Crease and stiffness testing of carton board, paper, printing and packaging materials are important measures to have correct and
uniform. As board stiffness and crease recovery (spring back) is important in the performance of cartons on high speed packaging
machines and when manual folding. The value of crease stiffness is technically important in the folding of carton blanks during their erection and closure.
The crease recovery (spring back) can result in forces, which distort the erected carton or cause stresses to be applied to closures, which reduce their effectiveness. Crease recovery is determined by the decrease in resistance offered by creased board after it is folded 90° at the crease measuring the recovery force after 15 secs. Board Stiffness is determined by bending a 50mm length of board through a 15° angle.