation. An approach to the problem considering the machining process as a high strain process is done, in which are used the conservation equations discretized by SPH for mass, momentum and energy, and additionally the principles of solid mechanics for an elastic-plastic model, employing the Johnson and Cook model for determining the plastic regime. In this way are shown the basics of chip formation, SPH implementation, presentation of machining model and its comparison with other models and experimental data. The SPH model shows an adequate machining behavior of the chip morphology on the initial forming moments and temperature in the primary shear zone.
... Models for the prediction of cutting forces range from empirical formulations [17,19], analytical approaches [20,21], to nonlinear finite element methods [22,23]. For the calculation of five-axis milling processes with complex engagement conditions, different empirical and analytical force models have proven to be suitable, where the cutting force is estimated from the extracted volume [6]. ...
Article
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Hybrid material composites can meet the increasing demands for high strength and low weight due to their different workpiece properties. Usually, hybrid components require post-machining after their fabrication. Due to the different material properties, new challenges arise in the machining process. It is essential to recognize the course of the material boundary in order to adapt the process planning accordingly and to enable a uniform material transition during machining. This paper presents a method for automated material recognition and automatic adaptation of the process parameters considering a uniform force level during the milling of hybrid materials. This way, the load on the milling tool in the material transition area can be reduced by up to 71%, which prevents premature tool failure. An optical laser line scanner is used to localize of material transitions within hybrid components. This enables a digital mapping of the material distribution in the discretized workpiece model. In combination with an empirical force model, it is possible to predict the cutting forces of the different materials and determine the material transition area for adapting them to specified target values.
... Numerical simulations for different types of milling processes have been the subject of many investigations, e.g., [9][10][11][12]. Modeling the spatial milling process was replaced in the early studies considering the orthogonal cutting process with the subsequent distribution of the 3D cutting process [13]. ...
Article
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The simulation of material machining using finite element models is a powerful tool for the optimization of simulated processes and tools, as well as for the determination of cutting process characteristics that are difficult or practically impossible to determine by experiment. The paper presents results of the numerical simulation of the titanium alloy Ti10V2Fe3Al (Ti-1023). The behavior of the machined material was modeled with the Johnson–Cook constitutive equation, and its damage mechanism was modeled using the Cockcroft and Latham model. The parameters of the constitutive equation for machined material behavior and damage were determined using a DOE sensitivity analysis during orthogonal cutting. The values of the cutting force components, as well as the minimum and maximum chip thicknesses, were used as target functions for the DOE analysis. The generalized values of the constitutive equation parameters and the fracture stress values determined by the DOE analysis were calculated as the set intersection of individual multitude values of these parameters. The simulation results of the studied cutting processes showed an acceptable agreement with the experimental data when the cutting speed and tool feed changed significantly. The deviation in the simulated values of the cutting forces from their measured values ranged from about 10% to about 20%.
... Therefore, a finite element method has been applied using ABAQUS/Explicit software to predict the cutting forces in micro-end milling by consideration of tool edge radius effect, thermo-mechanical properties, and failure parameters of the workpiece material. Like Ozel and Altan [12], a finite element method has been used to study the cutting process and predict chip flow, cutting forces, tool stresses, and temperatures. However, the simulation is focused on side milling using a flat end milling operation. ...
Chapter
Excessive stress in a machining process will lead to the failure of the cutting tool. In addition, it will cause the deflection of the cutting tool. In this paper, a simulation procedure based on Finite Element Method has been performed to analyse the stress distribution and deflection in the cutting tool of the end milling process. A three-dimensional model of a 2-flute flat end milling cutting tool has been developed using Solidwork software, and Abaqus software has been used to simulate the cutting tool. Static analysis has been implemented, and a concentrated force has been applied at the tip of the cutting tool. The value of deflection is determined by the magnitude of the total displacement. Based on the simulation, the result shows that the maximum stress occurred at hthe cutting tool’s edge. The maximum value for stress is 3.11×1033.11 \times 10^3 Pa and While the maximum value for total displacement is 3.546×1073.546 \times 10^{ - 7}. In conclusion, by applying the finite element method, the deflection of the cutting tool can be predicted by analyzing the stress and displacement.KeywordsStress distributionTool deflectionFinite element method
... If these are properly harnessed and exploited, they can lead to the emergence of local industries for the production of ceramic products and stabilized clay materials for building and road construction. Several studies have shown large deposits of different types of clays in commercial quantities in almost each of the 36 states and the Federal Capital Territory, FCT (Ezomo 2012;Ozegin et al. 2020;Özel and Altan 2000;Shuaib-Babata and Abdulrahaman 2018;Lanre Shuaib-Babata et al. 2019). The availability of these largely untapped raw materials notwithstanding, Nigeria sustains its local consumption through uncontrolled importation of clay products for industrial applications in the ceramic, medical, building, chemical, and petrochemical industries (Agboola and Abubakre 2009;Alaya-Ibrahim et al. 2020a;Eze et al. 2020;Irabor and Okunkpolor 2020;Ituma et al. 2018a). ...
Article
The use of clay for ceramic application and the quality of ceramic products has been reported in the literature. Such scientific information has helped to improve the quality of ceramic products. However, the concept is yet to improve indigenous methods of processing clay materials used by local ceramic industries. This paper characterizes clay soils from Dei-dei junction, Ushafa Hills and Nnamdi Azikiwe International Airport road in northcentral Nigeria and the locally processed clay material used by the Ushafa Pottery Center for ceramic application. It assesses clay minerals and examines their suitability for ceramic and high-temperature applications. XRD, XRF, FTIR, and TG (Thermogravimetric) results show that processed clay samples are rich in SiO2 Al2O3 and can be fired at high temperatures without shrinkage. Physical–chemical studies also reveal that raw materials have the best balance of material properties required for ceramic applications. Local processing of clay samples (water extraction method) increases SiO2, Al2O3, and K2O. TG analysis revealed that the 4.3% mass loss due to Fe2O3 and dihydroxylation of structural OH is insignificant. High % Fe2O3 in the processed sample cannot affect the firing process and quality of the ceramic products, as earlier predicted, but may affect the aesthetics of the final ceramic products. The need to develop indigenous methods of reducing Fe2O3 as an alternative to the chemical leaching of clay with acids is recommended. A model for the promotion of indigenous ceramic industries is presented as a guide for policymakers to harness the potential of deeper interaction among government, research, and organized private sector operators towards increased contribution of the solid mineral sector to national development.
