Single Abrasive Grain Research Articles

Anisotropic mechanism of monocrystalline silicon on surface quality in precision diamond wire saw cutting

The surface quality of wire-saw cut monocrystalline silicon is affected by its anisotropy. This work investigates the effect of anisotropy on the surface quality of monocrystalline silicon (100), (110), and (111) crystalline surfaces in wire-saw cutting processing. The material properties of monocrystalline silicon in different crystal directions are analyzed, and the expressions of elastic modulus of monocrystalline silicon (100), (110), and (111) crystal surfaces are derived, and the influences of material properties and process parameters on macroscopic sawing force and material removal are investigated. The single abrasive grains scratching the surface of monocrystalline silicon and the wire saw cutting and processing process were simulated, and the diamond wire saw cutting and processing of monocrystalline silicon experiment was carried out. The experiment results show that: When the wire saw cuts and processes the (100), (110), and (111) crystal surfaces, the cutting angle with better sawing performance is 30°. The macroscopic normal and tangential average sawing forces on the crystalline surface of monocrystalline silicon (110) differed by 7.22N and 2.54N. The average error between the experiment value of surface warpage and the simulation value is 5.47 %, which indicates the accuracy of the surface morphology prediction model.

Topography Modeling of Surface Grinding Based on Random Abrasives and Performance Evaluation

The surface morphology and roughness of a workpiece are crucial parameters in grinding processes. Accurate prediction of these parameters is essential for maintaining the workpiece’s surface integrity. However, the randomness of abrasive grain shapes and workpiece surface formation behaviors poses significant challenges, and accuracy in current physical mechanism-based predictive models is needed. To address this problem, by using the random plane method and accounting for the random morphology and distribution of abrasive grains, this paper proposes a novel method to model CBN grinding wheels and predict workpiece surface roughness. First, a kinematic model of a single abrasive grain is developed to accurately capture the three-dimensional morphology of the grinding wheel. Next, by formulating an elastic deformation and formation model of the workpiece surface based on Hertz theory, the variation in grinding arc length at different grinding depths is revealed. Subsequently, a predictive model for the surface morphology of the workpiece ground by a single abrasive grain is devised. This model integrates the normal distribution model of abrasive grain size and the spatial distribution model of abrasive grain positions, to elucidate how the circumferential and axial distribution of abrasive grains influences workpiece surface formation. Lastly, by integrating the dynamic effective abrasive grain model, a predictive model for the surface morphology and roughness of the grinding wheel is established. To examine the impact of changing the grit size of the grinding wheel and grinding depth on workpiece surface roughness, and to validate the accuracy of the model, experiments are conducted. Results indicate that the predicted three-dimensional morphology of the grinding wheel and workpiece surfaces closely matches the actual grinding wheel and ground workpiece surfaces, with surface roughness prediction deviations as small as 2.3%.

Modeling of Material Removal Rate for the Fixed-Abrasive Double-Sided Planetary Grinding of a Sapphire Substrate.

Double-sided planetary grinding (DSPG) with a fixed abrasive is widely used in sapphire substrate processing. Compared with conventional free abrasive grinding, it has the advantages of high precision, high efficiency, and environmental protection. In this study, we propose a material removal rate (MRR) model specific to the fixed-abrasive DSPG process for sapphire substrates, grounded in the trajectory length of abrasive particles. In this paper, the material removal rate model is obtained after focusing on the theoretical analysis of the effective number of abrasive grains, the indentation depth of a single abrasive grain, the length of the abrasive grain trajectory, and the groove repetition rate. To validate this model, experiments were conducted on sapphire substrates using a DSPG machine. Theoretical predictions of the material removal rate were then juxtaposed with experimental outcomes across varying grinding pressures and rotational speeds. The trends between theoretical and experimental values showed remarkable consistency, with deviations ranging between 0.2% and 39.2%, thereby substantiating the model's validity. Moreover, leveraging the insights from this model, we optimized the disparity in the material removal rate between two surfaces of the substrate, thereby enhancing the uniformity of the machining process across both surfaces.

