Packaging automation: Efficient bottle handling

An automated intermediate bottle storage system at the Alpla plant in the U.K. uses robots to load plastic bottles from the blow molders into trays and also moves the stacks of trays automatically into and out of the storage area.

Alpla is a worldwide plastic bottle manufacturer with 122 production plants. At one of its plants in the U.K., it recently installed a distinctive system for handling and storing plastic bottles that changes the traditional method of storing empty plastic (PET, HDPE, PP, etc.) and aluminum containers for future downstream processing.

Supplied by Autefa automation Gmbh, the system, which is called an intermediate bottle storage system (iBSS), is ideally suited for onsite or through the wall installations where bottle production and filling are done on the same site. In the traditional method of bottle handling, most onsite operations produce and bulk palletize the bottles or pack the bottles in plastic bags and temporarily store the pallets or bags in an onsite warehouse. the pallets or bags of empty bottles are then retrieved from the warehouse on demand, and the empty bottles are depalletized or debagged and sent through the wall to downstream operations.

This traditional method of operation requires significant money to be spent for packaging supplies, labor and capital equipment. Dunnage is required for pallets, tier sheets, top frames, stretch wrapping and/or strapping and labeling. Labor is needed to transport pallets or bags to interim storage, and then retrieve them for downstream processing.

Once they are retrieved for downstream processing, labor is needed to manually remove stretch wrap, straps or bags. Capital equipment is necessary to depalletize the bottles onto accumulation conveyors or, in some cases, the containers are dumped into bins, and are then unscrambled and placed onto accumulation conveyors.

IBSS automates bottle handling

The Autefa iBSS drastically changes that above mode of operation with the primary intent of reducing costs for both the bottle producer and the filler. "We were looking for a bottle handling and storage system that would reduce our labor and material costs," says Martin Stark, Alpla's engineering director. "After examining the systems that were available, we decided that Autefa would best meet our needs."

The iBSS is placed between the blow-mold area and the filling area with lanes of tabletop conveyor transporting the bottles. if bottles are intended to go directly to the filling lines, they bypass the iBSS and go directly to the lines. If bottles are to be placed into interim storage, they are picked by Autefa tray loading/unloading robots and placed into metal trays.

These filled trays are stacked vertically, and are then automatically placed into a storage system sized to meet the customer's inventory requirements. When the bottles are needed for downstream processing, the stacks of trays are automatically retrieved and returned to the tray loading/unloading robot systems, where each tray is unloaded and the bottles placed back onto the tabletop conveyor for delivery to the filling lines.

In this operation, bottles are delivered to the iBSS on a series of tabletop conveyors that run parallel to the tray loading/unloading robots. Sensors monitor the flow of bottles and start and stop the conveyors to maintain consistent bottle flow. In the loading/unloading area, a two-axis, pick-and-place robot with custom gripper heads picks up a number of bottles and places them in a stainless steel storage tray. The robot can have one to four gripper heads and will pick up bottles from the corresponding number of parallel conveyors.

40,000 bottles/hr

When a tray is full, it is transferred to the full-tray stack, and the next empty tray is placed for loading. Capacity of a single-robot system depends on the sizes of bottles being handled and the number of grippers installed, but it can go as high as 40,000 bottles/hr for a four-gripper system.

Empty trays are delivered to the loading/unloading area in stacks typically about 15 trays high and the trays are placed in the loading zone one at a time. To accomplish this, the entire stack is raised and the bottom tray is conveyed into the loading zone.

Once the tray is filled, the process is reversed, and the full tray is conveyed onto the full-tray stack. As with the empty trays, this is accomplished by raising the entire stack and conveying the tray into the bottom position. The stack is then lowered onto the bottom tray.

There is no weight placed on the containers inside the trays because each tray is self supported, and the bottles are kept controlled and fixed at all times. The tray stack also has a specially designed top tray that serves as a dust seal. Each tray is identified by a permanently affixed the stacks of empty and filled trays are transported to and from storage by SAT-Carriages that run on a floor-mounted rail system.

When a SAT-Carriage carrying a stack of full trays reaches the assigned storage lane, the stack is lifted slightly and placed on a carriage that carries it into the lane. The procedure is reversed to deliver stacks of bottles back to the loading/unloading robots.

The iBSS incorporates a computerized data management system that controls the data base of stored bottles and trays. Should a bottle quality problem occur, the system can identify, locate and isolate the particular trays or trays of the suspect bottles.

These trays can then be automatically retrieved and staged in a defined area for examination. A customized listing of reports can also be generated to highlight inventory levels, identify segregated quality lots, determine available space left in storage, etc.

System advantages

"Autefa has been a great help throughout the project," says Stark. "They were present for installation and startup, and still provide assistance if we have any problems." The primary goal of the iBSS is cost reduction with a secondary goal of improved quality control.

Savings can be realized in the following categories:

Dunnage: no bags, pallets, tier sheets, top frames, strapping, stretch wrapping or labeling is required.

Capital equipment: the iBBS automatically balances the capacity differences between the blow molders and the fillers so smaller blow molders operating 24 hours, seven days a week can produce enough bottles for filling lines running 12 hours, six days a week. no baggers, debaggers, depalletizers, unscramblers, bins, strappers, stretch wrappers, labelers and fork trucks are required. A capital investment is necessary to purchase the iBSS, but this is a one-time cost and typically has a two to three year payback.

Labor: the iBSS does not require a designated, full-time operator. typically, an existing operator in an area close to the iBSS is assigned to oversee the system should an alarm condition require operator intervention. Typically, the iBSS requires approximately 80 percent less labor compared to a production plant with a traditional bagging/debagging installation.

Quality: there is no damage to the bottle body nor neck. Suspect bottles or production lots can be identified, segregated and controlled, thus preventing sub-quality production from being shipped.

Flexibility: the system provides total flexibility between the blow molders and the filling lines. Any blow molder's production can be diverted to any filling line on short notice.

Perspective: the system is designed to gently handle the containers without causing any storage damage to the container such as scratches or dents.

With the need to reduce bottle weight for further cost reduction, the iBSS is well suited to handle the demands of the future market. "The Autefa system has worked out very well for us," says Stark. "it has really exceeded our expectations. On top of everything else, it has eliminated the bags that we used to store our bottles in, so we don't have the costs of the bags or the environmental concerns."
More information is available:

Autefa Automation - U.S., part of Autefa automation
Gmbh, 843/667-3405. http://www.autefa.de/