... The finite element method (FEM) is a widely-used approach for simulation of physical processes, under which a complex problem (or geometry) is subdivided into its smaller parts for which the approximations of interactions can be computed via relatively simple equations. Examples of FEM applications in machining include the simulation of the Chapter 1. Introduction 5 chip formation and the cutting forces in precision machining [1] and the simulation of the tool stress and temperature in high-speed milling [82]. Over the years the physics-based FEM models have been specialised to niche applications, such as for 3D simulation of titanium alloy micro-end milling chip flow and tool wear [113] or for simulation of the 3D interactions of various composite material drilling techniques and their effect on composite delamination [98]. ...
Thesis
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Manufacturing enterprises are challenged to remain competitive due to the increasing demand for greater product variability and quality, intensifying complexity of the production processes, as well as a drive for sustainable manufacturing and the increasing regulatory impact resulting in high labour and energy costs. Consolidated around the discussion of Industry 4.0, the efficient and effective solutions to these challenges lie outside the mainstream production methods. One of the drivers of transition towards the novel manufacturing paradigm is the technological modernisation of the production processes motivated by the increasing availability of computational capacities. Manufacturing digitalisation is a critical part of the transition towards Industry 4.0. Digital twin plays a significant role as the instrument that enables digital access to precise real-time information about physical objects and supports the optimisation of the related processes through conversion of the big data associated with them into actionable information. A number of frameworks and conceptual models has been proposed in the research literature that addresses the requirements and benefits of digital twins, yet their applications are explored to a lesser extent. The work presented in this thesis aims to make a proposition that considers the novel challenges introduced for data analysis in the presence of heterogeneous and dynamic cyber-physical systems in Industry 4.0. In this thesis a time-domain machining vibration model based on a generative adversarial network (GAN) is proposed as a digital twin component. The developed conditional StyleGAN architecture enables (1) the extraction of knowledge from existing models and (2) a data-driven simulation applicable for production process optimisation. A novel solution to the challenges in GAN analysis is then developed, where the comparison of maps of generative accuracy and sensitivity reveals patterns of similarity between these metrics. The proposed simulation model is further extended to reuse the knowledge extracted from a source model and adapt it to a given target environment, enabling the elicitation of information from both physics-based and data-driven solutions. This approach is implemented as a novel domain adaptation algorithm based on the GAN model: CycleStyleGAN. The architecture is validated in an experimental scenario that aims to replicate a real-world manufacturing knowledge transfer problem. The experiment shows that the transferred information enables the reduction of the required target domain data by one order of magnitude. The thesis thus builds a strong case for a StyleGAN-based digital twin to be developed to support practical implementation of technologies paving the road towards the target state of Industry 4.0.
... Kim et al. 18 proposed a finite element method for predicting temperature and stress distribution in micromachining process. Deform2D software was used by Ozel and Altan 19 to simulate end milling operations and to predict the stress on the tool and the cutting temperature. Lazoglu and Altintas 20 used FDM to model cutting temperatures in continuous and intermittent cutting. ...
Article
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Milling, as a common machining method, is widely used in rough machining and final finishing of various materials. In this paper, according to the milling temperature produced in the milling process, the formula of heat distribution coefficient for workpiece milling is established. By means of Deform-3D finite element software to carry out orthogonal cutting simulation of workpiece, the influence of different machining parameters on milling heat distribution coefficient is studied, the optimal machining parameters are determined, and the milling temperature experiment is carried out to verify the simulation temperature. The experimental results show that the simulation temperature is very close to the experimental workpiece temperature, and the error is very small, which verifies the accuracy of the method. At the same time, the influence of different initial temperature of workpiece on the milling force and stability is also studied. The results show that proper heating of the workpiece can effectively improve the milling stability of the thin-walled parts.
... The increase of the computational efficiency provided by the improvements to the software and hardware solutions over the recent years significantly lowered the barriers that previously limited the practical applicability of simulations (Smith and Tlusty, 1991). The machining domain steadily increases its reliance in simulation modelling for analysis of tool stress (Özel and Altan, 2000), forces (Afazov et al., 2010), surface finish (Campomanes and Altintas, 2003), machining stability (Altintas and Weck, 2004) and verification of the physicsbased models (Altintas et al., 2014;Thepsonthi and Özel, 2015;Shetty et al., 2017;Greis et al., 2020). ...
Article
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Digitalisation of manufacturing is a crucial component of the Industry 4.0 transformation. The digital twin is an important tool for enabling real-time digital access to precise information about physical systems and for supporting process optimisation via the translation of the associated big data into actionable insights. Although a variety of frameworks and conceptual models addressing the requirements and advantages of digital twins has been suggested in the academic literature, their implementation has received less attention. The work presented in this paper aims to make a proposition that considers the novel challenges introduced for data analysis in the presence of heterogeneous and dynamic cyber-physical systems in Industry 4.0. The proposed approach defines a digital twin simulation tool that captures the dynamics of a machining vibration signal from a source model and adapts them to a given target environment. This constitutes a flexible approach to knowledge extraction from the existing manufacturing simulation models, as information from both physics-based and data-driven solutions can be elicited this way. Therefore, an opportunity to reuse the costly established systems is made available to the manufacturing businesses, and the paper presents a process optimisation framework for such use case. The proposed approach is implemented as a domain adaptation algorithm based on the generative adversarial network model. The novel CycleStyleGAN architecture extends the CycleGAN model with a style-based signal encoding. The implemented model is validated in an experimental scenario that aims to replicate a real-world manufacturing knowledge transfer problem. The experiment shows that the transferred information enables the reduction of the required target domain data by one order of magnitude.
