| Abstract: | An experimental program was carried out to study the dynamics of parison swell and development in extrusion-blow molding. Two commercial blow molding grade polyethylene resins were employed in conjunction with an Impco, Model A13-R12 reciprocating screw blow molding machine equipped with a cylindrical bottle mold. Parison weight swell was measured with the aid of a parison pinch-off mold. In order to obtain more reliable and useful information regarding diameter and thickness swell of the parison and the dynamics of parison formation and development, high speed cinematography was employed. Data obtained by this technique are more reliable than results obtained with the pinch-off mold alone. They also give further insight into the phenomena of swell, sag, and parison spring back or recovery. |
