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Aiming at the removal of native oxide film on 2024-T3 Al alloy before plasma electrolytic oxidation, the methods to reduce the fatigue damage caused by grit blasting are explored. Effects of the grit size and pressure on surface roughness, residual compressive stress (RCS), and fatigue life of the Al alloy are studied. Increasing grit size and pressure leads to the increase in the surface roughness and RCS. Based on the theorem of momentum and tool cutting principle, mechanism of the grits on the craters and RCS is revealed. It is found that the angularness of the small-sized grit results in the formation of long scratches. The grit with high kinetic energy induces the large craters and high RCS. The craters are the primary fatigue crack initiation source. Moreover, the craters with long scratch and large height lead to the premature fatigue failure of the grit blasted specimens. However, Fatigue behavior is insignificantly affected by the RCS. The results provide new insights into the fatigue deterioration mechanism and life optimization of the grit blasted samples. Consequently, a parameter optimization scheme for the fatigue life of the grit blasted Al alloy is proposed.

Thermoplastic composite materials are widely used for aerospace, automobile and structural applications due to their good combination of high strength to weight ratio and specific modulus. Combined with the ease of melt processing, good resistance to corrosion, low friction, and noise damping are attributes which make them a popular choice in a wide range of emerging applications. Random, short-fibre, E-glass fibre reinforced Polyamide 6 (PA6) composites were manufactured by injection moulding in three different fibre volume fractions (25%, 33% and 50%) and the samples were scanned using micro-CT. The tribological properties of PA6 and glass fibre reinforced PA6 were investigated in the abrasive wear mode by using a pin-on-disc test setup. The tests were done at an abrading distance of 257 m and applied load of 10 N. The abrasive wear experiments were performed against three abrasive grit size papers (220, 500 and 1000 grit), to ascertain the wear response of the studied materials with respect to these adverse running conditions. Moreover, the mechanical properties of PA6 and PA6 composites were examined using tensile testing and compression testing. The surface roughness of the worn surfaces was analysed using a 3D digital profilometer. The worn surface topographies were scanned using field emission scanning electron microscopy. It was observed that the optimum fibre loading that was associated with the highest wear resistance was 33% volume fraction of glass fibres, and the wear performance deteriorated with higher fibre loadings. The increase in the grit size showed a significant reduction to the wear rates of all compositions. The results confirmed that the wear performance of polyamide composites is highly dependent on the tribological system under which it is being tested. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Adverse health effects caused by exposure to airborne particles have been detected in recent years, however there is little knowledge about exposure to ultrafine particles with a diameter <100 nm. In this study, particle number concentration and size distribution in a range of particle diameters from 10 nm to 10 µm were determined during oak wood sanding. A hand-held orbit sander in combination with three types of grit size (P60, 120 and 240) of sandpaper were used. Measurements were obtained using a portable particle size distribution analyzer and an optical particle size spectrometer, carried out at 15-min intervals for each treatment by static sampling in the breathing zone. We also compared the optical particle size spectrometer to the aerosol monitor in order to evaluate the mass concentration of airborne particles in the range of 1 to 10 µm in diameter. Sanding paper with the finest grit, P240, showed a significantly higher number concentration of ultrafine particles, compared with P60 and P120 grits. The differences among particular grit size were statistically significant for microparticles. The size distribution of particles during sanding was not affected by grit size. For each grit size, apparent peak values of ultrafine and microparticle number concentrations were determined at approximately 15 nm, and 0.1 µm, respectively. Optical particle size spectrometer and aerosol monitor showed comparable results of mass concentration for the respirable fraction. [ABSTRACT FROM AUTHOR]

