Packaging Machines - Secondary Packaging Technologies, Basics Part 2
Cartoning Machines: Cartons are available in a variety of styles, shapes and sizes. They will generally be of board stock but may sometimes be made from plastic sheet or corrugated. The basic carton is made at the converter by folding a die-cut piece of board into a four-sided tube glued together at the manufacturer's joint. Some packagers running large format, high-speed or high-volume lines may dispense with pre-folded cartons and have their cartons supplied in unglued, die-cut and scored blanks. These flat blanks are much more efficient from a shipping and handling standpoint. On the packaging line, a carton former erects the cartons and delivers them to the cartoning machine (for product loading) as if they had come folded from the converter. There are also cartoning machines available that wrap the carton blank around the product forming the carton in the machine at the point of packaging. Some carton design have flaps on only one end, leaving the other end open, but cartons are usually closed at both ends. Flaps may be either tucked or glued. If tucked, there are three flaps, two minors and a major. The minor Flaps are folded over the carton end. The major flap has a tab that is tucked into the carton as it is folded in. In some instances, a locking tab is die-cut into the body of the carton. This tab is designed to fold over and into a slot on the tucked major flap, this locking tab helps the major flap remain closed on cartons where the flap is long or where the product may try to force the end flap open. Glue cartons are similar except there are two major flaps. After folding the minors, the inner major flap is folded, glue is applied and the outer major flap folded down on top. Another important variation is the automatic bottom carton. These cartons have one end folded and glued closed in a special folded in a format. As the carton is erected, the blank unfolds, forming the carton with finished base automatically. No additional tucking or gluing is required. Automatic bottoms are usually used as an aid to manual erection and packaging but, may occasionally be used with automated cartoners. Automatic bottom cartons may be erected automatically on many standard cartoning machines by moving the gluing and folding guides out of the way or removing them. Vertical and horizontal cartoners (manual product loading) In a vertical cartoner, the carton erecting conveying/loading and closing is performed. A typical vertical cartoner has four chains laid out one above the other between two sprockets on vertical shafts. Attached to each of the chains will be a number of fingers or "lugs," which form pockets. One pair of upper and lower lugs will form the rear or pusher end of the pocket. The lugs mounted on the other pair of chains form the front of the pocket. The cartoner will include some means of manually rotating the chain drive sprockets relative to each other to provide adjust-ability of the pocket length. There will also usually be some means of adjusting the height of the uppermost chain pair. This is necessary to assure that the lugs provide sufficient support at both the top and bottom of the carton. Carton blanks are placed in a horizontal magazine that is perpendicular to the chains. A pusher mechanism provides a constant pressure to keep the cartons at the front of the magazine. This pusher may be spring loaded but system using a weight is generally preferable. When the cartoner cycles, an arm with a vacuum gripper/suction cup swings out and grips the back panel of the carton: that is, the panel which will be at the back of the pocket formed by the lugs. As it pulls the carton out of the magazine, guide pushes against the side panel, forcing the carton open. As the carton moves forward, a guide folds the leading minor flap to a horizontal, closed position. The rear minor flap requires a folding mechanism to push it forward and closed. This folder /pusher may be on a reciprocating arm or it may be mounted on a rotating wheel. A horizontal guide rail under the carton holds the minor flaps closed. The major flap(s) are now either glued or tucked closed. Some products, such as candy pieces, may be packed using the carton as the primary package. Vertical cartoners with automated loading is usually the first choice. These machines may be built with a series of funnels over each lug pocket. A suitable tiller is mounted and discharges into the funnel as the carton passes. The use of the funnel gives the filler a much larger target to hit. Other loading methods may use robots or may convey the product, such as a bottle, over the carton and drop it in. Both, especially the drop method, require a free entry the product to fall correctly. After the carton has been loaded, a similar process to that described for bottom closing is used to close the carton top. Generally a carton with a glued bottom will have a glued top, However as each station is independent of the other, it is possible to build a cartoner to provide a glue bottom and tuck top and some are built this way for special applications. Horizontal Cartoners: Horizontal cartoners may be intermittent or continuous motion. The product is fed via magazine to a pick off station. The horizontal cartoners usually run at higher speeds, so the carton magazine needs to be longer to reduce the need for frequent refilling. Sometimes, to avoid the limitations of pushers, the magazine may use a conveyor to move the cartons to the pick off point. This allows the magazine to as long as necessary while retaining good control of carton pressure. All the pickoff station cartons may be picked out of the magazine by a reciprocating arm or by a continuously rotating assembly. The picker consists of a rotating disk with multiple horizontal arms each with vacuum suction cups. As the disk rotates, the arms counter-rotate on the disk. This allows them to pull the carton out of the magazine, pass them over a pre-breaker bar to begin opening them and then place them into the lug pockets. Some designs have an additional stationary bar with suction cups. As the un-erected cartons are rotated past the stationary bar, the minor panel is gripped momentarily to help open the carton. After the carton is pulled out of the magazine, it is placed in the pocket formed by the chain lugs and conveyed to a loading area. If manual, this may be a shelf or table. More typically is an automatic loading conveyor. This is a conveyor consisting of a series of three-sided pockets that run synchronously and aligned with the carton. Product is loaded into the pockets and, as both travel along the cartoner, a cam-actuated pusher pushes the product from the pocket into the carton. This way, a single product or multiple products can be put into the pack. Placement of the products into the pocket may be manual, automated or combination. A benefit to the pocket and pusher is that if the product and the carton are a tight fit, a funnel can be used to help guide the product in. Pushing rather than dropping the products also keep them grouped correctly. After loading the minor flaps then the major flap(s) are folded and tucked or closed with the glue, the ends are normally closed simultaneously after loading.
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