For example: Plate thickness S=4mm, width L=3m, σb=450N/mm². Generally slot width V=S*8. Therefore P=650 4² 3/4*8=975 (KN) = 99.5 (Ton) The result is very close to the data in the bending force chart. As you can see, method #1 to calculate the press brake tonnage is based on the mild steel material.