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 fibreboard applied this same principle to paper when they put arches in the corrugated medium. These arched are known as flutes and when anchored to the linerboard with a starch-based 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 appliedto the side of the board, the space 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 liner board provides additional strength and protects the flutes from damage.
The five most common profiles are the ones illustrated below, but new flute profiles – both larger and smaller than those listed – have been created for more specialized boards. Generally, larger flute profiles deliver greater vertical compression strength and cushioning. Smaller flute profiles provide enhanced structural and graphics capabilities for primary (retail) packaging. Different flute profiles can be combined in one piece of combined board. Mixing flute profiles allows designers to manipulate the compression strength, cushioning strength and total thickness of the combined board.
Source: Fibre Box Handbook