An investigation of the wear of abrasive grains by rubbing on ferrous and non-ferrous surfaces

The wear characteristics of abrasive grains have been extensively studied using stationary grains carrying a load of 1 or 2 lbs. bearing against a disk rotating at approximately 800 r.p.m. Mean wear volume was found to increase linearly with sliding distance. Carbon steel disks gave lower wear rates for the friable grains than the ductile grains while the reverse was found to be true for Waspaloy and stainless steel. The effect of sliding speed on wear rate and coefficient of friction is also discussed.     

On the attritious wear of abrasive grains

The overcut fly milling operation that closely simulates fine grinding has been used extensively to study the performance of several grain types at moderate and low wheel speeds. Results indicate that the wear of abrasive grains for a particular grain-work-piece combination is a function of chip thickness, chip length and wheel speed. For a constant chip length, the wear rate increases exponentially with increasing chip thickness. There is, however, an optimum value of chip length which gives minimum wear at any particular chip thickness.     

An investigation of the abrasive wear of mineral-cutting tools

The paper describes an investigation of wear of tools in cutting abrasive rock and is relevant to the problems encountered in the coal mining industry. The emphasis of the paper is on tribological aspects rather than tool performance aspects and the treatment is at a macroscopic level. A range of tool geometries and materials were included in the investigation and the effects of length of cut and depth bf cut studied.It is concluded that the wear of a cutting tool differs from the wear observed in conventional sliding contact situations with respect to the relationship between wear and applied load. This is attributed to the displacement control, rather than load control, of the cutting process and the consequent degradation of the abrasive under high contact pressures. The rate of removal of material by wear at the cutting edge of the tool, within the range of variables examined, (a) is independent of the rake and clearance angles of the tool and the width of the wear flat, (b) is proportional to the distance cut (excluding an initial high rate) and the width of the tool, and (c) decreases with increasing depth of cut and tip hardness.     

An investigation on three-body abrasive wear test at elevated temperature

A high temperature three-body abrasive wear tester has been designed and made. In order to exhibit the effect of oxidation on the wear amount of specimen and to simulate various service conditions, the oxygen content in atmosphere, the time of exposing specimen in atmosphere and the intensity of abrasion can be controlled in the tester. In the temperature range 20–900 °C, both the discriminability of wear resistances of materials and the data reproducibility of the tester are quite satisfactory. Moreover, an intermittent oxidation-abrasion test procedure has been established for investigating the interaction of oxidation and abrasion at elevated temperature. By comparing the result of test performed in argon atmosphere with that in ambient atmosphere, the respective effects of oxidation and abrasion on volume loss of specimen can be clearly distinguished.     

Simulation of grinding with wear of the abrasive grains

A geometric model of grinding is developed. For the first time, this model takes account of wear of the abrasive grain. That permits prediction of the surface roughness at any time of tool operation. The wear is taken into account in terms of the physicochemical and mechanical interaction of the abrasive and the workpiece. This is of great importance for multiproduct manufacturing.     

Physicochemical wear of abrasive grains during grinding processes

One of the modes of the wear of abrasive grains that occur during grinding is physicochemical wear, which is caused by the intensive interaction between an abrasive material and a material being ground. Despite the short duration of contact between a grain and a blank at high surface temperatures with the friction of the material being ground against the wear site of the abrasive grain, as well as juvenile and subsequently oxidized surfaces, predetermine the physicochemical interaction between the abrasive material and the material being ground. The problem of developing a quantitative characteristic of these processes has not yet been solved. A system of coefficients of the chemical affinity of the abrasive material and the material being ground that characterize the intensity of the physicochemical processes that occur in the zone of contact is proposed.     

