Abrasive Grain Size Research Articles

THE EFFECT OF ABRASIVE GRAIN SHAPES ON QUALITY OF FERRITE MAGNETS GRINDING PROCESS

A research was conducted on the grinding process of ferrite magnet with Strontium ferrite type (SrO.6 (Fe2O3)) using electroplated single layer grinding wheels. Many cracks have been found on work pieces during this work, which is coming from grinding processes. Research is conducted starting from chemical composition test and the effect of the shape and size of the abrasive grain of grinding wheels to the quality of grinding process results by measuring crack ratio of the work piece. In this experiment, 3 (three) model design of grinding wheels with three different size and shape of abrasive grains are made. All of processing parameters are set at the same value as ordinary process. The experimental results shown that 3rd model have the best results from the outputs number and also the lowest reject crack ratio compared to 1st and 2nd models. This is because the 3rd model has blocky shape which its distribution structure is denser and more uniform compared to the irregular shape, so that continuous grinding on hard and brittle work pieces is more stable and suitable

INVESTIGATION ON PERFORMANCE OF EXTRUSION HONING PROCESS ON QUALITY OF SURFACE TEXTURE

The EH approach overcomes this limitation of conventional finishing method. The present study focus on the impact of number of passes at the specimen's entry and exit sides of the carrier media. The improvements in surface finish (Ra) on both side i.e entry and exit are evaluated as well. A dimensionless expression for Ra is also developed. The relation is implemented using Buckingham’s π theorem and comparison of developed model is performed with experimental results. SEM analysis is made to portray surface texture produced by selected process parameters such as number of passes, volume fraction and grit size of abrasive grains.

Effects of honing process parameters on residual stress fields of grey cast iron engine cylinder liners: Experimental and numerical study

Super polishing methods are widely employed to improve the surface integrity of machined parts. These methods not only improve the surface texture of the machined parts, but also modify the residual stresses induced at the outer layer of the machined surface. In this study, the effects of honing process parameters on the distribution of residual stresses at the surface of grey cast iron investigated numerically and experimentally. To this aim, a finite element (FE) model developed to evaluate the effects of process parameters, including cutting speed, grain size, and pressure of honing tools, on the residual stresses induced at the surface of samples. The friction coefficient introduced as an updating parameter in the model to get the best correlation between the results of FE and experiments. In addition, the X-ray diffraction method used to experimentally measuring the distribution of residual stresses at the honing surface of the samples. The experimental and numerical results showed that in majority of combinations of the process parameters, the maximum compressive residual stress occurs at a depth of approximately 0.03 mm from the cutting surface of the sample. Additionally, it was seen that decreasing the size of abrasive grains and cutting speed and increasing the pressure on the cutting tool result in higher levels of induced compressional stresses at the surface of samples. However, the depth at which the maximum residual stress occurs can proceed up to 0.06 mm by an increase in the diameter of abrasive grains and cutting speed.

Effect of Abrasive Grain Size on the Abrasion Volume Loss of Subfossil and Recent Oak Wood in Three Characteristic Sections

Subfossil wood is a valuable and rare material often used for production of expensive furniture and decorative artistic items of unique beauty. Its mechanical and tribological properties are still being studied and are considered specific due to the particular conditions of its long-lasting formation in aqueous sediment sludge. Various elements that have been impregnated into the wood tissue over many years make the machining and grinding of this type of wood rather difficult compared to normal recent wood. The main objective of this study was to determine the influence of the abrasive grain size of sandpaper on the abrasion volume loss of recent and two subfossil oak samples in three characteristic sections (cross, radial, and tangential). The results showed that the average size of abrasive grains and the orientation of the wood structure have an influence on the abrasion volume loss of all three samples. The phenomenon of the critical size of abrasive grains was observed in all samples and on all sections. As the size of abrasive grains increased to the critical size, the abrasive volume loss of the sample increased simultaneously. The lowest abrasion volume loss was observed on recent oak. In all samples, the lowest volume loss was measured on the cross sections, and the tangential and radial sections had mutually equal values. It was also found that the increase in the size of abrasive grains to a critical value resulted in the increasing value of the absolute difference between the abrasion volume loss of the cross, radial, and tangential section samples, while the relative relations between the abrasive volume loss values of three different sections (C/R, C/T, R/T) within the same grit of sandpaper remained quite similar.

