Workpiece Surface Texture Research Articles

The influence of workpiece surface texture on visual measurement of roughness

Abstract In view of the universal applicability of color information index and the ability of spectrum index to measure small roughness, this paper studies the influence of machined surface texture on roughness machine-vision measurement. Based on the micro-topography of different types of texture surface, the correlations between the average color difference, five typical spectral indices and the surface roughness parameters of two types of texture representative workpiece milling and grinding are focused on in the discussion. On this basis, the influences of the angle of light source and camera relative to the surface normal of the sample and the sample surface texture direction on roughness measurement are further discussed, and the reasons for the difference in index to characterize different process roughness are analyzed from the mechanism. The experimental results show that the different surface textures have different effects on light scattering, which in turn affects the sensitivity of the index to the roughness parameters.

Roughness prediction model of milling noise-vibration-surface texture multi-dimensional feature fusion for N6 nickel metal

Roughness is one of the important indicators for judging the quality of surface processing. In order to efficiently predict the surface roughness of nickel metal during milling, in this paper we built a multivariate signal monitoring system for nickel metal processing status and used the sound level meter, the three-way vibration sensor, the industrial camera, and the roughness measuring instrument to collect noise, vibration, surface texture, and roughness during milling. The three-way vibration is reduced by principal component analysis, and the correlation of each signal is analyzed by grey relational theory. The particle swarm optimization (PSO) algorithm is used to optimize the least squares support vector machine (LSSVM), and a roughness prediction model of multi-dimensional feature fusion is established, which takes the characteristic values of noise, vibration, and workpiece surface texture as input values and roughness as the output value. The results show that the prediction accuracy of the obtained roughness model based on PSO-LSSVM is 92.54%. The research can provide a theory guide for scientific monitoring of the surface roughness of milling workpieces.

An online visual measurement method for workpiece dimension based on deep learning

Image preprocessing and edge detection are the two most critical steps when applying machine vision to measure workpiece dimension in industrial field. The surface of the workpiece is usually covered with interference regions, which makes edge detection difficult. Aiming at the problem, the Full Convolutional Network (FCN) model is used to detect interference regions of workpiece images, and then interference regions are processed by the directional texture repair method. To avoid the influence of workpiece surface texture after rough machining, a method based on Holistically-nested Edge Detection (HED) model for rough edge detection of workpiece images is proposed. The edge is obtained by HED, and then it is post-processed based on the non-maximum value suppression and double threshold segmentation methods in the Canny operator to obtain a refined edge image. In order to further improve the accuracy of the dimension measurement, sub-pixel level edge detection accuracy is achieved by cubic spline interpolation. Finally, the method is validated by a shaft workpiece. The measuring accuracy of the outer diameter of the workpiece can reach 0.02 mm, which can effectively meet the requirements of fast semi-finishing inspection. This research provides a common workpiece dimension measurement method in industrial field and methodological guidance for the application of deep learning in industrial inspection.

Multi-objective optimization of magnetic abrasive finishing by desirability function with genetic algorithm

Thermal stability and Surface hardness of the super-finished surface is a very important aspect to preserve the surface texture of workpiece in the MAF process. In this present study, the multi-objective optimization of EN-31 finished through the MAF process. “Increase in Temperature” and “Increase in Hardness” are considered for optimization to diminish their impact on the super-finished surface of EN-31. In present work Desirability function analysis (DFA) has been used to optimize the desired responses of the MAF process. Experiments were designed according to Taguchi L9 orthogonal array for the finishing of EN-31. The experiment results are processed using DFA and Desirability fitness function is established to convert the single response to multi-response. Genetic Algorithm (GA) is used to enhance the results of DFA and the regression model was developed to obtain the objective function of Genetic algorithm. Smaller-the-best criteria were used for ‘Increase in Temperature’ and ‘Increase in Hardness’ for obtaining favorable process parameters. The best optimal parametric combination is obtained by using the GA-DFA hybrid approach is at 2.5 mm (working gap), 20 gm (abrasive weight), and 2.0 A (Current) and 300 rpm (rotational speed).

