Abrasive Particle Size Research Articles

Investigation of technological parameters effect on metal removal during centrifugal rotary machining

Introduction. The study results on the single interaction under the centrifugal rotary part machining in the abrasive discrete medium are presented. Simultaneously with the numerical simulation, experiments were carried out on a centrifugal-rotary unit, and the maximum depth of penetration into the surface of the part, the single-track sizes, metal removal in one blow of an abrasive granule, were investigated. The removal of metal from workpieces was investigateddepending on the processing modes, characteristics of the abrasive particle and the processed material. Materials and Methods. The dependences for determining the metal removal from workpieces (steels 45, copper Cu-OF, and aluminum alloy D16T) are taken into account depending on the grain size (N3) of abrasive particles. The process of a single interaction of an abrasive particle and the workpiece surface is considered within the framework of the dynamic contact problem of the elasticity theory. The authors have carried out finite element modeling of the considered structures in CAE ANSYS package. Results. The results of theoretical and experimental studies on the metal removal from workpieces depending on the grain size of abrasive particles are presented. The technique of their implementation, the tool and equipment used are described. The results of theoretical and experimental studies are compared. Their fine precision is established. Abrasive tools and processing modes are selected. Discussion and Conclusions. The dependences constructed in the work provide determining the rational values of the technological parameters of the centrifugal rotary machining (CRM) process. They can be used under designing the CRM processes. Therefore, time and financial resources can be saved to achieve the desired surface quality.

The Surface Condition of Ni-Cr after SiC Abrasive Blasting for Applications in Ceramic Restorations.

Abrasive blasting is a process widely used in dentistry. One of the uses is the development of metal surfaces for connections with ceramics in fixed prosthetic restorations. The purpose of this paper was to check how the rough surface profile (width, height, and depth on unevenness) impacts the surface’s condition, like its wettability and percentage of stuck abrasives. The Ni-Cr alloy surface was abrasive blasted by silicon carbide with the various pressure parameters (0.2, 0.4, and 0.6 MPa) and abrasive particle sizes (50, 110, and 250 µm). Cleaned surfaces were examined for roughness, wettability, and percentage of stuck abrasive particles on the surface. The surface after abrasive blasting using 110 µm of abrasive size and 0.4 MPa pressure has the best wettability results. The width of unevenness may cause it. When the unevenness has too small or too large width and depth, the fluids may not cover the entire cavities because of locking the air. The surface condition of dental alloys directly affects metal–ceramic connection strength. The knowledge about the impact of the abrasive blasting parameters on the bond strength will allow one to create durable dental restorations.

Elbow precision machining technology by abrasive flow based on direct Monte Carlo method

The investigation was carried out on the technical problems of finishing the inner surface of elbow parts and the action mechanism of particles in elbow precision machining by abrasive flow. This work was analyzed and researched by combining theory, numerical and experimental methods. The direct simulation Monte Carlo (DSMC) method and the finite element analysis method were combined to reveal the random collision of particles during the precision machining of abrasive flow. Under different inlet velocity, volume fraction and abrasive particle size, the dynamic pressure and turbulence flow energy of abrasive flow in elbow were analyzed, and the machining mechanism of particles on the wall and the influence of different machining parameters on the precision machining quality of abrasive flow were obtained. The test results show the order of the influence of different parameters on the quality of abrasive flow precision machining and establish the optimal process parameters. The results of the surface morphology before and after the precision machining of the inner surface of the elbow are discussed, and the surface roughness Ra value is reduced from 1.125 µm to 0.295 µm after the precision machining of the abrasive flow. The application of DSMC method provides special insights for the development of abrasive flow technology.

Effect of Abrasive Particle Size Distribution on Removal Rate of Silicon Wafers

The effects of silica abrasives of five different particle sizes (10 nm, 40 nm, 60 nm, 80 nm and 100 nm) on the removal rate of silicon wafers were studied. The experiments were performed under two conditions, by taking the abrasive particles of uniform size and of two different sizes. The mixture of abrasive particles of two sizes increased the removal rate of the silicon wafer, and this improvement was more apparent when 10 nm particles were mixed with any other particle size. According to the stability of the slurry, the size pair of 10 nm and 60 nm presented the optimal result for the particle size mixing of abrasives. The physical model of the abrasive distribution between the silicon wafer and the polishing pad was established. The mechanism of the effect of mixed abrasive on the increase of silicon wafer removal rate was presented. Further, the contact area between the abrasive and silicon wafer was calculated by MATLAB. Based on this, the removal rate of the silicon wafer by the abrasive with mixed-sized particles was predicted with an error value of less than 10%.

