Two-Dimensional Simulation of Injection Molding of Rubber Compounds

A general finite-element and finite-difference computer program has been developed for filling a thin cavity during injection molding of rubber compounds. This program employs a finite-element representation of the cavity in the planar dimensions and a finite-difference representation in the gapwise direction and is capable of accommodating any type of rheological equation and vulcanization model and incorporates both viscous heating and heat of vulcanization. A detailed example of an application of this program has been presented for filling a quarter-disk cavity with rubber compounds having a viscosity function obeying a modified Cross model and curing kinetics according to our recently proposed nonisothermal vulcanization model. The pressure, velocity, and temperature fields and melt-front locations have been calculated during the filling stage. The evaluation of state of cure distribution in the rubber moldings has been predicted in the postfilling stage. Comparisons of the prediction of the model with experimental data regarding pressure distribution, melt front position, and distribution of degree of cure in molded parts will be presented in the near future.