| Summary: | 博士 === 中原大學 === 機械工程研究所 === 99 === For traditional injection molding products, the poor design of the gate location, non-uniform parts thickness and various parts design will cause the unbalance of injection pressure and part’s density. It seriously influences the molding yield rate and causes the warpage of the part. However, “In mold Decoration (IMD)” is a new surface decoration technology for injection molded parts. During IMD processing, the film is performed as the shape of mold cavity and attached to one side of the mold wall (usually cavity surface). Heat transfer toward the mold cavity side during molding IMD part is significantly hesitated. During filling stage, the unsymmetrical contact temperature on the cavity and core sides will causes warpage of the parts. The tradition solution is to set the different initial temperature on the cavity and core sides. However, the warpage cannot be obvious reduced, meanwhile, the significant mold temperature differences setting between cavity and core sides will causes damage of the mold and reduces the application life of mold.
In this study, we use “Gradual-Thickness-Variation (GTV)”on the part thickness design combing different cavity and core temperature setting to reduce the warpage of IMD parts and common plastic parts. As a result, there are three factors are able to fix warpage which are the deformation of product shape, displacement of neutral axis and reduce the time of temperature balance on thickness direction. Under the same factors of warpage level, using interpolation method to estimate the relation between different GTV ratio design and the difference of mold temperature. Consequently, the warpage results for difference mold temperature is directly relative with GTV ratio design, and the result of 20% GTV ratio is approximated with 3℃for difference of mold temperature, the result of 30% GTV ratio is approximated with 5.3℃for difference of mold temperature and the result of 40% GTV ratio is approximated with 13.9℃ for difference of mold temperature. This research has established the rules for fixing warpage of injection molding parts and IMD parts to provide manufacturing as a reference.
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