DEPTH OF DRAWN SHELL

The maximum depth of a box-type shell, attained in a single drawing pass, may be determined
on the basis of the following variables:
• Type of material and its thickness
• Size of corner radius through the center of stock
• Size of the bottom radius
• Ratio between corner radii and length of straight portions of shortest side
• Width of the flange
• Blank shape and overall size of the shell
• Type of die and press
The size of corner radius is the main factor in determining the depth of a square or rectangular
shell. The distance between the corner radii centers should be at least six times the
value of a corner radius. If such a distance should be smaller than 6R, the
depth of the drawn shell has to be decreased proportionately.
The bottom (bend) radius along the straight sides should be the same size as the corner radius
or larger.
Another way of determining if a given part needs more than one drawing operation is to
build a die for the last drawing station and try it.