| Summary: | 碩士 === 中原大學 === 機械工程研究所 === 103 === During plastic injection molding process, if the air and the gas from the plastic could not vent properly, there would cause some defects, such as encapsulation and weld lines or even poor transfer because of the cavity was not filled completely. Besides, nowadays mold flow analysis software cannot be carried out the accurate analysis after mold design. Every time inserting venting gap need to modify the grids to simulate. If the designer''s own concept is not skillful, it may cause different design and some defects, resulting in poor venting, thereby lengthening the design cycle, even with the impact of their production costs.
Therefore, this study controlled the venting gaps in the injection molding process to discuss the venting design by the defects and combined CAD, also the secondary verification as the ultimate goal. To discuss the influence of venting by the data from injection machines, like injection pressure and remain plastics in cavity. This study uses a round and flat product with different thickness to discuss the effect of venting on the product quality by scan, electronic scales and etc. methods. Experimental results show that the venting mechanism makes the gas exhausted from the cavity to make residual quantity decreases, which means increases the amount of melt shot. Since the gas pressure within the mold because of the residual gas would increase the melt plastic flow resistance. With the venting gap, the melt could smoothly fill the cavity. Thus this study increases raw product weight, reduces encapsulation, and improves defects.
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