| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 98 === The objective of this research is to develop a quasi hydrodynamic polishing process using a ball polishing tool, to improve the surface roughness of the hardened and tempered STAVAX plastic mold stainless steel on a CNC machining center. A set of computational fluid dynamics（CFD）software was used to analyze and simulate the shear stress and velocity of the fluid between the fluid and the workpiece for hydrodynamic polishing in this research. The optimal process parameters for hydrodynamic polishing have been determined by the Taguchi’s experimental method. The determined optimal quasi hydrodynamic polishing parameters for plane surface were as follows: the film thickness of 4 μm, the spindle speed of 15,000 rpm, the percentage of metalworking oil of 100 %, and the feed rate of 0.5 mm/min. Using the determined optimal quasi hydrodynamic polishing parameters, the surface roughness of the burnished test specimens could be improved from 0.02 μm（Ra）on average to 0.008 μm（Ra）on average. Applying the optimal quasi hydrodynamic polishing parameters to a diamond turning fabricated Ni-plated STAVAX mold steel, the surface roughness of 0.0017 μm（Ra）on average was possible. In addition, the turned concentric lay on the mirror-like surface could be removed by the developed process efficientiy.
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