SIG allCap machines
As many as 15,000 drink cartons are sent through the SIG allCap machines every hour.

Most people take it for granted that drink cartons are reclosable, even though that capability has only been possible for the past ten years or so. Plastic pour spouts have made it possible to close drink cartons, which also helps beverages stay fresh longer. Small flip tops or screw caps attached to the carton improve quality and allow drinks to be poured without creating a mess. Research has also shown that consumers greatly value being able to pour the contents smoothly.

Swiss-based SIG Combibloc is one of the world’s leading manufacturers of aseptic cartons and is also a supplier of the corresponding filling machines. Some of the company’s innovations include combiLift and combiTwist. With combiLift, the packaging can be opened by simply pulling up on the flap. With combiTwist, the package can be opened with a single twist of the hand.

Attaching the spout
As many as 15,000 drink cartons pass through the SIG allCap machines every hour, so the repetitive precision of the system is extremely important. The company uses pneumatic components to ensure precise positioning for the pour spouts.

During the packaging process, the container’s spout is attached to the filled and sealed drink cartons in the last step using an applicator. Here, the accurate setting of the spout over the perforation in the carton is extremely important. Depending upon the type of closure, the foil lining is punched through at the appropriate location or else the screw cap would not have a tight seal.

Pneumatics make it work
Gripping mechanisms controlled by Bosch Rexroth pneumatic valves and cylinders place the caps at exactly the right spot. Upon leaving the applicator station, any faulty cartons are discarded immediately. The pneumatic system is especially well-suited for this, since the cylinders always return to the same end position. Specific positioning is not necessary here, as the same force is always applied to the same location. Both compact and miniature cylinders are used, as they can process large quantities with low levels of friction and wear. The pneumatic system operates at a working pressure of 87 psi.

The pneumatic directional control valve manifolds are washdown rated and feature pressure regulation for the individual valves that control the machine’s cylinders. Maintenance units with high flow rates provide clean compressed air in the system and simultaneously keep the necessary operating pressure constant in the machines. All of the pneumatic components in the SIG allCap machines are coordinated with each other, which significantly reduces maintenance expenses for the machines.

According to Sig engineers, “Because of the high performance of the applicator — approximately 15,000 drink cartons/hr — we have short cycles of operation. Pneumatics satisfies this requirement, being inexpensive and uncomplicated. Furthermore, the operation within a rough environment, with water, heat, juice, detergents, has caused no problem.”

Beyond these benefits, the Sig designers noted that there are no special maintenance or pneumatic systems adjustments necessary. This, they explained, was seen as a huge advantage for the pneumatic system.