An Improved Tool Wear Monitoring Method Using Local Image and Fractal Dimension of Workpiece

Tool wear is a key factor that dominates the surface quality and distinctly influences the generated workpiece surface texture. In order to realize accurate evaluation of the tool wear from the generated workpiece surface after machining process, a new tool wear monitoring method is developed by fractal dimension of the acquired workpiece surface digital image. A self-made simple apparatus is employed to capture the local digital images around the region of interest. In addition, a skew correction method based on local fast Fourier transformation energy is also proposed for the surface texture direction adjustment. Furthermore, the tool wear quantitative evaluation was derived based on fractal dimension utilizing its high reliability for inherent irregularity description. The proposed tool wear monitoring method has verified its feasibility as well as its effectiveness in actual milling experiments using the material of AISI 1045 in a vertical machining center. Testing results demonstrate that the proposed method was capable of tool wear condition evaluation.

Ultrasonic assisted turning of AISI 52100 steel using nanoparticle-MQL method

High cutting force and high cutting tool-chip interface temperature occur during machining of high strength materials like AISI 52100 by using conventional turning method and this makes to the difficult machining operation. Besides, in conventional turning (CT) of these materials, which has high abrasion resistance and hardness properties, an additional process such as grinding is required to achieve the desired surface quality. Ultrasonic assisted turning (UAT) method has been widely used in the machining industry in recent years, as it exhibits better surface quality, lower cutting forces, and cutting temperature than the CT method. This paper focused on experimentally and statistically determining the effects of different cutting parameters and cooling conditions (dry and minimum quantity lubrication-MQL) on surface roughness, workpiece surface texture, tangential direction cutting force, and cutting tool-workpiece interface temperature in the machining of AISI 52100 material by using UAT and CT methods. The experimental results revealed that significant improvements determined in the cutting forces and the surface roughness occurred in UAT compared to CT in all the cooling conditions. However, the increasing cutting speeds caused to observe higher interface temperature values in dry turning by the UAT method. Variance Analysis (ANOVA) was carried out to determine the significance grade of independent variables on dependent variables. According to ANOVA results, while the cutting speed is the most important factor on the surface roughness and the cutting zone temperature, and the cooling method is the most important factor on the cutting force. The effects of turning methods on corresponding surface topography, including surface defects, were evaluated. It is determined that in the surface topography analysis, feed marks are the main texture of the workpiece in the CT method while micro-level indentations and protrusions occurred on the workpiece surface in the UAT method.

Mechanism Research and Discussion of the Quality of Precision Machining of a Fifth-order Variable-diameter Pipe Using Abrasive Flow

The solid-liquid two-phase abrasive flow precision machining technology is widely used in aerospace, precision machinery, the automotive industry and other fields, and is an advanced manufacturing technology that effectively improves the inner surface quality of workpieces. In this paper, the fifth-order variable-diameter pipe parts are researched. By discussing the collision between the abrasive particles and the wall surface, it is revealed that the material removal of the workpiece is caused by plastic deformation, and the mechanism of precision machining of the abrasive flow is clarified. Through numerical analysis and experimental research, it is found that the incident angle can affect the precision machining quality of the abrasive flow. When the inlet velocity of the abrasive flow is 45 m/s and the incident angle is 15°, the fifth-order variable-diameter pipe can obtain the best surface quality. Abrasive flow machining improves the surface quality of small holes better than that of large holes. To obtain uniform surface quality, it is necessary to use two-way machining to perform abrasive flow machining. The surface texture of the fifth-order variable-diameter pipe workpiece after precision machining by abrasive flow becomes clear and smooth, and the surface quality is significantly improved. The research results can provide theoretical guidance and technical support for the popularization and application of solid-liquid two-phase abrasive flow precision machining technology, with significant academic value and application value.

An efficient approach to improving the finishing properties of abrasive flow machining with the analyses of initial surface texture of workpiece

Abrasive flow machining (AFM) is a non-traditional finishing process by using the semi-solid abrasive media as a finishing tool, and usually applied to finish fine, complex components in manufacturing industries. In AFM process, the final surface quality and finishing efficiency are crucial finishing properties which have drawn wide attention and are always affected by initial surface texture of the workpiece. In the present research, the flow direction of abrasive media is determined according to the calculation of surface anisotropy ratio Str and texture direction Std of the initial surface texture by using the autocorrelation function, and selection of particle size is given after calculation of the spatial frequency of the initial surface texture using a fast Fourier transform. It was found that the flow direction of abrasive media should be perpendicular to the oriented surface texture, and the particle size in abrasive media has a strong relationship to the first harmonic frequency f1 of surface texture. Finally, the above approach was employed to the surface finish analysis of an aero-engine blade, and its efficiency was verified in the improvement of finishing properties.

