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In this thesis, several machining strategies to remove axially symmetric form error with small wavelength by Hydrodynamic Polishing process (abbreviated as HDP) were proposed. Three strategies were proposed progressively in the study so as to remove axially symmetric form error with small wavelength. The first and second tactics were based on a basic algorithm, say, directly solving of a set of simultaneous equations. In the first strategy, a set of simultaneous equations was constructed by relating the total machining action of each dwelling point to the corresponding initial error. Subsequently, a set of dwelling time was obtained by directly solving the simultaneous equations. The second strategy evaluates solutions in a similar way like the first one but more restrictions were concerned in solution evaluation. The third strategy is an optimal based method. A set of dwelling time was obtained by minimizing an objective function with given constraints. A series of computer simulations were conducted to estimate the residual error and examine the validity of the strategies. From the computer simulation, the first and second strategies were confronted with negative-time problem, so that merely limited improving of form precision was obtained. The proposed optimal strategy was shown to have high potential for improving the machining precision by the HDP process. Based on the proposed strategies, a better form precision of the work surface with small wavelength can be obtained.

No description available.

Ultraprecision single point diamond turning is required to produce parts with sub-nanometer surface roughness and sub-micrometer surface profiles tolerances. These parts have applications in the optics industry, where tight form accuracy is required while achieving high surface finish quality. Generally, parts can be polished to achieve the desired finish, but then the form accuracy can easily be lost in the process rendering the part unusable. Currently, most mid to low spatial frequency surface finish errors are inspected offline. This is done by physically removing the workpiece from the machining fixture and mounting the part in a laser interferometer. This action introduces errors in itself through minute differences in the support conditions of the over constrained part on a machine as compared to the mounting conditions used for part measurement. Once removed, the fixture induced stresses and the part’s internal residual stresses relax and change the shape of the generally thin parts machined in these applications. Thereby, the offline inspection provides an erroneous description of the performance of the machine. This research explores the use of a single, high resolution, capacitance sensor to quickly and qualitatively measure the low to mid spatial frequencies on the workpiece surface, while it is mounted in a fixture on a standard ultraprecision single point diamond turning machine after a standard facing operation. Following initial testing, a strong qualitative correlation exists between the surface profiling on a standard offline system and this online measuring system. Despite environmental effects and the effects of the machine on the measurement system, the capacitive system with some modifications and awareness of its measurement method is a viable option for measuring mid to low spatial frequencies on a workpiece surface mounted on an ultraprecision machine with a resolution of 1nm with an error band of ±5nm with a 20kHz bandwidth. / Thesis / Master of Applied Science (MASc)