Rotary wheel blow molding systems

Rotary wheel blow molding systems are used for the high-output production of a wide variety of plastic extrusion blow molded articles. Containers may be produced from small, single serve bottles to large containers up to 20-30 liters in volume - but wheel machines are often sized for the volume and dimensional demands of a specific container, and are typically dedicated to a narrow range of bottle sizes once built. Multiple parison machines, with high numbers of molds are capable of producing over one million bottles per day in some configurations.

Description

Rotary blow molding "wheels" are targeted to the high output production of containers. They are used to produce containers from one to seven layers. View stripe and In Mold Labeling (IML) options are available in some configurations. Rotary wheels, which may contain from six to thirty molds, feature continuously extruded parisons. Revolving sets of blow molds capture the parison or parisons as they pass over the extrusion head. The revolving sets of molds are located on clamp "stations".

Rotary wheels come in different variations, including both continuous motion and indexing wheels, and vertical or horizontal variations. Wheel machines are favored for their processing ease, due to having only single (or in some cases, two) parisons, and mechanical repeatability.

In some machinery configurations, the molds take on the shape of a "pie" sector. Thus, if two or more parisons are used, each blow molded "log" has a unique length, requiring special downstream handling and trimming requirements. In other machine configurations, the molds utilize "book style" opening mechanisms, allowing multiple parisons of equal length. However, machines of this style typically have lower clamp force, limiting the available applications.

The mold close and open actuation is typically carried out through a toggle mechanism linkage that is activated during the rotational process by stationary cams. This mechanical repeatability is considered an advantage by most processors.

The method of wheel rotation is typically conducted through an electric motor with a "pinion" gear or small gear to or in mesh with a rotating "bull" gear or large gear. All utilities for blowing containers and for mold cooling are carried through the main shaft or the axle from which the wheel rotates about. These utilities include compressed air and water. Sequencing functions necessary to inflate the parison, hold the container prior to discharge and discharge are completed by mechanical actuation to pneumatic valves – resulting in a high degree of repeatability.

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

Applications

The growth of wheel machinery in the United States was spurred by the conversion of motor oil containers from paperboard cans to plastic bottles, and the conversion of laundry detergent from powder to liquid form. Additional high volume applications have included single-serve juices and drinkable yogurt, condiments, and household cleaning supplies.

Books, general references

Soroka, W, "Fundamentals of Packaging Technology", IoPP, 2002, ISBN 1-930268-25-4
Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009, ISBN 978-0-470-08704-6

Packaging

General topics	Active packaging Child-resistant packaging Disposable food packaging Food packaging Luxury packaging Modified atmosphere/modified humidity packaging Package pilferage Package testing Packaging engineering Pharmaceutical packaging Reusable packaging Shelf life Sustainable packaging Tamper-evident Tamper resistance Wrap rage

Containers	Aerosol Container Aluminium bottle Aluminum can Ampoule Antistatic bag Bag-in-box Bags and flexible containers Barrel Beer bottle Biodegradable bag Blister pack Boil-in-Bag Bottle Box Bulk box Carboy Carton Chub Clamshell Corrugated box design Crate Disposable cup Drum Envelope Flexible intermediate bulk container Foam food container Folding carton Growler Insulated shipping container Intermediate bulk container Jar Jerrycan Jug Juicebox Keg Multi-pack Oyster pail Packet (container) Padded mailer Pail Paper bag Paper sack Plastic bag Plastic bottle Popcorn bag Retort pouch Sachet Security bag Self-heating can Self-heating food packaging Shaker-style pantry box Shipping container Skin pack Spray bottle Tin can Tube Unit load Vial Wooden box

Materials and components	Adhesive Aluminium foil Bioplastic Biodegradable plastic BoPET Bubble wrap Bung Cellophane Closure Coated paper Coating Corrugated fiberboard Corrugated plastic Cushioning Desiccant Double seam Foam peanut Glass Hot-melt adhesive Kraft paper Label Linear low-density polyethylene Liquid packaging board Low-density polyethylene Metallised film Modified atmosphere Molded pulp Nonwoven fabric Overwrap Oxygen scavenger Packaging gas Pallet Paper Paper pallet Paperboard Plastic film Plastic pallet Plastic wrap Polyester Polyethylene Polypropylene Pressure-sensitive tape Screw cap Screw cap (wine) Security printing Security seal Shock detector Shock and vibration data logger Shrink wrap Slip sheet Staple (fastener) Strapping Stretch wrap Susceptor Tear tape Temperature data logger Time temperature indicator Tinplate Velostat

Processes	Aseptic processing Authentication Automatic identification and data capture Blow fill seal Blow molding Calendering Canning Coating Containerization Curtain Coating Die cutting Die forming (plastics) Electronic article surveillance Extrusion Extrusion coating Glass production Graphic design HACCP Hermetic seal Induction sealing Injection molding Laminating Laser cutting Molding Papermaking Plastic welding Plastics extrusion Printing Quality assurance Radio-frequency identification Roll slitting Shearing (manufacturing) Thermoforming Track and trace Vacuum forming Ultrasonic welding Vacuum packaging Verification and validation

Machinery	Barcode printer Barcode reader Bottling line Calender Can seamer Cartoning machine Case sealer Check weigher Conveyor system Extended core stretch wrapper Filler Heat gun Heat sealer Industrial robot Injection molding machine Label printer applicator Lineshaft roller conveyor Logistics automation Material handling equipment Mechanical brake stretch wrapper Multihead weigher Orbital stretch wrapping Palletizer Rotary wheel blow molding systems Shrink tunnel Staple gun Tape dispenser Turntable stretch wrapper Vertical form fill sealing machine

Environment, post-use	Biodegradation Environmental engineering Glass recycling Industrial ecology Life-cycle assessment Litter Paper recycling Plastic recycling Recycling Reusable packaging Reverse logistics Source reduction Sustainable packaging Waste management

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