In machining process, cutting forces are difficult to measure accurately due to the dynamic characteristic of measurement system. The cutting forces compensation requires the frequency response ...function (FRF), which cannot be measured in actual production. This paper proposes an effective method for FRF modelling and calculating based on transfer path analysis (TPA) and receptance coupling substructure analysis (RCSA). The measurement system is divided into three substructures: workpiece, table dynamometer with screws, joint surface between two previous substructures. The joint surface is simplified as a spring-damping model with contact stiffness and damping. The FRF of workpiece is obtained by finite element method (FEM), which is adjustable for different workpieces and tool positions. The FRF of dynamometer can be measured only by single impact test. The contact parameters can be identified by a few impact tests, which can be applied to other cutting conditions. The FRF between tool tip and dynamometer output is first derived based on TPA and RCSA. Second, a joint surface parameters identification algorithm as well as its simplified algorithm is presented through a few impact tests. Finally, impact tests and milling tests are implemented for parameters identification, algorithm verification and cutting forces compensation. The experimental results show that the proposed method has sufficient accuracy for the assembly FRF prediction.
•The RFR from tool tip to dynamometer is derived based on TPA and RCSA.•The joint surface parameters identification algorithm is presented based on a few impact tests.•The simplified algorithm for parameters identification is drived.•A number of tests are implemented and validate the effectiveness of the proposed method.
•Influence of tool run-out (axial and tilt offset), tooth trajectory, variable entry and exit angles, and size effect on cutting forces in the micro end milling process is evaluated.•Instantaneous ...tool deflections are determined based on the distributed load acting on the cutting edge and the tool is assumed to be the continuous Timoshenko beam.•The tool run-out parameters and cutting forces coefficients are calibrated by the measured cutting forces.•Simulation and experiment results show a good agreement to validate the proposed tool deflection model.
This paper presents the modeling of cutting forces and instantaneous tool deflection in the micro end milling process. The cutting forces directly lead to the tool deflection, which will have influence on the quality of machined surface. In order to calculate the instantaneous tool deflection, it is necessary to model the cutting forces. According to cutting edge size effect and the minimum chip thickness, the cutting forces model of micro end milling process is proposed in the ploughing-dominant and shearing-dominant regimes, respectively. The tool run-out which consists of axial and tilt offset is also taken into account as well as the tooth trajectory. Thus, the tool deflection can be established based on the obtained cutting forces. To obtain the more precise model of instantaneous tool deflection, cutting forces are regarded as a distributed load acting on the cutting edge instead of a point load, and the tool is assumed to be a continuous Timoshenko beam. Based on the calibrated tool run-out parameters and cutting forces coefficients, the experimental results carried out on Al6061 for a wide range of cutting conditions show a good agreement with the proposed instantaneous cutting forces and tool deflection models.
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•A 3D friction model is developed based on oblique cutting theory.•Conventional and ultrasonic assisted turning and face turning are simulated.•Cutting forces and cutting angles determine the ...friction value.•The differences of forces plus inclination and rake angles are very effective on friction value.
As turning is a 3D operation, development of a friction model considering all cutting forces and angles, is essential. In this study, shear friction model is extended based on oblique cutting theory. The developed model calculates friction value using measured cutting forces coupled with their related angles. To use the model, the operation is carried out in two methods of turning and face turning (with and without ultrasonic vibrations). Then the friction values based on experimental results are calculated. A finite element method is developed to evaluate the accuracy of the values. The results show that the values of simulated tool temperatures are in good agreement with the experiments. Furthermore, the effect of cutting forces on friction values are discussed.
Current research studies devoted to cutting forces in drilling are oriented toward predictive model development, however, in the case of mechanistic models, the material effect on the drilling ...process itself is mostly not considered. This research study aims to experimentally analyze how the machined material affects the feed force (Ff) during drilling, alongside developing predictive mathematical–statistical models to understand the main effects and interactions of the considered technological and tool factors on Ff. By conducting experiments involving six factors (feed, cutting speed, drill diameter, point angle, lip relief angle, and helix angle) at five levels, the drilling process of stainless steel AISI1045 and case-hardened steel 16MnCr5 is executed to validate the numerical accuracy of the established prediction models (AdjR = 99.600% for C45 and AdjR = 97.912% for 16MnCr5). The statistical evaluation (ANOVA, RSM, and Lack of Fit) of the data proves that the drilled material affects the Ff value at the level of 17.600% (p < 0.000). The effect of feed represents 44.867% in C45 and 34.087% in 16MnCr5; the cutting speed is significant when machining C45 steel only (9.109%). When machining 16MnCr5 compared to C45 steel, the influence of the point angle (lip relief angle) is lower by 49.198% (by 22.509%). The effect of the helix angle is 163.060% higher when machining 16MnCr5.