Three-body abrasive wear with small size diamond abrasives

Three-body abrasive wear rate was measured as a function of abrasive size and applied load using molybdenum alloy spheres of diameter 25.4 mm as test specimens. Diamond abrasives in the size range 1–60 μm normally used for metal lapping were tested. Tests were conducted at lap loads ranging from 9.8 to 107.9 N. For a given load it was found that there is a maximum abrasive size beyond which the wear rate will not increase and may even decrease. Several explanations of this critical size effect reported in the literature were evaluated on the basis of physical evidence.Wear rate generally increases linearly with increasing load. However, this did not occur with small abrasives. This deviation from linearity was found to be the result of an unusually effective abrasive wear condition. An explanation of this effect is given.     

Distribution of diamond grains in fixed abrasive wire sawing process

For over 20 years, wire sawing has been the primary method used for slicing ingots of silicon, sapphire, and silicon carbide into wafer substrates. Fixed diamond wire sawing has recently emerged as an alternative to slurry wire sawing as a means to shorten the time required for slicing and reduce the usage of slurry. The distribution of diamond grains on the wires strongly influences slicing performance in terms of material removal, surface topography, and subsurface damage. However, few studies have investigated this topic. This study established a model with which to simulate the distribution of diamond grains. Simulation results demonstrate that a higher density distribution reduces the rate of material removal because the loading is shared by the abrasives, thereby preventing the grains from penetrating deeply enough into the workpiece to facilitate the removal of material. Lower distribution density was shown to increase the loadings on the abrasives. These results demonstrate the importance of distribution density of diamond abrasives on the wire with regard to slicing performance.     

Experimental investigation of oil pockets effect on abrasive wear resistance

The experiments were carried out using a block-on-ring tester. The stationary blocks were modified by a burnishing technique in order to obtain surfaces with oil pockets of spherical shape. The area density of oil pockets varied in order to explore their effect on wear resistance and wear intensity. Specimen surfaces had dimples with depths 45-60 μm and diameters 1-1.2 mm. The area density of oil pockets S_p was in the range 4-20%. The block samples were made from bronze B101 (CuSn10P) of 138 HB hardness. The rotated rings were made from 42CrMo4 steel, hardness of 40 HRC obtained after heat treatment. The tested assembly was lubricated by mineral oil L-AN 46. The experiment was carried out under artificially increased dustiness conditions. The dust added to oil consists mainly of SiO₂ (74%) and Al₂O₃ (15%) particles. During the test friction force and temperature of block sample were registered. The tendencies of block surface topography changes during wear were analysed. It was found that sliding pairs with textured specimens were not superior to a system with a turned block with regard to abrasive wear resistance.     

磁力研磨法去毛刺的实验研究

研制了去毛刺实验装置,用有限元法分析了加工间隙磁场分布,实验结果表明利用磁力研磨法能够去除棱边毛刺,并保持适宜的棱边圆角半径。     

A preliminary investigation of frictional heating during abrasive wear

The frictional heating occurring under conditions of slow abrasive wear was estimated by measuring the thermoelectric output between abrasive particles and a wear pin. It is suggested that wearing surfaces locally reach temperatures high enough to affect properties determining the wear rate, and this is discussed with reference to specific materials.     

Correlation between the surface quality and the abrasive grains wear in optical glass lapping

The subject of this study is to determine the relation between the optical glass surface quality and the wear of abrasive grains used in finishing process. The glass surface quality was characterized by the roughness (rms,CLA and peak to valley). Alumina abrasive grains (Al₂O₃) are used with average sizes (80, 40, 20, 7 μm) respectively. After 2 min lapping for each fraction of grains the following RMS are obtained 1.39, 0.57, 0.51, 0.33 μm. The corresponding peak to valley are respectively 7.5, 3.66, 2.88, 2.10 μm. The grains wear was characterized by the grains edges wear (roundness) and by their fractures. An optical microscope (CMM Scope Check) and a SEM are used for their observation. The alumina grains size distribution was also studied using a laser diffraction particle size analyzer (Shimadzu Sald-2001).     

A study of abrasive wear mechanisms using diamond and alumina scratch tests

Scratch tests using alumina (Al₂O₃) abrasive particles and Vickers diamond pyramids were employed to study material removal mechanisms in the abrasion of cobalt-base powder metallurgy alloys 6 and 19. The alloys were specially prepared to produce either fine or coarse carbides in order to study the effects of carbide size. Scanning electron microscopy was used to analyze the scratch grooves, the scratch tools and the wear debris particles.