Numerical simulation of single abrasive grain grinding of silicon carbide surface

Numerical simulation of single abrasive grain grinding of silicon carbide surface

Material deformation and chip formation under single abrasive grain action

The purpose of the work is to determine the volume of material destroyed by a single grain (microasperity), which produces elastic and plastic deformation of the material when an abrasive tool interacts with the treated surface. To calculate the intensity of deformation of the plastically displaced material of the workpiece under the action of a single grain, the slip-line technique (method of characteristics) was used. To determine the volume of material destroyed by a single grain as a result of polydeformation when moving in the tangential direction, the following is determined: area of the deformed material; intensity of the shear deformation; speed of the shear deformation rate; number of plastic deformation cycles necessary for the destruction of the material in various zones of the sliding line field. The solution to these problems is found using the radii of curvature of the sliding lines in the physical planes and in the planes of the velocity hodographs for the meridional and normal to the axis planes of the grain section. The determination of the elastic deformation of the material is taken into account when calculating the roughness of the treated surface. Chip formation under the action of a single grain is considered taking into account the determination of the cross-sectional area of chips. This formed the basis for a determination of material removal during abrasive processing. The theoretical provisions for the determination of the above indicators are confirmed by experimental data. Thus, the studies carried out by the slip-line method formed a basis for determining the volume of plastically deformed material, the magnitude and rate of deformation under the action of a single grain, as well as the volume of the removed material as a result of repeated plastic deformation and in the form of chips. The performed investigation forms an integral part of studies into the process performance and roughness of the machined surface when finishing workpieces with elastic polymer-abrasive tools and free abrasive particles.

Grain shape-protrusion-based modeling and analysis of material removal in robotic belt grinding

The accurate prediction of material removal (MR) remains a persistent challenge in the field of robotic belt grinding, particularly with the consideration of the stochastic nature of abrasive grains. Starting from the characteristics that abrasive grains with different shapes participate in grinding, this work presents a novel MR model that extends from microscopic grain-workpiece interaction to macroscopic wheel-curved surface contact. Specifically, the irregular shapes of single abrasive grains are generalized into four typical types, namely, semi-sphere, cone, equilateral-triangular pyramid, and square pyramid. Based on the effective abrasive grains determined by stochastic grain protrusion heights, the microscopic contact force and material removal volume shared by different effective individual abrasive grains are modeled and analyzed subsequently. Together with the macroscopic contact pressure solved by the Hertzian contact theory, the material removal model is derived by considering the geometrical characteristics of different-shaped abrasive grains. Finally, the grinding experiments on the Ti–6Al–4V test block and aero-engine blade were conducted under controllable grinding parameters, through which the effectiveness and applicability of the proposed model were validated, and the material removal characteristics with different structured abrasive belts were investigated.

Experimental and Finite Element Investigation of a Scratch on the Surface of a Workpiece from a Single Abrasive Grain

Experimental and Finite Element Investigation of a Scratch on the Surface of a Workpiece from a Single Abrasive Grain

Investigation of the Effect of Single Abrasive Grain Cutting Factors on Trace Microrelief on the Workpiece Surface Using Finite Element Modeling

Investigation of the Effect of Single Abrasive Grain Cutting Factors on Trace Microrelief on the Workpiece Surface Using Finite Element Modeling

Effect of pad surface morphology on the surface shape of the lapped workpiece

Double-sided lapping is currently the mainstream manufacturing method for obtaining plane-parallel optical workpieces with high surface shape accuracy, and the fixed abrasive lapping pad is the main machining tool. However, the effect of pad surface morphology on the workpiece surface shape has rarely been studied, and its formation mechanism has not yet been revealed. In this paper, based on probabilistic statistics and contact mechanics, an analytical model that takes into account the pad surface morphology for predicting the workpiece surface shape evolution is developed. Notably, this model considers the cross-scale relationship between the formation of lapped surface shape and the scratching process of a single abrasive grain in material removal for the first time. Furthermore, the real-time dynamical contact relationship between the workpieces and the measured actual pad surface morphology is also considered. The surface shape and peak-to-valley value of the workpiece under different parameters were simulated and analyzed, and the influence mechanism of the local profile and macro shape of the lapping pad on the lapped workpiece surface shape are clarified. Moreover, the double-sided lapping trial experiments were performed to validate the theoretical model, and the experimental results demonstrated good agreement with the simulation results. The maximum error of the surface shape evolution prediction model is less than 14.6 %. This result verifies the correctness and validity of the established model. This work not only provides new ideas for controlling the workpiece surface but also forms the theoretical basis for understanding the double-sided lapping process.

