Thermal Effects on Polymer Laminated Steel Formability in Ironing

In the current manufacturing processes for can making, a time consuming and therefore expensive process involves spraying a food-contact safe polymer coating onto the can interior before filling. This process can be eliminated by using a prelaminated metal workpiece as long as the polymer will survive the manufacturing operations involved in can making. The most demanding operation in can making is ironing because of the high pressures involved as well as the necessary generation of new surface. Previous research [5] has demonstrated the feasibility of using a polymer coated steel sheet stock for can making. However, ironing is commonly performed with elevated tooling temperatures which result from friction and plastic deformation in the workpiece. As such, it is possible that the polymer could significantly soften or melt during the ironing process when tooling/workpiece contact is most intimate. In this paper, the thermal effects of hot tooling on polymer coated steel formability are explored through both experiments and mathematical models.