Architects have known for thousands of years that an arch with the proper curve is the strongest way to span a given space. The inventors of corrugated fiberboard applied this same principle to paper when they put arches in the corrugated medium. These arches are known as flutes and when anchored to the linerboard with adhesive, they resist bending and pressure from all directions.
When a piece of combined board is placed on its end, the arches form rigid columns, capable of supporting a great deal of weight. When pressure is applied to the side of the board, the space in between the flutes acts as a cushion to protect the container’s contents. The flutes also serve as an insulator, providing some product protection from sudden temperature changes. At the same time, the vertical linerboard provides even more strength and protects the flutes from damage. Flutes come in several standard shapes or flute profiles (A, B, C, E, F, etc.).
Due to variances in flute sizes between manufacturers, there is no longer guidelines for flutes.
In addition to these five most common profiles, new flute profiles—both larger and smaller than those listed here—are being created for more specialized boards. Generally, larger flute profiles deliver greater vertical compression strength and cushioning, while smaller profiles provide better resistance to process and printing crush.