Abrasive Process Research Articles

Experimental investigation on abrasive water jet machining of neem wood plastic composite

In this article, the neem wood plastic composite material has been fabricated by mixing neem wood saw powder with polypropylene (PP) matrix by injection molding method to study the machining characteristics of the abrasive water jet machining process. The volume percentage of neem wood saw powder, the volume percentage of additive agent talc mixed with PP matrix (A), table traveling speed (Ts), and water-jet pressure (Wp) have been considered as process parameters. The experiments were conducted and analyzed to predict the optimum parameters setting for surface roughness (SR) and kerf angle (KA) using the Taguchi method. It was observed that KA and SR have been greatly impacted by the percentage of neem wood saw powder, table traveling speed, and water-jet pressure. The SR and KA were minimized by reducing the percentage of neem wood powder, table traveling speed, and water-jet pressure. The SR has been decreased by adding talc agent, conversely, the KA has been increased. The concurrent optimum process parameters setting to minimize both SR and KA had been estimated by the weighted product method (WPM). The predicted results from Taguchi and WPM had been verified by microscopic analysis and confirmation experiments.

Experimental and numerical characterization of abrasive belt wear and debris formation during dry grinding of nickel-based superalloys with diamond abrasive belts

Nickel-based superalloys are the constituent materials of critical components of aero engines. Abrasive belt grinding is an effective method for the precision machining of such difficult-to-machine materials. However, the wear of the abrasive belt greatly affects the quality and integrity of the machined surface. In this study, a physical simulator of abrasive belt grinding was used to carry out diamond belt grinding experiments. The wear behavior of abrasive belts and the shape of debris at different temperatures were mainly investigated. In addition, a three-dimensional finite element model of single abrasive grain grinding was established to analyze the formation of debris. The variations of abrasive belt wear and debris morphology with temperature within the experimental temperature range were obtained. There are four types of wear behavior of diamond abrasive belts: grain flattening, grain shed, dependency blockage, and adhesion blockage. The self-sharpening of the abrasive belt plays an important role in improving the quality of the machined surface. The finite element model accurately simulates the shape of debris at different temperatures and the shape of debris changes apparently with temperature. The critical temperature for the formation of good surface quality is obtained. The research results provide guidance for the selection of abrasive belt grinding process parameters.

A Field Study on the Lithological Influence on the Interaction Between Weathering and Abrasion Processes in Bedrock Rivers

AbstractLithology is an important control on the efficiency of bedrock incision and thus the pace of landscape evolution. Rock strength is commonly considered the limiting lithologic factor that resists erosion. Yet, rock strength is a dynamic property that oscillates during advection of rock to the channel surface as damaging processes weaken rock and erosion exposes fresh rock. We approach the problem by investigating damage on bedrock surfaces that vary by the frequency they are eroded in channels of different lithologies. Our data set includes measurements of channel slope and width to characterize channel morphology, and Schmidt hammer rebound, P wave velocity, slake durability, and porosity to characterize the mechanical properties of channel surfaces. The average damage accumulation rate of lithologies ranges over 41% of the mean. We find a range of damage patterns among the different lithologies. Local surface damage increases with erosion frequency in channels comprised of coarse‐grained bedrock but decreases with erosion frequency in channels comprised of fine‐grained bedrock. We interpret these patterns to develop from lithological influences on weathering, abrasion, and the threshold of damage to erosion. The cross‐channel damage patterns between channel floors and margins are well correlated with stream power demonstrating links between microstructural rock properties, reach‐scale morphology, and landscape‐scale processes. We conclude that the morphodynamics of bedrock channels are sensitive to the lithological influences on the direction and magnitude of feedback in the coevolution of bedform morphology and the mechanical properties of the surface.