Assessment of Surface Quality in Extrusion Honing Process Using Dimensional Analysis Approach

It is critical to obtain the desired surface quality on the internal and external portions of machined part. The estimated level of surface texture can be induced on the exterior regions using traditional finishing processes such as grinding, honing, and so on. While the problem emerges when processing core miniature components such as micro bores, inlet/outlet valves etc. The EH process overcomes this limitation of conventional finishing method. It is a novel micro machining process that extrudes the pressured flow of carrier media blended with abrasives into the confined passage to generate desired level of surface texture. Owing to abrasion process micro machining occurs by taking away the negligible amount of stock material. The present study focuses on the impact of number of passes at the specimen’s entry and exit sides of the carrier media. The improvements in surface finish (Ra) on both side i.e., entry and exit are evaluated as well. A dimensionless expression for Ra is also developed. The relationship is implemented using Buckingham’s π theorem and comparison of developed model is performed with experimental results. SEM analysis is made to portray surface texture produced by selected process parameters such as number of passes, volume fraction and grit size of abrasive grains.

Абразивный инструмент из сферокорунда для обработки древесины

In the manufacture of hard abrasive tools for sanding wood and wood-based materials, spherical corundum is an effective material. The use of spherical corundum abrasive wheels makes it possible to increase the productivity of wood sanding, as well as to expand the application area of hard abrasive tools by reducing tool loading and eliminating burns of the treated surface. In order to substantiate the rational conditions of application of abrasive wheels made of spherical corundum it is necessary to determine the dependences linking the surface geometric parameters of the wheel, which directly influence the cutting, with the volume characteristics regulated by the formulation: grain size, content of abrasive grain and binder. The dependencies allow us to assess the nature and degree of influence of tool factors on the distance between the cutting elements of the operating surface of the spherical corundum wheel. The distance between abrasive grains on the wheel surface exceeds the distance between the walls of the abrasive grain in the vast majority of possible ratios of volume characteristics. The greatest influence on the surface geometric parameters has the size of abrasive grains. As it increases, the surface geometric dimensions grow, with a very sharp increase in the distance between abrasive grains on the wheel surface. The second most influential is the profile depth coordinate, which largely determines the ratio of distances between grains and between the grain walls. The relative grain and binder content in the wheel has less influence on the surface properties than the grain size and profile depth. The distance between grains on the wheel surface decreases slightly with their increase; they have no effect on the distance between the abrasive grain walls. The characteristics of the internal volumetric structure (grain size, grain content and binder content) are regulated in the production of abrasive tools. The peripheral surface of the wheel (its relief) is directly involved in the sanding process. For describing the relief of a spherical corundum wheel, it is necessary to determine the relationship between the volume characteristics and its surface geometric parameters, which are necessary to determine all the main parameters of the sanding process.

Effects of grain size and protrusion height on the surface integrity generation in the nanogrinding of 6H-SiC

The size and protrusion height of abrasive grains of a grinding wheel are not uniform, which can greatly influence the surface integrity generation of a ground component. The purpose of this paper is to explore such effects on the deformation and material removal mechanisms of 6H-SiC subjected to nanogrinding with the aid of molecular dynamics simulations. It was found that a nanogrinding process can fall into one or more of the following regimes with respect to material removal, i.e., no-wear, adhering, ploughing and cutting regimes, depending on both the depth of grain cut and size of abrasive grains. The plastic deformation in 6H-SiC starts with surface amorphization under the grinding stresses, followed by the activation of partial and perfect dislocations in the shuffle set of the material’s basal plane.

Influence of regeneration process parameters on geometry and defects of clearance surface of planer knives used in wood planing process

A properly implemented strategy regarding the planer knife regeneration process, may not only restore the original cutting ability of the tool, but even increase its operational quality, including its durability for industrial woodworking processes. This article presents experimental results and discussion in respect of sharpening planer knives with cubic boron nitride grinding wheels. Both the grinding conditions and machining surface quality were analyzed. Application of improper size or loads of abrasive grains may lead to the appearance of grinding burns on a machined surface, or result in a surface with cracks and grooves. The results of the measurements carried out indicate that surfaces with reduced values of roughness and waviness parameters can be obtained, even up to 22% (as in the case of the reduced peak height parameter, Spk) in relation to new knives, prepared at a factory. The value of St and Sds parameters are almost the same as reference knife (deviation up to 3%). Due to machining marks, the total waviness exceeds 33%. Our research also shows that due to the technological quality of the knife surfaces, it is beneficial to use CBN grains with a low depth of cut (ae no more than 0.02 mm), but a moderate or high feed rate (the best choice is about 470 mm/min for vft). Presented results constitute an important know-how for the grinding process with the use of grinders used by operators (like WEINIG Rondamat 980) during the sharpening of planer cutter heads in the wood industry.