Quantitative analysis on the surface topography of Ti-6Al-4V machined by abrasive suspension jet

Surface topography is the intrinsic determinant of the roughness that is a significant evaluation standard for the machining quality of the abrasive suspension jet (ASJ). To achieve quantitative analysis on the surface topography machined by ASJ, this paper measured the roughness and the scratch size of the cutting surface with an ultra-deep three-dimensional microscope. Ti-6Al-4V (TC4), a typical hard machining material widely used in aviation industry, was chosen as the cutting target. From a macroperspective, the cutting surface is divided into four zones from top to bottom including the initial zone, the smooth zone, the transition zone, and the rough zone. With 1.6-μm set as the standard roughness, the length of the initial zones and the smooth zone were analyzed and determined. From a microperspective, there are a large number of particle scratches with micron scale size laid on the cutting surface. The experimental results showed that the length of the scratches in the initial zone was less than the one in the smooth zone, while it was opposite in the scratch depth and width, and that the initial zone is larger than the smooth zone in surface roughness could be explained. The abrasive particle size is the only influent parameters of the scratch size, and small abrasive particles can be used for reducing the roughness in the initial zone and smooth zone. The conclusions can provide theory guidance for abrasive water jet processing titanium alloys precisely.

Estimation of magnetorheological fluid constituent’s concentration for efficient finishing process

ABSTRACT Efficacy and outcome of all magnetorheological finishing (MRF) processes depend on rheological properties of the magnetorheological (MR) fluid which consists of carbonyl iron particles (CIPs), abrasives and carrier fluid. Thus it is important to understand particle distribution in MR fluid which affects the rheological properties of the fluid under the influence of the applied magnetic field and hence the finishing process. A hexagonal microstructure model of MR fluid is considered and a modified model of abrasive doped MR fluid is developed for generation of estimation curve based on ratio of size of abrasive particles to CIP. MR fluid was prepared based on these estimated values and was used for finishing of N-BK7 glass on Ball End MRF (BEMRF) machine. MR fluid with four different abrasive size to CIP size ratios were prepared with CIP volume fraction of 32.9% and Cerium Oxide particles volume fraction of 12.5% with 54.6% water. Another experiment with size of cerium oxide particles to size of CIP ratio of 0.761 is taken for four different concentrations of abrasives and CIPs. Best results with 79.85% improvement in roughness and 0.672 µg/minute MRR were obtained for fluid prepared as per proposed estimation curve for efficient finishing process.

Fluid-structure interaction modeling of the abrasive waterjet drilling of carbon fiber reinforced polymers

Abstract The major challenges facing engineers while fabricating high precision components from carbon fiber reinforced polymers (CFRP) especially when using an abrasive waterjet (AWJ) include the predominant interlaminar delamination and tapered kerfs. Therefore, in the present work, a comprehensive 3-D transient fluid-structure interaction (FSI) model is developed and numerically simulated to investigate mechanisms leading to delamination and hole-geometric defects while drilling autoclave cured aerospace grade multidirectional CFRP laminates. The FSI model comprised a two-way interaction between the computational fluid dynamics (CFD) flow model and structural finite element (FE) model. The CFD model explored the dynamic jet characteristics while impinging the anisotropic CFRP surface. The resulting forces from the CFD domain acted as loads in the transient FE model to predict the initiation of cracks and delamination. Subsequently, extensive experiments were conducted to validate the proposed numerical model. The results illustrated that during abrasive waterjet drilling of CFRP, delamination was initiated by the hydraulic impact as the abrasive waterjet penetrated the workpiece. Additionally, the study revealed that an increase in abrasive waterjet pressure and abrasive particle size resulted in a higher inter-ply debonding and crack propagation. Correspondingly, an increase in the standoff distance (SoD) resulted in reduced crack propagation and delamination. Further, the liquid-solid interface exhibited asymmetric cracks. The present findings not only provide requisite guidelines to achieving high-precision drilling of multidirectional CFRP but also provide technical guidelines to improving the performance characteristics of the abrasive waterjet machining (AWJM) process.

Effect of the Lapping Platen Groove Density on the Characteristics of Microabrasive-Based Lapping.

