Simulation Of Milling Process Research Articles

Continuous Feed Grinding Milling Process of Soda-Lime Glass Using Smoothed-Particle Hydrodynamics

A smoothed-particle hydrodynamics (SPH) modeling technique was applied in conjunction with the Johnson–Holmquist (JH-2) ceramic material constitutive model to replicate the fracture of soda-lime glass in a milling manufacturing process. Four-point bending tests were conducted to validate the soda-lime glass bulk material properties prior to its implementation in ABAQUS CAE™ Explicit (Version 2017). The JH-2 material constitutive model replicated the fracture load and time to fracture for the four-point bending load cases as per ASTM C158. This study showed how SPH in combination with a validated JH-2 material model in a milling process simulation was able to replicate the output size distribution at 5000 and 6500 revolutions per minute (RPM). For operations at 3000 RPM or lower, it was shown that it is necessary to include additional effects in the model, such as fluid–structure interactions, to improve the correlation with the experimental data. The SPH model was validated through an experimental campaign using high-speed cameras and a particle Camsizer. The experimental results clearly indicate a direct relation between the mill’s RPM and the output particle size distribution.

Mathematical modeling and simulation of generation milling process to manufacture complex face gear surface through multi-axis machine kinematics

Manufacturing of face gear is a complex process, due to its varying geometry, hence the application is not wide as conventional gear geometry. The developments in analytical tools and kinematics of the CNC machine tools motivate researchers to explore the manufacturing process and associated applications. This article presents an efficient method for the generation milling of spur face gear utilizing a nutating head multi-axis CNC machine tool where the tool swings about an arbitrary axis in an inclined plane. The mathematical model of the disk milling cutter and face gear geometry were derived from the shaper geometry by applying the theory of gearing, equation of meshing and coordinate transformation. The cutter location (CL) data was evaluated by aligning the tool orthogonal unit vector and the tooth surface normal vector at the contact point by calculating the appropriate transformation matrices. The evaluation of machine coordinates on a multi-axis CNC milling machine was analyzed with respect to the machine pivot point and the axes movement during generation milling for the face gear drive was studied on the nutating head machine. The NC data is derived from the CL data using the inverse kinematics and the machining simulation was carried out using suitable software. The tooth surface deviation of a maximum of 43.5 μm was observed between the simulated model and the theoretical model, which is well within the requirement of roughing. The generation milling process with the proposed machine configuration is concluded as a profound face gear manufacturing technique.

DEM breakage calibration for single particle fracture of maize kernels under a particle replacement approach

The Discrete Element Method (DEM) has become increasingly popular for simulating breakage operations and grinding equipment performance. Two main breakage approaches can be found in literature: bonded particle models and particle replacement models. This work is focused on fitting the parameters of a DEM particle replacement breakage model for maize, implemented in software Rocky DEM. Once all required experimental and calibration procedures were developed for maize specific DEM properties and parameters, single particle compression tests were carried out to fit the parameters of the breakage model, which was extensively analyzed for validating its capability of representing the material. Maize properties showed to be in agreement with literature sources. Compression tests simulated in DEM led to the same results as their experimental counterparts, validating the model’s capability of representing maize breakage. These results are the basis for further simulation of a full milling process in a hammer mill.

Elastic–plastic constitutive model of the milled mixture of sugarcane based on phase transition state

AbstractExtracting juice from sugarcane is a complex and nonlinear process. It is very important to comprehend mechanical properties and constitutive model of the milled mixture of sugarcane for understanding sugarcane crushing process. In this paper, mechanical properties of the milled mixture were investigated by uniaxial compression tests, repeated loading tests and direct shear tests. The elastic–plastic constitutive model was established by using isotropic elastic materials and Modified Cam‐Clay model based on phase transition state. Both Poisson's ratio and Young's modulus of the milled mixture were proportional to the loading stress; the compression index and swelling index are 2.23 and 0.10, respectively; and the cohesive force and friction angle are 25.25 kPa and 21.63°, respectively. At last, the proposed constitutive model was verified by uniaxial compression tests. This paper can provide a theoretical basis for the study of mechanism and simulation of sugarcane crushing processes, and is of guidance for the improvement of sugar production process and equipment.Practical applicationsIn this article, the prepared cane and bagasse are collectively called the milled mixture of sugarcane, which includes solid fiber, juice, and air. The interaction of three components of milled mixture can lead to difficulties in extracting juice, an increase in processing energy consumption and other undesirable conditions. In this paper, the mechanical properties and constitutive model of milled mixture of sugarcane are studied. This research can provide a new method for the simulation of sugarcane milling process, and has enlightening significance for the optimization of crushing equipment and technological parameters to improve juice extraction efficiency.

