Prediction Of Surface Topography Research Articles

Surface profile and milling force prediction for milling thin-walled workpiece based on equivalent 3D undeformed chip thickness model

With the development of the aviation manufacturing industry, the application range of thin-walled parts is rapidly increasing. Accurate machining process and surface topography prediction are the keys to ensuring machining quality. This article is based on the relative geometric relationship between the real motion trajectory of the milling cutter and the workpiece; the undeformed chip thickness equation and the two-dimensional surface contour feature algorithm are established. By introducing the parameters of milling cutter critical height, milling cutter helix angle, and lag angle parameters, the three-dimensional surface profile prediction model and the equivalent three-dimensional model considering the chip formation process are derived. And the calculation equations of the instantaneous chip cross-sectional area and the blade-workpiece contact length of the three phases of chip formation are established, respectively. The multiple linear regression method was used to fit the orthogonal test results of titanium alloy Ti-6Al-4 V, so as to complete the dynamic milling force identification, and finally establish the milling force prediction model. The accuracy of the prediction model was verified by the single factor method, and the influence of different parameters on the milling process of thin-walled parts was observed. The results show that the established model has high accuracy in predicting the surface profile and milling force of thin-walled parts. This study provides guidance for efficient prediction of the milling process of thin-walled parts.

Surface topography modeling and analysis of camshaft generated by swing grinding process

In conventional grinding (CG), camshafts with wide profiles suffer from poor quality and low efficiency because the large contact area between the grinding wheel and camshaft profile limits the diffusion of grinding temperature, leading to burning defects. Swing grinding (SG) can mitigate these problems as it involves a reciprocating motion along the axis of the grinding wheel; however, the lack of understanding of machined surface topography has restricted its application. Therefore, in this study, a surface topography prediction model was proposed that based on the distribution, shape, and trajectory of grains. The model was verified through experiments, and the mean error was 12% for Rax and 9% for Ray; the roughness along the grinding direction was Rax, and the roughness along the vertical grinding direction was Ray. Compared to CG, SG has a 3% lower Ray. The influence of the wheel speed and feed rate in SG is consistent with that in CG. Rax exhibited a periodic trend with an increase in the swing amplitude and a monotonically decreasing trend with an increase in the swing frequency. The variation trend of Ray with the swing amplitude was the same as that of Rax. Furthermore, Ray exhibited a nonlinear increasing trend with an increase in swing frequency.

Hybrid model based on recursive feature elimination with cross validation and Tradaboost for workpiece surface topography prediction of five-axis flank milling

Hybrid model based on recursive feature elimination with cross validation and Tradaboost for workpiece surface topography prediction of five-axis flank milling

Predictive model of the surface topography for compliant grinding of brittle materials

During uneven and time-dependent compliant grinding of brittle materials, the surface topography is difficult to predict as ductile and brittle regions are coupled due to compliance occurring in macro/micro tool-workpiece contact. This paper proposed a predictive model for surface topography prediction by considering its ductile-brittle transition in compliant grinding. Shape adaptive grinding and monocrystalline silicon were chosen as an example to validate the proposed model based on progressive grinding tests (spot, line, area). Feed-Spindle Projection Angles are further investigated, revealing that 0° angle can obtain a ground surface with lower area roughness and smaller brittle fragments than 45° and 90°

Surface Topography Prediction Model in Milling of Thin-Walled Parts Considering Machining Deformation.

With the continuous improvement of the performance of modern aerospace aircraft, the overall strength and lightweight control of aircraft has become a significant feature of modern aerospace parts. With the wide application of thin-walled parts, the requirements for dimensional accuracy and surface quality of workpieces are increasing. In this paper, a numerical model for predicting surface topography of thin-walled parts after elastic deformation is proposed. In view of the geometric characteristics in the cutting process, the cutting force model of thin-walled parts is established, and the meshing relationship between the tool and the workpiece is studied. In addition, the influence of workpiece deformation is considered based on the beam deformation model. Cutting force is calculated based on deformed cutting thickness, and the next cutting–meshing relationship is predicted. The model combines the radial deflection of the workpiece in the feed direction and the changing meshing relationship of the tool–workpiece to determine the three-dimensional topography of the workpiece. The error range between the experimental and the simulation results of surface roughness is 7.45–13.09%, so the simulation three-dimensional morphology has good similarity. The surface topography prediction model provides a fast solution for surface quality control in the thin-walled parts’ milling process.