Sustainable solution to low-cost alternative abrasive from electric ceramic insulator waste for use in abrasive water jet machining

Increasing demand and resource overuse has prompted the exploration of spent secondary materials as a primary raw material for a variety of applications, leading to a more sustainable environment. Spent electric grid ceramic insulator, one of the waste materials of ceramic industry, has a good hardness and strength. It can be reused as value-added material in the Abrasive Water Jet Machining (AWJM) industry. The present work deals with the generation of cost-effective replacement material for abrasive water jet machining from electric insulator rejects (EIR). Mechanical crushing method is opted to generate the abrasive grit for the machining process. Grit generation pattern and the friability of the electric insulator rejects were determined experimentally. The results indicate that the friability of the processed electric insulator rejects is comparable with the commercially available garnet abrasive. Geometric parameters such as sphericity, elongation ratio, and shape factor for the processed electric insulator rejects were studied using scanning electron microscopy. The machining performance indicators for standard aluminium material such as volume of material removal, kerf angle, surface roughness, and cutting width were measured for electric insulator rejects and compared with existing garnet abrasive grain. The experimental results of the newly generated electric insulator reject abrasive were compared with the performance indicators of the garnet abrasive. The observed deviation was lower proving that it can be used as an alternative abrasive in the abrasive jet machining process. Cost analysis and recycling ability predict the economical usability of the newly generated abrasives.

MODERN CHANGES COUNTOUR OF COASTLINE SPITS OF THE SEA OF AZOV

Problem Statement and Purpose. At present the studying of the shores and their dynamics configuration and especially the most active parts – the heads of the Azov spits, is caused by both reasons dynamic and geopolitical changes as well. A large number of spits is a characteristic feature of the shores of the Azov Sea. There are spits all over the coast of the Azov Sea. However, spits oriented deep into the Azov Sea shore line there are just on the northern sea area. The reason of intense lithodynamic processes in the coastal zone of the Azov is the high velocities of currents in the bottom layer as a result of storm winds. In the coastal zone of the sea the cycle of abrasion rate from 1 to 4 m per year (sometimes up to 15m per year) was established. Fluctuations in the level of the Azov Sea are provides by many natural factors acting simultaneously and input to abrasion processes. The largest range of fluctuations is associated with wind activity phenomena. Data & Methods. In the paper takes into account the regular field studies of the position of the coastline of the distal parts – the streamer heads using of satellite radio navigation systems – GPS receivers. The radio navigation equipment recorded the exact route along the interaction zone. The sampling was carried out in a calm period on the sea surface. The data in situ (recorded routes) were compared with retrospective data of GIS systems. Cartographic materials, various specialized sources of information and satellite images were also used for the further analysis. Results. In fact, this paper is an attempt for the first time analysis of the available retrospective, modern and satellite monitoring data for the comparing of the dynamics of the Azov spits in frame of Ukraine area. As an example the dynamics of the coast line of the spits: Biryuchiy Island, Obitochnaya, Berdyanskaya and Belosaraiskaya were done. The study of the modern state of the Ukrainian coast line in the Azov Sea, the possible degradation of the coastal part of the sea and the reasons causes of it isessential for the sustainable development of the economy, the recreational potential of the region, the social level of the population and the geopolitical situation in the event of delimitation in the Azov Sea.

Nanoscale smooth and damage-free polycrystalline diamond surface ground by coarse diamond grinding wheel

Fabrication of smooth damage-free diamond surfaces has been a popular subject in the manufacturing research field. In this study, the polycrystalline diamond was ground by a vitrified bonded diamond wheel to obtain damage-free diamond surfaces with low surface roughness and high quality. Atomic force microscopy verified that surface roughness of Sa 4.20 nm, Sa 2.06 nm, and Sa 0.548 nm were achieved under grinding speeds of 750, 1050, and 1350 rpm, respectively. Electron energy loss spectroscopy spectra confirmed the existence of a graphitic layer (black layer) with a thickness of ~15 nm in the subsurface after grinding. The “black layer” showed an easy ability to be removed under scratch and high-temperature oxidation. Moreover, transmission electron microscopy demonstrated that no damaged layer was observed in the subsurfaces at 750 rpm and 1050 rpm grinding speed. For grinding speed of 1350 rpm, stacking faults and micro-crack appear in the subsurface, thus forming a damaged layer with several microns in thickness. Our work proposes a new strategy to efficiently fabricate nanoscale smooth and damage-free diamond surfaces by diamond wheel grinding. More innovatively, this work demonstrates a unique removal mechanism for abrasive processing of hard-and-brittle materials, as distinct from either mechanical grinding or chemical mechanical grinding.