... Although this is only a thumb rule to decide the safety of design, many industries go with this method because it reduces the post production work. In the next stage, the parts which have to be purchased directly from market are listed and selected from required standard catalogues [8]. Only standard parts are purchased because it certainly ensures quality. ...
Article
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The paper presents a novel design for CNC special purpose machine spindle. The design of spindle consists of 'system design' and 'mechanical design', where system design takes care of space availability, ergonomics and physical constraints. Models of spindle and the parts of its assembly are made using SOLIDWORKS modeling software tool. The analysis of the spindle shaft and spindle assembly is made for different cutting speeds to know the deflections and stresses in the spindle shaft and spindle assembly parts. Simulation is conducted using ANSYS software tool. The deflections and stresses obtained are found to be within the safe limit. Hence, the present design made is safe for CNC spindle.
... FEM models are proposed for various cutting conditions, including the turning of structural steel [8], titanium alloys [8], and alloyed steels [9]. The state of tools was also modeled at high-speed flat end milling [10] and high-speed cutting [11,12]. The generalized results of using the FEM to simulate the cutting process are considered by van Luttervelt et al. [13] and Athavale and Strenkowski [14]. ...
... The computational constraints limiting the usefulness of simulation modelling in previous decades is significantly compensated for by the modern hardware and software advances. Thus, simulations have become a critical tool utilised in the analysis of the various aspects related to the machining processes, such as process stability [4], surface finish [9], cutting forces [1] or tool stress and temperature [51] and in the validation of physics-based models [70,62,5] over the last several decades [65]. Their further refinement with hybrid data-driven and knowledge-based approaches is an ongoing research topic [23]. ...
Article
Full-text available
Manufacturing digitalisation is a critical part of the transition towards Industry 4.0. Digital twin plays a significant role as the instrument that enables digital access to precise real-time information about physical objects and supports the optimisation of the related processes through conversion of the big data associated with them into actionable information. A number of frameworks and conceptual models has been proposed in the research literature that addresses the requirements and benefits of digital twins, yet their applications are explored to a lesser extent. A time-domain machining vibration model based on a generative adversarial network (GAN) is proposed as a digital twin component in this paper. The developed conditional StyleGAN architecture enables (1) the extraction of knowledge from existing models and (2) a data-driven simulation applicable for production process optimisation. A novel solution to the challenges in GAN analysis is then developed, where the comparison of maps of generative accuracy and sensitivity reveals patterns of similarity between these metrics. The sensitivity analysis is also extended to the mid-layer network level, identifying the sources of abnormal generative behaviour. This provides a sensitivity-based simulation uncertainty estimate, which is important for validation of the optimal process conditions derived from the proposed model.
... The development of features of faults was proven using scalogram and its variation in mean frequency. The intensity of wear of tool is function of not only process temperature but also chip properties such as chip size, chip shape, chip color [67,68]. The wavelet packet decomposition method is used for feature generation accompanied by sound signals for tool condition monitoring of milling process. ...
Article
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The 4th Industrial Revolution (Industry 4.0) necessitates implementing the prognostics and health management (PHM) practices in manufacturing processes. The traditional machine learning approach has well assisted the PHM practices within the same data distributions. However, when a high noise environment, versatile operating conditions, and cross-domain machining is considered, it still lacks key steps of generalizing unknown tool faults. In an attempt to address PHM practices under such domains, a generic Deep Learning-based scheme is gaining significant attention. In this paper, an inclusive review is presented in order to provide an insight into the application of DL in tool condition monitoring (TCM), particularly in milling. Commonly used DL algorithms and their applications toward TCM are initially discussed and number of illustrative DL models applied for TCM is presented. Later, emergent DL themes & their computational techniques are summarized with an intention to provide framework for domain generalization. Finally, challenges in further exploration and futuristic trends in TCM are discussed.
... In the theoretical analysis of cutting temperatures, it is significantly important to determine quantitative effects of cutting parameters including process and tool parameters such as cutting speed, feed rate, and tool coating. Ozel and Altan [14] simulated the flat end milling operation by predicting chip flow, cutting forces, tool stresses, and temperatures. They also implemented the flow stress data of the workpiece material and the friction data at the tool-chip interface to the simulation and concluded that the highest temperatures occur on the rake face of the cutting tool independent from the cutting parameters due to the frictional heat source at the tool-chip interface. ...
Article
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Interrupted cutting operations, such as milling, produce fluctuating tool temperatures which directly affect the process outputs. Thus, prediction of cutting tool temperatures enables process planning, selection of materials for tool substrate and coating layers, and tool geometric design for improved productivity in machining operations. Theoretical analysis of temperature is a cost effective way to predict the tool temperatures. Considering the industrial needs, a theoretical model should be fast, easy to implement, and reliable. To that end, a novel hybrid model, which assembles analytical and numerical methods, is proposed in this study. This novel transient thermal model simulates the interrupted cutting with coated cutting tools. The proposed model includes an analytical heat flux calculation at the tool-chip interface considering the sticking-sliding contact behavior. The determined heat flux is, then, used to perform a numerical solution of the transient heat conduction problem in the cutting tool geometry with temperature-dependent thermal properties. The developed model is validated with experimental results found in literature under different cutting conditions. The results show that the model can predict the maximum temperatures generated in a thermal cycle with an accuracy of 2–10%. Thus, the proposed model can be further used to determine the process parameters, properties of coating layers, and tool geometric design.
... Similarly, heat generation takes place due to contact among the workpiece and tool [73]. Hence by increasing cutting speed, cutting tool temperature increases [74]. Additionally, an infrared camera was utilized to obtain the other side of the cutting edge's temperature for monitoring temperature range. ...
Article
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Due to continuous cutting tool usage, tool supervision is essential for improving the metal cutting industry. In the metal removal process tool, supervision is carried out either by an operator or online tool supervision. Tool supervision helps to understand tool condition, dimensional accuracy, and surface superiority. For downtime in the metal cutting industry, the main reasons are tool breakage and excessive wear, so it is necessary to supervise tool which gives better tool life and enhance productivity. This paper presents different conventional and artificial intelligence techniques for tool supervision in the processing procedures that have been depicted in writing.
