Blow molding parison programming-wall

Die shaping and programmed parison techniques can be combined. In the most sophisticated wall thickness control systems, the use of deformable die rings permits both the mandrel motion and the die shape to be controlled as the parison is extruded. This permits extremely accurate control of the thickness profile of the parison and hence of the blow molded container. 

With dip biow moiding, the biow pin dips into the dip chamber [9j. After the neck ring is fiiied, the biow pin is puiied back. Axial variations in parison wall thickness can be achieved by programming the motion of the dip chamber piston. Figure 1.161 shows the production of the parison. The parison is then taken over by the blow mold, and the product is biown. After that, the blow pin is withdrawn, and the blow process is continued with an auxiliary blow pin. 

---