3D FEM Simulation of Titanium Alloy (Ti6Al4V) Machining with Harmonic Endmill Tools

AbstractUsually, end milling operations have been carried out using conventional uniform helix tools with fixed helix angles. Thus, many studies have been conducted to study the effects of these tools on the thermomechanical properties of a milling process. Recently, there have been works that point to the benefits of using harmonic endmills. Harmonic endmills consist of cutting edge profiles that have continuously harmonically varying helix angles. The variation is described using a harmonic function of axial position (elevation) of points on the cutting edge. In this work, a 3D finite element simulation using ABAQUS, is carried out for the complex milling process of Titanium alloy Ti6Al4V. The envelope of the harmonic tool is first generated using a set of MATLAB codes and stored in a Standard Triangle Language (.stl) format. The machine tool is introduced into an FEM program which has been designed to provide for dynamic effects, thermo‐mechanical coupling, material damage law and the criterion for contact associated with the milling process. A Johnson‐Cook material constitutive equation which combines the effects of strain hardening, strain softening, and temperature softening is used. To account for the chip separation criterion, the Johnson Cook damage evolution equation is used. The milling process simulation for Ti6Al4V is then carried out. In the end, the stress distribution and the cutting forces are obtained.

On the Milling Process Simulation of an Injection Mold Part

The paper presents the 3-phases milling process simulation of a surface of a polystyrene injection mold, by using CATIA software. The cutting regime parameters are computed and are used, together with other data, as inputs for the simulation process. On the basis of milling process simulation, the software generates the manufacturing program for the NC machine tool.

Identification of the model parameter for milling process simulation with sensor-integrated disturbance observer

This study presents a novel parameter identification method using a disturbance observer for computer numerical control (CNC) machine tools with ballscrew-type feed drive systems, which are generally adopted in industrial applications. In the proposed method, the disturbance force acting on the feed drive system was estimated using a multi-inertial disturbance observer using both CNC servo and accelerometer signals. Model-based milling simulation is performed with reference to the estimated disturbance forces, and hence model parameter identification can be systematically achieved. In the milling process model, the structural vibration and cutting forces caused by machine-process interactions are considered. Furthermore, the model is considered the disturbance forces transmitted to the feed drive system via a mechanical structure. To verify the proposed method, a basic end-milling experiment was conducted. It was confirmed that the multi-inertial disturbance observer assisted by the accelerometer is equivalent to the dynamometer in terms of the disturbance force estimation within the frequency range of 600 Hz and less. The model parameters identified using the proposed method were almost identical to those obtained using conventional methods. However, the identification results of the modal parameters and tool eccentricity were slightly different from those estimated using the conventional methods. The milling simulation using the identified parameters agreed with the measurement results obtained using the dynamometer. Hence, inverse analysis of the in-process data can effectively improve the identification accuracy of the model parameters.

An effect of osteon orientation in end milling operation of cortical bone based on FEM and experiment

Controlling of the cutting force and temperature in removal bone process in orthopedic surgeries (such as: cutting, tuning, milling …) can avoid thermal necrosis and cell death, wear and breakage of the tool. Increasing implication of milling process in orthopedic operations, measuring and controlling of process cutting force and temperature can be effective for developing orthopedic and fast cure of the patient. Considering lack of bone milling experiments data -in this paper- numerical simulation of bone milling process have used for acquiring process cutting force and temperature and comparison with already reported experimental data. Based on orientation of osteon and bone fibers, mechanical properties of bone are different in two directions. Thus, numerical analysis was performed in two perpendicular directions. Furthermore, response surface method was used for mathematical modeling of the process and deriving second order regression equations for process force and temperature, each as a function of cutting speed and feed rate. Results revealed good agreement between numerical and experimental results, as errors were below 4 % and 8 % for prediction of temperature and cutting force respectively. Findings of the present study can improve control and optimization of the cutting force and temperature of bone milling process in orthopedic surgeries.

