Effect of thickness and hole size The plot average of punch heights (averaged over all choices of % open area) versus thickness are shown in Charts 7-12. Each of these has graphs for the 2 choices of hole size: 4.71 mm and 1.55 mm. These charts do not show any consistent trend of formability with thickness. However it can be seen that the formability of the sheets with 1.55 mm holes is consistently less than that of the specimens with 4.72 mm holes.