Introduction: Dentists in many other countries use dental diamond burs not only for gross tooth reduction but also for a wide variety of intracoronal procedures. With continuing use, however, the cutting capability of the carbide bur tended to decline while that of the diamond point remained quasi-constant. Difference in diamond is its rough surface compared to tungsten carbide bur. Diamond is slow cutting compared to tungsten carbide bur. Literature search revealed that most of the study done to evaluate cutting efficiency of diamond and tungsten carbide bur use on bovine teeth, cast metal and ceramic. Individually there was no comparative study on wear off of both found, and no study on wear off of these cutting tools on human teeth, no study on element present on diamond abrasive point and tungsten carbide bur after use. Aim: To compare morphological change in diamond abrasive points and tungsten Carbide burs after multiple use. Materials and Methods: This was an in-vitro Scanning Electron Microscopic study on 160 freshly extracted human mandibular molar teeth. Teeth are cleaned from debris and tissue with ultrasonic. In all teeth Class V cavity prepared in cervical third of crown in dimension of 3 mm occluso cervical height, 4 mm, mesiodistal width 4 mm, 2 mm depth, except in control group using different cutting tool. Total 80 piece of cutting tool were selected for class V cavity preparation in tooth. Among these 40 were abrasive points and 40 were tungsten carbide bur. Abrasive points were considered as Group A. Tungsten Carbide bur were considered as Group B. Group A abrasive points were again divided in to four sub group A1, A2, A3, A4 according to number of times abrasive points used for cavity preparations. Group B tungsten carbide bur were again divided in to four subgroup B1, B2, B3, B4 according to number of times tungsten carbide bur used for cavity preparations. The samples were analysed under scanning electron microscope. Results: In group-A, 9(22.5%) diamond abrasive point had score 0, 10(25.0%) diamond abrasive point score 1, 13(32.5%) diamond abrasive point had score 2 and 8(20.0%) diamond abrasive point had score 3.In group-B, 10(25.0%) tungsten carbide bur had score 0, 20(50.0%) tungsten carbide bur had score 1 and 10(25.0%) tungsten carbide bur had score 2.Distribution between score vs. groups was statistically significant (p=0.0082). Level of mean score was significantly higher in group-A than group-B. Difference of mean score in two groups was statistically significant (p=0.0158). Conclusion: With multiple use of diamond abrasive points and tungsten carbide bur, they reduce cutting efficiency as number of use increases. Because there is loss of diamond particles after one time use, morphological change after five-time use, and even exposure of partial metal blank after ten time use. In tungsten carbide bur after one time use and five-time use, we found morphological alteration, and after ten time use there was loss of blade integration in few places. Change in cutting tool may lead to inadvertent effect of teeth and pulp. [ABSTRACT FROM AUTHOR]

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.

Adverse health effects caused by exposure to airborne particles have been detected in recent years, however there is little knowledge about exposure to ultrafine particles with a diameter

For the research the samples of ash (Fraxinus excelsior L.), birch (Betula L.), black alder (Alnus glutinosa L.), Scots pine (Pinus Sylvestris L.) and spruce (Picea abies L.) wood were used with dimensions of 270×215×15 mm. All wood samples were tangentially planed, defect free and kiln dried. Before the research, the average moisture content, wood density, number of annual rings per 1 cm, average width of annual ring and wood surface grain direction were evaluated. Different wood surface roughness of the samples was obtained sanding wood samples in the eccentric sanding stand, using standard open-type sandpaper with different grit size. The arithmetic mean value of the single roughness depths of consecutive sampling lengths parameter Rz of the sanded wood samples were measured in five sectors along the wood grain, across and in the angle of 45°, using a contact stylus profilometer. In total 1800 measurements were done during testing series. Obtained measurement results were processed by digital Gaussian filter according to DIN EN ISO 11562. In the research the dependence of wood surface on wood species, grain direction and grit size of abrasive material was evaluated.DOI: http://dx.doi.org/10.5755/j01.ms.21.2.5882

The authors have performed analytical processing of great body of experimental data (obtained by them) on static strength and morphometric characteristics of standard (to DSTU 3292-95) synthetic diamond grits. This has revealed tendencies and an extent of variation of morphometric characteristics of the grits within a wide range of grades and grit sizes. A review of the relevant publications has been done, which has demonstrated the originality of the proposed problem statement. The paper defines the lines of further development of such investigations and shows their practical significance. [ABSTRACT FROM AUTHOR]

This study demonstrated the strength of a theoretical model founded on the Box-Behnken experimental design method to determine the surface roughness (Ra parameter) of solid Oriental beech (Fagus orientalis Lipsky) wood. The working parameters (sanding belt grit size of 60 to 100, feeding speed of 4 m/min to 10 m/min, and sanding cutting depth of 0.1 mm to 0.3 mm) of a wide belt sanding machine were determined. The Ra of the samples was experimentally described so that the experimental results were also remodeled with the Box-Behnken method to find the optimum parameters for the lowest Ra. An adjusted correlation factor of 93.6% for the Ra confirmed the compatibility between the experimental and theoretical findings. The high correlation (strength) allowed for a more detailed discussion of the effect of the working parameters on the Ra. The theoretical approach showed that the grit size factor had the largest effect on the Ra compared with the other factors. The optimum parameters were found to be a grit size of 100, feed speed of 4 m/min, and sanding depth of 0.1 mm for a minimum Ra for Oriental beech wood. The experimental data supported these parameters. [ABSTRACT FROM AUTHOR]