Intelligent decision-making support system for the commissioning of a small hydroelectric power plant in the Republic of Tyva

This paper investigates the cutting forces arising when using a single abrasive grain. Analytical studies were carried out using a model of a single abrasive grain in the form of a rod with a radiused apex acting on the workpiece material. The slip-line method (method of characteristics) was used to calculate the deformation intensity of a plastically edged workpiece material under the action of a single grain. Mathematical models were developed for the following factors: plastic deformation of the material, edging of the stagnated zone and its friction against the grain surface when moved upwards in the form of chippings, grain friction against the plastically deformed material, and the action of the dynamic component of plastic deformation. The significance of the dynamic component in the overall balance of forces related to plastic deformation was established by determining the ratio of dynamic stress on the break line and shear yield point. This dependence calculated for D16T and 30HGSA materials showed the feasibility of accounting for the dynamic component system based on a small hydropower station located in the Todzhinsky district of the Republic of Tyva. For an adequate assessment of the operational reliability of hydropower units, a logical and probabilistic method based on the kinetic theory of fault tree was used. The method allows the failures of the used equipment, as well as unplanned shutdowns of units due to a shortage of water resources in the Great Yenisey (low water, overdrying, and frozen frost), to be taken into account. The development of a generation system based on a small hydroelectric power plant for the settlements in the Todzhinsky district of the Republic of Tyva offers a load of up to 2,500 kW, which helps to reduce the cost of purchasing, delivering, and storing diesel fuel, while diesel generators can be used as backup power sources. 3 scenarios of structuring a small hydroelectric power plant were considered that involved various numbers and total capacity of hydrogenating units: 5x500 kW, 4x630 kW, and 3x800 kW. Therefore, by using the multi-criteria optimization method, the optimal structure of the generating system based on a small hydroelectric power plant having three hydroelectric units (each characterized by a capacity of 800 kW) was selected from the three proposed options, taking into account the reliability and uncertainty of the initial information.

Method for processing experimental data when investigating residual stresses by drilling probe holes and digital image correlation

This paper investigates the cutting forces arising when using a single abrasive grain. Analytical studies were carried out using a model of a single abrasive grain in the form of a rod with a radiused apex acting on the workpiece material. The slip-line method (method of characteristics) was used to calculate the deformation intensity of a plastically edged workpiece material under the action of a single grain. Mathematical models were developed for the following factors: plastic deformation of the material, edging of the stagnated zone and its friction against the grain surface when moved upwards in the form of chippings, grain friction against the plastically deformed material, and the action of the dynamic component of plastic deformation. The significance of the dynamic component in the overall balance of forces related to plastic deformation was established by determining the ratio of dynamic stress on the break line and shear yield point. This dependence calculated for D16T and 30HGSA materials showed the feasibility of accounting for the dynamic component subsequently processed by free orthogonal cutting and rolling contact deformation using a special machine with numerical control. Further, using the same machine, drilling of probing holes was performed with video recording of the surface image prior to and following drilling. By varying the speckle images, the displacements of material particles on the sample surface were determined by the digital image correlation method, following which the radial deformations were determined by differentiating the obtained displacement values. Statistical analysis of a sample of radial deformations equidistant from the centre of the hole while varying the rotation angle by Fourier transformation with the calculation of the distribution period showed that the distribution is periodic. It is established that the periodograms constructed using experimental data have local maxima at a period value close to 180 degrees. This determines that the main calculated components of the residual stresses and the angle of their rotation be constant when selected to calculate the values of radial deformations at arbitrary points around the hole. The paper presents an approach that allows residual stresses to be determined by drilling probing holes and assessing the displacement of material particles on the sample surface due to the redistribution of residual stresses. For the analytical description of experimental data, it is proposed that an approximating periodic function be used, and the physical meaning of its coefficients is determined.

Study on surface quality of CNTs/2009Al composites in grinding process with a volume fraction ratio of 3%

Composite materials made of aluminum-based carbon nanotubes (CNTs/Al) are often employed in industries like aerospace and national defense that place a high priority on material processing accuracy at the material’s surface. The most popular machining technique for enhancing the surface quality of materials is grinding. This paper built a prediction model for the surface roughness of CNTs/2009Al composites and identified the process of micro-grinding. Using the ABAQUS software, a non-uniform finite element simulation model of the single abrasive grain grinding process of CNTs/2009AL composites was created. An electroplated diamond grinding rod with a diameter of 2 mm was used in the micro-grinding experiment on the CNTs/2009Al composite, and the impact of the grinding parameters on the quality of the machined surface was examined. According to the findings, the feed speed has the least impact on the material’s surface roughness, whereas the spindle speed and grinding depth both have a significant impact. The measurement of the minimal roughness is 0.117 m. A shallower grinding depth, a lower feed rate, and a correspondingly higher spindle speed should be used in order to provide a superior surface quality. According to the prediction model of micro-grinding surface roughness and laser confocal microscope scanning, the primary phenomena of CNTs in the grinding process include pull-out, fracture, and elastic deformation.