Surface Topography Prediction Model for Free-form Surface Milling under a Dynamic System Response

At present, numerous studies on surface topography prediction models for plane workpieces have been performed at home and abroad. Given the complexity of curved surface models (especially free-form surfaces that cannot be expressed in analytic formulas), prediction models for the surface topography of free-form surfaces are rarely studied. This paper aims to establish and simulate a 3D surface topography model of ball-end milling for all types of curved surfaces, including simple surfaces and free-form surfaces. The dynamic factors influencing the surface topography, such as the spindle runout initial phase angle, runout amplitude, axial drift initial phase angle, and axial drift amplitude are considered in this model. Moreover, some processing parameters influencing the surface topography, such as cutter tooth number, machining inclination, radial cutting depth, feeding frequency and feed per tooth are also considered in this model. The simulation results can be used to optimize the milling process of the actual free-form surface to improve workpiece surface quality or to predict the surface topography of the given machining parameters.

Surface topography prediction in peripheral milling of thin-walled parts considering cutting vibration and material removal effect

The thin-walled parts have the characteristics of low stiffness and time-varying dynamics in the milling process, and the vibration in the milling system plays a major role in surface topography generation. In this paper, a novel surface topography prediction model is developed considering cutting vibration and material removal effect for the peripheral milling of thin-walled parts with curved surfaces. Compared with the traditional surface topography generation model, the relative tool-workpiece vibration, material removal effect and workpiece surface geometry are considered simultaneously. The time-varying dynamic modal parameters of the thin-walled part are estimated through the structural dynamic modification method. Then the influences of cutting vibration and material removal effect are investigated. The milling experimental results indicate that the proposed model can predict the surface topography and roughness parameters accurately under the machining condition of large axial cutting depth, which can also perform well at a slight chatter state. The material removal effect and system vibration jointly contribute a great deal to surface topography generation.

Modified iterative approach for predicting machined surface topography in ball-end milling operation

Machined surface topography prediction is an important and useful tool for optimizing cutting parameters. However, accurate prediction of machined surface topography in ball-end milling operation has been extremely challenging, due to the complexity in tool-workpiece interaction induced by the trochoidal motion of cutting edge and computing burden. In this present research, a modified iterative approach was proposed to solve the intersections between the cutting-edge sweeping surface and the discrete Z-vector model of workpiece, which were used to predict the machined surface topography in ball-end milling operation. Firstly, the accurate model of cutting-edge sweeping surface was established utilizing homogeneous coordinate transformation, in which the tool runout was considered. Secondly, the cutting-edge sweeping surface was dispersed into a series of patches in accordance with equal parameter interval, and the in-cut patch was extracted by using the minimum and maximum axial immersion angle of the cutting edge. Thirdly, the intersection between each in-cut patch and discrete Z-vector was solved using the Newton’s method, which was used to update the endpoint of the corresponding discrete Z-vector. Finally, ball-end milling experiments of AISI P20 steel were carried out to validate the proposed approach as well as investigate the effect of cutting parameters on the machined surface topography and roughness. The predicted machined surface topography and roughness were in good agreement with the measured results. Moreover, the proposed approach needs less computing time than the traditional iterative approaches at the same predicting accuracy. This research also provides guidance for optimizing cutting parameters to control surface quality in ball-end milling operation.

Modeling, simulation, and prediction of surface topography in two-dimensional ultrasonic rolling 7075 Al-alloy

