POLYMER FLOW LENGTH SIMULATION DURING INJECTION MOLD FILLING

The maximum flow length of a polymer for a given set of processing con ditions is important in injection molding to avoid incomplete mold fil ling. Experimental analysis, using various processing conditions, can generate the actual influence of processing conditions on the maximum flow length. However, the experimental determination of the flow lengt h for all known industrial polymers would be time consuming and expens ive. A non-Newtonian, nonisothermal model of mold filling was develope d to evaluate the flow length without requiring large amounts of compu tation time. The model implements the use of both a temperature and sh ear rate-dependent viscosity as well as viscous heating. This paper pr esents the model and its numerical implementation, followed by simulat ion results. The model is compared with other simulation programs and experimental results using both an amorphous Styron 484-27 polystyrene and a semicrystalline 640I polyethylene in a spiral mold geometry. Go od agreement between the three is observed.