Effect of Machining on Workpiece Surface Characteristics in Electric Discharge Drilling (EDD)

In electric discharge drilling (EDD), rapid local heating and cooling of the workpiece surface by means of electric discharges results in surface layers (recast, heat affected and base material). In this study, the main workpiece surface texture measures, namely the recast layer thickness (RLT) and average surface roughness (Ra) characteristics were investigated for varying machining parameters (discharge current and pulse on time). The conducted experiments revealed the strong dependence of surface characteristics on machining parameters.

Adaptive inverse control of chatter vibrations in internal turning operations

Abstract In this article, adaptive inverse control of chatter vibrations in internal turning process is addressed. The active boring bar is composed of a slender steel cutting tool, an electrodynamic shaker as controllable actuator and an IEPE accelerometer as feedback sensor. The SISO control system actuates in the direction normal to the cut surface. A novel adaptive inverse control algorithm is presented in this paper. This algorithm is mainly used in the feed-forward Active Noise Control (ANC) applications and is known as the Filtered-x Normalized Least Mean Square (FxNLMS). In order to extend the application of adaptive inverse control algorithms in the field of Active Vibration Control (AVC), the FxNLMS algorithm with feedback architecture is suggested for the specific problem of chatter suppression in internal turning operations. The performance of developed adaptive feedback controller is experimentally verified during the internal turning of Aluminum alloy 6063-T6. The value of critical limiting depth of cut is anticipated to be nearly 0.2 [mm] for the slender boring bar. However, the stable cutting process is conducted by the active boring bar in the presence of adaptive controller up to depth of cut 2 [mm]. That is, the boundary of stability is enhanced by at least 10 folds. It has been observed that the amplitude of chatter vibrations is efficiently suppressed adjacent to the fundamental resonance peak of the active boring bar. In addition, the feedback FxNLMS controller effectively attenuates the boring bar’s vibration by at least 70 dBs. Moreover, the periodic chatter marks are eliminated from the surface texture of workpiece and the roughness of cut surface is remarkably improved. The obtained results suggest that the practical application of adaptive inverse control algorithms for chatter rejection can be extended to other machining processes as well.

Tool wear in dry turning and wet turning with non-toxic cutting fluid

PurposeThis study aims to determine the properties of a new non-toxic cutting fluid and compared with cutting fluid based on mineral oil.Design/methodology/approachThe tool wear was measured under dry and wet cutting conditions. The non-toxic cutting fluid was compared with cutting fluid based on mineral oil. The experiments were carried out using CTX 310 ECO numerical control lathe. The wear of the cutting tools was measured by means of stereo zoom microscopy (SX80), while the elements were identified through scanning electron microscopy (JSM 7100F). The workpiece surface texture was studied using a Talysurf CCI Lite non-contact 3D profiler. The contact wetting angle was established with a KSV CAM 100 tester.FindingsThe non-toxic cutting fluid has reached comparable coefficient of friction with a coolant containing mineral oil. The use of the non-toxic cutting fluid with low foaming tendency resulted in lower wear.Practical implicationsMachining processes require that cutting fluids be applied to reduce the tool wear and improve the quality of the workpiece surface. Cutting fluids serve numerous purposes such as they act as coolants and lubricants, remove chips and temporarily prevent corrosion of the product.Originality/valueThe investigations discussed in this paper have contributed to the development of non-toxic and environmentally friendly manufacturing because of the use of cutting fluid containing zinc aspartate and its comparison with commonly used cutting fluid.

Machine Vision System for Correlating Wire Electrode Status and Machined Surface in WEDM of AlSi3N4 MMC’S

The technological developments in various sectors and requirement of complex shapes in manufacturing industries, the need for advanced materials has increased. Composite materials are one such advanced material. The most widely used composite materials is metal matrix composite. Conventional machining of these materials causes serious tool wear due to the presence of abrasive reinforcing particles and thus reduced tool life. Wire electrical discharge machining (WEDM) is quite successful for machining of metal matrix composites. Wire Electrical Discharge machining (WEDM) is a specialized thermal machining process capable of accurately machining parts of hard materials with complex shapes. One of the main research fields in WEDM is related to the improvement of the process productivity by avoiding wire breakage. Recently, vision systems are being exploited for such application mainly due to their high resolution, reliability and ease of automatic processing of data. Machine vision system is the technology used to provide image based automatic inspection and analysis for such applications as automatic inspection, process control and robot guidance in industries. This paper presents machine vision system, capable of providing wire electrode status and workpiece surface texture information in Wire electric discharge machining of aluminium silicon nitride (AlSi3N4) composite material. The images of wire electrode and machined surface specimens were acquired using the machine vision system. From the analysis, a good correlation between the wire electrode and corresponding surface image was found. It is expected that these results would support further to establish a criteria for wire replacement in WEDM operation.