Two-dimensional ultrasonic rolling (TDUR) is a kind of surface finishing and deformation strengthening technology, which can improve the surface quality and reduce the surface roughness of the workpiece so as to improve its fatigue resistance. In order to study the formation process of the surface topography of 7075 Al-alloy treated by TDUR, a dynamic model of the rolling system was established based on the principle of TDUR to obtain the dynamic force of the roller on the workpiece during the rolling process. The penetration depth model of the workpiece surface under the action of the static load and longitudinal ultrasonic impact was constructed based on the Hertz contact theory and the metal elastic-plastic deformation theory. Then, the simulation model of surface topography was established using the space transformation theory based on the penetration depth model and the trajectory of the roller. Sequentially, the surface topography was reconstructed with the Z-map method. Using the simulation results, the axial profile curve data was extracted, and the surface roughness was calculated by the surface roughness calculation model. Finally, a designed TDUR experiment was carried out to verify the theoretical surface topography and roughness models. And it shows that the simulated surface topography and predicted roughness are in good agreement with the experimental results. The maximum relative error between the predicted roughness and the experimental results is no more than 9%. Under the experimental conditions, the turning marks can be almost eliminated when the static load Fs is 215 N. At this time, the surface profile height was about 1.5 μm, and the roughness Ra is 0.413 μm, which is 78% lower than that of turning. Therefore, the surface topography and surface roughness models proposed in this work can be used to effectively predict the surface topography and surface roughness of 7075 Al-alloy treated by TDUR.

A multi-scale model of real contact area for linear guideway based on the fractal theory

High precision, efficiency and reliability are the unremitting pursuits of machinery manufacturing industry. As one of the pivotal function parts of high-end NC machine tool, precise linear guideway determines the machining precision and operation performance. Accurate evaluation and prediction of surface topography are the crucial effects on the matching performance of linear guideway. In this paper, the real contact area is regarded as a key parameter, a multi-scale method with the fractal theory is proposed. First, the contact area of a single asperity was obtained with Hertz contact theory. Afterwards, the contact area between rough surfaces was deduced by the fractal theory. Finally, using the proposed multi-scale contact mechanics model, the real contact area between rough plane and cylinder was obtained by integral solution. Compared with the former fractal model and GW model, the proposed model on the real contact area calculation of linear guideway is more accurate and comprehensive. The effect factors of load, fractal parameter and friction were discussed, the increasing rate of real contact area of smoother surface is greater as load increases. The proposed model may provide practical guidance for assembly accuracy and surface quality requirements at design stage.

Prediction of plastic surface defects for 5-axis ball end milling of Ti-6Al-4 V with rounded cutting edges using a material removal simulation

The resulting surface quality after 5-axis ball end milling is of superior importance because finish milling is often the last process step determining the functional performance of a component. However, the prediction of surface topography is still a challenging task. Especially in ball end milling with the characteristic sickle shaped chip cross section, ploughing effects in the area of low chip thickness result in plastic deformation and surface defects (also known as burr). This paper provides a new approach to predict those surface defects by considering the minimum chip thickness for complex milling engagement conditions within a virtual process design. This allows the choice of suitable process parameters without extensive experimental efforts.

A novel 3D surface topography prediction algorithm for complex ruled surface milling and partition process optimization

The ruled surface is an important modeling method of the product. With high-performance requirement, more and more complex ruled surfaces with the characteristic of variant curvature are used in auto, aviation, or die mold. The time-varying tool position and orientation make the prediction of surface topography very difficult in the five-axis machine tool processing. In this paper, a three-dimensional surface topography prediction method is proposed. The point cloud of cutting edge is obtained after a series of matrix transformation by calculating the instant information of the local tool coordinate. Then, lots of tiny bounding boxes are constructed based on the profile of the workpiece. The 3D surface topography is obtained by the Boolean operation between the enveloping body of cutting edge and the tiny bounding boxes. The geometric error of the machine tool, the vibrations, and the deformation of the tool is also considered in the generation of the surface topography. The presented method is validated by a case study of the S test piece. The prediction results are verified by the measuring experiment at the same time. Finally, a partition optimization method on the surface topography for the complex surface of the S test piece is presented. The dynamic modification of the cutting parameters in different partitions of the milling process can greatly improve the surface quality without reducing efficiency.

