Papers by Keyword: Slicing

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: Anisotropic materials are used in various fields because of their superior mechanical properties such as high specific strength. However, the surface generation mechanism in loose abrasive machining such as multi-wire sawing of anisotropic materials has many unknown characteristics. This study mainly aims to clarify the sliced surface generation mechanism in multi-wire sawing of glass fiber reinforced plastics (GFRP). Therefore, the slicing experiments and the wet lapping experiments are carried out in this study. In this paper, we describe the fundamental slicing characteristics of GFRP and the influence that the orientation angle of reinforcement fibers has on the newly generated surface of GFRP. We find that high-precision machining of GFRP is possible using a multi-wire saw. The slicing rate and thickness variation are not dependent on the orientation angle. However, sliced surface roughness depends on the orientation angle, and it tends to decrease when the orientation angle increases. In addition, sliced surface generation and polished surface generation involve similar mechanisms and produce very similar surface characteristics.

Abstract: The stratification of STL files model is an important link of rapid prototyping systems. In order to improve the efficiency of layered, this paper puts forward a layered optimization algorithm: According to the triangle mesh generation's two axis coordinates, we can group and sort from small to large, then get the line intersection on these triangular mesh, and output section contour line and data in turn. This algorithm can not only save time, but also improve the layered efficiency, because it is not necessary to establish topology relation of the triangle mesh and to deal with the connection relationship of delivery line. Through analysis of the turtle and bucket teeth model stratified, the practicality and high efficiency of the proposed algorithm is verified.

Abstract: Brittle materials, such as silicon, silicon carbide and sapphire have been conventionally sliced for wafers by a multi-wire saw method with slurry in industrial fields. Recently, the multi-wire saw method with a fixed diamond abrasive wire has been available as a commercial product at acceptable cost, and the high slicing performance is expected compared with the normal multi-wire saw method with slurry. However, there still remain some problems such as bad working environment with abrasives, cleaning cost of sliced wafers, crack generation on the sliced surface and a large kerf loss against a wafer thickness. On the other hand, the developed multi-wire EDM slicing method would accomplish the high performance slicing of silicon and silicon carbide with a narrow kerf width under a clean process environment. However, the thinner wire is challenging process with a normal round shape wire electrode. Therefore, the new wire electrode with track-shaped section was proposed in order to satisfy both the narrow kerf width and the high wire tension even in the case of thin wire electrode. In this study, the running control of wire electrode with a track-shaped section was experimentally investigated, and the possibility of proposed process was discussed.

Abstract: Parts precision is one of the key points in industrial application of rapid prototyping technology (RPT), and also the pivot of RPT research, but presently high precision is hard to achieve. This paper focuses the emphases on the principle of error analysis. Obtain chord errors corresponding to the number of triangles with pro/E software during the STL, and the formula for computing stair errors taking the quarter of sphere for an example during the slicing. In the end, propose the measures to improve the principled errors, viz. sloping slicing, adaptive slicing, direct slicing and so on, and further propose the theoretical range of adaptive slicing thickness.

Abstract: According to the requirements of integral Stereolithography (integral SL) System, a new direct slicing method under Pro/ENGINEER environment is developed. 3D CAD models are sliced with Pro/TOOLKIT in Pro/ENGINEER environment, and section image of 3D models can be obtained and saved as image format. Dynamic masks are produced with the cross-section images which obtained through the slicing method by dynamic pattern generator, and then 3D real prototyping is fabricated conveniently with integral SL System. A 3D tower model is sliced with this method, and the tower prototyping also is fabricated with integral SL System. Compared with the STL format files slicing method, the new slicing method can achieve high accuracy of layer section profile. The direct slicing method provides a new solution for integral SL system to build objects with high accuracy.

Abstract: Welding arc deposition is a high efficient rapid forming technology which can be used to rapidly form metal functional parts directly. While, Traditional slicing methods in the rapid forming process always produce ‘staircase’ or additional support structure which reduce deposition accuracy and efficiency, bring about the dissipation of materials. Even that it cannot exploit the advantages of welding arc deposition method. This paper proposes a slicing strategy which is suitable for rapid forming based on welding arc deposition. During slicing stage, the CAD model is decomposed into different pieces based on its geometrical feature to make each piece can be deposited in one direction without support structure, and layer thickness is determined according to the height of each sub volume and welding parameter database. A typical part is built with this method. It shows that this method is feasible and high efficient.

Abstract: According to the requirements of integral Stereolithography (integral SL) System, a new direct slicing method with SolidWorks for integral Stereolithography System is developed. Slicing function of SolidWorks is employed to slice CAD models directly, and section image of 3D models can be obtained and saved as image format. Dynamic graphic masks for the integral SL System are created according to the cross-section images that obtained through the slicing method, and then 3D real prototyping can be fabricated conveniently. A 3D cup model is sliced with this method, and the cup prototyping also is built with integral SL System. This experiment shows that direct slicing CAD models with Solidworks can be used for integral SL system, and the method of direct slicing CAD models can improve the efficiency of slicing process. Compared with the STL format files slicing method, the new method does not need to inspect and repair models data, and it can achieve high accuracy of layer section profile. The direct slicing method provides a basis for integral SL system to fabricate objects with high accuracy.

Abstract: Development of high performance diamond impregnated wire is the key of application for fixed-abrasive wire sawing technology. In this paper, some experimental studies were done for development of electroplated diamond wire saw by employing the bright nickel bath. The wire saw electroplating process was developed, the effects of cathode current density and time at tack-on stage on diamond grits density and adhesion between saw matrix and plating coating were discussed. The wire saw cutting experiments were carried out for analysis the used wire wear using the scanning electron microscope (SEM). The experimental results show the optimum tack-on current density to obtain the wire saw with good abrasive distribution and adhesion is 1.5~2.0A/dm2, and the time of pre-plating, tack-on and buildup is 6, 8~10 and 18min in turn. Diamond wire saw wear includes coating wear and grain-abrasion, and the primary wear form is grits pulled-out.

Abstract: Warp accuracy and nanotopography in the silicon wafer slicing process influence the final quality of the wafer. Therefore, methods to improve these factors are important. And this will require the achievement of low costs and high quality processing – conflicting requirements – with larger sized wafers than in previous generations. The present study was performed to assess mechanical factors, such as machine static accuracy and thermal deformation, to improve the accuracy of multi-wire saws. This report deals with the influence of thermal deformation of the ingot and wire guides upon processing accuracy, and describes the assessment results.