Machining of aluminium nitride ceramic using developed hot abrasive jet machining: an experimental and simulation approach

ABSTRACT This novel implementation will analyse the cutting performance of hardstone aluminium nitride with regards to roughness of the surface and material erosion in hot abrasive jet machining (HAJM). Forty five sets of tests have been carried out taking into account five machining constraints (compressed air pressure, compressed air velocity, abrasive temperature, abrasive grain size and percentage concentration of hot abrasives). To optimise the model and determine the conditions for maximising the erosion rate and minimising the surface roughness, a particle swarm optimisation (PSO) was used with experimental investigation as well as predictive modelling. The results were validated experimentally, and the results were well-established between test results and PSO forecasts. The nature of the produced target profile was obtained through CFD simulation in HAJMing. In addition, HAJMed surface microstructures were analysed with microscopic images. The results of RSM data have been validated by testing and RSM prediction. In addition, a multi-objective optimisation problem based on the empirical models was used and the multi-objective particle swarm optimisation (PSO) were determined. In AlN ceramic materials, the RSM with PSO determined the optimal machining restriction for an exact HAJMing condition.

Study on three-dimensional topography modeling of the grinding wheel with image processing techniques

A novel method for three-dimensional characterization and topography modeling of alumina abrasive grains and single crystal corundum grinding wheel trimmed by a diamond roller is proposed in this paper. An alumina abrasive grain is modeled with a random and arbitrary pyramid determined by the relative position of its five vertices. It is revealed that the relative position is related to the apex angle and volume ratio of abrasive particles. Considering the strong randomness of abrasive grain properties, high-precision characterization of the distribution, size and shape of abrasive grains is extracted through image processing techniques such as identification, segmentation, marking, and removal of connected domains. Meanwhile, a new set of parameters is defined to quantify the identified topographical features of abrasive grains on the wheel surface. It is illustrated that the angle of abrasive grains and its area ratio that can be extracted from dressing tests of the grinding wheel play a dominant role in the establishment of the grinding wheel model. Finally, three-dimensional topography model of the grinding wheel is built with the distribution, size and shape models of active abrasive grains and broken abrasive grains. The results show that the simulated topography model agrees well with the experimental measurements regardless of the distribution, area ratio, size, density or number of abrasive grains.

Effect of Grain Size and Density of Abrasive on Surface Roughness, Material Removal Rate and Acoustic Emission Signal in Rough Honing Processes

Honing processes provide a special cross-hatch pattern to the internal surface of cylinders that favors oil flow. However, along honing operation the abrasive grains wear out and lose their ability to cut material. The honing chips mixed with oil fill the pores of the abrasives and they start cutting in an incorrect way, leading to clogging. In the present paper, honing experiments were carried out according to a 32 factorial design, with different grain size and density of abrasive grains. Roughness, material removal rate, and tool wear were determined. Acoustic emissions were also measured and the chirplet concept was applied in order to detect differences between correct and incorrect cutting operations. As a general trend roughness and material removal rate increase with grain size and with density of abrasive. However, when clogging occurs roughness and material removal rate decrease, because the abrasive grains tend to deform the material instead of cutting it. When the honing process is working appropriately, the chirplet diagram of the harmonic part of the signal shows constant marks. On the contrary, when it does not work properly, marks disappear with time and their frequencies decrease. The results of the present paper will allow monitoring the honing process in order to change the abrasives when they are not working properly.