Study on abrasive belt grinding process assisted by ultrasonic elliptic vibration

Study on abrasive belt grinding process assisted by ultrasonic elliptic vibration

Constrained abrasive jet polishing with a tangentially aligned nozzle shroud

In order to improve surface polishing quality and efficiency for hard and brittle components, a novel nozzle with specifically designed shroud was proposed for an abrasive jet polishing process. The removal mechanism of the abrasive jet under such a nozzle was investigated by simulating the jet flow in the interaction area of the nozzle shroud and workpiece. The simulation results show that the speed of the abrasive jet increases greatly by the shroud and the direction of the jet is aligned near parallel to the workpiece surface to minimize impact damage to workpiece surface. The constrained abrasive jet polishing (CAJP) experiments were conducted on the quartz glass component, a typical hard and brittle material, showing that the material removal mainly relied on the shearing and scratching of the workpiece surface rather than the mechanical shock impacts, which is consistent with the simulation findings.

Determination of the Efficiency of Hot Nano-Grinding of Mono-Crystalline Fcc Metals Using Molecular Dynamics Method.

Abrasive processes are essential to the manufacturing field, due to their capability of rendering high-quality surfaces with minimum effect on workpiece integrity. As it is especially difficult to perform sufficient experimental work, numerical studies can be successfully employed to evaluate techniques for the improvement of the efficiency of nanometric abrasive processes. In the present study, for the first time, cases of nanogrinding on workpieces of three different fcc metals, namely, copper, nickel, and aluminum are investigated under different preheating temperatures, in order to determine the efficiency of the hot nano-grinding technique. For the simulations, a molecular dynamics model for peripheral nanogrinding is developed including multiple abrasive grains and realistic grain trajectory and grinding forces, and chip characteristics and subsurface alterations are evaluated. The results indicate that using elevated preheating temperatures is beneficial for nanogrinding, as forces can be considerably reduced and material removal can be facilitated, especially for temperatures over 40% of the material melting temperature (Tm). However, the detrimental effect on workpiece integrity is also evident at higher preheating temperatures, due to the high temperature on the whole workpiece, posing limitations to the applicability of the hot nano-grinding technique. Based on the findings of this study, preheating temperatures in the range of 0.4–0.55 Tm are recommended.

The Features of Distribution of Chemical Elements, including Heavy Metals and Cs-137, in Surface Sediments of the Barents, Kara, Laptev and East Siberian Seas

Over the recent few decades, due to climate warming and the continuing exploration of Arctic seas’ mineral resources, the scientific interest in contamination problems has deepened significantly. In this study, for the first time, we characterize the distribution features of 47 elements (major and trace elements, including heavy metals, metalloid As, and Cs-137 technogenic radionuclide) in surface bottom sediments from some areas of the Barents, Kara, Laptev, and East-Siberian Seas. The lithogenic material was the main factor that controlled variability in many elements (Be, Al, Ti, Cr, Ga, Rb, Sr, Y, Zr, Nb, Ba, REE, Pb, Th, U, W, and Cs). Among the hydrogenic processes, the formation of Fe and Mn oxyhydroxides has the greatest impact on the Mn, Fe, Co, Ni, Cu, Ge, and Mo, and insignificantly V and Sb, variability in sediments. These, along with minor to moderate values of enrichment factor (EF) for most elements, allowed us to conclude that the observed element distribution is related to predominantly natural processes of thermal abrasion, river-run, and atmospheric input. The exception is As, which exhibited the elevated EF (up to 20) in the western and central Kara Sea, as well as in the Vilkitsky Strait. Since no significant relationship between As and Fe andMn oxyhydroxides distribution was found, we may assume primarily an anthropogenic source of As, related to the peat and/or coal combustion. According to the criteria of Ecological Risks assessment, all the examined areas have a low degree of risk. Data on the specific activity of Cs-137 correspond to the background average values characteristic for these regions. The highest levels of Cs-137 concentration (Bq/kg) were detected in the sediments of the Ob and Yenisei Rivers’ estuaries.