•Sequential approach in CCD is beneficial as it saves number of experiment.•The effects of varying parameters on cutting forces.•Quadratic model is fitted for all the cutting forces.•The results were ...proved to predict values close to experimental value.•Sensitivity analysis revealed that cutting speed is most significant factor.
In the present investigation an attempt is made to evaluate the effect of certain cutting variables on cutting forces in straight turning of aluminum metal matrix composites under dry cutting condition. Cutting speed, depth of cut and weight percentage of SiCP are selected as the influencing parameters. The application of response surface methodology and face centered composite design for modeling, optimization, and an analysis of the influences of dominant cutting parameters on tangential cutting force, axial cutting force and radial cutting force of aluminum metal matrix composites produced through stir casting route. Experiments are carried out using aluminum (LM6) alloy reinforced with silicon carbide particles. The mathematical models are developed and tested for adequacy using analysis of variance and other adequacy measures using the developed models. The predicted values and measured values are fairly close, which indicate that the developed models can be effectively used to predict the responses in the turning of aluminum metal matrix composites. The contour plots of the process parameters revel that the low cutting forces are associated with the lowest level of depth of cut and the highest level of cutting speed and the sensitivity analysis revealed that cutting speed is most significant factor influencing the response variables investigated.
Modelling of the cutting forces in micromilling is challenging due to the size effect and existence of a minimum chip thickness. This paper presents the development of a cutting force model for ...micromilling of brass. The prediction of cutting forces derives from a simplified orthogonal process. A finite element (FE) model is employed to simulate two-dimensional cutting forces in orthogonal microcutting, with the ploughing and tool edge effect taken into consideration. The flow stress of workpiece material is modelled by using the Johnson–Cook constitutive material law. The FE model is used to evaluate the critical chip thickness and to extract the cutting force coefficients. The cutting force coefficients are modelled as a function of instantaneous uncut chip thickness, which is independent of cutting speed but influenced by tool edge radius. To rectify the issue of sharp increase of the force coefficients under very small uncut chip thickness, a critical uncut chip thickness value is introduced and the coefficients are adjusted by using a tangent slope for uncut chip thickness smaller than the critical value. A generalized analytical force model based on numerical findings is developed to predict the micromilling force by considering the tool trajectory and tool runout. The simulation results of micromilling forces are compared against experimental measurement, where an agreement of force trends is shown along with the increasing feedrate and depth of cut.
•A hybrid 2D cutting force model in micromilling brass is developed.•Force coefficients are modelled as a function of instantaneous uncut chip thickness.•FE simulation of micro orthogonal cutting is used to extract force coefficients.•A new approach to rectify the issue of sharp increase of the force coefficients.•Tool trajectory, tool runout and helix angle are considered in the force model.
Analysis of cutting forces is critical for understanding, control and optimization of machining operations. Table-dynamometers are the most common tools to measure the cutting forces directly. ...Workpiece geometry restrictions, high cost, altered dynamics, and limited frequency bandwidth are challenges associated with the direct measurement of the cutting forces using table-dynamometers. In this study, utilization of cost-effective spindle current sensors along with accelerometers is proposed to indirectly predict the cutting forces at the tool tip during milling operations. First, receptance coupling (RC) method is used to obtain dynamics between the tool tip and the accelerometers which are located on the spindle housing. The application of the RC method requires a series of impact hammer tests along with finite element simulations to identify the dynamics of machine tool structure. The measured accelerations are then integrated in frequency domain to obtain displacement of the spindle housing where the accelerometers are attached. A Kalman filter is then designed and applied to the displacement signals to reconstruct the AC component of the cutting forces. Next, the spindle current signals measured through the hall-effect sensors are processed to acquire the tangential and radial cutting forces. Finally, due to different frequency bandwidth of the measured signals through the accelerometers and hall-effect sensors, the reconstructed cutting forces are fused to improve the cutting force measurement accuracy. The proposed method is also verified by conducting a series of half and full-immersion milling tests, and the reconstructed results are compared to the measurements of a reference piezoelectric-based table-dynamometer. Results show that the proposed sensing scheme can predict the cutting forces effectively only at a fraction of the cost of traditional table-dynamometers without affecting overall workpiece geometries.
