The fluting separates the liners and gives corrugated board its compression strength and rigidity.  Different flute profiles have different performance characteristics.

 

Flute Form

Flat Crush kPa

Flute height mm

 Relative Compression
F >400 0.7-0.8 70%
E >400 1.1-1.2

80%
B 180 2.1-2.9 100%
C 165 3.5-3.7 110%

F Flute
A very fine flute providing excellent crush resistance, rigidity and an excellent print surface.

E Flute
A fine flute used for smaller cartons offering excellent crush resistance.

B Flute
By far the most widely specified flute profile.  It offers good compression strength whilst having superb crush resistance.

C Flute
A larger flute than 'B' offering greater compression strength but it may be more easily crushed.

Double Wall
A combination of two flute sizes, 'B' and 'C' being the most common.  Double wall is specified when compression strength is of paramount importance.