Optimization of the Shearing Area and Locking Cycle for Extrusion Blow Molds.

The author presents results of a study in which mold design was investigated in reference to the bottom of blow molded bottles. The investigation was aimed at determining the shearing area and locking cycle so as to satisfy the technological requirements with a view to optimum serviceability and economical operations. Recommendations and requirements discussed include - during mold locking, the extruded parison is to be welded so that the weld attains a notch ratio F//k equals 1; the residual film thickness should ensure shearing with the minimum power requirements; with a view to a short cycle time, the non-productive time ″mold locking″ should take place during the end-phase; and the temperature of the parison should be within a very wide range without a major change occurring in the weld quality.