Investigation on blanking of thin sheet metal using the ductile fracture criterion and its experimental verification

Blanking operation is widely used to cut sheet or plates by a shearing process between punch and die. The process of shearing and the conditions of the sheared surface are influenced by the punch, the die, the speed of punching, the lubrication, the clearance between the punch and the die, and the properties of the workpiece material. This study investigates the blanking operation of very thin sheet metals like membranes, which are used for lithium-polymer battery containers of cellular phones. The punch–die clearance and radius for a given sheet material and thickness are examined, using the finite element technique and Cockroft and Latham’s fracture criterion. This criterion successfully applied to a variety of loading situations, is used in the present investigation to estimate fracture locations during the deformation process. The shearing mechanism is studied by simulating the blanking operation of an aluminum foil and a copper foil. The numerical predictions are compared with the experimental results.