The goals of this study were to measure the formability of perforated sheets of stainless steel and aluminum and develop the following relationships:

1. Effect of the open area on Formability

2. Effect of the thickness and hole size on Formability

3. Differences in the formability of materials—aluminum alloys 3003, 5052, and 6061 as well as stainless steel types 304L, 316L, and 409.

NOTE: Tests conducted on Stainless Steel and Aluminum were performed with the straight row of holes running parallel to the punch because it was determined to be the weaker of the two possible orientations during Part I of the study. Therefore, the results of this study are the worse case scenario.

Effect of Thickness and Hole Size

The plots of 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 two choices of hole size: 4.71 mm and 1.5 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.

Material Comparison
The six materials were compared by taking an average formability of all the tests with that material. This average punch height has been compared by means of Chart 13.

It clearly shows that the perforated aluminum sheets have a lower formability than steel sheets. Aluminum, 3003 has the least formability, whereas Stainless Steel 304L has the highest formability.