... Determination of temperatures at the tool tip during the different cutting process[12].D. Mihai et al. ...
Article
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The activities presented under this paper were focused on designing, manufacturing, testing and evaluation of a metallic antenna reflector for space applications. The main challenge was to obtain a low mass, while maintaining the reflector capability to withstand the mechanical loads encountered during the launching phase, as well as the harsh space environment with significant temperature variations, without any detrimental effect over the dimensional stability of the reflective surface. The chosen material was titanium alloy for the reflector and stainless steel for fasteners and mounting supports. Manufacturing parameters have been investigated aiming for low internal stresses during processing and to obtain the best results in terms of dimensional accuracy and surface roughness. One of the five analysed reflector architectures (reflector breadboards) was selected and manufactured using two different finishing operations, milling and turning, the latter being the one presenting the best results. Dimensional accuracy of the reflector breadboard, before and after vibration and environmental tests, was found to be smaller than the imposed requirements, thus validating the reflector proposed design. After the breadboarding activity, an optimized version of the antenna reflector (demonstrator), also validated by structural analysis, was developed. Unfortunately, the measured profile deviation of the demonstrator was higher than the imposed requirements (by 50%), mainly due to internal stresses during mechanical processing of the new geometry. Before the experimental evaluation of the reflector demonstrator, a surface coating was developed and applied to the reflective surface of the demonstrator. Despite the profile deviation, the demonstrator meets the imposed mechanical requirements and offers important lessons to be applied in the future development activities.
... From the overall research results, most of them focus on the research of cutting mechanism and the effects of chip formation and chip deformation, tool wear and deformation, and chip accretion on cutting force and surface residual stress [44,80,81]. Ozal et al. [82] simplified the straight tooth milling process by equivalent cutting layer simplification, simulated the milling force by orthogonal cutting model, and verified the correctness of the finite element model through cutting force experiment. Dong et al. [83] obtained the change in milling force in the process of helical tooth milling by establishing a 3D finite element model of oblique cutting process. ...
Article
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Aluminum alloy is the main structural material of aircraft, launch vehicle, spaceship, and space station and is processed by milling. However, tool wear and vibration are the bottlenecks in the milling process of aviation aluminum alloy. The machining accuracy and surface quality of aluminum alloy milling depend on the cutting parameters, material mechanical properties, machine tools, and other parameters. In particular, milling force is the crucial factor to determine material removal and workpiece surface integrity. However, establishing the prediction model of milling force is important and difficult because milling force is the result of multiparameter coupling of process system. The research progress of cutting force model is reviewed from three modeling methods: empirical model, finite element simulation, and instantaneous milling force model. The problems of cutting force modeling are also determined. In view of these problems, the future work direction is proposed in the following four aspects: (1) high-speed milling is adopted for the thin-walled structure of large aviation with large cutting depth, which easily produces high residual stress. The residual stress should be analyzed under this particular condition. (2) Multiple factors (e.g., eccentric swing milling parameters, lubrication conditions, tools, tool and workpiece deformation, and size effect) should be considered comprehensively when modeling instantaneous milling forces, especially for micro milling and complex surface machining. (3) The database of milling force model, including the corresponding workpiece materials, working condition, cutting tools (geometric figures and coatings), and other parameters, should be established. (4) The effect of chatter on the prediction accuracy of milling force cannot be ignored in thin-walled workpiece milling. (5) The cutting force of aviation aluminum alloy milling under the condition of minimum quantity lubrication (mql) and nanofluid mql should be predicted.
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The quality of metal tools used for mining and mineral processing is tested in service and evaluated based on their resistance to wear and fracture. These tools are mostly used by artisanal miners whose activity constitutes ~ 90% of the entire mining activities in Nigeria and several other mineral and mining nations in sub-Saharan Africa. The industrial-scale mining of baryte in Nigeria has also been unsuccessful due to tools wear and high cost of repair. Thus, the need to source materials with better wear resistance, reasonably high toughness, strength, and a balance of critical material properties for mining purposes. This paper presents a critical review of the wear resistance and fracture toughness of baryte mining tools. It assesses current limitations to metal tools used in baryte mining and failure of tools in service due to material deficiency and proposes cost-effective and indigenous solutions for improving wear and fracture toughness of tools. The paper also identifies factors underpinning the physical metallurgy of wear behaviour of baryte mining tools to optimise the overall mechanical properties in service. A desk-method study and topical issue-based discussion approaches were adopted in this review. Certain hard metal tools with excellent properties are identified. For cheaper and durable tools, it is critical to explore the qualities of low-carbon steel and cast iron by using technologies to reduce carbon content in cheap high-carbon steels or supplementing nitrogen (N) in certain metallurgical procedures. While other cost-effective methods of hardening steel using agricultural and domestic wastes (cassava leaves, potato sprouts, and bamboo shoots) are better alternatives, meeting the needs of artisanal miners for mining and cutting tools requires the introduction and adoption of laboratory-based techniques to solve real societal problems which is imperative for the development of indigenous technology for mineral extraction. This set of solutions goes beyond data gathering. It requires proper classifications of mining activities and the development of tools to meet specific needs. A recommendation for policy review on existing Mineral and Mining Acts is crucial to address poor infrastructure in mining and is helpful for the development of scalable prototype metal tools and materials with a balance of properties to withstand wear of tools and failure due to the contact with hard core and highly abrasive rocks and ores and excessive cyclic loading of the mining tools in service.
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We present a consistent explicit formulation of the adiabatic thermal softening effect. This formulation is analytically derived from the well-known thermoviscoplastic Johnson–Cook model and is expressed only in terms of the effective plastic strain and strain-rate and does not depend on the temperature. In extreme impact loading cases, the explicit formulation shows improvement in the numerical stability of simulations carried out with implicit solver and leads to more consistent results. The proposed explicit formulation can be considered as a new consistent thermoviscoplastic constitutive model that analytically reflects the contribution of the strain and strain-rate to the adiabatic thermal softening effect. To validate the accuracy of the proposed explicit model, numerical simulations of two bench-mark time-dependent problems are carried out in ABAQUS. Moreover, due to the explicit formulation, the effect of adiabatic thermal softening on bursting pressure and expansion of a spherical thin shell is analytically derived.
