Analysis of Mechanical Response during Folding of Creased and Uncreased Paperboard

Creasing and folding of paperboard are two essential operations to obtain a well-defined shape and strength of a package. Relative Crease Strength, RCS, is specified for process control of creasing and folding and is defined as the ratio between the maximal bending force for a crease and uncreased sample bend to the bending angle of 30 degrees at a rate of 5 degrees/sec. Thus, the present work had as objective to evaluate RCS measured in real industrial samples used for process control of creasing and evaluate the influence of paperboard properties and converting processes creasing and folding. As RCS can be measured only after creasing, the study can give directions to paperboard production process control. Creasing measurements were done on both machine direction (MD) and cross machine direction (CD) samples. The paperboard property that showed the highest correlation to RCS was Scott Bond. Based on this one pilot production with lower Scott Bond was evaluated. Lower values of RCS were obtained, as predicted. X-Ray microtomography revealed higher stratification between fiber layers in the paperboard with lower Scott Bond.