Evaluation of the Fluvial Response to Tectonic Uplift From Grain-Size Distribution in Riverbed Gravels at the Northeastern Margin of the Tibetan Plateau

Downstream fining of riverbed gravels is generally linked with the processes of hydraulic sorting and abrasion. Hydraulic sorting is when larger gravel clasts stop moving in response to decreasing flow energy, whereas, finer grains will continue to be carried downstream. Furthermore, transportation of gravel clasts causes abrasion, bringing about a gradual decrease in grain size. Hydraulic sorting and abrasion have different dominant effects on the downstream fining of clasts in rivers with different climatic and tectonic backgrounds. At present, most studies focus on humid areas, and relatively few studies have explored this issue for the northeastern margin of the Tibetan Plateau in arid and semi-arid areas. Detailed investigations of the grain size, lithology, and roundness of riverbed gravels have been performed here along the Taolai, Hongshuiba, and Fengle Rivers, which flow across the northeastern margin of the Tibetan Plateau and debouch into the arid inland of North China. The obtained data were subsequently employed in a hydraulic pattern of grain-size distribution of riverbed gravels in this area, which is characterized by the combined influences of tectonic activity and climatic aridity. Analysis reveals that there is no new rock type appearing in the lithological compositions of riverbed gravels along these rivers, only showing fluctuations in proportions of lithology even though they are adjacent to uplifting mountains. Fresh gravel material from these mountains does indeed mix into the fluvial bedload, inducing a notable decrease in roundness in the Taolai and Hongshuiba bedloads downstream from here. The downstream fining of gravel along the three rivers, with median grain sizes above 128 mm and falling into the range from 20 to 128 mm, can probably be attributed to hydraulic sorting and abrasion. Further analysis suggests that the former presents a high correlation with channel gradient, which may be sustained by fault activity at the northeastern margin of the Tibetan Plateau. The grain-size distribution in these riverbed gravels thus provides insights into the evaluation of fluvial responses to active tectonic uplift.

Parameter Identification of an Abrasive Manufacturing Process With Machine Learning of Measured Surface Topography Information

Abstract The correlation between manufacturing parameters and the resulting surface topography is most often described with standardized profile surface texture parameters (R-parameters). However, in many cases, they represent a strong simplification as the most common parameters are often neither function-oriented nor unambiguously correlated with the manufacturing parameters. Therefore, we investigate whether a neural network is a suitable alternative to establish a more comprehensive correlation between the surface topography and the manufacturing parameters. The learned correlation provides possibilities to be used for subsequent monitoring of the manufacturing process. Our approach is to predict the manufacturing parameters from a measured topography dataset with a convolutional neural network as a regression model. As the training of neural networks requires large amounts of data, stochastic surface models are applied to generate artificial profiles and thus increase the available amount of data. The prediction accuracy and consequently its correlation with the manufacturing parameters are evaluated for a case study of an abrasive process. In this case study, it is first determined whether artificial or measured profiles and which of their representations (frequency or time dependent) provide the best information to train the network. The network featuring the most reliable prediction of the manufacturing parameters is then used for further analysis. By comparing this network with a linear regression model between manufacturing parameters and R-parameters, its performance is benchmarked and can be suggested as a suitable alternative to predict and monitor manufacturing parameters based on the measured surface topography.