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Machining is the essential activity of a manufacturing organization and milling is one of them. The economy growth rate of a country depends upon the innovation and research in manufacturing sectors. In this paper an attempt has been made to identify the gap in optimization of process parameters in milling operations through extensive literature review. Literature review revealed that researcher were mainly focus on input process parameter such as cutting speed, feed rate and depth of cut and output process parameters such as material removal rate (MRR), surface finish. The Taughi method and response surface method (RSM) were frequently used to optimize the process parameter. It was found that very less work support the process parameter optimization in which different weightage has been assigned to output parameters as per application of machining process. The little work reported in which algorithm and application of multiple criteria decision making approaches such as particle swarm optimization (PSO), teaching learning based optimization (TLBO), Genetic algorithm (GA) was implemented to optimize the parameters. The guidelines were provided for further research in optimization of process parameters.
Preprint
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On-line milling rail profile is a new technology developed in recent years, which eliminates serious defects such as wavy wear layer on the top surface of rail profile through profiling milling and reshapes the shape of rail profile. Previous studies have focused on the maximum milling thickness, milling efficiency and the ability to eliminate rail contour defects, while ignoring the effect of residual corrugation on the wheel-rail contact condition after milling. This paper analyzes the reasons for the formation of residual ripples during rail profile profiling milling and determines the correlation between the wavelength and height of the residual ripples formed by milling and key parameters such as milling device and milling speed. Residual ripple models were constructed for the rail profile after milling at three most used milling speeds. The wheel-rail contact state was simulated and analyzed by considering the wheel weight loads of subway trains and freight trains, respectively. The results show that the residual corrugation significantly changes the wheel-rail contact stress on the upper surface of the rail profile and the strain-fatigue cycle distribution in the high contact stress region of the wheel-rail.
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In the machining processes, chip removal can be performed by the applied forces. Therefore, predicting the required forces and energy is an essential challenge to reach the efficient processes. In this research, employing various ductile damage models of the continuum damage mechanics (CDM), a few machining processes such as 3D plane machining, 3D drilling, and turning are numerically simulated. Using the numerical simulations of finite element method (FEM), variations of the applied forces on the workpiece and the maximum force as well as the mechanism of chip formation during the machining processes are estimated. Besides, to assess the ductile damage models, the numerical simulation results are compared with the experimental results. The comparison reveals that the Ayada, Ayada negative, and Johnson–Cook damage criteria can accurately predict the required forces and respectively are the reliable models for numerical simulations of chip removal in the machining processes.
Chapter
The study results for cutting gears by the Power Skiving method was presented based on a graphical and analytical model of chips and an analytical model of cutting force and torque. A methodology for modeling 3D chips and analyzing the cut layers of a disk cutter at the level of certain edges was developed. Based on the example under certain initial conditions, the capabilities of the developed models were shown to predict the load on a single tooth and the entire machine tool system during multi-tooth continuous cutting and the influence of power factors on the machining process. Two factors significantly influence the cutting force: the cross-sectional area and the cutting thickness. An increase in the cutting area proportionally increases the cutting force and the load on the system. The shear thickness affects the cutting force through its effect on the chip compression ratio: when the shear thickness decreases, the intensity of shear plastic deformation and cutting force increase. Shear intensity increases sharply at low chip thicknesses, characteristic of force shearing, so high cutting forces accompany this process.KeywordsGear MachiningPower SkivingSimulationChip ParametersCutting ForceShear DeformationProcess Innovation
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A síkfelületek megmunkálásának egyik legtermelékenyebb és leghatékonyabb eljárása a homlokmarás, mivel képes az anyagot a munkadarabról nagy sebességgel eltávolítani, egyúttal kiváló minőségű megmunkált felület állítható elő. Emiatt számos kutatás fő témája a homlokmarás, az egyik legjelentősebb kutatási irány a forgácsolóerők becslése/meghatározása. Ebben a cikkben e kutatási terület szakirodalomban megjelent eredményeit foglalom össze.
Chapter
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Single point incremental forming (SPIF) is an advanced sheet metal forming process in which the requirement of a press tool is completely eliminated. Due to this, it is also called die-less forming process. Complex geometries can be easily formed with this process. But in SPIF process, steeper wall angles are difficult to achieve because of the deformation characteristics of the process. To overcome this, a specific number of intermediate stages are added before achieving final geometry with a steeper wall angle. But during the multistage SPIF process, some extra deformed residues of previous stages appear at the bottom of the formed part.
Conference Paper
The highly required development in machining operation business is that the ceaseless application of cutting tool inserts and energy consumption condition state during monitoring system. On considering machine cutting operation ways, the state of tool need to be supervised by either manual operators or by continuous on-line tool inserts condition watching methods to pre-empt harm of each and every machine inserts and piece of work. On-line tool condition watching system is very indispensable in trendy producing industry in evolving needs of cost efficiency and better standards quality. This paper compiles several administering ways for tool condition watching within the conventional method that are practiced.
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This study attempts to comprehensively characterise the cutting process behaviour based on the stored energy field in the cutting deformation zones. Studying the cutting mechanism is difficult because the cutting process is accompanied by complex macro- and micro-phenomena. Therefore, it is proposed that the stored energy inside the deformed materials can be selected as the characterisation index of the cutting process behaviour including the stress, hardness, microstructure, and slip lines in the cutting deformation zones. The stored energy prediction model and constitutive model are established based on the hardening behaviour and microstructure evolution mechanism of the material. These models are then integrated into a finite element cutting model to obtain the stored energy field in the orthogonal cutting process. The simulation results are verified by combining transmission electron microscopy analysis and image quality method using electron backscatter diffraction technology. The relationships between the stored energy field and the distributions of the microstructure, stress and hardness are discussed. The results demonstrate that the subgrain size can be accurately predicted based on the stored energy. The distribution laws of the stress and hardness in the cutting deformation zones can be reflected by the stored energy field, and a convenient method for predicting the stored energy field by the hardness distribution is proposed and verified. Based on the aforementioned results, the formation mechanisms of the chips and the machined surface are analysed, and it is found that the slip lines can be sufficiently characterised by the gradients of the stored energy field. The cutting forces, chip thickness, and shear angle can be accurately predicted at different cutting speeds, indicating the reliability of the constitutive model. Moreover, the deformation characteristics of hardened zone are analysed and the thickness is estimated based on the stored energy field.
