| Summary: | 碩士 === 國立高雄第一科技大學 === 機械與自動化工程所 === 97 === The study was focused on the optimization design of metal injection molding (MIM) process in order to obtain an ideal shape and product characteristics of MIM parts by remedying the defect which makes it hard to control dimensional tolerance in MIM parts after the part shrinkage in the sintering process.
The method in this study was conducted throughout three experimental phases. The first phase aimed to search a suitable backbone polymer by combining 316L stainless steel powder with different backbone polymers. The second phase was targeted to find injection molding range by using injection temperature and injection speed as the control factors of the injection molding operation window. The third phase was concerned with searching the optimal parameter combination with multiple quality characteristics by means of the combination of Taguchi method and Principal Component Analysis (PCA) method.
The results of the study showed that: (1) Use of HDPE backbone polymer could obtain better dimensional precision of sintered qualities (improved over 22% and 43% of length and width, respectively) than use of LDPE. In addition, it enhances the unity of density (improved over 23%) and hardness (improved over 62%). (2) In search of injection molding operation window, binder agglomeration and coarse powder resulting from lower and higher injection speed respectively made a harmful impact on sintering process at a later date. Only under suitable injection speed could the quality be controlled and increased. (3) The results suggest that the optimal parameter combination derived from the combination of Taguchi method and PCA method efficiently decrease sensitivity to all kinds of noises, reduces variability of multiple quality characteristics, solves the problem about dimensional tolerance in sintered parts which was hard to control, and increases the unities of density and hardness.
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