Application of interpolation methods for the determination of position-dependent frequency response functions for the simulation of 5-axis milling processes

The occurrence of chatter vibrations in 5-axis milling processes is a common problem and can result in part failure, surface defects and increased wear of the cutting tool and the machine tool. In order to prevent process vibrations, machining processes can be optimized by utilizing geometric physically-based simulation systems. Since the modal parameters of the machine tool are dependent on the position of the linear and rotary axes, the dynamic behavior of milling processes can change along the NC path despite constant engagement conditions. In order to model the pose-dependent modal properties at the tool tip, the frequency response functions (FRFs) were measured at different locations of the workspace of the machine tool for various poses of the rotary axis of the spindle. To take the varying compliance within the workspace of a machine tool into account in a geometric physically-based milling process simulation, different interpolation methods for interpolating FRFs or parameter values of oscillator-based compliance models (OPV) were applied. For validation, the resulting models were analyzed and compared to measured data. In OPV interpolation, the individual oscillation modes were interpolated in their respective characteristics based on the oscillator parameters (eigenfrequencies, modal masses and damping values). In FRF interpolation, however, there was no differentiation between the modes, resulting in a wrong interpolation. It can therefore provide good results when only a small shift of the eigenfrequencies is expected, as in case of the analyzed machine tool, with only small movements of the translatory axes.

A novel CAD-based simulation model for manufacturing of spiral bevel gears by face milling

Bevel gears are employed in the transmission of motion and torque via non-parallel shafts. When higher strength and lower noise is the objective, spiral bevel gears are used because of their higher tooth contact ratio. Face milling and face hobbing are among the most significant operations for the machining of hypoid and spiral bevel gears due to their high productivity. Although the optimization of these processes is crucial for the production of high-quality gears and the minimization of the total manufacturing cost, there are not many studies reported in this research area, owing to the high complexity of process kinematics. Furthermore, several kinematic variations of the two methods are applied in industry and their results depend highly on the cutting tool geometry. A novel simulation model integrated into a commercial CAD platform has been developed. The model achieves the 3D kinematic simulation of both face milling and face hobbing processes, generating the undeformed solid chip geometry as well as the simulated tooth solid geometry of a spiral bevel gear pinion and a spiral bevel gear wheel as an output. The simulation approach has two main purposes. First, is the optimization of the process through the investigation of the effect of cutting parameters on the quality of the obtained solid tooth flank geometry and second, is the calculation of cutting forces with the use of the obtained solid chip geometries. Aiming towards the validation of the model, the resulted tooth flank geometry is compared with the theoretical tooth exported from a well-established commercial gear calculation and design software and it is verified by means of a novel validation algorithm, also developed as part of this study. This paper focuses on the presentation of the kinematic simulation methodology and the simulation results for the face milling process. An insight into the validation model is provided and validation results are also presented. Finally, a sample investigation of the effect of generating feed rate on the produced gear geometry is conducted with the use of both algorithms.

Dynamic simulation of sugarcane milling process based on Arbitrary Lagrangian–Eulerian algorithm

Understanding the process of the sugarcane milling is important for improving sugar extraction. The Arbitrary Lagrangian–Eulerian algorithm within LS-DYNA was successfully used for the first time to simulate the dynamic process of milling. The predictions of the numerical model were validated using experimental crushing data from a previous study and dynamic process of milling was examined in detail. The draining performance during milling needs to be carefully considered. It was found that the deformation of the sugarcane in the XY cross-section under loads consisted of two main phases; compression and expansion with reabsorption mostly occurring during the expansion phase. The feeding side of the nip is the main area for the draining of juice. A sensitivity analysis of parameters influencing load and pressure was conducted. This research method could be applicable to similar engineering problems where there is contact, collision, extrusion, large displacement, and large deformation.