Fixed Abrasive Polishing in an Anhydrous Environment: A Material Removal Model for Fused Silica

Due to the prevalent randomness and uncertainties associated with traditional loose polishing, fixed abrasive polishing in an anhydrous environment has been chosen as a new polishing method. In this paper, cerium oxide is the main component for polishing pellets, and the particle size distribution of cerium oxide is measured. A material removal model for fixed abrasive polishing of fused silica in an anhydrous environment is proposed. Based on this model, we simulate the roughness of fused silica in fixed abrasive polishing process by using a Monte Carlo method with a constant removal mechanism and obtain the percentage of plastic and chemical removal. The percentage result is then taken into the material removal equation to calculate the material removal rate. The final convergence value of the roughness with 2 μm particle size is about 1.8 nm, while the final convergence value of the surface roughness of the workpiece by Monte Carlo simulation is about 1 nm. The experimental material removal rate at 2 μm particle size is 5.48 μm/h, while the simulation result is 4.29 μm/h. The experiment data of roughness and material removal rate all verify the model.

Numerical Analysis of Multi-Angle Precision Microcutting of a Single-Crystal Copper Surface Based on Molecular Dynamics.

The molecular dynamics method was used to study the removal mechanism of boron nitride particles by multi-angle microcutting of single-crystal copper from the microscopic point of view. The mechanical properties and energy conversion characteristics of single-crystal copper during microcutting were analyzed and the atomic displacement and dislocation formation in the microcutting process are discussed. The research results showed that during the energy transfer between atoms during the microcutting process of boron nitride particles, the crystal lattice of the single-crystal copper atom in the cutting extrusion region was deformed and displaced, the atomic temperature and thermal motion in the contact area between boron nitride particles and Newtonian layer of workpiece increased, the single-crystal copper atom lattice was defective, and the atomic arrangement structure was destroyed and recombined. The interface of different crystal structures formed a dislocation structure and produced plastic deformation. With the increase of the impact cutting angle, the dislocation density inside the crystal increased, the defect structure increased and the surface quality of the workpiece decreased. To protect the internal structure of the workpiece and improve the material removal rate, a smaller cutting angle should be selected for the abrasive flow microcutting function, which can reduce the formation of an internal defect structure and effectively improve the quality of abrasive flow precision machining. The research conclusions can provide a theoretical basis and technical support for the development of precision abrasive flow processing technology.

Study on Mechanism of Roundness Improvement by the Internal Magnetic Abrasive Finishing Process Using Magnetic Machining Tool

An internal magnetic abrasive finishing process using a magnetic machining tool was proposed for finishing the internal surface of the thick tubes. It has been proved that this process is effective for finishing thick tubes, and it can improve the roundness while improving the roughness. However, the mechanism of improving the roundness is not clear, so it is necessary to study it theoretically. In this research, firstly, the roundness curve expression was derived using the principle of roundness measurement by the assumed center method, and the expression of roundness curve expanded by Fourier series was obtained. The influencing factors of roundness improvement were then analyzed. Secondly, the experiments were carried out on SUS304 stainless steel tubes. By confirming the mechanism analysis results and the experimental results, it was concluded that the internal magnetic abrasive finishing process using the magnetic machining tool was effective for improving the roundness of the thick tubes whose thickness is from 10 mm to 30 mm. As the thickness of the tube increased, the improvement in roundness decreased.

Feasibility of using wet abrasive jet machining to produce flat and crack-free micro-textures on reaction bonded silicon carbide

Reaction-bonded silicon carbide (RB-SiC) is a composite ceramic that comprises of hard SiC grains and brittle Si matrix. Surface texture with well machining qualities, in particular, is difficult to be fabricated on RB-SiC in conventional machining conditions since the removal of material inevitably induces some unexpected surface defects. In this paper, the feasibility of using a wet abrasive jet machining process (wet AJM) to produce smooth and crack-free micro-features on RB-SiC was investigated. Three commercial abrasives were employed to test the machining responses. The hardness of abrasive was found to be critical and dominate the machinability of RB-SiC. The hardest synthetic diamond (SD) abrasive could crush the SiC grains, thereby providing the highest machining efficiency and a relatively smooth face. The relatively soft abrasives, including aluminum oxide (Al 2 O 3 ) and green SiC, tend to break or rebound during the impact. After removing the Si matrix, SiC grains would be exposed and be to some degree protective of the target; therefore, the machined texture was shallow and rough. Since the particles in the lateral flow rolled freely, there were no obvious cracks on the inner surface of the machined texture compared to the machining without water. The variation of the machining profile had an inherent correlation to the mask thickness, nozzle motion speed and particle size. With these optimized parameters, it is feasible to use the wet AJM to fabricate complex micro-structural arrays on RB-SiC with good precision and surface quality.