Comparison of scratch tests with Al₂O₃ and diamond pyramids shows that many features produced by the extremely hard regularly shaped diamond tools are different from those produced by irregular Al₂O₃ particles. Except for differences produced by tool wear, multiple-pass Al₂O₃ scratch tests provide excellent reproduction of the material removal processes which occur in low stress Al₂O₃ abrasion. Al₂O₃ scratches produced both chip-like and fine irregular debris particles similar to those extracted from spent abrasive used in wear testing.

Material removal in the fine carbide alloys is facilitated by the direct removal of entire carbides within the volume of micromachining chips removed from the scratch groove. In coarse carbide alloys, machining chips from large carbides are observed, but the depth of cut in the carbide phase is less than that in the f.c.c. matrix and this leads to a decrease in the volume of material removed. Direct comparison of chips removed from fine and coarse carbide alloys by the same Al₂O₃ particle shows larger chips from the fine carbide material.

The effects of subsurface deformation and surface irregularities on material removal were studied by carrying out scratch tests on specimens subjected to prior abrasion and by investigating multiple-pass scratches in the same scratch groove.     

An equation for the abrasive wear of elastomeric O-ring materials

An empirical equation was obtained via dimensional analysis, which relates the abrasive wear volume to the friction force, specimen load, sliding distance and specimen breaking strength for O-ring materials. Wear experiments on O-rings molded from four nitrile compounds and one polyurethane material were conducted on a special pin-disc-type testing machine. Specimens cut from a size 330 O-ring were held against a roughened rotating steel wear cylinder with a load which varied from 5 to 15 lbf. Both the specimen and the wear cylinder were immersed in an abrasive mud of the type used for oil well drilling. The sliding velocity was held constant at 11 in s^?1. The wear resistance of the polyurethane was two times better than the best nitrile compound.     

Some observations on the wear of aluminium rubbing on steel

Wear tests on high pressure counterformal contacts between an aluminium alloy and a low carbon steel produced different regimes of wear depending on specimen geometry and whether the aluminium specimen was disposed as the stationary specimen or the counterface. Oxidative wear was maintained at high levels of unit load (200 MN m^?2) provided that the surfaces were not subjected to large-scale plastic flow. Wear rates were greatly increased when the amount of aluminium transfer onto the steel surface was substantial, and under these circumstances evidence of back transfer was observed.     

Principles of abrasive wear

The mechanisms of abrasive wear are reviewed and laboratory test methods assessed. The results of abrasive wear tests on technically pure metals, heat treated steels, cold work hardened materials, hard wear resistant materials and minerals against fixed abrasive grains are discussed. The correlation between abrasive wear resistance and the physical properties of materials is established; the effect of the relative hardness of the abrasive and impact loading is considered. The basic principles of abrasive wear derived are outlined.     

Cutting geometry of abrasive grains

The geometry of abrasive grains and their cutting section is considered. This is a very important characteristic of the working surface of abrasive tools.     

An AFM study of single-contact abrasive wear: The Rabinowicz wear equation revisited

A nanoscale study of the abrasive wear behaviour of a ductile monophasic metallic alloy (the stainless steel AISI 316L) is presented. By using atomic force microscopy (AFM) based techniques, particularly a diamond tip mounted on a stiff steel cantilever, the contact of a single abrasive asperity was simulated, and it was possible to determine accurately the load threshold below which no measurable wear occurs. It was observed that, once this nanoscale threshold for wear is overcome, the worn volume increases linearly with the load, as predicted by the Rabinowicz model. However, it was found that, although this critical threshold for measurable wear is most certainly related with the yield-onset of plastic deformation, it cannot be predicted by using directly a criterion based on the bulk microhardness. Hence, the results presented in this paper strongly indicate that indentation size effects play a crucial role on the response to abrasive wear at the asperity contact level.