Nowadays, the polishing process is one of the most important steps of the manufacturing of moulds and dies. Occupying up to 40% of the total production time and cost, it is decisive for the final appearance and quality of a surface. Because of its complexity, the polishing is mainly carried out manually; and the final quality depends of the expertise of the operator. That is why an automation of the polishing process is necessary. The purpose of this project was to find out the optimized sequence of polishing for a Mirrax ESR steel (Uddeholm Tooling AB) using the Strecon RAP-200 (robot assisted polishing equipment). Using a Design of Experiment, the machine parameters were tested in order to better understand their influences and interactions. The report starts with a description of general polishing knowledge and ends up with the results from a Design of Experiment. The information from this test are a first step in the evaluation of the Strecon RAP-200. Even if many results have been found out, only four parameters have been tested, and to be able to optimize the polishing sequence, further studies need to be carried out.

The goal of this thesis is to develop a novel polishing tool system, which can be attached to a CNC machine tool and execute a precision polishing job for an axially symmetric free surface. The precision polishing job is to remove the error surface profile, left by the previous machining process, on the work to improve its form precision. The system mainly includes a mechanism of 3 degrees of freedom, a misalignment compensator mounted on the mechanism, and an oscillation-free connector between tool and driver. The mechanism was designed to meet the required motions of tool trajectories. These motions are to assure the tool can play three specific functions. The first one is to keep the tool axis maintain a constant angle with the normal of polished surface. The second one is to control the wear rate distribution of tool to reduce the effect of tool wear on polishing rate. The final one is to achieve the goal of uniform polishing quality at every spot of polished surface. The conceptual design of this mechanism is done based on a strategy of problem decomposition. The misalignment compensator is to reduce the effect of tool misalignment on the variation of polishing rate. The compensator allows a translational motion and is constrained by a spring. When the tool is mounted on the compensator, the study will show that with a proper spring constant the effect of tool misalignment can be significantly reduced. The study will indicate that the smaller the tool mass is the higher the compensation efficiency can be. The oscillation-free connector is to separate the tool and its driver so that the mass of driver is not included in tool, while the driving function retains. It is composed of two parts. One part is connected to tool and the other one is mounted on driver. These two parts are not joined together by any mean. However, the motions of two parts will interfere with each other. Thus, the driving function between tool and drive can be maintained. It is noted that the vibration of driver can be successfully isolated from the tool if a soft material is attached to one part.

For the requirements of high-speed signal transmission has been increasing. Optical communication system is the way to solve the demands. The 980-nm high-power laser modules are used for optical communication system as the power of the amplifier for long distance communication. The QPSFE is used for coupling between the high-power 980nm laser diodes and the single mode fiber. This research established an on-line inspection system to inspect the fiber endface during the polishing process which is applied on a bare fiber polishing machine. The system we developed is to detect the fiber endface for QPSFE fabrication process. In this paper, we simply use couple charge device (CCD) as a position sensor to detect the grinding situation. The system had been successfully achieved on-inspection purpose, therefore; it will be the key technique toward the automatic bare fiber polishing system.

Abstract This paper proposes a model that integrates the microscale asperity contact and macroscale elastohydrodynamic lubrication (EHL) to simulate the pressure distribution in the chemical mechanical planarization (CMP). This model involves modified Reynolds equation used to describe the status of fluid field, the equation of the average asperity contact pressure by using statistics for solid contact pressure due to asperity contact, and the equation of the elastic pad deformation in bulk. Results show that with increasing relative velocity or load, the magnitude of the sub-ambient pressure decreases, the greater asperity contact pressure is formed to support the load, and the friction force also increases to cause the greater rotation angles. The magnitude of the fluid pressure is of the same order of magnitude as the applied normal load. Therefore, the addition of this fluid pressure may significantly change the distribution of the contact stress. The reason of the sub-ambient pressure existed is the deformation of the pad. In the material removal rate model, the elastic deformation of asperities is assumed, and the contact pressure is determined by Hooke¡¦s law. The indentation depth can be obtained from the force balance imposed on the particles by the wafer and the pad. Results show that the material removal rate decreases with increasing abrasive size, due to the increasing contact area between the abrasive and wafer. Keywords¡GElastohydrodynamic Lubrication, Chemical Mechanical Polishing

