Corrugated Cardboard Sheets
Corrugated fiberboard is a material consisting of a fluted and or liner corrugated sheet and one or two or three flat linerboards. It is made on "flute lamination machines" or "corrugators" and is used in the manufacture of shipping containers and corrugated boxes. Corrugated Sheets are made at the single-facer, it is heated, moistened, and formed into a fluted pattern on geared wheels. This is joined to a flat linerboard with a starch based adhesive to form single face board. At the double-backer, a second flat linerboard is adhered to the other side of the fluted medium to form single wall corrugated board. Linerboards are test liners (recycled paper) or kraft paperboard (of various grades). The liner may be bleached white, mottled white, colored, or preprinted.
Sheet types
3 Ply Sheet
A single-wall box is constructed using three layers of paper that are glued using starch into one single, sturdy sheet. The interior layer, called flutes or waves, play the biggest role in determining the box’s strength. When determining which flute would be suitable for your requirements, there are many factors to be taken into consideration. Each flute has properties which may be better suited to certain packaging requirements over another. Flutes are available in a variety of thicknesses. For example, shorter flutes such as E-flute can withstand crushing much better than the taller fluted boxes (such as C-flute). However, it's also important to understand that the shorter flutes don't absorb shock as well as the taller flutes, higher the flute and diameter determines the strength of the corrugated sheet.
5 Ply Sheet
Double-wall corrugated boxes are constructed with two layers of corrugated cardboard (flutes), with a linerboard facing between them. This 5-ply construction provides added strength and stability. Corrugated cases constructed in double-wall are better suited for heavier weighted or higher value items, which demand a greater strength from the board. The double fluting also adds greater protection, by providing a strong cushioning effect, absorbing any shock which may occur during transit. The greater rigidity provided by double-wall boxes make them the ideal choice for items which require longer term stacking storage.
7 Ply Sheet
7 ply or Triple wall boxes are made up of 7 layers of paper - Three fluting and four liners. The most common type is BCB and AAA (HEAVY DUTY CORRUGATION). Triple-wall corrugated sheets contain three corrugated mediums and four linerboard facings. This 7-ply construction is used where large container sizes are involved, such as pallet packs. Boxes made with Three wall corrugated sheets can hold significantly more weight. Variations between the quality and type of paper, i.e. Kraft 110-180 GSM is ideal for a sturdy and strong box. Such boxes can also further become strong with the use of coated board ranging from 250 GSM to 500 and above which makes it even stronger, durable and water proof.