Effects of process parameters on the Surface Finish of Flat Surfaces in Magnetic assist Abrasive Finishing Process

Study for advanced and cost efficient finishing processes like magnetic abrasive finishing (MAF) process has been an area of research in order to enhance the performance of existing finishing processes and makes the process more efficient for industrial utilization. Magnetic abrasive finishing (MAF) is one of the finishing process which can finish the surface of both magnetic and non-magnetic materials up to Nano-scale. Intent of this paper is to study all operating parameters (machining gap, current supply, input voltage, machining time, rotational speed, mesh size of abrasive, weight of abrasive, percentage of oil or binder in MAP, composition of MAP, type of abrasives), machining forces and their effects on the quality of surface finish achieved. In the view of existing literature, magnetic abrasive finishing for finishing of plane surfaces has undergon less attention. This paper reviews the results reported in past and recent researches. These results are used to study the performance of magnetic abrasive finishing process for flat surfaces and effect of variation in composition of magnetic abrasive powder on surface texture of work piece

Effects of dressed wheel topography on patterned surface textures and grinding force

This paper presents a series of analytical and experimental investigations into the patterning effect of a grinding wheel-dressed surface on workpiece surface texture and grinding forces. An analytical model is built for the profile of the dressing tip and utilized to describe the kinematics of the dressing process on the grinding wheel surface. The model also reflects the ground workpiece surface texture. The model describes patterned surface textures according to ridge width, ridge length, texture angle, and ridge function parameters. Comparison against modeled and measured values strongly suggests that conventional dressing and grinding processes can be pre-determined via the proposed model to generate a patterned workpiece surface. The measured grinding forces are investigated as they relate to tangential and normal components at a series of dressing and grinding parameters; these two components increase dramatically as dressing overlap ratio increases, nearly regardless of dressing depth. Under a given workpiece velocity, the measured forces are much greater at overlap ratio of 6 than at ratios of 1 or 3. There is an average difference of only 5.8% for all grinding forces. Conversely, the measured tangential and normal grinding forces increase markedly as workpiece velocity increases at a specific dressing overlap ratio. Dressing overlap ratio of 1~3 is recommended for generating patterned texture surfaces in a conventional grinding process. Grinding force ratio can serve to monitor the patterned grinding process (error within 12.9%) under the conditions discussed here.

Prediction of workpiece surface texture using circumferentially grooved grinding wheels

This paper investigates the ability of circumferentially grooved grinding wheels to create parallel ridges on a workpiece providing a textured surface that may be advantageous for certain applications. In this paper, the effect of wheel speed, workpiece feed rate, grinding direction, and groove factor on the height, spacing, and angle of these ridges were investigated. In addition, an analytical model based on the kinematics of grinding with circumferentially grooved wheels, as well as a corresponding simulation method to predict the patterns on the resulting ground surface were developed. A wide range of workpiece textures predicted by the analytical and simulation results were compared with experimental results. When comparing the experimentally measured texture angles on the workpiece, the angles predicted by both the analytical model and the simulation model had an average difference within 3.4 %. When comparing the experimentally measured spacing between ridges on the textured workpiece, the spacing predicted by both the analytical model and the simulated model had an average difference within 2.4 %. Finally, when comparing the experimentally measured heights of the ridges on the textured workpiece, both the analytical and simulation models differed from experiments by, on average, only 2.3 μm.

Research of Elliptic Ultrasonic Vibration Mechanism

Elliptical vibration cutting is a new processing technology of work piece surface texture generation, the technique based on conventional cutting machine main movement and feed motion of the tool, by changing the structure so that the tip motion to generate ellipse trajectory. This paper designed incentive range vibration frequency as 20~40 KHz, can generate elliptical vibration trajectory in the small space of X/Z axis 16um. Tests prove that, the ultrasonic elliptic vibration cutting mechanism improves the specimen surface texture, smooth discharging of chipping, greatly improving the surface finishes of the work piece.

