Abrasive Grains Research Articles

Grinding surface and subsurface stress load of nickel-based single crystal superalloy DD5

Nickel-based single crystal superalloys have broad application prospects in the aerospace field. Their excellent physical properties enable the workpiece to serve in complex environments for a long time, and are often used in the most complex stress and the worst working conditions. However, the damage caused by mechanical material removal deteriorates the wafer surface flatness and die strength, while its surface and subsurface formation principle has yet to be revealed. This study aims to analyze the influence of abrasive particles on the load of the workpiece during machining was scrutinized through the lens of stress tensor, yield performance, and third invariant. The results indicate that, a substantial stress load is exerted on the front end of the abrasive grain, leading to the yield deformation of the workpiece. Conversely, the stress load at the bottom of the abrasive grain is comparatively lower, resulting in tensile deformation and the formation of a discernible plastic damage layer. To delve deeper into the workpiece's damage phenomenon, this study conducts a comparative analysis from the standpoints of chips, surface morphology, and subsurface characteristics of DD5. Experimental results indicate that the chips on the contact surface exhibits a relatively smooth texture, while the grinding surface manifests grooves of varying depths. Concurrently, subsurface analysis reveals the presence of slip deformation and elemental flow. This investigation elucidates the intricate interplay between the grinding process and subsurface loading, offering valuable insights to enhance the quality and precision of nickel-based single-crystal superalloy workpiece manufacturing.

Research on the Grinding Performance of an Electroplated Coarse-Grained Diamond Grinding Wheel by Dressing

The coarse-grained electroplated diamond grinding wheels is increasingly favored in precision grinding of hard and brittle materials owing to its high material removal efficiency, high wear resistance and steady surface contour accuracy. However, how to determine whether the dressed grinding wheel surface topography can achieve the desired precision ground surface quality is still a huge challenge to this day. In this paper, a novel numerical simulation model, which was established basing on the statistical features of actual electroplated coarse-grained diamond grinding wheel and the kinetics of the grinding process, was proposed for theoretically and thoroughly studying the influence of the surface dressing depth of coarse-grained electroplated diamond grinding wheel on ground workpiece surface morphology. At first, the statistical features of actual electroplated coarse-grained diamond grinding wheel was acquired and a novel numerical grinding wheel surface model was established. Subsequently, a numerical ground workpiece surface simulation model was also developed. And then, the evolving mechanism of the grinding wheel surface topography with the dressed wheel surface abrasive grain protrusion height was theoretically studied by numerical simulation. Moreover, the influence of the wheel surface abrasive grain protrusion height on the ground surface roughness was thoroughly researched by means of theoretical model and experiments. The simulation and experiments results in this paper indicated that precision ground workpiece surface with nano-scale surface roughness can be acquired by grinding with a dressed grinding wheel with a certain abrasive grain protrusion height of 25% of the typical abrasive size. Comparing with the undressed grinding wheel (grinding wheel with original surface topography and not be dressed), the surface roughness Sa and Sq of the surface ground with a well-dressed wheel can achieving a significant decrease of 97.75–99.77% and 97.57–99.73%, respectively. Therefore, carefully dressing the electroplated coarse-grained diamond grinding wheel is of great significance for obtaining a precision ground workpiece surface quality.

Research on Grinding Force Prediction of Flexible Abrasive Disc Grinding Process of TC17 Titanium Alloy

Abrasive disc grinding is currently a key manufacturing process to achieve better accuracy and high-quality surfaces of TC17 components. Grinding force, which results from the friction and elastic–plastic deformation during the contact and interaction between the abrasive grains and the workpiece, is a critical parameter that represents the grinding accuracy and efficiency. In order to understand the influence factors of grinding force, the characteristics of the flexible abrasive disc grinding process were studied. Considering the contact state between the abrasive tool and the workpiece, the theoretical model of normal grinding force was established in detail, from macro- and micro-perspectives. By conducting single-factor and orthogonal grinding experiments of TC17 components, the influence of different process parameters on the normal grinding force was revealed. The normal grinding force prediction models of the abrasive disc grinding process were developed based on the Box–Behnken design (BBD) and particle swarm optimization–back propagation (PSO-BP) neural networks, respectively. The results showed that the normal grinding force was negatively correlated with the disc rotational speed, and positively correlated with the contact angle, grinding depth, and feed rate, and the interaction of the factor feed rate and grinding depth was the more influential factor. Both the BBD and PSO-BP force models had good reliability and accuracy, and the mean absolute error (MAE) and mean relative error (MRE) of the above two prediction models were 0.22 N and 0.16 N, and 13.3% and 10.9%, respectively.

