| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 94 === Abstract In this study, in order to establish the manufacturing technology of the lost foam casting process, the “seal ring” and “sleeve barrel” ductile iron castings were chosen as the carriers, and the effects of some selected processing parameters, such as pattern density, pattern coating, and gating system design, on the quality of the castings produced were studied. Based upon the results obtained, the following conclusions can be drawn: (1) The density of the foam pattern employed should remain in a suitable range, no higher than 0.02 g/cm3. (2) Vibration should be applied during the sand-filling process, and continue for a certain period of time after complete fill, in order to achieve better compaction and also reduce the propensity of mold collapse during casting. (3) For the “sleeve barrel” casting, designing an suitable over-flow (or a riser) at the upper, far side of the flange of the casting can serve as a reservoir for the thermal decomposed products of the foam pattern, which can effectively eliminate both the surface defects and internal shrinkage porosities, and hence, quality castings can be attained. (4) The percent solid contraction measured in the lost foam ductile iron castings is around 1%.
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