Zastosowanie polimerów jako mediów ściernych w obróbce przetłoczno-ściernej

The characteristics of the products’ treatment by the abrasive flow machining (AFM) makes it an appropriate method of finishing the surface with complex geometry, e.g. holes or channels. Traditional methods of machining cause difficulties in obtaining a homogeneous roughness during finishing complicated shapes due to uneven distribution of abrasive forces. Due to the high price of abrasive media, not every user can afford for using it for processing. In the frame of the research, the novelty abrasive media has been developed to improve the surface roughness of the elements of polymer products. The use of viscoelastic polymers as a media of flow abrasive machining was discussed. Moreover, it is suggested to modify the quantity and size of abrasive grains filling the abrasive media in order to increase the value of the grain pressure force on the machined surface and to obtain an even surface of complex holes in AFM process.

Pomiary i analiza wielkości mikroziaren ściernych

The paper discussed automated size and shape analysis of both abrasive grains and micrograins. In research on micrograins of boron carbide, silicon carbide, ordinary and noble electrocorundum stereoscopic optical microscopy was applied and MultiScan software solutions were used.

Abrasive wear behaviour of cast Al–Si–Mn alloys

In this paper, the effect of manganese (wt%) and size of the Al2O3 abrasive grains of abrasive wear behaviours of Al–Si–(0.16–0.76%) Mn alloy was examined. Abrasive wear experiments were conducted against abrasive Al2O3 paper grains with diameters in the variety of 38–250 µm, under the normal load range of 10, 20 and 30 N and the sliding velocity of 0.1 m s−1. Wear measurements have shown that the wear rate of the material is dependent on the manganese content and the abrasive grain size. The best wear resistance is in the content of 0.73 Mn, which is associated with increased toughness and strength. The Al–Si casting alloy which had 0.73% Mn content exhibited lower wear rate than the Al–Si–0.16/0.22/0.23% Mn alloys after scoured on fine abrasive Al2O3 grains (<65 µm). Wear experiments achieved on Al2O3 grains having sizes greater than 65 µm revealed that, the cast Al–Si– alloy which had 0.73% Mn content had lower wear rate than the cast Al–Si–0.16/0.22/0.23% Mn alloys.

Influence of processing time of a superhard ceramics sample on surface quality and edge rounding radius

The article shows studies of the influence of vibration treatment time of an abrasive mixture consisting of 15% Type UDD diamond grains and monocorundum, on the surface quality of a sample made of superhard ceramics and the resulting radius of edge rounding. The studied samples were obtained from cubic boron nitride; it being extremely hard in hot state, which makes it possible to use it at very high cutting speeds. It is also characterized by good strength and heat resistance The investigation of the quality of the treated surface, estimated by the magnitude of the residual burr and the height of the microroughness of the surface of the part is very important in the study of vibrating processing of superhard ceramics. In vibration treatment, an increase in the processing capacity does not lead to a deterioration in the surface roughness due to the lapping process, which was achieved by selecting the vibration amplitude. In the process of chip removal during the diamond grinding of ceramics, individual diamond grains are involved, as well as the bundle of the circle. When studying the nature of the destruction of the ceramic surface by diamond grains, it was found that the grain leaves a clear trace without obvious chipping along the edges of the track at the beginning and at the end of the scratch. Diamond grain, having a sufficient hardness, begins to cut the shavings immediately after contact with the material. But the middle part of the scratch along the entire length has significant breaks along the edges. The arising of chips when a certain depth of grain penetration is reached is explained by the fact that with the increase in cutting depth, some new edges of the diamond grain come into operation, which results in the microcutting forces increase in the zone of the contact with the sample material, formation of highly dispersed chips and large breaks. The forces arising during grinding result in good endurance of diamond wheels, high quality of processing, and make it possible to choose rational technical parameters. The necessity of edge rounding can be justified by the complex of tasks facing the technologists. This is the cleanliness of the surface during machining and the cutting edge wear reduction. The cutting edges rounding radius and the speed of its formation are functions of the processing time, size and type of abrasive grain. These parameters are chosen empirically in a specific instance

Effects of Process Parameters on Material Removal in Vibration-Assisted Polishing of Micro-Optic Mold.

