Papers by Keyword: Abrasive Grain

Abstract: Currently, two main methods of applying abrasive grains to the surface of a flexible backing - mechanical and electrostatic - are used for the manufacture of grinding tools. The mechanical method of abrasive applying involves pouring an abrasive onto a backing, on which an adhesive has been previously applied. In this case, grains are fixed on the surface of a backing in a non-optimal way in a chaotic manner without taking into account their geometric parameters. This subsequently leads to rather low performance of such tools, thereby not allowing the full use of their capabilities. In the electrostatic coating, abrasive grains are oriented along their major axis perpendicular to a backing. A large number of studies show that grain orientation by this method improves the cutting performance of an abrasive paper. At the same time, the mechanism of the effect of an electrostatic field on abrasives of various grain sizes, depending on the interelectrode space, has not been fully studied. Based on this, studies aimed at scientific substantiation of the process of orientation of abrasive grains on the working surface of an elastic tool in an electrostatic field are of great relevance. This work is devoted to the study of the effect of an electrostatic field on abrasive grains. The article presents some results of studies of the susceptibility of brown aluminium oxide 14A of various grain sizes to the electrostatic effect.

Abstract: To solve the problem of obtaining an effective composite abrasive material that allows preserving the focusing tube and increasing the cutting capabilities of the water jet, the authors obtained theoretical dependences that establish the relationship between the strength of the abrasive-polymer compound and its production modes

Abstract: A simulation of the material removal by a single abrasive grain in nanometric grinding is presented in this paper. Molecular Dynamics method is used for modeling the diamond grain and the copper workpiece. The Morse potential function is used to simulate the interactions between the atoms involved in the procedure. The abrasive grain follows a trajectory with decreasing depth of cut within the workpiece to simulate the interaction of the grain with the workpiece. The influence of the grain shape, being either square or rectangular, and of the orientation of the grain, where the grain has rake angle 10^o, -10^o and-20^o, are studied. From the analysis it is apparent that both grain morphology and orientation play a significant role on chip formation, grinding forces and temperatures. With the appropriate modifications, the proposed model can be used for the simulation of various nanomachining processes and operations, in which continuum mechanics cannot be applied or experimental techniques are subjected to limitations.

Abstract: In grinding process, the grinding wheel profiles are copied to workpiece surface. Therefore, the finished workpiece surface can be estimated by the grinding wheel surfaces. In this paper, new measuring method of the distribution of cutting edge in grinding wheel surface by two AE sensors is proposed. From experimental results, it is confirmed that the distribution of cutting edges in wheel surface can be measured easily by the proposed method compared to another measuring method.

Abstract: The form of grinding grains is an important parameter which as show researches, has a great impact on efficiency of use of grinding tools. Generally the methods used for an assessment of a form of grinding grains can be divided into two groups – qualitative and quantitative. The principle of an assessment of a form of grain on qualitative methods is based on grain reference on some signs in the relevant group of forms. All existing ways of a quantitative assessment of a form of grain are based on research of a horizontal projection of grain. However application of horizontal projection results in inaccuracy in the analysis of a form of abrasive grain. This work is devoted to accuracy increase at an assessment of a form of grinding grains.

Abstract: Photovoltaic power, a well known renewable energy source, has been introduced on a global basis. A popular variation has many solar battery cells constituted by a polycrystalline or a single crystal silicon wafer. Therefore each cell’s conversion efficiency from solar energy to electrical energy is very essential. Recently, a fixed grain wire method, in which the wafer is sliced by a wire fixing grains on the surface with a bond or an electrodeposition, is employed in that slicing process. Thus, the wire surface topography must be obtained in order to sustain reliable accuracy. In this paper, the measurement method of a diamond wire surface topography using an image processing method is proposed. According to this method, the distribution of grains on the surface can be expressed numerically after grains are extracted from the captured images of the wire surface. Finally, the effectiveness of the proposed scheme was verified through a measurement experiment for a diamond wire.

Abstract: It is very important to measure a grinding wheel surface topography. Therefore a three dimensional measurement system of grinding wheel surface with image processing has been proposed. This system can evaluate a variety of the wheel surface topographies. For example, a histogram of the area or the shape of cutting edges and the distribution map of every shape of cutting edges were obtained. In this paper, a three dimensional model of the cutting edges and a correlation between the state of the wheel surface and grinding mark on the workpiece are reported and the effectiveness is evaluated through an experiment.

Abstract: Grinding process is a very efficient machining technology because innumerable abrasive grains are fixed on the surface of grinding wheel. Especially, the distribution and shape of cutting edges which directly affect grinding process have a big influence on accuracy. Thus, it is very important to measure a wheel surface topography from a viewpoint of evaluating the wheel life and the performance and a relation between the one and the roughness. In this study, a three-dimensional measurement system of a grinding wheel surface with image processing is developed. In this system, the distribution and height of cutting edges are analyzed because only cutting edges can be selected from among all abrasive grains.

Abstract: In order to improve the accuracy of quantitative calculation of abrasive flow machining, the influence of geometrical parameters of abrasive grains on machining is analyzed by representing the geometrical shapes of abrasive grains with three parameters, namely height of abrasive grains, cone angle and wear height, establishing the calculation model of blunt conical abrasive grains for abrasive flow machining, deducing the force formulas of abrasive grains and calculating the maximum cutting depth in the event of smooth flow of abrasive grains in the boundary layer. It is shown by researches that the geometrical parameters of abrasive grains have significant influence on the maximum cutting depth as follows: The maximum cutting depth of abrasive grains increases linearly with the increase of height of abrasive grains, and varies in the form of hump with the changes of cone angle, the cutting depth has the maximum value when the cone angle reaches 60°; The maximum cutting depth of abrasive grains decreases rapidly with the increases of wear height, when the wear height increases to a critical value, the abrasive grains basically lose cutting ability.

Abstract: This study aims to clarify the friction and wear phenomena, which are of great importance in abrasive machining with atomic-scale material removal, such as polishing of magnetic disk substrates and CMP of semiconductor substrates. Various phenomena that occurred when a well-defined copper surface rubbed by an extremely fine rigid diamond abrasive, such asthe sliding without removal and the atomic-scale wear, were analyzed using a molecular dynamics model, in which the abrasive grain was connected to a three-dimensional spring and the holding rigidity of the abrasive grain was taken into account. A series of simulations using different indentation depths clarified that the one- or two-dimensional atomic-scale stick-slip phenomenon in proportion to the period of atomic arrays of workpiece surface occurred in the sliding processes without atomic removal. The results also demonstrated that the period and amplitude of the fundamental stick-slip wave varied when accompanied with atomic removal due to the increase in normal load.