1. Cardboard box manufacturing begins with the stripping of tree bark from trees. Then, the tree bark is made into pulps of wood chips. Then, the small chips are placed in a high pressure tank that will dissolve the substances holding the tree chips together.
2. The small pulps of tree bark will then transform into a fiber-like substance.
3. When the fiber-like substances are cleaned and refined, the fiber-like subsstances are placed in a paper-making machine where the fibers are fused together to make a square-like paper substance. Then, water is removed from the paper after being placed in steam rollers. The liners are then ready for shipping.
4. The rolls of kraft paper are available according to the size that they are manufactured in. These rolls are then transferred into the corrugating plant.
5. At the plant, grades are assigned to the papers which will be used in mediums and liners. The grades can be used to determine the strength of the cardboard boxes to meet the production requirements.
6. The rolls of kraft paper are moved to one end of the corrugator.
7. One roll of medium is loaded to run through the corrugating rolls, and a roll of liner is fed into the corrugator to be joined with the corrugated medium. Liner from another roll travels up over the corrugating rolls along a flat structure called the bridge. This liner will be glued to the corrugated medium later in the process.
8. For a large production run, additional rolls are loaded into automatic splicers. Sensitive detectors check the rolls of paper feeding into the corrugator. When a roll is nearly empty, the corrugator control system starts a splicer, and paper from the new roll is joined to the end of the paper going through the machine. Thus, production of corrugated cardboard is continuous, and no production speed is lost.
9. The medium to be corrugated is fed into the giant, electrically driven rollers of the corrugator, first through the preheating rollers and then into the corrugating rolls. Steam at 175 to 180 pounds of pressure per square inch (psi) is forced through both sets of rollers, and, as the paper passes through them, temperatures reach 350 to 365 degrees Fahrenheit (177 to 185 degrees Celsius).
10. The corrugating rolls are covered with I O flutes —horizontal, parallel ridges like the teeth of massively wide gears. When the hot paper passes between the corrugating rolls, the flutes trap and bend it, forming the middle part of a sheet of corrugated cardboard. Each corrugating machine has interchangeable corrugating rolls featuring different flute sizes. Installing a different A finished piece of corrugated cardboard consists of a single corrugated layer sandwiched between two liner layers. A finished piece of corrugated cardboard consists of a single corrugated layer sandwiched between two liner layers. flute size in the corrugator changes the width of the corrugated medium.
11. The medium travels next to a set of rollers called the single-facer glue station. Here, one layer of liner is glued to the medium. Starch glue is carefully applied to the corrugated edges of the medium, and the first layer of liner is added. From the single-facer, the medium and liner go to the double-backer glue station where the other layer of liner from the bridge is added following the same procedure. Continuing through the corrugator, the cardboard passes over steam-heated plates that cure the glue.
12. At the end of corrugator, a slitter-scorer trims the cardboard and cuts it into large sheets called box blanks. Box blanks pop out of the slitter-scorer like wide slices of toast and slide into an automatic stacker that loads them onto a large, rolling platform. From here, they will be transported to the other machines that will convert them into finished containers. Skilled production workers use a computer terminal and printer to prepare a job ticket for each stack of box blanks produced by the corrugator. With the job ticket, workers can route the stack to the right fabrication machines, called flexos (the name is short for flexographic machine). A flexo is a wide, flat machine that processes box blanks.
13. Printing dies and die-cutting patterns I 3 are prepared in a pattern shop on large, flexible sheets of rubber or tin. The dies and patterns are loaded onto the large rollers in the flexo, and the box blanks are automatically fed through it. As each blank passes through the rollers of the flexo, it is trimmed, printed, cut, scored, and, in a printer-folder-gluer, folded and glued to form a box. From the flexo, the finished boxes are automatically stacked and sent to a banding machine to be wrapped for shipping. Other equipment in a corrugating plant includes stand-alone die-cutters, die-cutters with print stations, and machines known as curtain coaters that apply a wax coating to fruit, vegetable, and meat containers. Box blanks requiring only simple, one-color printing and die-cutting can be run through a stand-alone die-cutter, print station, and curtain coater to produce water- or grease-resistant containers.