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Introduction. One of the most important tasks in cutting metals and alloys is the control of the temperature factor, since temperature is one of the limitations in determining cutting conditions. This approach makes it possible to determine rational (in some cases, optimal) milling modes. Experimental methods for determining the temperature are labor-consuming, costly and not always available. The labor-consuming nature lies in the need for constant adjustment of experimental equipment due to changing cutting conditions, electrical insulation of the tool and workpiece, the appearance of parasitic electrical micro-voltage (if we are talking about temperature measurement methods with thermocouples), constant calibration of instruments and selection of thermal radiation coefficients (if we are talking about non-contact measurement methods). In this regard, there is a need for a theoretical determination of temperatures during milling with minimal use of experimental data. The purpose of the work: to develop a method for theoretical calculation of temperature during milling (cutting) of nickel-based heat-resistant materials on the example of 56% Ni -Cr-W Mo-Co-Al alloy (56% Ni, 0.1% C, 10% Cr, 6.5% W, 6% Al, 6.5% Mo, 0.6% Si, 13 % Co, 1% Fe). Research methodology. To determine theoretically the cutting temperatures, a mathematical model is formed that takes into account the mechanical and thermophysical properties of the material being processed and its change depending on the temperature variations during milling, the geometry of the cutting tool and the features of the schematization of the milling process. The experimental part of the study is carried out on a console milling machine KFPE-250 with a CNC system Mayak-610. The 56% Ni -Cr-W Mo-Co-Al material is processed with a Seco JS513050D2C.0Z3-NXT cutter with different speeds and feeds. The temperature is measured using a Fluke Ti400 thermal imager. Results and discussion. A theoretical model for calculating the temperature (for the group of 77% Ni - Cr - Ti - Al - B, 66% Ni - Cr - Mo - W - Ti - Al, 73% Ni-Cr-Mo-Nb-Ti-Al and 56% Ni -Cr-W Mo-Co-Al alloys) during milling of heat-resistant nickel-based alloys is developed, which makes it possible to predict the temperature value at the face and flank of the tool when changing cutting conditions (speed, feed, depth, cutting tool geometry), as well as the cutting temperature. An analysis of the experimental and theoretically predicted values of the cutting temperature showed a satisfactory agreement between the corresponding values.
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This paper aims to identify the causes for the rejections of Boring Tool Holders (BTH) and develop a process control plan. From the CTQ characteristics, high rejection rates were due to the variations in key size and bore size dimensions. Define-Measure-Analyse-Improve-Control (DMAIC) approach was adopted to solve the problem. Data was collected and X-bar R control charts were drawn. The process was found not to be in statistical control. Fishbone diagram was constructed, and the root causes were narrowed down to tool wear and improper clamping of angular vise. Corrective actions were taken to make sure the angular vise was clamped properly and the tool life was monitored. This led to the process being in statistical control and thus, process capability analysis was conducted. All the values were found to be within the specification limits. The obtained Cpk values were 1.09 and 1.15 for key size and bore size respectively. This was later institutionalized by developing a process control plan that constituted the control stage.
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A three-dimensional finite element simulation model is developed to analyze the vibration-assisted dry end milling of Ti-6Al-4V alloy specimens. Results of finite element simulated forces in cutting and deflections of the cutter are compared experimented results. Cutting forces in the experiment are recorded using a Kistler 9272 force dynamometer and vibration signal data is acquired using a triaxialKistler (Model_8793) accelerometer. Two milling cutters, both uncoated and coated milling cutters are used for the experimental investigation. In the end, the impact of spindle rotational speed and feed rate on forces in cutting and subsequent tool deflections were also premeditated using the FE simulations. The investigation shows that there is a rise in forces of cutting as the feed is increasing and deflection also increases as the surge in feed rate and rotational speed. The experimental investigation will give the insights to understand the mechanics of the milling operation and thereby this data is cast-off to treasure the optimal machining conditions.
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The finite element method is an important supplement to the experiment on the research of metal cutting mechanism. A 3D thermo-mechanical coupling model was established based on ABAQUS, in which a model of the tool with real structure and a simplified model of the work-piece based on the cutting zone were established. It can greatly improve the computational efficiency because the volume of the work-piece model can be reduced by 70% when compared with the traditional rectangle model. The validation shows that the prediction error of the cutting force is less than 15%, and the prediction results of the chip morphology are in good agreement with the experiment results. In order to reveal the mechanism of high speed milling of 6061-T6 Aluminum alloy, single factor experiments were carried out based on the established model. The results show that the cutting force and cutting temperature rapidly increase with the increase of the axial depth of cut ap and the feed per tooth fz , but slowly increase with the increase of the radial depth of cut ae . The cutting force decreases with the increase of the spindle speed n. However, the cutting temperature increases with the increase of n firstly, and tends to be stable when n is over than 10,000 r/min.
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This paper details an investigation into the performance of PVD tungsten carbide coated ball nose milling inserts when conducting high-speed cutting of Inconel 718 under eco-friendly machining methods of cryogenic carbon dioxide (CO2) and dry cutting conditions. The experiments were performed at varying cutting parameters of; cutting speed: 120–140 m/min, feed rate: 0.15–0.25 mm/tooth, and axial depth of cut: 0.3–0.7 mm. The radial depth of cut was kept constant at 0.4 mm. A new cryogenic CO2 cooling system was introduced for efficient and consistent cooling performance during cutting. The analysis includes the tool life, tool wear patterns and mechanisms as well as its relationship with the chips’ morphology. The experimental results showed that cryogenic and dry cutting conditions reported approximately similar tool wear patterns. The tool wear started with smooth abrasion and chipping around the depth of cut line, which then progressed into flank wear and finally notching and flaking via mechanisms of abrasive and adhesive wears. However, severe BUE was repeatedly observed under dry cutting, which widened the flaking and accelerated the notching. Hence, cryogenic CO2 showed significant improvement towards increasing the tool life to a maximum of 70.8% relative to dry cutting. The consistent cooling effect by the cryogenic CO2 managed to efficiently reduce the cutting temperature at the cutting point to 80% compared to dry cutting, which is believed to be the main factor causing the aforementioned improvement. The strong influence of cutting conditions and tool wear patterns upon the chip morphology was also evident. Compared to cryogenic cutting, the shape and colour of the chips were found to be severe, distorted, and darker in dry cutting, which confirmed that it was thermally affected by the high cutting temperature.