Finite element model for topography prediction of electrical discharge textured surfaces considering multi-discharge phenomenon

The prediction of surface topography obtained with electrical discharge texturing (EDT) process is very challenging, due to stochastic nature and complex physics in occurrence of sparks. Though there are a few models for surface texture prediction in the literature, there are still ample opportunities to improve upon by adopting more realistic assumptions and formulations for simulation. This paper presents a numerical simulation of progressive development of surface topography due to sequential application of spark discharges on an instantaneous textured surface formed by all previous spark discharges. The model incorporates major single-spark features such as, Gaussian distribution of heat flux, temperature-dependent work material properties, latent heat of melting, and operating parameter dependent variation of factors such as, cathode energy fraction, spark radius, and plasma flushing efficiency; besides the multi-spark features such as, stochastic distribution of sparks with respect to: i) location, ii) energy level, and iii) chronological order. Finite element simulation of EDT is performed in ABAQUS with the help of user-defined subroutines for the dynamic simulation of spark discharges, flagging of elements attaining evaporation temperature from further heat flux application and storage of the highest temperatures attained by each element. An evolution of surface texture through the progress of spark erosions has been studied. As EDT continues, the number of craters overlapping generally tend to increase, whereas the center-to-center distance between a crater with its nearest neighbour tends to decrease. The simulated surface textures are validated with the experimental ones using two methods: error function method and Ra distribution method, and were found to be in good agreement.

A GPU-based prediction and simulation method of grinding surface topography for belt grinding process

Rapid simulation of grinding surface topography at different machining conditions can assist users to determine appropriate grinding parameters. Most simulation methods reported so far are time-consuming and can only simulate the surface topography on a micro-scale, which are certainly not effective and intuitive enough. Hence, in this work, a novel GPU-based prediction and simulation method of the grinding surface topography is proposed. With the method, an artificial neural network (ANN) model is first developed to model the grinding surface roughness and fractal dimension. Then, the Cook-Torrance illumination model is introduced to render the color and glossiness of the grinding surface, and a normal map generation method is proposed to render the rugged detail features of grinding surface topography. Finally, a GPU-based prediction and simulation algorithm is developed. A performance evaluation experiment of the ANN model and a comparative experiment between the simulated and actual grinding surface topography are conducted. The experimental results show that the proposed method can achieve fast prediction and photorealistic simulation of the grinding surface topography for the whole part surface, which provides a more intuitive and effective way to evaluate the surface quality under given processing parameters.

Study on the fabrication of micro-textured end face in one-dimensional ultrasonic vibration–assisted turning

Through fabricating the micro-textures to improve surface property, the surface texturing technology has become a widely used way to prepare the functionalized surface. This study proposed a surface texturing method of one-dimensional ultrasonic vibration–assisted turning to generate micro-textured end face. The generation principle for the micro-textured end face was presented through the description of cutting conditions, the theoretical analysis of textured features, and the simulation prediction of surface topography. The polycrystalline diamond cutting tools with different clearance angles (7° and 20°) and nose radiuses (400 μm, 200 μm, and 100 μm) were used in the experimental tests to investigate the influence of tool geometry on the micro-dimple features. The results show that the micro-dimples with different sizes and shapes can be successfully fabricated on the end face of Copper 1100. Same as the theoretical analysis and simulation prediction, through changing the cross-sectional profile of dimple along cutting direction, the clearance angle and the radius of observed point were verified to play a key role in the shape of micro-dimple. The oval-like dimples and the scale-like dimples can be respectively manufactured under the different intersection states between the flank face and the cutting trace. It was also confirmed that by choosing proper nose radius and the corresponding feed rate, the textured surface covered by micro-dimples of different widths can be generated. This texturing method used for fabricating the micro-textured end face was verified to be feasible and efficient, which laid a foundation for further research on the application of the textured surface.

Elliptical model for surface topography prediction in five-axis flank milling

In five-axis flank milling operations, the intersecting surfaces of different cutting edges create roughness on the milled surfaces that cannot be ignored in situations with strict requirements, especially in aeronautical manufacturing. To focus on motion problems in milling operations, this paper presents a new model that utilizes elliptical paths as cutting edge trajectories on 3D surface topography machined by peripheral milling. First, the cutter parallel axis offset and location angle are considered, which change the location of the ellipse center and intersection point of the cutting edges. Then, through the proposed model, the predicted surface topography is obtained, and the factors that affect the development tendency of roughness are analyzed. Next, the effects of the cutter location position (CLP) geometric parameters, cutter parallel axis offset and curvature on the roughness are evaluated by a numerical simulation. Finally, machining tests are carried out to validate the model predictions, and the results show that the surface topography predictions correspond well with the experimental results.

