Corrugated cardboard is made using large corrugation machines that are able to create corrugated cardboard at a speed of 500 lineal feet per minute. To create corrugated cardboard, the paper[paper?:paper sample maker cutting machine] is subjected to high pressure steam, which softens the fibers. The fibers are bent to create the required thickness of flute between the corrugated cardboard sheets.
Next, pressure is applied to the top and bottom of the corrugated cardboard to increase the strength of the material. The flat liner boards are brushed with an adhesive on one side and then the corrugated cardboard is sandwiched between the two layers of flat liner board. Corrugated cardboard can be made in different colors, but is most commonly manufactured in brown, white or mottled white.
The thickness of the flute can be modified to create different degrees of strength in the corrugated cardboard. There are 5 standard thickness in the US, indicated by letters A through F. The letter indicates when it was invented, and not the relative size of corrugated cardboard.
Within corrugated cardboard, there are different types of construction, depending on the end product requirements. Suppliers can create single wall, double wall, specific flute sizes, burst strength, edge crush strength and more. Special surface treatments, coatings and coverings can be provided as well.