Удосконалення механізму притирання вільним абразивом за допомогою використання силікатного складу

The results of an experimental study are presented that explain and confirm the mechanism of lapping friction surfaces with a silicate abrasive composition.
 It is shown that the stability of the silicate lapping paste over time can be achieved by introducing ferric trichloride (FeCl3), which in this case is a thickener of liquid glass and also has high hygroscopic properties. The adhesive properties of the silicate paste are improved by the addition of lubricant 1-13. This grease was chosen due to its water solubility. To increase the abrasive ability of the silicate paste, an abrasive powder was introduced. 
 It was found that the lapping performance of the silicate composition and the quality of surfaces are higher than when treated with the «KT» paste, which is currently used for lapping automobile engine valves. Based on the results of the study, the mechanism of lapping friction surfaces with a silicate paste is presented. The mutual movement of the surfaces results in cutting and scratching of the highest peaks of the bumps by the abrasive grains. When silicon oxide (SiO2) is added to the abrasive material, its particles are coated with silicon oxide. This is because liquid glass solutions have a high adhesive force and low surface tension. At the points of contact between the abrasive particles, the temperature rises, and since there is SiO2 around the abrasive, when the latter enters the contact zone, amorphous silica (SiO2) is formed. Since the abrasive grains are coated with a silicon oxide film, SiO2 penetrates into the cavities of micro-irregularities and adheres to the surface under repeated exposure to the abrasive. Thus, the surface to be treated is saturated with silicon oxide, which leads to an increase in its quality after grinding with a silicate composition.
 It has been proven that high surface quality is formed by amorphous silica. To confirm this mechanism, chemical and X-ray spectral analyses of the samples were performed, which showed the presence of SiO2 on the treated surface and a "strong bond" of silicon compounds with the metal surface layer. 
 It was found that the high quality of the surface is also due to the shape of abrasive particles and wear products. It has been confirmed that with the variable movement of surfaces relative to each other, abrasive grains take on a new position each time. At the same time, they are worn from all sides and acquire a rounded shape, and are simultaneously enveloped by a SiO2 foil.

Grinding force model for ultrasonic assisted grinding of γ-TiAl intermetallic compounds and experimental validation

Abstract The introduction of ultrasonic vibration in the grinding process of γ-TiAl intermetallic compounds can significantly reduce its processing difficulty. It is of great significance to understand the grinding mechanism of γ-TiAl intermetallic compounds and improve the processing efficiency by studying the mechanism of ordinary grinding of abrasive grains. Based on this, this study proposes a grinding force prediction model based on single-grain ultrasonic assisted grinding (UAG) chip formation mechanism. First, the prediction model of grinding force is established based on the chip formation mechanism of abrasive sliding ordinary grinding and the theory of ultrasonic assisted machining, considering the plastic deformation and shear effect in the process of material processing. Second, the UAG experiment of γ-TiAl intermetallic compounds was carried out by using diamond grinding wheel, and the unknown coefficient in the model was determined. Finally, the predicted values and experimental values of grinding force under different parameters were compared to verify the rationality of the model. It was found that the maximum deviation between the predicted value of tangential force and the actual value is 23%, and the maximum deviation between the predicted value of normal force and the actual value is 21.7%. In addition, by changing the relevant parameters, the model can predict the grinding force of different metal materials under different processing parameters, which is helpful for optimizing the UAG parameters and improving the processing efficiency.

Microscopic morphology modeling and prediction of flexible polished surface with belt flapwheel

Flexible polishing technology is widely used in the precision machining of aero-engine blisk blades. It has become one of the important research contents of flexible polishing technology to systematically study the flexible polishing process and understand the connotation of the microscopic morphology of the polished surface. In this paper, the flapwheel is used as a flexible abrasive tool, and the spatial kinematics model for the abrasive grains on the surface of the flapwheel and the geometric interference model for the abrasive grains and workpiece are established by transforming the spatial geometric coordinates. Based on the surface topography model for the abrasive tool, MATLAB software was used to simulate the micro topography generation process of the flexible polishing surface with flapwheel as abrasive tool, and the three-dimensional topography of the workpiece surface and its influence law under different process parameters were obtained. The polishing experimental results verified the simulation algorithm correctness and effectiveness.