Experimental investigation of external surface finishing of AISI 440C stainless steel cylinders using the magnetic abrasive finishing process

Magnetic abrasive finishing (MAF) is one of the advanced machining processes implementing the material removal in micro dimensions using the magnetic field force and magnetic abrasive particles (MAPs). In this process, the machining forces are low, the surface defects such as micro-cracks are so small and a desirable smooth surface is obtained. In this paper, the effects of parameters such as working gap, workpiece rotational speed, and the material removal mechanism (injecting the abrasive slurry of SiC and Al2O3, and diamond paste) on the surface roughness has been experimentally investigated in the MAF process on the external surface of the AISI 440C stainless steel cylinders. To do the experiments, a setup was designed and manufactured, and the experiments have been implemented according to the design of experiments (DOE) and the full factorial method. The experimental data were analyzed using the analysis of variance (ANOVA). The experimental data analysis showed that the working gap and the workpiece rotational speed have a significant effect on improving the surface roughness. The obtained surface roughness under the conditions of experimental working gap of 2 mm, the workpiece rotational speed of 355 rpm, using the Al2O3 and SiC abrasive slurry injection, and diamond paste has improved as 20, 30, and 50 %, respectively. The images of scanning electron microscopy (SEM) taken from the workpiece surface texture before and after the process confirm the obtained results.

The Theoretical Analysis and Experimental Study on the Distribution Characteristics of Motion Parameters in the Process of Honing Gear

Gear honing processing is a kind of processing method which belongs to the point-contact generating gear finishing. Its movement form is equivalent to a pair of gears transmission which the surface of the gear-honing-tool is adhered a layer of grinding grain. When it works in rolling processing, the contact-point between the workpiece and gear-honing-tool is moving. Then the moving point becomes a line in the space, and with the gear-honing-tool being in axial play, a standard flank of tooth is finished. Using the gear meshing principle, kinematics model of relative sliding velocity in the contact-point between the workpiece and tools is established, based on which the contact-line equation. and acceleration equation. at the contact-point are derived. The contact-line is solved in a given parameters of the workpiece and tool in MATLAB. The theoretical derivation and experimental results show that the speed in diverse along the direction of the tooth depth is the main reason for the roughness value and surface texture of workpiece. The acceleration of contact-line at the tooth flank is different, and it is leading reason that the processed workpiece gears appear profile distortion. Finally, the testing system is established for researching honing gear process. It is showed in the results that the acceleration difference can lead to the CBN abrasive falling away from gear honing tool, and even the "anti-cutting" phenomenon.

A time based method for predicting the workpiece surface micro-topography under pulsed laser ablation

The generation of micro-features in a predictable and repeatable manner by use of pulsed laser ablation requires an understanding of the temporal and energetic distributions of the laser beam upon the workpiece surface. Modelling the response of the material to known energetic and kinematic parameters of the pulsed laser ablation process can be carried out in a discretised time-based approach, allowing the workpiece topography to be simulated mathematically to reflect a real-life process. Considerations of the antecedent workpiece surface texture such as increases in irradiated area due to the surface gradient, and increases in laser spot size due to beam divergence throughout the elevation of the workpiece are used to predict energy densities and hence the resultant ablated depth and texture of the targeted surfaces. A fully calibrated Yb:YAG pulsed fibre laser (SPI G3.0 RM) was used to validate the model on three materials, highlighting the models strengths for different material types. It was found that Ni based workpieces presented redeposition phenomena under these laser ablation conditions. To analyse the model without redeposition, validations trials on materials that do not present such side effects, e.g. diamond, were carried out and differences were found to be up to 9.39%.

Study on Identifying Surface Quality of Work Pieces Based on Texture Analysis

In order to recognize the integrity of workpiece surface texture, this paper introduces the method of mended texture spectrum based on workpiece surface texture. The workpiece surface texture images can be described based on analyzing the influence of cutting parameters on the surface texture. The experimental results indicate that the cutting parameters have a great effect on the integrity of workpiece surface texture. In other words, the effect of cutting speed is evident, that of feed speed, depth of cut to a less extent. In addition, the integrity of texture changes greatly in short time with the increase of cutting parameters.