The grit size effect on high stress abrasive wear depth of stir cast hybrid self-lubricating Gr/SiC/Al composites was investigated in both as cast (AC) and heat treated (T6) condition. The tests were done at grit size of 100–200 µm, sliding distance of 75 m and applied loads of 5–15 N. The results obtained were differentiated with matrix alloy and SiC/Al composites. At 15 N load, the wear depth of hybrid composites w.r.t. matrix alloy reduced around 19.6% (at 100 µm grit size) and 16.4% (at 200 µm grit size) in AC condition; 26.9% (at 100 µm grit size) and 27% (at 200 µm grit size) in T6 condition. The wear mechanism was analyzed through wear surface analysis of pin and emery paper. [ABSTRACT FROM AUTHOR]

Sanding is the most common machining process used to prepare wood surfaces prior to coating. Hence, to improve surface quality and coating performance during this process, an optimal set of machining parameters should be established according to wood species and its final use. The effects of grit size and feed speed on surface properties and coating performance of red oak wood were studied. Surface quality was assessed by surface roughness, scanning electron micrographs, and wetting analyses. Coating performance was evaluated using pull-off adhesion tests on coated surfaces before and after an accelerated weathering. The results showed that smoother surfaces are obtained as the grit size number of the abrasive increased. On the other hand, minor differences were observed on cell damages and surface roughness as feed speed changed. Also, there was little difference among treatments concerning wetting behavior and surface energy. Pull-off strength was more affected by changes in grit size than feed speed. A P100-grit size program with a feed speed of 7 m/min resulted in a suitable roughness which provided good adhesion and high pull-off strength after aging test. [ABSTRACT FROM AUTHOR]

This study analyzes the critical static friction coefficient (μ0) and the static friction coefficient (μ) between work-piece and rubber belt during sanding medium density fiberboard (MDF) and particle board (PB). The purpose is to provide theoretical support for improving design techniques of sanding machine and choosing appropriate rubber belts for sanding. The results indicate that μ0 is a constant that can be calculated by maximum sanding force (sFMax) and maximum normal force (nFMax). Besides, there is an exponential relationship between intensity of pressure (P) and μ when work-piece is relatively static on a rubber belt. Among all sanding parameters, git size (G) has the greatest influence on μ. In single-factor experiment, we found that the smaller the nFMax is, the greater the μ is (for same rubber belts), but the variation rates of μ and nFMax are coincident. Six types of rubber belts are adopted, and the average μ of No. 1 and No. 4 are greater than others, but average μ of all the belts are lower than μ0, so when use such six types of rubber belts, a hold-down device or vacuum chuck should be equipped on the sanding machine. Patterns of rubber belts have some impact on μ, and appropriate patterns on the surface of rubber belts contribute to higher μ.

The paper presents an experimental study uponthe quantitative assessment of the surface qualityafter sanding, in case of some lignocellulosecomposite panels with decorative structure, made oflamellas obtained from different wood species,randomly jointed and having as special characteristicthe surfaces with transversal structure. The analyzedpanels were built-up in two variants: poplar withspruce wood and cherry with walnut wood. Theconstituted lamellas were finger-jointed in length andedge-jointed in width. The sanding operation wasperformed using grit sizes of 50, 80, 120 and 150. Inorder to measure the roughness parameters Ra, Rz,Rk, Rpk and Rvk, a MicroProfFRT equipment (withlight beam) was used. The results revealed that thevalues of the roughness parameters had a generaldecreasing tendency with grit size increasing. Theresulted values lead to the conclusion that the finalsanding grinding system applied on longitudinalsection of wood is not valid for the transversalsection of wood which is present on the surfaces ofthe studied panels. In this special case, whensurfaces have a transversal structure, an additionalsanding with a higher grit size is needed, in order toobtain a similar roughness value as for the surfaceswith longitudinal structure.