Metal matrix composites (MMCs) are a special class of materials carrying combined properties that belongs to alloys and metals according to market demands. Therefore, they are used in different areas ...of industry, and the properties of this type of material are useful in engineering applications. Machining of such composites is of great importance to finalize the fabrication process with improved part quality. However, the process implies several challenges due to the complexity of the cutting processes and random material structure. The current study aims to examine machinability characteristics. Effects of turning a metal matrix composite built of Al2O3 sinter, saturated with an EN AC-44000 AC-AlSi11 alloy, are presented in this paper. In the present study, a turning process of new metal matrix composites was carried out to determine the state-of-the-art material for various engineering applications. During the turning process, the cutting forces, a tool’s wear, and surface roughness were investigated. Further, the SEM (scanning electron microscope) analysis of cutting inserts was performed. The influence of MMC structure on the machining process and surface roughness was studied. The Al2O3 reinforcements were used in different graininess. Effects of conventional turning of the metal matrix composite with Al2O3 sinter of FEPA (Federation of European Producers of Abrasives) 046 and FEPA 100 grade were compared. Results analysis of these tests showed the necessity of continuing research on turning metal matrix composites built of an AlSi alloy and Al2O3 ceramic reinforcement. The study showed the properties of MMCs that influenced machinability. In this paper, the influence of feed rate’s value on surface roughness was carried out. The significant tool wear during the turning of the MMC was proved.
A review of helical milling process Pereira, Robson Bruno Dutra; Brandão, Lincoln Cardoso; de Paiva, Anderson Paulo ...
International journal of machine tools & manufacture,
September 2017, 2017-09-00, 20170901, Letnik:
120
Journal Article
Recenzirano
Helical milling is an alternative hole-making machining process which presents several advantages when compared to conventional drilling. In the helical milling process, the tool proceeds a helical ...path while rotates around its own axis. Due to its flexible kinematics, low cutting forces, tool wear, and improved borehole quality may be achieved. This paper presents a review of the helical milling process. As a first paper aiming to describe the current state of the art of helical milling process, the recent works about this process were summarized to point out the future trends in this field. Initially, the advantages of the helical milling were presented with regard to conventional drilling. Subsequently, the kinematics of the process was presented to standardize the nomenclature and to provide knowledge about the movements and parameters of helical milling. It was demonstrated the feed velocity decomposition in frontal and peripheral directions. Undeformed chip and cutting volumes of frontal and peripheral cut were described, and the ratio between the cutting volumes removed by frontal and peripheral cut was demonstrated to be dependent only of the borehole and tool diameters. Cutting forces and temperature studies were also summarized, corroborating that the helical milling is a smooth hole-making process. Afterward, tool life and wear studies in helical milling were summarized, testifying that the tool wear evolution can be monitored in frontal and peripheral cutting edges, with frontal cutting edges, in most cases, defining the tool life. Some statistical and soft computing applications on helical milling were also mentioned. To provide initial guidelines for applying helical milling, a screening of the current literature was performed summarizing equipment and cooling techniques used, and the levels of cutting conditions of helical milling applied for hole-making different materials. The quality of boreholes obtained by helical milling was assessed in terms of dimensional, geometrical, and microgeometrical deviations, besides burr and delamination levels, assuring that it can be obtained finished boreholes with helical milling. In the conclusions, future possibilities on research about helical milling were pointed out. This general review of helical milling may be referenced as a summary of the current results obtained in experimental and theoretical studies and to provide future research needs and opportunities.
•A review of helical milling process is presented.•Helical milling advantages, kinematics, undeformed chip and cutting volumes are discussed.•A screening of helical milling experimental studies is presented.•Helical milling results about wear, hole quality, cutting force and temperature are presented.•Recent results and future trends about helical milling are presented.
The authors present the results of laboratory tests analysing the impact of selected cutting data and tool geometry on surface quality, chip type and cutting forces in the process of orthogonal ...turning of sintered cobalt. The selected cutting data are cutting speed and feed rate. During the experiments, the cutting speed was varied in the range of
= 50-200 m/min and the feed rate in the range of
= 0.077-0.173 mm/rev. In order to measure and acquire cutting force values, a measuring setup was assembled. It consisted of a Kistler 2825A-02 piezoelectric dynamometer with a single-position tool holder, a Kistler 5070 signal amplifier and a PC with DynoWare software (Version 2825A, Kistler Group, Winterthur, Switzerland)). The measured surface quality parameters were
and
. The components of the cutting forces obtained in the experiment varied depending on the feed rate and cutting speed. The obtained test results will make it possible to determine the optimal parameters for machining and tool geometry in order to reduce the machine operating time and increase the life of the cutting insert during the turning of sintered cobalt, which will contribute to sustainable technology.
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