Process parameter conditions such as vibrating motion, abrasives, pressure and tool wear play an important role in vibration-assisted polishing of micro-optic molds as they strongly affect material removal efficiency and stability. This paper presents an analytical and experimental investigation on the effects of process parameters, aimed at clarifying interrelations between material removal and process parameters which affect polishing quantitatively. The material removal rate (MRR) and surface roughness which represent the polishing characteristics were examined under different vibrating motions, grain sizes of abrasives and polishing pressure. The effects of pressure and tool wear conditions on tool influence function were analyzed. The results showed that 2D vibrating motion generated better surface roughness with higher material removal efficiency while a smaller grain size of abrasives created better surface roughness but lower material removal efficiency. MRR gradually decreases with the increase of polishing pressure when it exceeds 345 kPa, and it was greatly affected by the wear of polisher when wear diameter on the polisher’s head exceeds 300 μm.

Three-dimensional characterization and modeling of diamond electroplated grinding wheels

This paper presents a study on the three-dimensional characterization and modeling of morphology of diamond abrasive grains and electroplated diamond grinding wheels. A diamond abrasive grain was modeled by a cubo-octahedron that was determined by the intersection between an octahedron and a cube. The study revealed that the side length of octahedron and its side-length ratio followed a normal distribution and a generalized extreme value distribution, respectively. High-precision characterizations of grain density and protrusion height were realized by measuring wheel replicas with laser scanning confocal microscopy (LSCM). It was found that the grain protrusion height followed a normal distribution with an average of ∼40% of the grain size. Considering the randomly-distributed shape, size, position and protrusion height of abrasive grains, a geometric model of electroplated diamond wheels was established. The results show that the predicted morphology of grinding wheels agreed well with the experimentally measured. The model enables an accurate kinematic simulation for designing precision grinding processes.

The Concentration’s Influence of the Abrasive Granules Particles on the Vibratory Finishing Optimization

The already initiated studies are based on size and forms of abrasive grains, but few studies have addressed the influence on the concentration of abrasive grains. This research has been done to remove some of the mysteries associated in the media abrasives or chips used in vibratory and barrel finishing, this process included within the functions and characteristics of media, its types and shapes, also the selection of the best grade for a given task. The present work provides guidance on the influence on the concentration of the particles (grain) of abrasive granules with the main parameters and technological indices of vibratory finishing treatment,in order to optimize abrasive granules and increase the productivity of the vibratory finishing taking into account media, which has certain characteristics, make it unique in its capabilities.

Optimal the Process Variables of Internal Grinding for Shrink Fit Tool Holder

The goal of this study was to investigate the optimal variables settings in internal grinding for shrink fit tool holder. The effects of the main grinding variables on finishing responses were comprehensively investigated based on Taguchi method. The main process variables such as abrasive grain size (AGS), grinding wheel speed (GWS), feed rate for rough (FRR), depth for rough (DR), feed rate for finishing (FRF), depth for finishing (DF), dressing speed (DS), and workpiece rotational speed (WRS) were chosen to determine their effects on grinding performances related to roundness and surface roughness in the internal grinding of the shrink fit tool holder. The experimental response values were transferred to signal-to-noise (S/N) ratios, and then the significant process variables associated with the grinding performance were examined by analysis of variance (ANOVA). In addition, the optimal combination levels of the grinding variables were also obtained from the response graphs of S/N ratios to improve the surface quality of internal grinding. The experimental results show that the significant grinding variable affecting the roundness was FRF. In addition, the significant variables with regard to surface roughness were AGS, GWS, FRR, DR, DF, and DS. The optimal grinding variable settings were achieved. Consequently, the finishing characteristics of internal grinding could be enhanced to meet the requirements of modern manufacturing applications.

Badania wpływu wielkości ziaren ściernych na jakość technologiczną w procesie przecinania AWJ stali S235JR

The influence of the abrasive grain size on the technological quality of the intersection of non-alloy structural steel S235JR, is presented. The experiment was carried out on a high-pressure water-jet APW 2010BB abrasive cutting machine using the abrasive garnet #80 and #120. Studies included the assessment of intersection surface macrostructure: slit width, shape defects and surface roughness. Experiment has confirmed that the size of abrasive grains significantly influences the macrostructure of the intersection surface. Smoother cuts can be made with finer grains, but finer abrasive particles have less kinetic energy, leading to reduction in the erosion capacity of the water-jet. The study was carried out at variable feedrate, therefore it was possible to determine the influence of the feedrate on the average square surface deviation. Increasing the feedrate resulted in a decrease in the entire width of the cut slit, which was especially noticeable in the lower cut zone of the workpiece.