Theoretical and Experimental Analysis of Grinding Stability of Beam Workpiece

Grinding chatter is a kind of self-excited vibration in which the grinding system continuously absorbs energy from the grinding machine, increasing the mechanical energy of the system. Grinding chatter can damage the surface of the workpiece and accelerate the abrasion of the grinding wheel. The theoretical analysis of the grinding chatter for the beam surface was launched based on the behavior of a single abrasive grain, whose cutting thickness is a key factor affecting grinding stability. The dynamic grinding force model has been developed, which is the interaction interface between the grinding wheel and the workpiece. In this paper, rail beam grinding was taken as an example. The vibration performance of the rail beam was described with the Timoshenko beam. The characteristics of the frequency domain of the grinding wheel-workpiece system were observed, and the condition of the stability at any position in the longitudinal direction of the beam was gained, which could be quantitatively characterized with the stability limit curve. The grinding experiments of the rail beam surface demonstrated that as chatter developed, the chatter marks could be investigated on the surface of the rail, and the energy of the chatter signal was mainly concentrated around the chatter frequency, which was higher than the natural frequency of the grinding wheel.

Force of cutting by a single abrasive grain

This paper investigates the cutting forces arising when using a single abrasive grain. Analytical studies were carried out using a model of a single abrasive grain in the form of a rod with a radiused apex acting on the workpiece material. The slip-line method (method of characteristics) was used to calculate the deformation intensity of a plastically edged workpiece material under the action of a single grain. Mathematical models were developed for the following factors: plastic deformation of the material, edging of the stagnated zone and its friction against the grain surface when moved upwards in the form of chippings, grain friction against the plastically deformed material, and the action of the dynamic component of plastic deformation. The significance of the dynamic component in the overall balance of forces related to plastic deformation was established by determining the ratio of dynamic stress on the break line and shear yield point. This dependence calculated for D16T and 30HGSA materials showed the feasibility of accounting for the dynamic component of the cutting force under the velocity of a single grain impacting the workpiece surface of above 50 m/s. Graphs depicting the relative grain force and the relative depth of grain penetration are given. The proposed calculation method for cutting forces using a single grain can be used to determine the total force of interaction between the single grain and the work-piece material. In order to adopt the defined processing method and the workpiece material, the number of grains in contact, the contact duration, and the cutting speed should be found. On this basis, the process performance and the quality of the workpiece surface can be calculated.

New Calculation Methodology of the Operations Number of Cold Rolling Rolls Fine Grinding

This article considers the methods of calculating the number of operations for the fine grinding of cold rolling rolls which allows one to ensure the least labor-intensive processing of the part. Based on the analysis of the patterns in the operation of single abrasive grains, the dependence of the productivity of the fine-grinding process on the grain size of the wheel, the grinding allowance, the grinding mode, the size of the workpiece, and the wheel, is proposed. To analyze the productivity of the finishing grinding processes, a productivity indicator, independent of the size of the wheel and the workpiece, is analyzed, and the impact on the productivity indicator of the number of finishing grinding operations, as well as the following sequence of their optimization, is established. To simplify the calculation of the optimal number of operations, graphs and a nomogram are constructed. According to the proposed methodology, the calculation of the number of finishing operations of cold rolling rolls of various sizes was carried out. Experimental verification of the proposed theoretical dependencies and methods for calculating the optimal number of grinding operations was also carried out.

Study on optimization of surface processing technology of silicon nitride bearing ring

Based on the difficult machining characteristics of silicon nitride materials, this manuscript focuses on optimizing the precision machining process of silicon nitride bearing components and improving the machining efficiency and quality of silicon nitride bearing components. Firstly, the mechanism of crack formation and propagation in hard and brittle materials under the action of abrasive particles is discussed in this paper, and based on this, a kinematic model of single abrasive grain cutting on hard and brittle materials is established. The effect of workpiece linear velocity, grinding wheel linear velocity, grinding wheel oscillation velocity and feed velocity on inner surface roughness of Si3N4 ring was discussed through grinding test. The experimental results show that the surface roughness can reach about Ra0.20 ∼Ra0.33 μm through a large number of grinding experiments by adjusting the combination of process parameters μm. On this basis, use the optimized process parameters calculated by the surface quality prediction model constructed in this manuscript to conduct grinding test again, and the surface roughness value reaches about Ra0.19 ∼Ra0.23 μm. The purpose of optimizing the process parameters is realized. Finally, the surface roughness can be further reduced and maintained at Ra0.05 ∼Ra0.06 μm by further superfinishing the surface after the process optimization with an oilstone. The research work of this manuscript realized the optimization of precision machining process of silicon nitride bearing ring and the rapid optimization of machining process through the established prediction model, which improved the precision machining efficiency of ceramic bearing components. Through the study of this manuscript, a process route of controllable processing of inner surface quality of Si3N4 ring is formed, from preliminary selection of process parameters by optimization model to precision grinding and then to ultra-finishing of whetstone, which provides theoretical reference for efficient and precise manufacturing of practical bearing components.

