A special consideration of sheet metal formability is in the application of cold rolled sheet metals in the
production of food and beverage cans. Cold rolling significantly reduces the percent elongation to failure of a sheet
metal, but cold rolling per se may not necessarily hinder complex shape forming provided special incremental
forming methods are used. Thus, for example, heavily cold rolled AA3104 aluminium alloy sheet used in beverage
can making may have a 1-2 percent elongation, yet for the manufacture of a beverage can body it is drawn, redrawn,
wall ironed in stages, and flanged without difficulty, many of these operations could be considered
The principal problem with the conventional tensile test for gauging the formability of sheet metals revolves
around tensile instability, as is especially the case with cold rolled tempers. An early solution to resolving this
A dedicated CBT machine was designed and fabricated at the University of New Hampshire (UNH) for the
evaluation of formability of automotive aluminum alloy sheet and even advanced high strength steels. There are five
components to this device (Fig. 4): 1) a hydraulic cylinder to apply the tension to the specimen, 2) a movable carriage that contains the specimen, hydraulic cylinder and grips, 3) an assembly of 3 rollers, 4) a ball screw to
traverse the carriage (and thus gage length) past the stationary roller assembly to create the CBT process, and 5) a
data acquisition system which collects process parameters, i.e., the axial load on the specimen and the displacement
of the cylinder