Abstract The tool wear characteristics of the hydrodynamic polishing process under various lubricating conditions are examined in this study. Both the experimental and theoretical studies will be done in this paper. In the experimental study, the relationships between tool wear and its possible influential factors will be examined. In the theoretical study, the mathematical model will be established to interpret the qualitative and quantitative relationships between tool wear characteristics and various operating parameters. For the experimental study, a series of experiments will be done to investigate the effect of various factors on the tool wear and machining rate, under non-contact or semi-contact lubricating condition. The factors may include the tool¡¦s angular speed, the applied load, the tool¡¦s surface irregularities, the slurry viscosity, and the properties of tool, workpiece and abrasive particle (such as surface energy). To establish the mathematical model, the principle of dynamics, law of minimum potential energy and elasto-hydrodynamic lubricating theorem of hydrodynamic polishing process are adopted to derive the removal rate model of a particle under differential contact conditions or under various material parameters (such as surface energies or speed constants) from the energy point of view. In addition, the wear rate of tool is to be analyzed. To deal with the random nature of tool¡¦s surface irregularities, the probability theory is applied to calculate the average wear rate of tool, under semi-contact or non-contact condition or under various material parameters. It is shown that both the tool waviness and radius of tool curvature changed and had specific trends in the wear process. Especially, the wear rate of tool under semi-contact lubricating condition was not necessarily large than that under the non-contact one. The experimental data indicated that the effects of tool wear on machining rate highly depended on the lubricating condition of tool. The trend of machining rate versus accumulated machining time under non-contact lubricating condition was very different from that under the semi-contact one. A mathematical model relating the removal capability of an abrasive particle at the tool¡¦s or workpiece¡¦s surface and various operating parameters are proposed. The qualitative properties of removal capability the under different material parameters and various contact conditions are obtained by the computer simulations. The analysis indicates that the relationships between the removal capability and various material parameters (such as surface energies of adhesion or operating conditions) are not monotonic. Under the contact condition, it is shown that the tool¡¦s surface energy of adhesion and the speed constant has a negative effect on the removal capability at tool¡¦s surface. On the other hand, the surface energy of adhesion on work and the speed constants have a positive effect on the removal capability at tool¡¦s surface. For the workpiece, the converse implications are also true. Three types of patterns for removal capability at tool¡¦s surface due to the degree of embedding of a particle were obtained. There are increase or first increase then decrease or decrease directly, respectively. Under non-contact condition, it is shown that the removal capability has a negative relationship with local film thickness. In addition, a mathematical model relating the tool or work piece wear rate and various operating parameters are also proposed. The qualitative properties of tool wear rate under various lubricating conditions are obtained by the simple statistic analysis. The analysis indicates that the relationships between tool and workpiece wear rate and various parameters are also not monotonic. Under non-contact condition, the tool or workpiece wear rate will first increase then decrease due to the tool periphery speed increase. The magnitude of wear rate will decrease or increase due to the material parameters. Under the semi-contact condition, the up-and-down trend is also occurred in the relationship between tool or workpiece wear rate and the tool periphery speed. Accordingly, the relationships between wear rate and tool periphery speed, in a lubricating range covering the non-contact and semi-contact conditions, will reveal a twin-peak pattern. Generally, the workpiece wear rate under the semi-contact condition is not less than the non-contact one. However, the tool wear rate under the semi-contact condition is not necessarily large than the non-contact one. For a specific condition, under the semi-contact condition, the magnitude of the tool wear rate under different speed will increase or decrease by choosing different tool¡¦s surface adhesive energy and speed constant and the relationship between tool wear rate and tool speed will become complex. The wear rate could increase or decrease significantly. In other word, the tool wear rate under the semi-contact condition may be smaller or large than the non-contact one. Hence, a tool with large surface adhesive energy and speed constant should have a lower tool wear rate or higher work wear rate under certain lubricating regime. Finally, the experimental study tests that the proposed model is closely related with the experimental data. The study showed that the qualitative trends of experimental data are consistent with the analytical predictions. Some of the qualitative relationships between tool wear and machining rate could be properly explained from the elasto-hydrodynamic lubrication theorem and the proposed wear theorem for hydrodynamic polishing process.

Abstract This study is to examine the phenomena caused by rolling action of a nano-particle against the work surface. The analysis was done by the molecular dynamics method. The distributed computing scheme was adopted in these simulations to increase the computing efficiency. The study includes the interfacial force between the nano-particle, the work and the roughness of the work surface, and the damage layer thickness of the work surface. It is done by first identifying the main factors, and then to understand how the phenomena is affected by these factors. Finally, the results of these simulations were discussed. The results show that the interactive force most comes from the breaking process between the work surface and the nano-particle. When the nano-particle¡¦s rolling speed is increased, the interactive force is enhanced. But if the speed has reached a high value, the interactive force will be saturated. The interactive force is not significantly affected by temperature. When the adhesive strength between the nano-particle and the work is higher, the interactive force is higher. The roughness of the work surface is affected by the rolling speed of the nano-particle, the temperature, and the adhesive strength between the nano-particle and the work. If the temperature or the interactive force is higher, the roughness of the work surface is higher. If the rolling speed is higher, the roughness of the work surface will increase. But if the rolling speed has reached a high value, the roughness of the work surface will not increase. The damage layer thickness of the work surface is little affected by the rolling speed of the nano-particle or temperature or the adhesive strength between the nano-particle and the work surface.

Thesis (Ph. D.)--OGI School of Science & Engineering at OHSU, 2004. / Includes bibliographical references.

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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Dr. Steven Y. Liang; Committee Member: Dr. Chen Zhou; Committee Member: Dr. Paul Griffin; Committee Member: Dr. Shreyes N. Melkote; Committee Member: Dr. Steven Danyluk.