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Full-text available
The mechanistic and unified mechanics of cutting approaches to the prediction of forces in milling operations are briefly described and compared The mechanistic approach is shown to depend on milling force coefficients determined from milling tests for each cutter geometry. By contrast the unified mechanics of cutting approach relies on an experimentally determined orthogonal cutting data base (i.e., shear angle, friction coefficient and shear stress), incorporating the tool geometrical variables, and milling models based on a generic oblique cutting analysis. It is shown that the milling force coefficients for all force components and cutter geometrical designs can be predicted from an orthogonal cutting data base and the generic oblique cutting analysis for use in the predictive mechanistic milling models. This method eliminates the need for the experimental calibration of each milling cutter geometry for the mechanistic approach to force prediction and can be applied to more complex cutter designs. This method of milling force coefficient prediction has been experimentally verified when milling Ti6Al4V titanium alloy for a range of chattel; eccentricity and run-out free cutting conditions and cutter geometrical specifications.
Article
The model merged the cutting geometry analysis of Martellotti with empirical force predicting equations so that instantaneous force system characteristics may be studied. The model has been implemented via a computer program, cutting forces, force distributions, force centers, and cutter deflection are presented.
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The concept of an effective orthogonal cutting edge in turning is considered. The orientation of this edge in the radial-longitudinal plane, as commonly modeled through an effective lead angle, is studied. The methods of effective lead angle prediction used in numerous previously developed force models are plagued with large errors over ranges of process inputs, in particular feed rate and depth of cut. Four previously developed methods of effective lead angle prediction are reviewed and compared to a new method presented here. This new method accounts for the size effect as introduced through the variation in chip thickness along the cutting edge, especially along the tool nose region. The difference in the new method is that the effect of continuous chip thickness variation along the cutting edge is included when evaluating the specific machining energies rather than using an average chip thickness, which has been used in the other methods. Therefore, the differential normal and friction force components acting on the rake face are functions of chip thickness through both the elemental chip load and the specific energies. Their directions are characterized by the orientations of the rake face and edge. By numerically integrating the differential force components modeled in this fashion, a significant improvement in effective lead angle prediction accuracy is realized. This improved accuracy is verified using experimental data obtained for 1018 steel and 304 stainless steel at varying levels of feed rate, depth of cut, cutting speed, nose radius and tool lead angle.
Article
In this work, a methodology was developed to determine flow stress at high deformation rates and temperatures that are encountered in the cutting zone, and to estimate friction at the chip-tool interface simultaneously. Orthogonal cutting experiments were used together with FEM simulation of the cutting process. This technique was applied to machining of P20 mold steel (30 HRC) using uncoated carbide tooling. The friction at the chip-tool contact was estimated by using the flow stress data determined at high speed cutting conditions. This data was used in modeling of turning with nose radius cutting tools where the cutting process is simulated with plane strain and axisymmetric plastic deformation analysis. The resultant cutting forces, tool stresses and temperatures were predicted in the primary and secondary cutting edges accordingly. Furthermore, this technique was extended to modeling of cutting process in flat end milling using straight cutting edge inserts with nose radius corners.
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This study is part of the ongoing research at ERC/NSM on the investigation of high speed milling processes for machining dies and molds. A special flat end milling operation, using a single insert indexable tool with a straight cutting edge (i.e. zero helix angle), was selected to investigate chip formation in milling. Dry milling of P- 20 mold steel using a plain tungsten carbide (WC) cutter was simulated for selected cutting conditions (cutter diameter: 15.88 mm, cutting speeds: 50, 100 and 200 m/min, feeds: 0.1 and 0.155 mm/tooth, axial depth of cut: 1 mm, and radial depth of cut: 15.88 mm). Chip formation, cutting temperatures, tool stresses and cutting forces were predicted from Finite Element Method (FEM) simulations. The experiments were conducted in a horizontal high speed milling center to measure cutting forces. Predicted cutting forces and chip shapes were compared with experimental results. This study demonstrates the effectiveness of FEM simulations in predicting process variables in a simple flat end milling operation.
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A mechanistic force system model for the face milling process has been developed and implemented on the computer. The model predicts the force system in face milling over a range of cutting conditions, cutter geometries, workpiece, and process geometries including relative positions of cutter to workpiece, spindle tilt, and runout. Machining tests have been conducted for both flycuting and multitooth cutting with polycrystalline diamond tools on plain surfaces. The 390 casting aluminum alloy has been used as the workpiece material. Force data from these tests were used to estimate the empirical constants of the mechanistic model and to verify its prediction capabilities. Data bases from flycutting tests have been used to predict forces under multitooth face milling and the results indicate good agreement with observed data from multitooth tests.
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A solid modeling system has been developed for optimizing metal removal rate of numerical control and milling. The solid modeler can continuously simulate in-process workpiece geometry for three-dimensional (up to 5-axis) NC milling. Integrated with a metal cutting model and a machinability database, the solid modeler can estimate the chip load and cutting force for each tool motion (block of NC data).Using the simulation, an adaptive feed rate is computed for each tool motion according to the conditions of the part, the cutting tool, and the machine tool. The adaptive feed rates are automatically added to the NC codes to achieve a higher metal removal rate than conventional constant feed rates can achieve. Furthermore, common problems such as chatter, ot tool breakage are minimized. The modeling of in-process workpiece geometry and metal removal, an algorithm for adjusting feed rates, and examples of its practical applications are discussed in this paper.