Microabrasive-based lapping is widely used in the manufacturing of single-crystal substrates such as sapphire, SiC, and GaN. Although many studies have been conducted to improve the lapping process characteristics, most of them focused on process conditions or consumables. In this study, the effect of the lapping platen groove density on the lapping characteristics was studied using a sapphire substrate. Groove density was defined as the ratio of groove width to groove pitch, and the displacement of the lapping head was measured to calculate the oil film thickness. It was confirmed that, for groove densities below 0.30, hydroplaning occurs when the oil film thickness increases. When the oil film thickness is larger than the abrasive particle size, the material removal rate is low because the abrasive does not participate in the lapping process. When the oil film was developed, the experimental results showed a high surface roughness and poor flatness of the substrate, as only large abrasive particles participated in the lapping process. Therefore, to improve the lapping characteristics, it is important to reduce the groove density by reducing the groove pitch, which prevents the development of the oil film.

Mode transition from adsorption removal to bombardment removal induced by nanoparticle-surface collisions in fluid jet polishing

The effects of impacting particles from a jet of liquid on the removal of a surface material (on the impacted workpiece) were investigated. Experimental observations show that the cross section of the material removed changed from ‘W’-shaped to ‘U’-shaped as the size of abrasive particles was increased. Comparisons between removed material profiles and particle collision distributions indicate that the particle-surface collisions are the main reason for the material removal. The deduced number of atoms removed by a single collision implies that a transition occurs in the removal mode. For nanoscale particles, the polished surface is likely to be removed in an atom-by-atom manner, possibly due to the chemisorption of the impacting particles on the impacted surface. Contrarily, for the case of microscale particles, bulk material removal produced by particle bombardment is more likely to occur. The present mechanism of material removal for particle-surface collisions is further corroborated experimentally.

Orthogonal Experimental Research on Dielectrophoresis Polishing (DEPP) of Silicon Wafer.

Silicon wafer with high surface quality is widely used as substrate materials in the fields of micromachines and microelectronics, so a high-efficiency and high-quality polishing method is urgently needed to meet its large demand. In this paper, a dielectrophoresis polishing (DEPP) method was proposed, which applied a non-uniform electric field to the polishing area to slow down the throw-out effect of centrifugal force, thereby achieving high-efficiency and high-quality polishing of silicon wafers. The principle of DEPP was described. Orthogonal experiments on important polishing process parameters were carried out. Contrast polishing experiments of silicon wafer were conducted. The orthogonal experimental results showed that the influence ratio of electric field intensity and rotation speed on material removal rate (MRR) and surface roughness was more than 80%. The optimal combination of process parameters was electric field intensity 450 V/mm, rotation speed 90 rpm, abrasive concentration 30 wt%, size of abrasive particle 80 nm. Contrast polishing experiments indicated that the MRR and material removal uniformity of DEPP were significantly better than traditional chemical mechanical polishing (CMP). Compared with the traditional CMP, the MRR of DEPP was increased by 17.6%, and the final surface roughness of silicon wafer reached Ra 0.31 nm. DEPP can achieve high-efficiency and high-quality processing of silicon wafer.

Quality Prediction and Discussion of an Abrasive Flow Precision Polishing Baffle Servo Valve Nozzle Based on Orthogonal Experiments

Through range and variance analyses of an orthogonal experiment, the key factors of abrasive flow precision polishing (AFPP) are confirmed. The influence of grinding speed, abrasive concentration and abrasive particle size parameters on AFPP is secondary to action factors. The optimum AFPP process parameters are obtained. Under these parameters, the Ra value of the surface roughness of the nozzle orifices is acceptable. From 0.679 µm before abrasive flow polishing (AFP) to 0.143 µm, the quality of small holes improved obviously. The quality prediction model of the AFPP baffle servo valve is established through experimental research and data calculation, which can effectively predict the surface quality of the AFP baffle servo valve nozzle. The results of the AFP experiment show that the prediction model is effective and feasible and can obtain the best surface quality. The research results can provide theoretical guidance and technical support for the development of quality control technology of AFPP nozzles.

Abrasive Size and Fiber Direction Effects on the Wear Behaviour of CFRP Composite under Rotary Abrasion

Rotary wear tests were performed on unidirectional graphite fiber reinforced epoxy to study the effect of fiber orientation and abrasive particle size on the wear resistance and mechanism of the graphite/epoxy polymer composite. The tests were performed at a constant load of 1250 grams for 10000 cycles with abrasive particle sizes of 15 and 55 μm using Taber rotary platform abrasion tester. The surface topology and material removed along the wear track were obtained for a range of fiber orientations. The surface roughness was found to decrease as the fiber orientation increased from 0° to 90°. Negative skewness indicated the presence of numerous valleys on the surface. These variations in the surface roughness parameters were more pronounced for higher particle size of 55 μm. Maximum wear occurred at 135°. Further, the wear mechanism and type of damage were identified through SEM micrographs. Distinct damage could be identified at 0°, 45° and 90°.

