A Numerical Model of the Extrusion Blow-Molding Process

The present study is relevant to the final stage of the extrusion blow- molding process, after the parison of molten polymer has been extruded. A general 3D finite element code has been developed to model the simultaneous closing of the mold and the blowing stage to obtain the final shaped product. The basic mechanical model is the membrane assumption and hence, the code is limited to thin parison processing. It is isothermal but includes sliding and friction along molds of arbitrary shape. The material behavior law is either linear elasticity or elastoviscoplasticity. Experimental work has been carried out at Solvay to validate this model on an extruded blow-molded lab scale part. Comparisons of thickness profiles show reasonable agreement between the computa tion and the experiment.