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Obtaining accurate baseline force data is often the critical step in applying machining simulation codes. The accuracy of the baseline cutting data determines the accuracy of simulated results. Moreover, the testing effort required to generate suitable data for new materials determines whether simulation provides a cost or time advantage over trial-and-error testing. The efficiency with which baseline data can be collected is limited by the fact that simulation programs do not use standard force or pressure equations, so that multiple sets of tests must be performed to simulate different machining processes for the same tool-workpiece material combination. Furthermore, many force and pressure equations do not include rake angle effects, so that separate tests are also required for different cutter geometries. This paper describes a unified method for simulating cutting forces in different machining processes from a common set of baseline data. In this method, empirical equations for cutting pressures or forces as a function of the cutting speed, uncut chip thickness, and tool normal rake angle are fit to baseline data from end turning, bar turning, or fly milling tests. Forces in specific processes are then calculated from the empirical equations using geometric transformations. This approach is shown to accurately predict forces in end turning, bar turning, or fly milling tests on five common tool-work material combinations. As an example application, bar turning force data is used to simulate the torque and thrust force in a combined drilling and reaming process. Extrapolation errors and corrections for workpiece hardness variations are also discussed.
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The three-dimensional finite-element machining simulation method has successfully been employed to analyse machinability of both leaded CrMo an leaded MnB steels based on realistic plastic flow properties of the work-pieces and friction characteristics at the tool-chip interface. There is no remarkable difference in the predicted cutting forces, temperature rise, tool wear and surface integrity, but a slight difference can be seen. The MnB steel shows a slightly lower cutting temperature and wear rate on the rake face of a P20 carbide tool since the flow stress is smaller than that of the CrMo one. The use of a button tool is rather effective in the light of the reduction of the rake temperature and crater wear. These tendencies are in good agreement with experiments. Finally, the analysis of production cost has revealed that both steels give almost the same production cost-cutting speed characteristics below 400 m/min. However, since the material cost of the MnB steel is about 20% cheaper than that of the CrMo one, the substitution of the MnB steel for the CrMo one is cost-effective as well.
Article
A model of three-dimensional cutting is developed for predicting tool forces and the chip flow angle. The approach consists of coupling an orthogonal finite element cutting model with an analytical model of three-dimensional cutting. The finite element model is based on an Eulerian approach, which gives excellent agreement with measured tool forces and chip geometries. The analytical model was developed by Usui et al. [ASME J. Engng Indust. 100(1978) 222; 229], in which a minimum energy approach was used to determine the chip flow direction. The model developed by Usui required orthogonal cutting test data to determine the tool forces and chip flow angle. In this paper, a finite element model is used to supply the orthogonal cutting data for Usui's model. With this approach, a predictive model of three-dimensional cutting can be developed that does not require measured data as input. Cutting experiments are described in which good agreement was found between measured and predicted tool forces and chip flow angles for machining of AISI 1020 steel.
Article
This paper presents the development, verification, and implementation of a mechanistic model for the force system in end milling. This model is based on chip load, cut geometry, and the relationship between cutting forces and chip load. A model building procedure based on experimentally obtained average forces is presented and both instantaneous and average force system characteristics are described as a function of cut geometry and feed rate. A computer program developed to implement the mechanistic model provides tabular and graphical outputs which show force distributions as functions of the axial depth of cut and rotation of the cutter. Force characteristics during concerning cuts are predicted by the model and verified via a set of cornering cut experiments typical of aerospace machining operations. Force characteristics in cornering are examined as a function of axial depth of cut and feedrate.
Article
This paper presents a new procedure to determine instantaneous cutting force coefficients which are required for process simulation by mechanistic modeling. This new procedure drastically reduces the number of experiments for calibration and improves the accuracy of dynamic cutting forces and force signatures by considering the size effects. Comparisons are shown to illustrate the effectiveness of the proposed method in determining the chip flow angle and those predicted by various existing analytical models. The importance of using instantaneous cutting force coefficients instead of conventional average coefficients is demonstrated through simulation based on the mechanistic models.
Article
This paper summarizes the results of an investigation where the FE code DEFORM 2D was applied to simulate a plane strain cutting process. To perform the simulation with reasonable accuracy and to study continuous and segmented chip formation it was necessary to modify the existing version of the code. Damage criteria have been used for predicting when the material starts to separate at the initiation of cutting for simulating segmented chip formation. For this purpose, special subroutines have been implemented and tested. The influence of several parameters such as cutting speed, rake angle, and depth of cut has been studied. Results of extensive FEM simulations and the comparison with experimental data are reported.
Article
The high speed machining is now recognized as one of the key manufacturing technologies for higher productivity and throughput. The paper reviews recent development in high speed machining and related technology especially in the last decade. The state of the art of high speed cutting, cutting tools and machine tools for high speed cutting are presented. The realization of hsc demands new unconventional solutions for machine tools and their components. The optimization and the safety precautions of the tools are very important. Time reduction of more than 50% can be achieved.
Article
Thesis (Ph. D.)--Ohio State University, 1998. Includes bibliographical references (leaves 164-178). Advisor: Taylan Altan, Dept. of Electrical Engineering.
Experiments on and Finite Element Modeling of turning free-cutting steels at cutting speeds up to 250 m/min
  • T H Childs
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T.H. Childs, M.H. Dirikolu, M.D.S. Sammons, K. Maekawa, T. Kitagawa, Experiments on and Finite Element Modeling of turning free-cutting steels at cutting speeds up to 250 m/min, in: Proceedings of First French and German Conference on High-speed Machining, 1997, pp. 325–331.
Inter-relationship between shear processes occurring along tool face and shear plane in metal cutting
  • N N Zorev
N.N. Zorev, Inter-relationship between shear processes occurring along tool face and shear plane in metal cutting, Proceedings of International Research in Production Engineering, ASME, New York (1963) 42–49.
Experiments on and Finite Element Modeling of turning free-cutting steels at cutting speeds up to 250 m/min
  • Childs