Research of the effectiveness of internal grinding with varied grain-size wheels

The grinding of holes using technological primitives with characteristic changes in the abrasive effect on the surface being processed is considered. Equations for changing the number of active grains in technological primitives are obtained. A process is developed for internal grinding with wheels of different grain sizes, which ensures high grinding effectiveness by combining elements of rough, finishing and fine processing in one technological transition. Keywords:internal grinding, technological primitive, abrasive grain, grinding wheel, grain size tk_xt2001@mail.ru

Morphology of Microchips in the Surface Finishing Process Utilizing Abrasive Films.

In this study, the surface of new lapping films was analyzed, and the lapping finishing process was applied to RG7 tin bronze alloy. The research focused on examining lapping films with electrocorundum grains of nominal sizes 30, 12, and 9 μm, commonly used for achieving smooth surfaces. The manufacturing process involves placing abrasive grains and binder onto a polyester tape, resulting in a heterogeneous distribution of abrasive grains. The study investigates the impact of this random distribution on the performance of lapping films during material removal. Scanning electron microscopy was used to analyze the surface structure of abrasive films, revealing distinctive structures formed by the specific aggregation of abrasive grains. This study explores the influence of different nominal grain sizes on surface finish and aims to optimize lapping processes for diverse applications. The research also delves into microchip analysis, examining the products of the lapping film finishing process. Microchips were observed directly on the abrasive tool surface, revealing insights into their morphology and distribution. The chip segmentation frequency was determined, and they amounted to approximately 0.8 to 3 MHz; these are very high frequencies, which are unique for known chip-forming processes.

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.

Intelligent Detection of Robotic Arm Roller Wear Based on Combined DWAE and GRUNN Models

Abstract Long time and high intensity work makes the wear of the roller of the robotic arm increase gradually, which will affect the performance and service life if not regularly overhauled. In this paper, the sensor is used to obtain roller data from the mechanical arm, and the roller wear characteristics are extracted by combining them with the LSTM model. Based on the autoencoder, the wavelet function is introduced to establish a deep wavelet autoencoder, and the DWAE-GRUNN model is established by combining the gated recurrent unit neural network, which is used for the intelligent detection of the wear of the roller of the robotic arm. The model’s classification performance can be improved by using the CTC loss function, and the parameters can be optimized using the sparrow search algorithm. For the application of the DWAE-GRUNN model in the intelligent detection of roller wear of mechanical arms, this paper validates the model based on the aspects of performance, coefficient selection, and detection results. It is found that the average correct detection rate of the model in this paper is 95.97%, and the optimal accuracy is obtained when the weight attenuation coefficient of the DWAE structure is 0.005. The friction force changes inversely with the degree of smoothness after 3.1h of the detection time of the robotic arm roller, and the stiffness, cumulative large abrasive grains, and cumulative small abrasive grains also show significant changes. Using the DWAE-GRUNN model, changes in the wear of the robotic arm roller can be obtained, providing data support for timely maintenance.

Models of Abrasive Grains in Tools: A Review

Models of Abrasive Grains in Tools: A Review

Material removal rate in AJM of zirconia ceramic using silicon carbide abrasive: Investigation, modelling, and optimization

This research focuses on material removal rate in abrasive jet machining (AJM) of zirconia ceramic under varying process conditions (grain size of silicon carbide abrasive, air pressure, stand-off-distance). Combined approach of orthogonal array, and response surface methodology are respectively, applied for assessment, predictive modelling as well as response optimization. The influence of air pressure emerged as the most critical factor in enhancing MRR during AJM of zirconia ceramic. At elevated pressures, the surface morphology exhibits characteristic deep chipping and larger crater marks. The proposed predictive model for MRR utilizing the regression method proves effective, demonstrating adequacy, statistical significance, and probabilistic validation, indicated by its high R2-value (0.995), P-value below 0.05 (0.016), and substantial AD-test P-value (0.327). By employing DFA to solve the response optimization problem, optimal MRR (0.0000619 gm/min) for AJM of zirconia ceramic is achieved at abrasive grain size of 750 μm, air pressure of 7 kgf/cm2, and stand-off distance of 2 mm.