Dynamic simulation of robot milling process based on ADAMS

In this paper, a stability model for milling chatter based on instantaneous cutting thickness was established, and the flap diagram of the stability region was drawn accordingly. The finite element simulation of dynamic milling process was carried out by using AdvantEdge, and the dynamic simulation was carried out by using ADAMS, and the torque of each joint was obtained. The conclusions show that: 1) The torque on all joints of the robot reaches the maximum value and fluctuates greatly at the initial cutting, and then tends to be stable; 2) the linear velocity jitter of the end-effector is less than 2.5·10−5m/s, and the angular velocity jitter is less than 3.3·10−5s−1, meeting the processing requirements.

Discrete Element Simulation of Asphalt Pavement Milling Process to Improve the Utilization of Milled Old Mixture

Discrete Element Simulation of Asphalt Pavement Milling Process to Improve the Utilization of Milled Old Mixture

Feed Rate Variation Strategy for Semi-Conical Shell Workpiece in Ball Head End Milling Process

The semi-conical shell workpiece is a special kind of thin-wall part that is commonly used in aerospace and mold industries. Due to the special stiffness distribution and weak rigidity for the area with a large radius, the machining quality of the semi-conical shell is sensitive to both cutting force and vibration. Conventionally, constant conservative machining parameters are chosen to ensure the workpiece deformation and surface quality, which will reduce the machining efficiency. Based on the cutting force and vibration response simulation of the whole milling process. A feed rate variation strategy is proposed for the ball head end milling process of the semi-conical shell workpiece. The cutting force, dynamic performance and stability prediction are obtained considering the shape and boundary conditions of the workpiece and the contour tool path of the milling process. Variable feed rate is used in the milling simulation to find the harmony between machining quality and efficiency. User-defined vibration amplitude and another user-defined cutting force threshold are used to find the optimal feed rate for each simulation segment. Both continuous and discrete feed rate variation strategies are proposed, and the improved discrete feed rate variation is applied in the milling experiment. About 25% of the consumed time is saved with almost the same machining quality by the experimental results.

Simulation of the round insert face milling process of AISI 316LN stainless steel with machining-based plastic behavior modeling

A proper plastic behavioral model is required to simulate metal cutting. Here, we model the plastic behavior of AISI 316LN stainless steel during face milling. We used a numerical approach to derive a plasticity model appropriate for machining; a two-dimensional cutting force prediction and a genetic algorithm were conducted for that. The force prediction was performed considering a geometrical relationship between the work material and cutting tool. We used the Johnson-Cook (JC) constitutive material model, and initial model parameters were obtained via tension testing at low strain rates (0.001–1 s−1). The genetic algorithm optimized the model parameters; the predictive accuracy with respect to cutting force was high in the model with optimized parameters. We used the optimized JC model for finite element analysis and simulated face milling with a round insert. We measured the cutting forces to validate our modeling approach; the simulated and measured principal forces were in good agreement (error rate ≤ 3.9% under all machining conditions). Our model improved the accuracy of plastic behavior prediction by 93.0% versus the original model. The high accuracy was retained even when the machining environment changed.

Milling process simulation for the variable pitch cutter based on an integrated process-machine model

Milling process simulations provide a useful way to design and adjust the technical parameters of milling process. As the milling process involves coupling of multiphysics, interactions between the cutting force model and the dynamic model of the tool-spindle system must be analyzed in order to simulate the milling process precisely. This study proposes an integrated process-machine model based on computer graphics method for simulating the milling process of a variable pitch cutter. This method considers both the influence of the transitional surface and vibrations along different cutting directions. In this method, the cutting force model of the variable pitch cutter and the frequency response function (FRF) of the spindle system are first determined. Then, the interactive interface is established to evaluate the interaction between the cutting force model and vibration of the tool noses, which is calculated through an interaction effect. The undeformed chip thickness considering the vibration of the tool nose and the transitional surface is calculated using a computer graphics method and then input into the cutting force model. Finally, the model precisely predicts the cutting force, and surface appearance of the workpiece precisely is predicted by considering the vibration of the tool noses.

