Factors Influencing the Warpage in In-Mold Decoration Injection Molded Composites

Abstract

This report studied, both experimentally and numerically, the factors affecting the warpage in in-mold decoration (IMD) injection molded parts. All experiments were conducted on an 80-ton injection-molding machine. The materials used in the experiments included poly(ethylene terephthalate) (PET) films and 30 %g lass fiber-filled PET resins. U-shaped plate parts with three different angles (908 ,1 358 ,a nd 1508)a tt he corners were molded. The influence of various processing parameters on part warpage was investigated using an experimental matrix, with its design based on the experimental-parameterdesign method developed by Taguchi. The experimental results suggested that all molded parts warped toward the side of the decoration film. For the parameters selected in the experiments, the corner angle and the melt injection pressure were found to be the principal factors affecting the warpage of IMD injection molded parts. The 908 angled parts exhibited the greatest amount of warpage, while the 1508 angled parts showed the least amount of warpage. Additionally, acommercially available code (Moldex 3-D) was used to simulate the temperature distribution during the filling process and the molded part warpage. Calculated warpage satisfactorily matched with the experimental data. It has been shown that the warpage of IMD injection molded parts is mainly caused by the imbalanced temperature distributiond uring cooling, due to the part geometry and the decoration films.

Optimisation of warpage on plastic injection moulding part using response surface methodology (RSM)

“…Packing pressure was the least significant factor contributed to the warpage condition as shown in Figure 3. These results show the uneven volumetric shrinkage occurred to the poor uniformity of thermal distribution in the mould [21]. According to Subramanian et al [22] and Huang et al [23] the temperature difference between upper and lower surfaces in the cavity and core can give effect to the shrinkage condition.…”

Warpage Optimisation on the Moulded Part with Straight Drilled and Conformal Cooling Channels Using Response Surface Methodology (RSM), Glowworm Swarm Optimisation (GSO) and Genetic Algorithm (GA) Optimisation Approaches

“…The next influencing parameters are melting temperature and the cooling time. These findings are due to uneven shrinkage because the uniformity of heat distribution is low in the mould insert which resulted in the uneven cooling conditions [ 28 ]. As stated by Subramanian et al [ 29 ], the temperature variance in core and cavity surfaces affect shrinkage condition.…”

Warpage Optimisation on the Moulded Part using Response Surface Methodology (RSM) and Glowworm Swarm Optimisation (GSO)

“…Packing pressure was the least significant factor contributed to the warpage condition as shown in Figure 4. This result shows the uneven volumetric shrinkage occurred to the poor uniformity of thermal distribution in the mould [22]. According to Subramanian et al [23] and Huang et al [24] the temperature difference between upper and lower surfaces in the cavity and core can give effect to the shrinkage condition.…”