Papers by Keyword: Multi-Cavity

Abstract: The key of qualities of optical lens created by injection molding are geometric errors and distribution of residual stress. This study analyses a mobile phone camera lens with aspheric optical lens created by one mold and 16 cavities. Mold flow analysis was used to simulate geometric shapes of different gates and design cooling systems to control mold temperatures. Mold temperature was controlled during the actual injection process and simulation results were used as the basis for mold design. The effects of cold-wall-mold on lens residual stress are discussed. The experiment result showed that higher mold temperatures are helpful to reduce residual stress. An aspheric mould measurement system was used to measure both the mold and the product. The results showed that the replicating capacity is satisfactory with a molding error of 3.604μm.

Abstract: Filling imbalance for PP, long GF-PP, elastomer PC and GF-PC in a multi-cavity mold with a geometrically balanced runner is investigated by using the visualization glass-inserted injection mold and infrared thermometers, through visualizing the flow behavior of the melt in the runner and cavity and measuring the melt temperature near the cavity entrance simultaneously. In addition, velocity distribution in the secondary runner for PP and elastomer is also determined by use of marker tracers in order to further investigate the mechanism of filling balance. The results show that the degree of filling imbalance depends on the velocity difference of the upper and lower melt and its development in the secondary runner during the filling process. The melt viscosity difference in the primary runner dominate the melt velocity difference in the secondary runner., and the viscosity difference depends on the temperature difference and viscosity sensitivity to temperature and shear rate. The development of the velocity difference of the upper and lower melt in the secondary runner depends on the melt viscoelastic property and the runner wall condition.