Study on cutting speed and energy utilization rate in processing stainless steel with abrasive water jet

Cutting speed and energy utilization rate are two very important technical indexes for judging metal processing with abrasive water jet (AWJ). Cutting speed is related to the time benefit, while energy utilization rate is related to the economic benefit of AWJ processing. Based on theory of inelastic impact mechanics and hydrodynamics, the mathematical model of cutting speed and energy utilization rate in processing stainless steel with AWJ was established. And the discrete numerical analysis of the mathematical model was carried out. The effects of different jet parameters on cutting speed and energy utilization rate were explored. Cutting experiments were carried out to verify the model. The results show that with the increase of outlet pressure, the cutting speed increases linearly. With the increase of outlet pressure of 5 MPa, the cutting speed increases by 0.075 mm/s. When the outlet pressure increases from 10 to 46 MPa, the energy utilization rate decreases from 137 to 51.2 MJ/mm3. With the increase of mass fraction of abrasive, the cutting speed and energy utilization rate will increase first and then decrease. When the mass fraction increases from 5 to 25%, the cutting speed increases from 0.1504 to 0.2024 mm/s then decreases to 0.1308 mm/s, and the energy utilization rate increases from 35.13 to 43.93 MJ/mm3 then decreases to 23.73 MJ/mm3. The change of size of abrasive particle has no significant effect on cutting speed and energy utilization rate.

Compressive strain formation in surface-damaged crystals.

The mechanism of formation of residual strain in crystals with a damaged surface has been studied by transmission electron microscopy in GaAs wafers ground with sandpaper. The samples showed a dislocation network located near the sample surface penetrating to a depth of a few micrometres, comparable to the size of abrasive particles used for the treatment, and no other types of defects were observed. A simple model for the formation of a compressive strain induced by the dislocation network in the damaged layer is proposed, in satisfactory agreement with the measured strain. The strain is generated by the formation of dislocation half-loops at the crystal surface, having the same component of the Burgers vectors parallel to the surface of the crystal. This is equivalent to the insertion of extra half-planes from the crystal surface to the depth of the damaged zone. This model can be generalized for other crystal structures. An approximate calculation of the strain generated from the observed dislocation distribution in the sample agrees with the proposed model and permits the conclusion that this mechanism is in general sufficient to explain the observed compressive strain, without the need to consider other types of defects.

The effect of the rumen washing mechanism in sheep differs with concentration and size of abrasive particles

Measures of tooth wear have widespread use as proxies in palaeobiological reconstructions. In order to apply these proxies, an understanding of potential influence factors on wear is important. The processes during the digestion in the ruminant organism lead, possibly inadvertently, to a washing of material before it is regurgitated for rumination chewing. Therefore, ruminants might experience less tooth wear from external abrasives such as dust and grit, which can be washed off, compared to nonruminant herbivores. Details of the washing mechanism, including its efficiency in relation to abrasive size, have not been explored so far. Here, we describe the location and quantity of external abrasives in the gastrointestinal tract of sheep fed seven diets containing external silica abrasives varying in concentration (0, 4, and 8%) and size (4, 50, and 130 μm). As typical for ruminants, external abrasives accumulated mainly in the fourth stomach section, the abomasum. Compared to the diet, the dorsal rumen contents – from where material for regurgitation and rumination is recruited – were depleted of external abrasives for the 130 μm silicates, and for the 8% concentration of 50 μm silicates, but not for the 4 μm silicates or the 4% concentration of 50 μm silicates. These results suggest that the rumen washing mechanism is probably more protective against abrasion from grit and sand, and potentially less efficient against fine dust.

