Blow Molding Process Comparison: Wheels (Continuous Extrusion)

Rotary Wheel Blow Molding Machinery

The rotary wheel blow molding machines are the machine of choice for very high volumes of containers for markets such as liquid detergent and juice in North American markets. Wheels are typically chosen over shuttles because of processing ease (and cost) due to single parison technology and lower cost per container for high-volume applications. This is especially true for coextrusion and multilayer applications. Machines can be designed to handle a wide range of container sizes, but are typically committed to a narrow range of container variation after built. Because the containers are blow with a needle (instead of blow pin), it is not unusual to blow containers in a neck to neck configuration to increase the production output. Wheels come in various configurations including indexing, continuous motion, vertical (like a ferris wheel) and horizontal (like a merry go round). Some even now have the capability to produce calibrated neck containers, such as a reciprocating screw (Intermittent extrusion). Most, however, rely on downstream trimming equipment to trim and finish the container.

PROS:

• Lowest cost method for high volume production requirements
• Simple design and controls for maintenance
• Single parison well suited for multilayer application for repeatability and cost
• Easy to utilize IML
• Can achieve very high production volume from a single machine

CONS:

• Typically can not be converted to different number of cavities after being built
• High investment requires commitment to high volume production situations
• Requires secondary trimming and finishing equipment

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