Study of the Electrostatic Method of Applying Abrasive Grains to the Grinding Tool Backing

Study of the Electrostatic Method of Applying Abrasive Grains to the Grinding Tool Backing

CONTROL SYSTEM FOR WATERJET CUTTING PROCESS WITH SWIRLING WORKING FLUID JET

In mechanical engineering, the procurement process is one of the most important in the life cycle stage of manufacturing products from metal materials. In this regard, there are disadvantages in the manufacture of parts: low productivity, complexity and high cost of cutting tools, and the impossibility of cutting. The work proposes an approach to increase the productivity of using the cutting properties of abrasive grains and expanding the contact area of a waterjet jet with the workpiece surface being processed by twisting the jet and adjusting the values of the jet oscillation frequency to the thickness of the workpiece. As a result of research verification, the approach showed good prediction accuracy.

Investigation of CMP Process of Silica Substrate by Ceria Abrasive: Insights from Molecular Dynamics Simulation with Neural Network Potential

Chemical mechanical polishing (CMP) is a process of surface planarization by chemical and mechanical driving forces. CMP is expected to solve various problems, including the surface roughness on semiconductor devices. An aqueous slurry, including abrasive grains and chemical components, is used in the CMP process. Development of slurries with high polishing rate, excellent planarity, and superior processability is not only a key challenge, but also a significant opportunity for the future of our industry. In order to achieve the development, it is necessary to understand the detailed mechanism of CMP, which involves complex phenomena accompanied by interfacial chemical reactions and mechanical friction. Computational scientific approaches, such as density functional theory (DFT) and molecular dynamics (MD) simulations, are powerful tools for understanding complex tribochemical phenomena at the atomic scale. However, these methods require much computation time and present difficulties for large-scale simulations. To overcome this limitation, a computational method called Neural Network Potential (NNP) is a powerful tool because it achieves a good balance between accuracy and computational efficiency by constructing potential energy surfaces based on a neural network-based method. We performed NNP-MD simulations of the ceria/silica interface with the development of CMP slurry including ceria abrasive grains, which is typically used on the surfaces of silicon layered devices. As a result, we succeeded in observing polishing phenomena at the interface at the atomic scale, namely Ce-O-Si bond formation between ceria abrasive grains and silica substrate, hydrolysis reaction of Si-O bond, and associated mono-silica dissociation from the substrate. We also performed simulations of systems containing chemical compounds added to the slurry for the purpose of controlling the polishing rate and observed the role of additives on the CMP process. In this presentation, we will show simulation results and discuss the mechanism of CMP of silica substrates with ceria abrasive grains in terms of dependence on surface morphology at the atomic scale and the role of additives. Reference [1] Tran*, R., Lan*, J., Shuaibi*, M., Wood*, B., Goyal*, S., Das, A., Heras-Domingo, J., Kolluru, A., Rizvi, A., Shoghi, N., Sriram, A., Ulissi, Z., & Zitnick, C. (2022). The Open Catalyst 2022 (OC22) Dataset and Challenges for Oxide Electrocatalysis. arXiv preprint arXiv:2206.08917.

Surface gradient structures in single-crystal nickel alloy induced by ultrasonic-assisted high-speed grinding

The gradient structures in surface layer of single-crystal nickel alloy (SX alloy) were produced (i.e., nanograin, submicron grain and coarse single crystal of bulk material) by means of ultrasonic-assisted high-speed grinding (UAHSG). The surface layer with a grain size gradient (from 29.7 to 111.8 nm) along depth from the treated surface featured impressive nano-indentation hardness (up to 12.1 GPa) beyond the initial SX alloy. The coupled effects of high rotation speed of abrasive grain (100 m/s) and the severe ultrasonic vibration impact (up to 4.3 times per contact cycle) induced large strain (up to 6.67) and ultrahigh strain rate (∼109 s−1), resulting in the superiority of such a structure gradient. This study suggests a new approach of UAHSG that can not only achieve high machining efficiency, but also make nickel alloy stronger by tailoring the surface layer gradient structures.

Measurement of number-weighted particle size distribution for CMP slurry using nanoparticle chip

Chemical mechanical polishing/planarization (CMP) slurry contains mainly abrasive grains (primary particles) with few aggregations (secondary particles). Measuring the particle size distribution (PSD) of CMP slurry is crucial for improving the productivity of the CMP process. For the quality management of CMP slurry, it is necessary to evaluate both the sizes and quantities of both the primary and secondary particles. Conventional PSD analysis methods, except for image analysis, face challenges in identifying primary and secondary particles for PSD measurements. For image analysis, the particles must be transferred from a suspension to a substrate using the conventional sampling method; however, this creates aggregates, resulting in a change in the PSD of the particles on the substrate compared to that in suspension under poly-dispersed conditions. Thus, this study proposed a novel particle sizing method using nanoparticle chip (NPC) to assist in the image analysis of the PSD. The NPC can pick up a single particle in a small volume droplet to avoid aggregation and maintain the poly-dispersed condition of the particles in suspension. The primary and secondary particles can be identified using scanning electron microscope (SEM) or atomic force microscope (AFM), and the PSD can be evaluated by measuring the area and height of the particles. Further, the quantities of both the primary and secondary particles can be counted from the substrate. This study presented a comparison of the diameter measurements using NPC and the conventional method. The results show that the NPC identified the primary and secondary particles and decreased the measurement error of the particle diameters. Consequently, the NPC proves to be superior to the conventional method for use in the PSD analysis of CMP slurry.