A forward closed-loop virtual simulation system for milling process considering dynamics processing-machine interactions

In this paper, a closed-loop virtual simulation system has been developed to simulate the milling process considering the interactions between manufacturing processes and machine tool dynamics. The system consists of cutting force module, machining stability module, and surface generation module. The synchronous effects of the machining parameters, tool geometry parameters, and the dynamic performance of the machine tool system are considered in the model, and the instant machine dynamic motion error is compensated in the model as a feedback to correct the cutter trajectories. Instantaneous tool-workpiece contact status is used to calculate cutting force, and the peak-to-peak cutting force plot is used to predict the machining stability in time domain under different depths of cut and cutting speeds. The envelope curve of the cutting tool is used to reconstruct the machined surface texture. Moreover, to verify the feasibility of the proposed system, micro-milling experiments are conducted with results showing that the simulation system enables the effective prediction of micro-milling process such as the cutting forces and machined surface quality. It can be potentially applied in production on processing parameter optimization and surface topography prediction.

Effects of surface splicing characteristics of the hardened steel mold on the machined surface topography

The car cover mold has characteristics of large structure size, complicated surface shape, dimensional precision, and high surface precision. The milling process of the splicing transition zone having different hardness can easily produce load mutation, which has an impact on the tool in the form of vibration. This vibration affects the surface topography of the splicing transition zone. In this article, we propose the surface motion model for ball-end milling cutter with impact vibration and the surface topography prediction model for splicing transition zone which is established based on the Non-Uniform Rational B-Splines (NURBS) surface control point reconstruction. Then, the effects of surface splicing characteristics (different hardness, over-seam scale, etc.) and processing parameters on the surface topography and on the residual height have been analyzed. Finally, based on the hardened steel surface splicing milling experiment, the accuracy of the surface topography model in which vibration impact has been incorporated is verified. At the same time, the corresponding roughness value and fractal dimension are calculated on the basis of two-dimensional contour graph under different splicing characteristics. The results show that the non-linear characteristics of the surface topography of the hardened steel surface are significant, and the best processing parameters can be obtained under different splicing characteristics.

Modelling and simulation of surface topography machined by peripheral milling considering tool radial runout and axial drift

Based on the Z-map model of a workpiece and the dynamic cutting forces model of peripheral milling in which the regenerative effect of tool radial runout and axial drift are considered, a model for the prediction of surface topography in peripheral milling operations is presented. According to the stability lobe diagram obtained by the zero-order analytical method, the relationship between spindle speed and surface topography, the tool radial runout, and the axial drift following the chatter are studied. The results show that a stable cutting status but a poor surface finish is obtained at the spindle speeds at which the dominant frequency of the milling system is integral multiples of the selected machining frequency, and a stable cutting status with a good surface finish can be obtained near and on the left side of the resonant spindle speeds determined by the predicted stability lobe diagram. The motion equations of any tooth end mill for peripheral milling are established, and these equations are based on the transformation matrix and the vector operation principle of motion-homogeneous coordinates. In addition, the simulation algorithm and the system of surface topography generated in peripheral milling are given based on the Z-map model. Cutting tests are carried out, and good agreement between the measured surface topographies and the topographies predicted by the model in this study is found in terms of their shape, magnitude, feed mark, profile height of cross-section, and surface roughness. The simulation results show that the milling surface roughness increases with the increase in feed per tooth, which further shows that this simulation system has high credibility. Thus, the simulation and experimental results can provide some practical instructions for the actual peripheral milling in determining the optimal machining conditions.

Trajectory Dependent Structural Vibration and Its Effects on Surface Generation

The vibration of machine tool plays an important role in surface generation. However, the vibration characteristics is different for different machine tool structures and different machining path. This paper proposed a new method of structural sensitivity analysis to identify trajectory dependent structural vibration and its effect on surface generation in milling. The experimental and theoretical results verify that (i) Multimode low-frequency vibration of the sensitive structures (MLFVSS) directly determines the surface topography in milling; (ii) The sensitivity is different for different structures or the same structure at different modes; (iii) Structural vibration characteristics is related to the machining path, resulting in different influence of the structural vibration on surface generation at different position of the machining path. Finally, a surface topography prediction model was established based on the experimental results. This study is helpful to the optimization of machine tool structures and the selection of machining parameters.