Simulation of a single interaction of an abrasive particle with the surface of a part during blasting

It is shown that when modeling a single interaction of an abrasive particle with the surface of a part in the process of collision under air (liquid) pressure, it is necessary to take into account the specifics of impact-abrasive wear, when the separation of a wear particle is preceded by metal destruction. In the process of schematization of the contact interaction during abrasive blasting, some commonality with the shot blasting process and a number of assumptions typical for grinding, when micro cutting with a single abrasive grain is considered, are taken into account.

Dynamic grinding force model for face gear based on the wheel-gear contact geometry

The non-uniform grinding conditions due to the wheel-gear contact geometry lead to the changeable of grinding force in face gear grinding. As a result, the classical grinding force models for other gears are not applicable to the grinding process of face gear. In this work, a dynamic grinding force model for face gear was developed based on the wheel-face gear contact geometry. In this process, surface of a virtual pinion engaged with the face gear was divided into many micro-elements to calculate the undeformed chip thickness and number of effective abrasive grains. Considering the mechanical properties of the tool and workpiece materials, equations for the total normal and tangential force components were derived by using the grinding force model of single abrasive grain. For verifying the model, the measurement coordinate system was established to convert the spatial components of experimental grinding force into the normal grinding force and tangential grinding force. Experimental results show reasonable consistency with simulation results that validate the proposed model. Besides, main reason for the changeable of grinding forces from top to root of tooth surface can be summarized by the change of material removal rate caused by the interference grinding width of adjacent grinding trajectories. Characteristics of surface morphologies and surface roughness prove this reason as well. This work provides a method to obtain a uniform grinding force during the process of grinding face gear and can be utilized to optimize the grinding process for higher tooth surface integrity.

A U-net-based intelligent approach for belt morphology quantification and wear monitoring

A novel method based on image signals is proposed to achieve the fast morphology quantification of single abrasive grain and precise wear monitoring of pyramid abrasive belt in a robotic grinding system. The Regions of Interest (ROI) of multiple abrasive grains are precisely and adaptively segmented based on the U-Net deep learning algorithm, and the Intersection over Union (IoU) of predictions reaches above 0.9. Identification of effective abrasive grains is achieved by the intensity distribution, region boundary, and nearest neighbor searching for centroids. In addition, the morphological parameters of effective abrasive grains are calculated to quantify the multiple worn forms such as continuity, non-uniform, and adhesion. The calculated dimensional parameters (area ratio and perimeter ratio) intuitively characterize the evolution of belt wear in the time domain, and the calculated shape parameters (aspect ratio and extent) greatly illustrate the effect of force and adhesion on abrasive grain wear. A comprehensive experimental study of the grinding performance shows that the material removal rate is mainly affected by the macroscopic morphological wear of the compact grains, and the machined surface quality depends more on the interaction between small abrasive agglomerates and workpiece. Furthermore, the thresholds of the mean area ratio and perimeter ratio with high independence for variable process parameters can be used as the judging criteria for determining the belt service life.

Research on mechanism of ultrasonic-assisted nano-cutting of sapphire based on molecular dynamics

Ultrasonic vibration grinding improves the surface quality and processing efficiency of sapphire machining compared with conventional grinding, but its nano-scale deformation mechanism is still unclear. In this study, the molecular dynamics method was used to simulate the ultrasonic vibration cutting of a single abrasive grain along the [010] direction on the sapphire (0001) surface to study the effects of different vibration directions, amplitudes and frequencies on the cutting force, stress, temperature, number of amorphous atoms, surface morphology and subsurface damage layer. The results show that the tangential and radial vibration cutting reduces the tangential force, normal force and total force compared with conventional cutting. At the same time, it is also found that different vibration directions have different effects on material removal efficiency and subsurface damage depth. In the material removal efficiency, the radial vibration cutting has the highest removal efficiency, and the tangential vibration cutting and conventional cutting have the same removal efficiency. In the subsurface damage depth, the subsurface damage depth in tangential vibration cutting is the smallest, the subsurface damage depth in conventional cutting is the second, and the subsurface damage depth in radial vibration cutting is the largest.