How It's Made - Cardboard Boxes

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Cardboard boxes come in a wide variety of sizes shapes and colors but most share three basic structural components. One wavy sheet of paper called a flute, that is sandwiched between two flat sheets called liners. Together they form what's called a corrugated board. Production starts with a massive role of partially recycled paper. The width of the paper varies depending on the size of the boxes their making. Several feeds a machine called the corrugator. The machine presses the paper between two ridged rollers and is blasted with hot steam. This shapes the waves of the flute. Another roller applies glue to one side of the flute. The glues main ingredients are water and starch, which won't contaminate fresh produce the boxes may later contain. Next, the machine adheres one-liner sheet and then the other. The waves create an air cushion between the flute and the liners, strengthening the board. For added strength, some boxes have a double liner. http://www.interplas.com/corrugated-b... Two flutes and three liners. The flutes may vary in thickness for more cushioning. The factory uses partially recycled paper for the flutes because it is more malleable than nonrecycled paper. A razor-thin circular saw trims each side. The corrugator machine then cuts the board up to nine times depending on the size of the box they are producing. The corrugator final function is to separate the boards into layers using flexible tongs called fingers. Workers do a quality control check before sending the boards off for printing. The next machine stacks the boards into piles of between twenty-five and eighty depending on their thickness. This machine also feeds one board at a time to the upcoming equipment. It does at lightning speed at a rate of up to eight thousand boards per hour.

First, the trimmer perforates the boards to create flaps and handles. Rubber sponges cushion the blades so that they only cut the parts they're supposed to. During the trimming, a press condenses the boxes overlapping panels to level out their thickness. Workers usually cut out the sponges by hand to make sure they fit snugly around the blades. The trimmer runs at a speed of eight kilometers per hour. Processing up to ninety boxes a minute. Workers send the cut-offs back to the paper mill to be recycled as many as six times over.

A folding machine now bends them along score lines that the corrugator made earlier. It then applies cold glue to the sections that will join together to form the box. Hot glue on the cardboard is wax coated. The next machine folds over the glued sections. They are invisible once the box is finished. Another machine stacks the boxes in piles. A separator arm moves the boxes to trays called skids, for shipping.

The printing of the boxes began in the factories ink kitchen. Computer-guided dispenser squirts out different shades of ink following a precise recipe to create a particular color one of five thousand in the pallet. One pail holds about twenty kilograms of printing ink. Enough for about two thousand boxes, depending on the coverage needed. The factory uses water-based ink because it dries instantly. The printing press applies the ink to the boards one color group at a time, through four consecutive stations. This factory uses a flexographic printing system. A process that can print drawings and illustrations. Some companies use a lithographic press which can also print photographs.

Back on the trimming line, more complicated types of box flaps and handles require what is called a flatbed trimmer. It holds the boards in place with suction while making intricate perforations. After removing the trimmed bits workers give the boxes one last quality check. Then they stack them and send them off to the warehouse