Papers by Keyword: Precision Grinding

Abstract: With the growing application of wide-bandgap semiconductors such as SiC in power electronics, efficient and low-damage machining of large-diameter, high-quality 4H-SiC wafers has become a critical research priority. This study systematically compares the grinding behavior of the C-and Si-faces of laser-sliced 4H-SiC wafers and reveals the effect of crystallographic anisotropy on tool wear. In the experiments, a picosecond laser was used to induce internal crystal modification, and multiple pairs of 12-inch high-purity semi-insulating crystals and wafers were obtained through ultrasonic separation. These wafers were subsequently ground using #800/#8000 resin-bonded diamond wheels. Material removal and wheel wear were recorded in real time, and the wheel wear ratio (W/M) was adopted as the key evaluation metric. Nanoindentation and white-light interferometry were further employed to characterize the mechanical properties and surface morphology of the two crystal faces. Results show that in both rough and fine grinding, the C-face demonstrates superior material removal performance despite its higher hardness, whereas the Si-face is more prone to wheel degradation. For thin wafers, residual laser focus near the surface further aggravates wheel wear. These findings establish a link between crystallographic anisotropy, laser-modified layer position, and wheel wear behavior, providing an experimental foundation for clarifying the underlying mechanisms and developing face-specific grinding strategies for high-quality SiC wafer fabrication.

Abstract: In view of the fact that the endo-prosthesis heads of human hip-joint are operated in extreme conditions, in respect of load, the selection of corresponding material and also increase of precision and quality of machining of spherical surfaces is rather topical task.In the submitted work are reviewed the problems connected with definition of the influence degree of orientation of the sapphire crystal on its workability during diamond grinding with a butt of the ring and elaboration of the perspective, original scheme of formation of the incomplete spherical surface, particularly, of the sapphire head of endo-prosthesis of the human hip-joint.

Abstract: While grinding with CNC cylindrical grinding machines, there are many factors that determine the precision and accuracy of the finished product. These may include dimensional accuracy, surface roughness, circularity (roundness), cylindricity, etc. But all these factors pertain to the work. The condition of the tool, in this case, the cutting edges of the grinding wheel, also greatly influence the profile and precision of the work. So, in order to maintain the precision of the work, there is a need to repeatedly and regularly maintain the cutting edges in a good cutting condition, by the process of dressing. In other words, when the swarf gets adhered to the grinding wheel, the abrasive particles can no longer perform machining with the same efficiency, due to increase in contact surface area between the abrasive particles and the work. This dissertation describes a technique that can be adopted to continuously monitor the grinding forces generated during the grinding operation, by using an in-process 2-dimensional piezoelectric force sensor, which can simultaneously measure the force and break it down into its two force components. The force sensor not only calculates the force generated, but also quantifies the force variation. By analyzing the variation in the radial and tangential force components individually, and by conducting Fourier analysis on the observed data, it is found that deterioration of the grinding wheel and the dress pattern can be continuously monitored and controlled.

Abstract: Needs of precision optical mirrors are increasing in the astronomical space telescope. In the space having extremely large temperature differences, the aspheric optical mirror made of low thermal expansion ceramic is very effective in reducing the focus errors due to the thermal expansion. In order to develop the mirror made of a new low thermal expansion ceramic, parabolic mirror of the ceramic is ground and polished to test. By the grinding and polishing test, changes of form deviation profiles and surface roughness profiles are evaluated and machinability of the proposed ceramic is studied.

Abstract: Form accuracy and smooth surface is required in precision grinding. And the form accuracy and surface roughness are improved year by year. However, the more the surface roughness becomes smooth, the more the grinding marks become remarkable. The grinding mark deteriorates the uniformity of ground surface. In this study, relationship between the uniformity of non-axisymmetric aspherical ground surface and grinding condition is analyzed theoretically. As a result, it is found that there are optimum grinding conditions.

Abstract: After precise grinding n-WC/12Co coatings with diamond wheel , there is residual stress on the surface of parts ,the paper drawn conclusions about this study,it Pointed out the contents of further study ,the direction of farther study was prospected in this study too. The interaction between the abrasive grains and the workpiece was approximately regarded as ideal small-scale indentation phenomenon, it was used to evaluate the surface quality in ceramic machined processing that formation of grinding crack and its propagation process, the material removed process and the surface defects of the ceramic grinding, the cutting model proved that although the removed material is usually brittle removal, most of the grinding energy consumption was related with plastic deformation.

Abstract: This paper gives further discussions refer to the precision grinding of high performance ceramic materials through the two aspects of the Grinding Properties and depth.

Abstract: According to the demand of precision machining for optical aspheric lens, especially large scale optical aspheric lens, this paper presents an error compensation technique for precision grindging. Based on precision surface grinding machine (MGK7160), grating-type parallel grinding method is put forward to realize grinding paths planning for optical aspheric lens. In order to obtain surface metrology and evaluation after grinding, an on-machine measurement system is built. On the basis of compensation principle, machining error is separated to achieve error compensation. Grinding experiments are carried out and show that it can meet the demand of precision grinding, and the accuacy after error compensation attains 6.5μm.

Abstract: Large size optical aspheric lens is an important component in optical engineering. Aiming at the demand of precision processing for optical aspheric lens, this paper develops a precision grinding technique for large size optical aspheric lens. Based on precision surface grinding machine (MGK7160), grating-type parallel grinding method is put forward to realize grinding paths planning for optical aspheric lens. An on-machine measurement system is built to obtain surface measurement and evaluation after grinding. In order to ensure machining precision and efficiency, a diamond truer which self-developed is adopted to precision dress for arc diamond wheel. Finally, the experiment of precision grinding and error compensation validates machining accuracy for large size optical aspheric lens.

Abstract: The mechanical properties and microstructure characteristics in nano-ceramic coating material determine largely their grindability, there are a variety of wear mechanisms existing in grinding process, wear resistance of nanoceramic coatings are higher than normal ceramic coating, processing zone in ceramic materials can be divided into inelastic deformation zone and elastic deformation zone. In the process of nanoceramic coatings materials removal, inelastic deformation removal and brittle removal is the coexistence, the grinding force, existing in nanostructured ceramic coatings, is bigger than it in general structure ceramic coating. In plastic deformation materials removal mode, the grinding surface roughness is low, while in brittle removal , surface grinding roughness is high , prone to grinding surface/subsurface damage.