Machinability study of Aluminium 6082 reinforced with boron carbide and titanium by stir casting method using Abrasive water jet machining process

Aluminium Metal Matrix Composite (AMMC) has broad uses in the medical, aerospace, and automobile industries, which have long sought lightweight materials with superior designs and improved properties to improve performance. This analysis has aimed to prepare an AMMC to investigate its machining and mechanical properties. The AMMC is produced using a stir casting process by reinforcing boron carbide and titanium with aluminium 6082. The material’s mechanical properties are studied by using wear test, hardness test, and corrosion test. The wear rate increases when the load increases by varying the load and time with speed as a constant. It is found that the hardness of a material is increased due to titanium and boron carbide as the reinforcement particle in the fabricated AMMC. Using the pitting corrosion technique, the corrosion occurs on the AMMC under the estimated time at room temperature. In order to illustrate the machining characteristics of the aluminium metal matrix composite, an Abrasive Water Jet Machining (AWJM) process has been used. The experiments use L9 orthogonal Array using Taguchi’s method and ANOVA analysis. The input parameters considered are Traverse rate, Stand-off distance, and Nozzle diameter. To find the optimum value of circularity, cylindricity, and surface roughness by varied input parameters. The respective graphs are also plotted. Scanning electron microscopic analysis was performed on the wear-tested specimen and machining surface of the material to determine the distribution of reinforced material and investigate the material’s fracture mechanism. It is found that wear tracks, voids, delamination, micro pits, embedded garnet abrasive particles are located on the machined surface of the AMMC.

Experimental investigation on surface characteristics of Ti6Al4V alloy during abrasive water jet machining process

The evolution of industrial development enabled massive improvements in the lightweight materials for products with high strength to weight ratios and superior corrosion resistance used in turbine and aerospace structures. Titanium and its alloys possess excellent service properties especially in the biomedical field, due to inherent difficulties arise while cutting these alloys using conventional processing operations. Therefore, in this research, abrasive water jet machining (AWJM) is employed as a nontraditional process to investigate the post-processing surface characteristics of Ti6Al4V alloy. The effects of process factors including water pressure, abrasive flow rate, feed rate and stand-off distance on the characteristics of the cut surfaces have been investigated. Comprehensive experimentation is carried out to determine parametric ranges involving lesser heat affected regions and improved surface characteristics. Through Taguchi based design of experiments, it is observed that abrasive flow rate and stand-off distance are the most significant parameters that affect the surface roughness and material morphology.

Prediction of surface roughness of titanium alloy in abrasive waterjet machining process

Prediction of surface roughness of titanium alloy in abrasive waterjet machining process

Analysis of abrasives on cutting edge preparation by drag finishing

Cutting edge preparation has become more important for tool performance. The micro-shape, radius and surface topography of the cutting edge play a significant role in the machining process. The cutting edge of solid carbide end mills has some micro-defects after grinding. For eliminating aforementioned problem, this study investigates drag finishing (DF) preparation for solid carbide end mills to reconstruct cutting edge micro-geometry. This paper is to present the design of DF experimental setup and analyze the characterization of various abrasive media (K3/600, K3/400, HSC 1/300 and HSO 1/100) on the evolution of the surface/roughness along the cutting edge. In parallel, the mechanism of material removal and the kinematics trajectory of the drag finishing are presented. In fact, the form factor (also called as “K-factor”) of the cutting edge micro-geometry is quantified. Comparing with four lapping media, the higher material removal rate (MRR) and the lower surface roughness are obtained by HSO 1/100 abrasive process. The results show that the cutting edge K-factor, MRR and surface topography are influenced by the abrasive particles size, composition and process time.