An in-vitro study of temperature rise during rotary ultrasonic bone drilling of human bone

Temperature rise in surgical bone drilling is an important factor that leads to death of the bone cells, known as Osteonecrosis, and results into poor osteosynthesis i.e. implant failure. The present work aims to study the temperature rise during bone drilling by a recently developed operation theatre (OT) compatible machine. The temperature during the drilling process was recorded from K-type thermocouple devices, which were embedded in the human tibial bone at four different positions (at 0.5 mm, 1.0 mm, 1.5 mm, and 2.0 mm) from the drilling site. Comparative study revealed that rotary ultrasonic bone drilling (RUBD) technique produced lesser temperature (40 – 50%) than conventional drilling on human tibia. Statistical model was developed to predict the temperature rise in RUBD process using response surface methodology (RSM), and the optimum parameters were determined using Genetic Algorithm. Analysis of variance (ANOVA) was carried out at a confidence interval of 95 percent (α = 0.05) to determine the influence of various drilling parameters such as rotational speed, feed rate, drill diameter and abrasive particle size on temperature rise. It was observed that the rotational speed was responsible for the maximum temperature rise (51.8%) followed by drill diameter (18.8%), and abrasive particle size (14.3%); whereas, the feed rate contributed minimal (4%) temperature rise.

Investigation of Production and Abrasive Wear Behavior of Functionally Graded TiB2/Al and TiB2/Al–4Cu Composites

In this study, it is aimed to investigate the production and abrasive wear properties of functionally graded TiB2/Al and TiB2/Al–4Cu composites. Using in situ technique, titanium di-boride (TiB2) particles are being spontaneously formed in liquid matrix, resulting in a “Al(l) + TiB2(S)” semisolid at 900 °C. The semisolid solidifies under a centrifugal force at 1500 rpm rotation speed in a steel mold to produce functionally graded composites. The properties of composites such as density, abrasive wear, hardness and microstructure were examined by dividing into four zones from the outside to the inside of the composite. Volume loss of composites were examined by using L16(4124) orthogonal design, considering some factors such as matrix type of composites, region of composites, abrasive particle size, sliding speed and sliding load according to Taguchi method. The results showed that both TiB2/Al and TiB2/Al–Cu composites had two regions: the TiB2-reinforced and non-reinforced regions. It was determined that the volume loss increased with increasing load, speed and abrasive particle size and decreased with increasing TiB2 particles reinforcement ratio.

Influence of Abrasive Water Jet Parameters on Steel Surface

Descaling is a recent application of abrasive water jet machining. Several parameters can affect the steel surface and influence the descaling effect of abrasive water jet machining. The influence of the jet parameters has been experimentally studied, and the width of the surface morphology and roughness measured. The results show that the descaling width increases as the jet distance increases from 10 mm to 90 mm; the material removal at the cross section tends to be uniform. As the abrasive particle size is increased from 75 μm to 150 μm, the descaling width decreases whereas the material removal uniformity increases. Increasing the jet pressure from 30 MPa to 70 MPa increases the descaling width and material removal; the surface roughness improves to some extent, but the descaling uniformity decreases. As the jet angle is increased from 30° to 90°, the uniformity of the material removal decreases despite the increase in the descaling width.

Application of Taguchi’s method to evaluate abrasive wear behavior of functionally graded aluminum based composite

In this study, abrasive wear properties of functionally graded aluminum based composites have been studied by Taguchi’ approach. Using in-situ technique, various types of composites were produced under the same conditions in order to see the effects of the characteristic properties on the abrasive wear behavior of composites.Abrasive wear test results of composites have been examined by using L16 (2344) orthogonal design, considering seven factors, reinforcement type, regional variation, matrix type, abrasive particle size, applied load, sliding speed and sliding distance, according to Taguchi method.The results showed that the volumetric loss increases with increasing abrasive particle size, applied load, sliding speed and distance, and moreover TiB2 particles are more effective than Al3Ti flakes to decrease wear loss.

Effect of operating parameters and abrasive particle size on three-body abrasion performance of alkali-treated eucalyptus fiber reinforced polyvinyl chloride composite

The use of natural fiber polymer composites is being considered in many applications. In the current work, the three-body abrasion performance of an alkali-treated eucalyptus and polyvinyl chloride (PVC) composite was studied at different applied loads (40 to 130 N), sliding velocities (1.86 to 3.73 m/s), sliding distance (up to 4.0 km), and abrasive particle size (0.25 to 0.75 mm). The results showed that the applied load and sliding distance affected three-body abrasion. At lower applied loads and shorter sliding distances, higher specific wear rates (Ws) and more obvious worn surface features were exhibited, while sliding velocity had less of an effect on the wear behavior. The Ws and worn surface roughness increased as abrasive particle size increases, and deeper grooves and higher deformation on the worn surface were found due to the enhanced material loss from the larger particle size abrasive.