The corrugated board can be further subdivided according to the size of the pit pattern on the core paper, namely its height and the number of pits per unit length. There are four types of paper core pits. The following table shows the paperboard produced by Mitsubishi and Langston pit machines.
Carton made from thicker "A" pits has better compressive strength at the top and bottom than "B" and "C", but the "B" and "B" pits have thinner "B" "The pit pattern has superior resistance to pressure. The "A" and "C" pits are used in the manufacture of cartons that are under pressure and packaged with pads. The "B" pit pattern is suitable for carton manufacturing where capacity and space are important, and stacking strength is less important. The "E" pit has the highest compressive resistance, but its shock absorption ability is slightly inferior. It is mainly used on offset (color printing) corrugated boxes that carry heavy objects.