PROCESS OPTIMIZATION BY APPLYING THE RESPONSE SURFACE METHODOLOGY (RSM) TO THE ABRASIVE SUSPENSION WATER JET CUTTING OF PHENOLIC COMPOSITES

The paper introduces the study on the cutting of the industrial composite phenolic resin, based on the thermoset materials reinforced with cotton cloth by the Abrasive Water Suspension Jet (AWSJ). The size reduction of abrasive grains during the formation of the jet and the erosion phenomenon are shown. The results of the machining process's critical factors as nozzle length, nozzle diameter, and abrasive mass flow rate on the maximal cutting depth, are indicated. To build a model of the process, the method of the response surface (RSM) was applied. The second-degree multinomial equation is selected for creating the cutting model. The research indicates the optimal control factors of the process, to achieve the best cutting depth performance.

ЭКСПЕРИМЕНТАЛЬНЫЕ ИССЛЕДОВАНИЯ КОМБИНИРОВАННОГО ПРОЦЕССА ЭЛЕКТРОХИМИКОМЕХАНИЧЕСКОГО ПОЛИРОВАНИЯ

This article presents the results of experimental studies of the electrochemical mechanical polishing process, which combines anodic dissolution, possessing high localizing properties, with the dynamic effects of abrasive grains. The essence of the combined process is described, when, under the influence of operating voltage, a continuous electrochemical dissolution of the treated surface occurs with the formation of oxide films on it, followed by their removal together with the treated metal by means of abrasive grains quasi-fixed in the polishing pad. The description and conditions of the conducted experiments are given. The influence of the weight content of the abrasive in the composition of the electrolyte-abrasive mixture on the removal of metal and the roughness of the treated surface is shown. The impact on the course of the combined process of the frequency of rotation of the polishing pad and the pressure of the workpiece on it is noted. At optimal values of the studied parameters, electrochemical-mechanical polishing makes it possible to ensure high geometric quality of the treated surface and high process productivity.

Effect of diamond grain shape on gallium nitride nano-grinding process

In the grinding process, the quality of the product in the process is affected by many factors. In order to improve the processing quality and take into account the processing efficiency, the selection of a reasonable abrasive grain shape can be considered. This is a low-cost and highly feasible approach. In this article, the molecular dynamics method was employed to simulate the process of grinding GaN with four common synthetic diamond of abrasive grains (spherical, octahedron, cubic and cub-octahedron), and the surface morphology, material removal rate, temperature, potential energy, grinding force, substrate structure deformation, subsurface damage and dislocation were investigated. The results show that the cubic abrasive grain has the highest material removal rate with the number of chip atoms per unit area about 1.68 times that of the cub-octahedron abrasive grain. The lowest subsurface temperature of the octahedron abrasive grain during processing is 498 K. In contrast, the other three grits have similar subsurface temperatures of 540 K, 535 K and 545 K, respectively. The tangential force per unit area of octahedron abrasive grain is about 0.68761 (spherical: 0.23987, cubic: 0.4476, cubo-octahedral: 0.4314), but its potential energy is the most stable during processing. The shape of the abrasive grain has no significant effect on the coefficient of friction, while it has a significant effect on the subsurface damage. The depth of subsurface damage is the smallest for both cubic and cub-octahedron abrasive grain (2.4 nm), while cub-octahedron abrasive grain is more capable of promoting the generation of dislocations within the substrate. In addition, the performance of cubic and cub-octahedron abrasive grain at different grinding depths was further explored. Number of chip atoms, temperature, grinding force and subsurface damage all increase with the grinding depth. Nevertheless, the machining performance of cubic abrasive grain is still superior to that of cub-octahedron abrasive grain when the grinding depth is more than 1 nm. The outcome of this study may provide a micro-scale insight into the selection of abrasive grain shapes for processing GaN substrates.