Materials Science Forum Vol. 594

Abstract: A mechanism design for the recycling process for removing the ITO-layer from color filter surface of TFT-LCD is presented. The defect rate of the ITO-layer is easily existent through the processes of semiconductor production. By establishing a recycling process for the ultra-precise removal of the thin film microstructure, the semiconductor optoelectronic industry can effectively recycle defective products, reducing both production costs and pollution. In the current experiment, the major interest is the design mechanism features of the removal process for a thin layer of ITO. For the recycling processes, a high flow velocity of the electrolyte provides a larger discharge mobility and a better removal effect. A thin thickness of the negative-electrode, an adequate gapwidth between the negative-electrode and the workpiece, or a higher working temperature corresponds to a higher removal rate for the ITO-layer. An adequate feed rate of the color filter combined with enough electric power produces a fast removal rate. An effective mechanism design and a low-cost recycling process using the electrochemical removal requires quite a short time to make the ITO layer remove easily and cleanly.

Abstract: The objective of this research is to design and fabricate a general purpose 3D digitizer based on grinding technique to completely acquire the geometry of an object, including its inner structure, and accurately create its CAD model. How the 3D digitizer works is as follows. First a thin layer of an object that is fixed in epoxy is removed by a grinder and the image of the cross section is taken by a CCD camera. The process is repeated until the images of all the cross sections of the object are captured. Then the images are stacked up by using software 3D-DOCTOR to obtain the 3D CAD model. The accuracy of the 3D digitizer developed in the research was within 0.03 mm when measuring a length of 5.50 mm and the gauge R&R percentage was 25.99%. The performance shows that the 3D digitizer is promising for use in industry.

Abstract: Image-processing technology is widely used in industry for automatic inspection and measurement through the capturing of object images by CCD (Charge-Couple Device) cameras and the built-in algorithms. VR (Virtual Reality) is a high-end user interface that involves real-time simulation and interactions through multiple sensorial channels. Three important characteristics of VR are: immersion, interaction, and imagination which enable the users more direct and useful communications with manufacturing prototyping systems. In this paper, an image processing system was developed for measuring small parts such as 3C rivets automatically. If using optical sensors to measure such small parts, the mechanism is complicate. However, if using image process technology, the mechanism is simple and the measurement is efficient. All we have to do are to develop measuring algorithms as well as computer programs. A VR-based image processing system was also developed by importing 3D CAD objects and applying the relationships between these objects. Therefore, the image processing algorithms as well as the layout of the measurement system can be tested by using the proposed VR system without any real machine such as transfer mechanism, CCD camera, and computer with image processing program.

Abstract: Rather than designated directly as solid if the micromesh (or cell) larger than a nucleus is chosen as the nucleation site, the growth of a nucleus in the cell is considered in the application of the modified cellular automaton model to simulate the evolution of dendritic microstructures in the solidification of Al-Cu alloy. The growth velocity of a nucleus or a dendrite tip is calculated according to the KGT (Kurz-Giovanola-Trivedi) model, which is the function of the undercooling. In this study, the dendritic microstructures, such as the free dendritic growth in an undercooled melt and the dendritic growth in the directional solidification, are simulated with the modified growth algorithm in the nucleation cell. The simulated results for the temporal and final morphologies are shown and are in agreement with the experimental ones.

Abstract: Dendrite needles grow from an undercooled melt and their shapes depend on the temperature distribution on the solidification front, which are specified by some parameters such as undercooling, capillary length, diffusivity, convection and kinetic effects. Neglecting the convection and kinetic effects, this study numerically computes the quasi-steady-state integral-differential equation to obtain the shape of a dendrite using solvability condition and investigates the effect of parameters changing the temperature field on the shape of a dendrite. The results reveal that the tip shape enlarges with the decreasing undercooling and increasing capillary length. On the other hand, the increase of thermal diffusivity only slightly reduces the tip radius and shape of a dendrite.

Abstract: By carefully researching and analyzing on cooling process of medium thickness steel plate, a mathematics model of heat transfer and its corresponding simulation model are established and evaluated with finite discrimination for a selected cooling object, and a simulation model is established. Through simulation and locate testing, the calculated values obtained are agreed very well with the measured ones. This indicates that the simulation model can preferably reveal the accelerated cooling process of medium thickness steel plate and can be applied to guide the manufacture of medium thickness steel plate.

Abstract: This paper describes for breaking behaviors on the surface layer of a white-coated paperboard during indentation of a center bevel blade. Cutting load response of the paperboard was measured regarding the indentation depth of the blade and the deformation flow in a side view of the paperboard was observed by a CCD camera in order to investigate the effect of blade tip angle on the surface failures of the paperboard. The surface breaking strength of paperboard was analyzed by using Finite Element Method (FEM). Through the experiment and FEM simulation, the followings were revealed. 1) There is a certain critical value of tip angle C at which an inflection load response disappears and also the surface failures are restricted. 2) When the tip angle is less than the C, there is an inflection point as the surface-layer breaking and its surface breaking point was strongly related to the maximum principal stress on the surface. 3) After the surface breaking, the deformation flow and its cutting resistance are strongly affected by the de-laminated and the raised-up of the inner-layer.

Abstract: Point collocation methods have no mesh, no integration. While, the robustness of the point collocation methods is an issue especially when scattered and random points are used. To improve the robustness, some studies suggest that the positivity conditions can be important when using the point collocation methods. For boundary points, however, the positivity conditions cannot be satisfied, so that it is possible to get large numerical errors from the boundary points when using the point collocation methods. The author has proposed a point collocation method with a boundary layer of finite element. In this method, by introducing a boundary layer of finite element in boundary domain of workpiece, unsatisfactory issue of the positivity conditions of boundary points can be avoided, and the complicated boundary conditions can be easily imposed with the boundary layer of finite element. A forging process is analyzed by using the point collocation method with a boundary layer of finite element.