This paper studies the influence of the grit size of silicon carbide particles on the mechanical and electrical properties of stir cast aluminum matrix composites. A two step-mixing method of stir casting technique at (500 rpm) has been adopted. Type 1170 Al with (99.66 % C.P) and silicon carbide (SiC) particulates of 240 grit size (45 µm), 320 grit size (29 µm), 600 grit size (9 µm) and 1200 grit size (3 µm) were used. The incorporation of weight fraction of SiC ranges from 2.5 %, 5 %, 7.5 % and 10 %. The microstructures of the produced composites were examined using a scanning electron microscope. Mechanical properties were determined by using a universal testing machine of 30 KN load. Microhardness was performed on the composite specimens by using a LECO 700 HT tester with a load of 492.3 N and with a dwell time of 10 seconds. The electrical properties were determined using a Keithley instrument Model 2400 point probe machine. The results show that the modulus, yield strength and hardness of the composite increase at lower grit sizes of silicon carbide of 3 micron. The maximum hardness of 26.1 HVN and maximum modulus elasticity of 1517.6 N/mm was obtained at 7.5 % weight fraction of SiC. A boost in the mechanical and electrical properties of the produced alloys was gained by changing the grit size of the silicon carbide. [ABSTRACT FROM AUTHOR]

Ethanol production from starchy cereal grains is increasing rapidly due to increasing demand for alternative fuels. In Canada, wheat is the primary feedstock in ethanol plants. To improve the productivity of the ethanol plants in terms of product quality and yield, debranning of wheat grains may be employed. Debranning is advantageous in two ways. Firstly, bran removal increases the starch content of the feedstock, improving the fermentation efficiency of the ethanol plants. Secondly, bran, a valuable co-product can be used as an animal feed ingredient. In this study, experiments to optimize the debranning process were carried out using two kinds of abrasive equipment, the Satake and the TADD (tangential abrasive dehulling device) mills. Wheat samples (30 and 200 g) were debranned in the Satake mill at 1 215, 1 412, and 1 515 r/min rotational speeds, 30, 36, and 40 grit sizes, and 30, 60, and 90 s retention times, and in the TADD mill at 900 r/min rotational speed, 30, 36, 50, and 80 grit sizes, and 120, 180, 240, and 300 s retention times. In addition to debranning efficiency, the starch separation efficiencies of the two mills were calculated in different debranning conditions. In the Satake mill, the 30 g and 200 g sample size, 1 412 r/min and 1 515 r/min rotational speeds, all grit sizes, and 60 s of retention time demonstrated the highest debranning efficiency. Correspondingly, optimal results in the TADD mill were obtained with 200 g sample size, 900 r/min rotational speed, 50 and 80 grit sizes, and 180 s and 240 s retention times. However, based on the experimental results, Satake mill provided better debranning values compared to the TADD mill. The starch separation efficiency values supported these results. [ABSTRACT FROM AUTHOR]

This study analyzes the critical static friction coefficient (μ0) and the static friction coefficient (μ) between work-piece and rubber belt during sanding medium density fiberboard (MDF) and particle board (PB). The purpose is to provide theoretical support for improving design techniques of sanding machine and choosing appropriate rubber belts for sanding. The results indicate that μ0 is a constant that can be calculated by maximum sanding force (sFMax) and maximum normal force (nFMax). Besides, there is an exponential relationship between intensity of pressure (P) and μ when work-piece is relatively static on a rubber belt. Among all sanding parameters, git size (G) has the greatest influence on μ. In single-factor experiment, we found that the smaller the nFMax is, the greater the μ is (for same rubber belts), but the variation rates of μ and nFMax are coincident. Six types of rubber belts are adopted, and the average μ of No. 1 and No. 4 are greater than others, but average μ of all the belts are lower than μ0, so when use such six types of rubber belts, a hold-down device or vacuum chuck should be equipped on the sanding machine. Patterns of rubber belts have some impact on μ, and appropriate patterns on the surface of rubber belts contribute to higher μ. [ABSTRACT FROM AUTHOR]

Finishing mirror-like surfaces on chemically vapor-deposited diamond film using an in-process composite electroplating of diamond grains onto the tool surface, the tool can maintain its sharpness in a grinding process. The effect of diamond grit size of the tool on the grinding characteristics of diamond film is investigated. To promote optimum grinding efficiency, a high variation rate in the surface roughness of diamond film and a small growth rate in the coating thickness are desired. A distribution model of the diamond grits in the coating layer is deduced, and a composite electroplating in-process sharpening grinding mechanism is developed using a body-centered tetragonal structure. A two-stage composite electroplating in-process sharpening grinding procedure is used to grind the diamond film. A grit size of 25 µm is selected to conduct the composite electroplating in-process sharpening grinding for 30 min at an initial surface roughness of 1.1 µm. Then, the operating conditions are switched to a grit size of 3 µm and a grinding time of 180 min, and a mirror-like surface on the diamond film with an average surface roughness of 0.03 µm is obtained. [ABSTRACT FROM PUBLISHER]

method has been proposed for analytical calculation of the pressing force of a complex steel/hardmetal workpiece against the wheel working surface, which is restricted by the diamond grit strength, in elastic-mode infeed surface grinding. [ABSTRACT FROM AUTHOR]