FPGA Based Real Time Simulations of the Face Milling Process

The article presents a successful implementation of the milling process simulation at the Field-Programmable Gate Array (FPGA). By using FPGA, very rigorous Real-Time (RT) simulation requirements can be met. The response time of the FPGA simulations is significantly reduced, and the time synchronization is better than in a typical RT system implemented in software. The FPGA-based approach is characterized by enormous flexibility when it comes to input and output operations that can be implemented deterministically in RT. Complex simulation software has been implemented using the High Level Synthesis technique, which is a relatively easy and fast approach for FPGA programming without using complex Hardware Description Languages. The hardware functions are based on procedures written in high-level C programming language. The mathematical descriptions of simulations, results of computer simulations, Hardware-in-the-Loop Simulation experiments, and real experiments are presented. The approach presented in this paper can be used to simulate the dynamics of various mechatronic systems.

Smooth particle hydrodynamics modeling of cutting force in milling process of TC4

Milling is one of the main methods for processing titanium alloy. At present, the complex process of milling is usually simulated by finite element method, which often has problems in mesh distortion and mesh reconstruction. Therefore, a meshless three-dimensional milling simulation model was established for TC4 titanium alloy using the smooth particle hydrodynamics (SPH) method. Firstly, the established SPH model was analyzed by the LS-DYNA software, and the stress distribution, temperature field, and cutting force during milling were studied under specific conditions. Subsequently, the cutting force was simulated under different cutting parameters and the effects of these parameters on the cutting force were determined. Finally, based on a series of cutting force experiments, the accuracy of the simulation model was verified. This study proves the feasibility of SPH method in the simulation of titanium alloy milling process and provides novel methods for investigating the processing mechanism and optimizing the processing technology of titanium alloys.

Milling process simulation of old asphalt mixture by discrete element

Great amount of milling materials are produced every year because of the rapid increase of pavement maintenance. However, the utilization of the milling materials is still low because many broken aggregates and large-piece of asphalt mixture are produced in the milling process. Improving the quality of milling materials to increase its recyclability is an important research direction. In this study, a discrete element model of asphalt mixture was established, AC-16 asphalt mixture specimens were created, which used Styrene-butadiene-styrene (SBS) modified asphalt after aging, and the parameters of the PFC model were determined by uniaxial compression test and simulation of the test by PFC. The force of the cutter tool was analyzed, the optimal conditions for reducing the damage of asphalt mixture aggregate and avoiding the cutting down of asphalt mixture into larger pieces in the milling process were investigated through the simulation of milling process under different milling conditions. Results show that for AC-16 asphalt mixture, using a cutting speed of 0.5 m/s and cutting angle of 45° can reduce the amount of broken aggregates, and the cutting angle of 40° when the cutting depth is 25 mm at a cutting speed of 1 m/s should not be adopted to avoid the milling down of large pieces of old asphalt mixture.

ボクセルモデルを用いた切削シミュレーションにおける微小時間および微小空間解析の高速処理手法

In order to improve machining efficiency, it is required to recognize machining status and optimize cutting conditions. Cutting force is meaningful information to recognize machining status. In the instantaneous rigid force model, which is the most popular model for milling force prediction, milling force is calculated based on the geometrical intersection between cutting edge and workpiece for each feed per tooth. In this model, both of static tool deflection and tool dynamic vibration are not considered. In order to overcome this problem, a new high speed computational algorithm in our voxel based milling process simulation is proposed. The proposed algorithm permits to consider both of static tool deflection and tool dynamic vibration in our voxel based milling process simulation. In the proposed algorithm, the intersection between cutting edge and workpiece is calculated in each minute time interval or minute tool rotational angle interval. Furthermore, the proposed algorithm permits to shorten the computational time of detecting removal voxels to calculate uncut chip thickness discretely. Therefore, high precision analysis can be performed in minute space resolution. The effectiveness of the proposed algorithm is validated by experimental 3-axis milling tests. Predicted milling forces under several cutting conditions have good agreement with the measured milling forces.