Rotary Wheel Blow Molding Systems - Advantages & Disadvantages

Advantages & Disadvantages

Very tight weight and dimensional tolerances can be obtained on wheel equipment, as the parison is captured on both ends. It is pinched in the preceding mold on the leading end, and positioned by the stationary flowhead die on the other end. In shuttle machinery and reciprocating screw machinery multiple parisons are extruded and are free hanging. Because there is always some variation in the parison length on these machines, bottle weight and tolerance consistencies are not as tight as on rotary wheel machinery.

Other advantages of wheel equipment include:

• Continuous extrusion
• Multi-layer coextrusion, with one to seven layers of plastic in the finished part
• In some applications, In Mold Labeling (IML) can be integrated with little or no cycle time penalty
• Parison programming capability, for optimization of wall thickness
• Reduced cycle time on light weight containers, compared to shuttle machinery. Conversely, wheel equipment may suffer cycle time penalties on thick containers
• Easily implemented view stripe capability
• Ability to achieve very high outputs from a single machine - lowest "cost per bottle" when compared to other blow molding equipment
• Higher production efficiencies than most other extrusion blow molding equipment types

Disadvantages:

• Inability to produce bottles with calibrated neck finishes
• Downstream trimming required
• Machines typically dedicated to a narrow range of sizes. Product change can be difficult, especially when downstream trimming changeovers are required.
• High initial capital investment