Oxide films were formed at 350 °C in borate buffer solution on AISI 304 stainless steel priory abraded with wet SiC paper of different grit size. The films were characterised by Atomic Force Microscopy (AFM) and studied by capacitance, impedance, and photocurrent measurements. The images obtained by AFM microscopy show the evolution of the surface roughness of the films with increasing grit size. Capacitance measurements show that, in all cases, the electronic structure of the films is comparable to that of a p–n heterojunction. This structure is due to the development of space charge layers in the outer iron oxide region at the film/electrolyte interface and in the inner chromium oxide region at the film/metal interface. However, donor and acceptor densities are closely related to the surface roughness via the grit size of the wet SiC paper. An increase in capacitance leading to higher doping densities is manifested by an increase in grit size. These parameters are also frequency dependent. An investigation of the frequency dispersion in relation to the evolution of the surface roughness was performed by analysing the Bode plots through the impedance measurements. The photocurrent results, obtained for the oxide films formed on the different abraded AISI 304, show an increasing photoresponse with decreasing grit size. In spite of this, a constant value of the band gap energy was obtained whatever the oxide film considered. The photocurrent response near the absorption edge is also discussed. The photocurrent response at fixed wavelength and as a function of the applied potential is also influenced by the grit size. [ABSTRACT FROM AUTHOR]

This article shows the quantitative evaluation of the residual grit on a blasted substrate, and the removability of the residual grit is examined. Carbon steel plates were blasted by white alumina grit with mean diameters of 338 to 1106 µm. The velocity and the number of grit particles were measured during blasting. The residual grit was removed from a substrate surface by the dissolution of the blasted substrate surface. A mixed acid solution was used as the dissolution solution. The residual grit weight was 7 to 17 g/m2. The amount of the residual grit and the penetration depth of the embedded grit increased with increasing grit size. The penetration depth was 5 to 9% of the mean diameter of the grit. The residual grit weight and the penetration depth increased with the increase of the momentum of the grit particle. [ABSTRACT FROM AUTHOR]

Experiments were designed and conducted to evaluate the effects of cooling and dressing methods and five other factors on the grinding of glass. Surface roughness of the ground samples was measured and microscopic studies of the ground glass surfaces were performed. The column effect method and plotting method were applied to analyze and interpret the experimental results. The results showed that the average surface roughness heights of ground glass were improved by 5–36% and 42–52%, respectively, when an improved coolant system and dressing device were employed. The average surface roughness heights decreased by 52–58% and 30–37%, when smaller grit sizes and a resin-bond grinding wheel rather than a metal-bond grinding wheel were used, respectively. In addition, the surface roughness averages decreased by 18–23% and 13–18% when a smaller table-feed rate was used and truing of grinding wheels was performed, respectively. Moreover, compared with the surface roughness heights of the sample that was ground using the existing coolant system and manual dressing method, the surface roughness heights of the sample ground using both the improved coolant system and device-dressing method were improved by 46–70%, because of the positive interaction of these two factors. [ABSTRACT FROM AUTHOR]

The most urgent problems in meso-, micro- and nano-technological productions are controlling wetting of metals and alloys and liquid spreading over engineering surfaces after their hardware abrasive processing. Nowadays, there is a lack in theoretical basis and comprehensive experimental studies to predict the texture formation and change of the functional surface properties (including wetting) of metals and alloys after abrasive processing. In this study, based on the analysis of the three dimensional roughness parameters (amplitude, hybrid and feature) and elemental composition of the near-surface layer, the features of texture formation, changes in the surface free energy and wettability of copper and steel surfaces that are widely used in industry were established after their hardware abrasive processing. The use of abrasive material with an average grit size of up to 100 μm was found to significantly change the surface roughness. The abrasive processing significantly modifies the polar component in the surface free energy, while not influencing its dispersed component. The texture parameters allowing one to control both the growth and decrease of the polar component in the surface free energy were determined. It is shown that the abrasive processing directly influences the wettability properties and allows varying the contact angles in a sufficiently wide range of from 54.0° to 108.2° (for copper surfaces) and from 71.6° to 89.5° (for steel surfaces). [Display omitted] • To change the roughness of metals, abrasives with a grit size of up to 100 μm must be used. • The polar component of the SFE depends on the surface roughness. • The roughness parameters predicting the change in the SFE and wetting were established. [ABSTRACT FROM AUTHOR]