Effect of mechanical perforation on the press-forming process of paperboard

Press-forming is a process which is used to manufacture three-dimensional containers, such as trays and plates from paperboard. The forming is done from a pre-creased blank which is drawn into shape with a mould set consisting of a punch, die and a blank holder. Due to subsequent processes the air permeability of the formed material sometimes needs to be manipulated. However, such manipulation can in addition influence the mechanical performance of the materials, which has not been previously investigated. Mechanical perforation of multi-layer paperboard tray blanks with different perforation patterns was done to change the air permeability of the material. The air permeability and the tensile strength of the perforated materials were measured to analyse the effect of different patterns. The samples were analysed using a wide area 3D measurement system. After this, the perforated blanks were press formed to investigate the three-dimensional formability and the functionality of the materials in the manufacturing process. The results show a clear impact on the air permeability and the strength of the paperboard in tensile test and forming processes. Based on the results, suggestions for perforation patterns to maximize the functionality of the materials in the manufacturing processes are presented.