Studies of design and technology influence on optical properties of injection molding parts by simulation

The methodology of obtaining a factors rating of the runner system design and technology process influencing on optical properties of the plano-concave lens of polycarbonate has been examined, using Taguchi method for injection molding simulation.The biggest influence on the refraction index (n) and the difference of the refraction index (Δn) among part areas characterizing its optical heterogeneity is made by the runner system design whilst the principal factor influenced on birefringence is melt temperature.Different type of the refraction index and birefringence dependence from the packing pressure (in the last case is being observed a minimum value under the packing pressure 60 MPa) can be explained when considering the combinations of phenomena.These phenomena take place in a mold cavity in the process of melt filling, packing and shrinkage processes determining strain-stress state of molding in an injection mold and after ejecting from the mold.